Fabrication of electrochromic coatings using green solvents and water-soluble molecular components

Abstract

The present disclosure provides methods for the fabrication of electrochromic films that are soluble in green" solvents, such as water. The resulting electrochromic films are suitable for integration into electrochromic devices and systems. The invention enables scalable, low-toxicity production of electrochromic components with reduced environmental impact, while maintaining functional performance for a range of optoelectronic applications.

Description

FABRICATION OF ELECTROCHROMIC COATINGS USING GREEN SOLVENTS AND WATER-SOLUBLE MOLECULAR COMPONENTSFIELD OF THE INVENTION

[0001] The presently disclosed subject matter relates to the methods of producing electrochromic films using green solvents, their corresponding devices and systems. In particular, methods of fabricating such electrochromic films using green solvents (e.g., water) are presented. Corresponding metal-linkers and metal-coordinated organic complexes are utilized in the green processes presented.BACKGROUND

[0002] The presently disclosed subject matter is directed to the on-surface formation of functional metallo-organic assemblies (MAs) from aqueous solutions. A highly versatile fabrication process was developed to allow the formation of homogeneous, high chromophoredensity coatings on transparent conductive oxides (TCOs) using water-soluble molecular components. 3D coordination networks are formed on TCOs using an aqueous solution of two different divalent iron polypyridyl complexes (1, 2) and an aqueous solution of synthesized palladium complexes (Figures 1A-1B).

[0003] These coatings are deeply colored in their ground state and become transparent upon electrochemical oxidation. In some embodiments color to color transitions are also present. The colorful and uniform assemblies have submicron thicknesses, covering surface areas as large as 36 cm2while having electrochemically addressable iron centers (Fe2+ / 3+). The electrochromic properties of spin-coated assemblies were evaluated in laminated device architectures with optical windows of 2.0 cm x 2.0 cm. These devices exhibit large changes in color intensity between bleached and colored states with ATmax = 39-46% at A,max = 598 nm (gray) or kmax = 579 nm (purple). Furthermore, these low-voltage operable (from -1.2 V to +2.8 V) ECDs were reversibly addressed up to 1000 redox cycles (> 95% stability).

[0004] Iron polypyridyl complexes 1 and 2 have excellent electrochromic properties because of their intense metal-to-ligand charge-transfer (MLCT) bands that bleach upon metal -centered one- electron oxidation. Coordination of the vacant pyridine groups to palladium(II) complex having labile ligands, accompanied by loss of the labile ligands, is known to result in a polymeric coordination network. Complexes 1 and 2 are robust and can easily be prepared in a gram scale. However, the fabrication of these MAs in environmentally benign conditions remains an openquestion due to the insolubility of the complexes in aqueous solution due to the presence of long aliphatic arms.

[0005] Based on the above-mentioned challenges, there has been growing interest in fabricating electrochromic (EC) films using water, green solvents or a combination, nevertheless with limited success. Typically, water-processable EC films are mainly limited to conducting organic polymers. The synthesis of water-soluble organic polymers is a complex phenomenon, as these EC polymers are hydrophobic due to long alkyl side chains and building blocks. To make these polymers water-soluble and promote ionic conductivity with aqueous electrolytes, the polarity of the polymers has been modified to reduce the hydrophobic feature.SUMMARY

[0006] In one embodiment the invention provides a method of producing an electrochromic (EC) film, the method comprising: providing a substrate; depositing at least one metal linker; depositing at least one metal -coordinated organic complex to form an electrochromic (EC) layer; repeating the depositing steps to obtain an EC film disposed on the substrate; wherein the at least one metal linker and / or the at least one metal-coordinated organic complex are comprised within aqueous solutions that comprise: water, green solvents, green resins, or a combination thereof.

[0007] In one embodiment the invention provides a method of producing an EC film, the method comprising: providing a substrate; depositing at least one metal linker; depositing at least one metal -coordinated organic complex to form an electrochromic (EC) layer; repeating the depositing steps to obtain an EC film disposed on the substrate; wherein the at least one metal linker and / or the at least one metal -coordinated organic complex are comprised within solutions that comprise: water, green resins, or a combination thereof.

[0008] In one embodiment the invention provides a method of producing an EC film, the method comprising: providing a substrate;depositing at least one metal linker; depositing at electrochromic molecule to form an electrochromic (EC) layer; repeating the depositing steps to obtain an EC film disposed on the substrate; wherein the at least one metal linker and / or the at least one metal -coordinated organic complex are comprised within solutions that comprise: water, green resins, or a combination thereof.

[0009] In one embodiment the electrochromic molecule is a metal complex. In one embodiment the electrochromic molecule is a metal -coordinated organic complex. In one embodiment, any of the electrochromic molecules are soluble in a green solvent such as water. The counter ion is selected to ensure that the electrochromic molecules are soluble in a green solvent such as water. In one embodiment the counter ion consists of any of the following selected from: Cl", PFe', NCh’ , and SO42'. In one embodiment the counter ion comprises any of the following selected from: Cl; PF6NO3and SO42'.

[0010] In one embodiment the water is selected from: deionized water, ultra-pure water, distilled water, purified water, nanopore water, tap water, desalinated water, filtered water, or a combination thereof. In one embodiment the green solvents are selected from: solvents derived from waste materials, solvents derived from carbohydrates, solvents derived from lipids, deep eutectic solvents, terpenes, ionic liquids, switchable solvents, petrochemical solvents or a combination thereof. In one embodiment the green resins are selected from: acrylonitrile butadiene styrene (ABS), polycarbonate, epoxy, nylon, PETG (polyester derived from glycol and terephthalic acid), lactic-acid (LA) resin, biopolymer and nylon. In one embodiment the EC film is continuous. In one embodiment the method further comprises washing the layer, drying the layer or a combination thereof, after the depositing at least one metal linker, depositing at least one metal-coordinated organic complex, or a combination thereof. In one embodiment the at least one metal-coordinated organic complex comprises at least one functional group, the functional group capable of binding to the at least one metal linker. In one embodiment the binding comprises a coordination bond between the functional group and the metal linker. In one embodiment the at least one metal-coordinated organic complex is a polypyridyl complex. In one embodiment the depositing steps comprise any of the following selected from: roll-to-roll, spin coating, dip coating, spray coating, ultrasonic spray coating, drop casting, blade-coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) and Meyer bar coating or a combination thereof. In one embodiment the ultrasonic spray coating is conducted at an atomization pressure ranging between 0.75 kPa and 1.50 kPa and at a nozzle to substrate distance ranging between 3.0 and 8.0 cm, and at a spraying solution flow rate ranging between 0.4 and0.8 mL / min. In one embodiment the method further comprises the substrate being held at temperature ranging between 40 to 150 °C. In one embodiment the polypyridyl complex comprises one or more isomers of the same compound, or a mixture thereof. In one embodiment the isomers are enantiomers and wherein the polypyridyl complex comprises one or two enantiomers of the same compound or a mixture of the one or two enantiomers. In one embodiment the spin coating step to deposit the at least one metal linker, the at least one metal - coordinated organic complex, or a combination thereof, has a first spin rate and a first spin time. In one embodiment the first spin rate ranges between about 100 to about 2000 rpm. In one embodiment the first spin time ranges between about 0.3 sec to about 60 sec. In one embodiment the spin coating step to deposit the at least one metal linker, the at least one metal -coordinated organic complex, or a combination thereof, further comprises a second spin rate and a second spin time. In one embodiment the second spin rate ranges between about 200 to about 5000 rpm. In one embodiment the second spin time ranges between about 1 second to about 240 seconds. In one embodiment the washing is carried out with any of the following selected from: water, alcohols, ethers, esters, hydrocarbons, ketones, or a combination thereof. In one embodiment both depositing steps are repeated between about 2 to about 80 times. In one embodiment the metal of the at least one metal linker is selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y. In one embodiment the at least one metal linker is selected from NaiPdC , (SOjII-j-Pylp-PdiCl)?.. In one embodiment the at least one metal linker comprises any of the following selected from: 3- pyridinesulfonic acid, 2-pyridinesulfonic acid, 4-pyridinesulfonic acid, 2-pyridinecarboxylic acid; 3 -pyridinecarboxylic acid; 4-pyridinecarboxylic acid; 2-pyridinephosphonate; 3- pyridinephosphonate; 4-pyridinephosphonate.

[0011] In one embodiment the polypyridyl complex is represented by Formula I:whereinM is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh,Os or Ir; n is the formal oxidation state of the transition metal, wherein n is 0-6;X is a counter ion selected from (NCh)' and (SC )2'; m is a number ranging from 0 to 6;Ri to Ris each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2- Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2- Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR20, -COR20, -COOR20, -OCOOR20, - OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2o)2, -NO2, -SR20, -(Ci-C8)alkyl, -O- (Ci-C8)alkyl, -CON(R2o)2, or -SO3H;Ai to Ae each independently is a group of Formula III, z.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula I via R19R19 each independently is selected from a covalent bond, C-C, C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, - Si(R2o)2-, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, -CN, -N(R2o)2, -CON(R2o)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2- Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR20, -COR20, -COOR20, -OCOOR20, - OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2o)2, -NO2, -SR20, -(Ci-C8)alkyl, -O- (Ci-C8)alkyl, -CON(R2o)2, or -SO3H; andR20 each independently is H, (Ci-Ce)alkyl, or aryl.

[0012] In one embodiment the polypyridyl complex is represented by Formula II:wherein n is the formal oxidation state of Fe, wherein n is 0-6;X is a counter ion selected from (NCh)' and (SC )2'; m is a number ranging from 0 to 6;Ri to RI8each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2- Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2- Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR20, -COR20, -COOR20, -OCOOR20, - OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2o)2, -NO2, -SR20, -(Ci-C8)alkyl, -O- (Ci-C8)alkyl, -CON(R2o)2, or -SO3H;Ai, A3, and A5 each independently is a group of Formula III, z.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula II via R19Ri9 each independently is selected from a covalent bond, C-C, cis / tran C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, -Si(R2o)2-, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, -CN, -N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2- Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2- Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, -O- (Ci-C8)alkyl, -CON(R20)2, or -SO3H;Bi to B3 each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2- Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2- Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, -O- (Ci-C8)alkyl, -CON(R20)2, or -SO3H; andR2O each independently is H, (Ci-Ce)alkyl, or aryl.

[0013] In one embodiment the substrate comprises any of the following selected from: glass, doped glass, metal-oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)- coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si( 111), SiO2, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, carbon-based materials, graphene, carbon nanotubes, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic,alumina, electrically-conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminium or any combination thereof.

[0014] In one embodiment the polymer is selected from: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyacrylamide (PAM), polystyrene (PS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate glycol-modified (PETG), polyimide (PI), polyester elastomers, polymethyl methacrylate (PMMA) or any combination thereof.

[0015] In one embodiment the concentration of the at least one metal linker in the corresponding the aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding the aqueous solution ranges between 0.1 mM and 10 mM.

[0016] The method of claim 1 wherein the aqueous solutions further comprise a water- miscible solvent. In one embodiment the water-miscible solvent is selected from: acetaldehyde, acetic acid, acetone, acetonitrile, 1,2-butanediol, 1,3 -butanediol, 1,4-butanediol, 2- butoxyethanol, butyric acid, diethanolamine, diethylenetriamine, dimethoxyethane, dimethylformamide, 1,1 -dimethylhydrazine, 1,2-dimethylhydrazine, dimethyl sulfoxide, 1,4- dioxane, ethanol, ethylamine, ethylene glycol, formic acid, furfuryl alcohol, glycerol, methanol, methyl diethanolamine, methyl isocyanide, N-methyl-2-pyrrolidone, 1-propanol, 1,3- propanediol, 1,5-pentanediol, 2-propanol, propanoic acid, propylene glycol, pyridine, sulfolane, tetrahydrofuran and tri ethylene glycol, or any combination thereof.

[0017] In one embodiment the aqueous solutions further comprise at least one solvent selected from: acetone, ethanol, methanol, 2-propanol, ethyl acetate, ethyl lactate, isopropyl acetate, methyl ethyl ketone, 1 -butanol, tert-butanol, 2-methyltetrahydrofuran, supercritical carbon dioxide (scCCh), dihydrolevoglucosenone, limonene, propylene carbonate, formic acid, gammavalerolactone (GVL) and ionic liquids, or any combination thereof.

[0018] In one embodiment the drying is selected from: stream of air, stream of nitrogen, heating and vacuum drying, or a combination thereof.

[0019] In one embodiment the invention provides an electrochromic device comprising: the substrate and electrochromic (EC) film produced by the methods of the invention; an electrolyte disposed on the EC film; an ion storage layer; and a counter electrode in contact with the ion storage layer; wherein the electrolyte is disposed between the EC film and the ion storage layer.

[0020] In one embodiment the electrolyte is selected from: ACN / PC / PMMA / trifluoromethylsulfonamide lithium salt, polymethyl methacrylate (PMMA), propylene carbonate (PC), LiCFsSCh, LiBF4, Li2+2xZni-xGeO4 (LiSICON), glassy lithium phosphorus oxynitride (LIPON) and LiClCh or any combination thereof. In one embodiment the ion storage layer comprises any of the following selected from: polymers, copolymers, metalorganic polymer, coordination polymer, molecular film, metallic coating, transparent conducting oxides, metal oxides, metal fluorides, metal nitrides, metal sulfides, nanocrystalline metal oxides, mixed metals oxides, redox-active species, carbon-based materials, graphene-based materials, buckminsterfullerenes, nanotubes, 2D materials, biomolecules, nanowires, polymethyl methacrylate (PMMA), benzocyclobutene (BCB) based polymers, poly(3,4- ethylenedioxythiophene), poly(styrenesulfonate), conjugated dithiolenes, polyelectrolytes, organic salts, inorganic salts, quinone-based compounds, viologen-based compounds, antimony- doped tin oxide (ATO), pyridine blue (PB), polyaniline, polypyrrole, lithium cobalt oxide, lithium cobalt oxide, indium tin oxide, fluorine doped tin oxide, niobium oxide, molybdenum oxide, zinc oxides, aluminum oxide, nickel oxides, ceric oxide, metal doped nickel oxides, lithium doped nickel oxides, lithium doped titanium oxides, polymetal oxides, nanoparticles, metallic nanoparticles, nickel hexacyanoferrate, iron hexacyanoferrate, lithium hexacyanoferrate, sodium hexacyanoferrate, manganese hexacyanomanganate, halogen-doped metal oxides, lithium sulfide, lithium garnet, lithium phosphorous oxynitride, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, sodium nickel chloride and activated carbon. In one embodiment the counter electrode comprises any of the following selected from: glass, doped glass, metal-oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si(l l l), SiCh, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically-conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminium or any combination thereof. In one embodiment the EC device further comprises a lamination.

[0021] In one embodiment the invention provides an electrochromic device system comprising: the electrochromic (EC) device of the invention; at least one sensor configured to detect an optical state; a power supply; anda controller configured to control the colored state of the EC device by means of an applied potential; wherein the controller and the power supply are configured to apply a bias potential across the EC film thereby inducing at least one change in the optical state of the EC film and wherein the at least one sensor is configured to communicate the optical state to the controller.

[0022] In one embodiment the EC device system is configured such that the EC device is in a bleached state when a bias potential is applied. In one embodiment the EC device system comprises at least one EC device. In one embodiment the applied potential for the bleached state ranges between 0.1 to 10 V. In one embodiment the at least one sensor is an electro-optic sensor. In one embodiment the at least sensor is selected from: photodetector, photodiode, phototransistor, photomultiplier tube (PMT), spectrophotometer, reflectance spectrometer, transmittance spectrometer, colorimeter, color sensor, UV-vis spectrophotometer, UV sensor, infrared sensor, image sensor, complementary metal-oxide semiconductor (CCD) sensor, charge- coupled device (CCD) sensor, polarimeter, photoluminescence sensor, fluorescence sensor, optical sensor, ammeter, voltmeter, ohmmeter, multimeter, potentiometer, galvanometer, magnetometer, hall effect monitor and light dependent resistor (LDR), or a combination thereof.

[0023] In one embodiment the invention provides a metal-based complex represented by a compound of Formula VIII:whereinA and A' are each independently a nitrogen binding, single or fused, 5-10 membered heteroaromatic ring, or a single or fused, 5-10 membered aromatic ring, which comprises at least one metal binding group, covalently bound to the ring;L and L' are each independently an anionic ligand;M is Pd, Pt, Cu, Zn, Fe, or Ru;LI and LI' are each independently absent, or are metal binding groups, covalently bonded to the A and A' rings respectively, wherein if LI and / or LI' are absent then ring A and / or A' are heteroaromatic; n, m are each independently an integer number between 1-5;W and Ware each independently water soluble groups; andR is linear, branched or cyclic.

[0024] In one embodiment the A and A' are selected from: pyridine, pyrimidine, pyrazine, pyridazine, imidazole, pyrrole, quinoline, oxazole and indole.

[0025] In one embodiment the L and L' are selected from: Cl, Br, I, [NCh]’, [SO4]2', [PO4]3', [PFe]', [BF4]', tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (= BARF), borane anions and [B(R)4]-.

[0026] In one embodiment the W and W' are selected from: SO3H, COOH, PO(OR)2, NHC(O)H, NHC(O)R, NH2, NH(R), N(R)2, C(O)NH2, C(O)NH(R), SO2-NH2, SO2-NH(R), SO2-N(R)2, CN and NO2.

[0027] In one embodiment the R is a selected from a C1-C8 alkyl group.

[0028] In one embodiment the metal -based complex is represented by the structure of FormulaWherein Xi, X2, X3, X4, X5, Xe, X7, Xs, X9 and X10 are each independently a carbon atom or nitrogen atom; wherein at least one of Xi, X2, X3, X4and X5 is carbon; and wherein at least one of Xe, X7, Xs, X9 and X10 is carbon.

[0029] In one embodiment the invention provides a method of producing a (SO3H-3- Py)2Pd(Cl)2solution, the method comprising: reacting an aqueous solution of pyridine-3-sulfonic acid in water with an aqueous solution of palladium (II) chloride, producing a solution comprising (SO3H-3-Py)2Pd(Cl)2.

[0030] In one embodiment the invention provides a method for producing a trans-(SO3H-3- Py)2Pd(Cl)2solution.

[0031] In one embodiment the reacting is carried out between 20 and 100 °C. In one embodiment the reacting is carried out for between 0.5 to 5 hours. In one embodiment method the further comprises filtering the solution comprising (SO3H-3-Py)2Pd(Cl)2. In one embodiment the method further comprises drying the solution to increase the concentration of the solution. In one embodiment the drying is carried out under vacuum.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0033] Figures 1A-1C are schematic illustrations of molecular structures of the electrochromic complexes (Figure 1A showing Complex 1 and Figure IB showing complex 2) and a general schematic of the fabrication of electrochromic molecular assemblies (Figure 1C). Although Figures 1A-1B shows SC2' anions, other anions can be exchanged for these. Other options for anions are referred to as ‘X’ or ‘anion’ throughout (e,g., see Figures 2A-2B).

[0034] Figures 2A-2B show anion dependence of aqueous solubility for the iron(II)- polypyridyl complexes 1 (Figure 2A) and complex 2 (Figure 2B).

[0035] Figures 3A-3B show the fabrication of the electrochromic molecular assembly MAI from water (with Na2PdC14). Figure 3A shows a schematic of the fabrication process (this applies for complex 1 and / or complex 2, for 95% H2O). Figure 3B shows a schematic of the resulting layers of MAI formed by depositing alternating layers of aqueous Na2PdC14 and aqueous solution of complex 1 by spin-coating (n = 26) where transparent conductive oxides (TCOs) on glass were used as substrates.

[0036] Figures 4A-4D show surface characterization of[MAl|FTO / glass 10 Q / n] after 26 deposition cycles for MAI: complex 1 with Na2PdCh. Figure 4A shows ex situ absorption spectra. Figure 4B shows X-ray photoelectron spectroscopy (XPS) spectra showing the Fe2+2p, N Is, and Pd2+3d regions. Figure 4C shows a top view of scanning electron microscopy (SEM) micrograph. Figure 4D shows a cross section of [MAl|FTO / glass 10 Q / n] that was milled by a 30 keV Ga+focused ion beam (FIB), a Pt coating was used to prevent ion beam damage (the surface was first covered with a 3 nm thick layer of iridium).

[0037] Figures 5A-5G show data for molecular assembly, MAI, with Na2PdC14. Figure 5A shows photographs of MAI (2 cm x 2 cm) in the reduced (colored) and oxidized (bleached) states in 0.1M aqueous solution of LiCICh. Figure 5B shows absorption spectra corresponding to consecutive oxidation and reduction cycles of MAI; bare FTO substrates were used for the baseline (black). Figure 5C shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s; the arrows indicate the increase in the current with an increase in the scan rate where the substrate dimension is 2 cm * 1 cm. Figure 5D shows exponential and linear correlations between the peak currents (I) vs scan rates (v) (left) and I vs v1 / 2(right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits). Figure 5E shows SEC measurements of [MAI |FTO / glass] (2 cm x 1 cm) using double potential steps: 0.2 V to 1.4 V at different switching times in 0.1 M LiCIC / EbO electrolyte. Figure 5F shows the dependence of the contrast ratio (AT) on the switching time. Figure 5G shows SEC performance at the start and after 100 cycles for MAI.

[0038] Figures 6A-6B show the fabrication of the electrochromic molecular assembly MA2 from water with Na2PdC14. Figure 6A shows a schematic of an example of the fabrication process (this applies for complex 1 and / or complex 2). Figure 6B shows a schematic of the resulting layers of MA2 formed by depositing alternating layers of aqueous Na2PdCh and aqueous solution of complex 2 by spin-coating (n = 16) where transparent conductive oxides (TCOs) on glass were used as substrates.

[0039] Figures 7A-7D show surface characterization of [MA2|FTO / glasslO Q / n] after 16 deposition cycles, for MA2: complex 2with Na2PdC14. Figure 7A shows ex situ absorption spectra recorded during the formation of MA2 by alternating deposition cycles ofNa2PdC14 and complex 2. A bare FTO substrate was used for the baseline (black); inset: Absorbance intensity ofthe MLCT band (kmax = 598 nm) vs the number of deposition cycles, showing a linear growth behavior. Figure 7B shows X-ray photoelectron spectroscopy (XPS) spectra showing the Fe2+2p, N Is, and Pd2+3d regions. Figures 7C and 7D shows scanning electron microscopy (SEM) images: Figure 7C shows top view and Figure 7D shows a cross section of [MA2|FTO / glass 10 Q / n] that was milled by a 30 keV Ga+focused ion beam (FIB); a Pt coating was used to prevent ion beam damage (the surface was first covered with a 3 nm thick layer of iridium).

[0040] Figures 8A-8G show surface characterization of MA2: complex 2 with Na2PdC14. Figure 8A shows photographs of MA2 (2 cm x 2 cm) in the reduced (colored) and oxidized (bleached) states in 0.1M aqueous solution of LiCICh. Figure 8B shows absorption spectra corresponding to consecutive oxidation and reduction cycles of MA2. Bare FTO substrates were used for the baseline (black). Figure 8C shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s. The arrows indicate the increase in the current with an increase in the scan rate. Substrate dimension: 2 cm x 1 cm. Figure 8D shows exponential and linear correlations between the peak currents (I) vs scan rates (v) (left) and I vs v1 / 2(right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits). Figure 8E shows SEC measurements of [MA2 | FTO / glass] (2 cm x 1 cm) using double potential steps: 0.0 V to 1.5 V at different switching times in 0.1 M LiC104 / H20 electrolyte. Figure 8F shows dependence of the contrast ratio (AT) on the switching time. Figure 8G shows SEC performance at the start and after 2000 cycles for MA2.

[0041] Figures 9A-9C show a scheme for laminated devices from MAI and MA2. Figure 9A shows a schematic representation of the ECD of [MAI and MA2 | FTO / glass], using bare FTO / glass as the counter electrode. FTO / glass is used as substrates for both electrodes, which are separated by a gel electrolyte (LiC104 / PMMA / ACN) and a spacer (double-sided tape). Figure 9B shows photographs of the colored and bleached states (2 cm x 2 cm) for ECD of MA2; 10 layers are in the device and the electrolyte is (LiC104 + PMMA) in ACN. Figure 9C shows photographs of the colored and bleached states (2 cm x 2 cm) for ECD of MAI; 26 layers are in the device and the electrolyte is (LiC104 + PMMA) in ACN.

[0042] Figures 10A-10B show schematic representations of the fabrication of electrochromic molecular assembly MA3 from water (aqueous PdC12(Py-3-SO3H)2). Figure 10A shows steps in the fabrication of electrochromic molecular assembly MA3 (this applies for complex 1 and / or complex 2). Figure 10B shows MA3 which was formed by depositing alternating layers of aqueous PdC12(Py-3-SO3H)2 and aqueous solution of complex 1 by spin-coating (n = 26); transparent conductive oxides (TCOs) on glass was used as substrates.

[0043] Figures 11A-11D show surface characterization of MA3: complex 1 with Pd(Py-3- SO3H)2C12. Surface characterization of [MA3|FTO / glass 10 Q / n] after 26 deposition cycles. Figure 11A shows ex situ absorption spectra recorded during the formation of MA3 by alternating deposition cycles of PdC12(Py-3-SO3H)2 and complex 1. A bare FTO substrate was used for the baseline (black). Inset: Absorbance intensity of the MLCT band (kmax = 579 nm) vs the number of deposition cycles, showing a linear growth behavior. Figure 11B shows X-ray photoelectron spectroscopy (XPS) spectra showing the Fe2+2p, N Is, Cl" 2p, and Pd2+3d regions. Figure 11C and 11D show scanning electron microscopy (SEM) images: Figure 11C shows top view and Figure 11D shows cross section of [MA3|FTO / glass 10 Q / n] that was milled by a 30 keV Ga+focused ion beam (FIB). A Pt coating was used to prevent ion beam damage (the surface was first covered with a 3 nm thick layer of iridium).

[0044] Figures 12A-12G show results for molecular assembly MA3: complex 1 with PdC12(Py-3-SO3H)2. Figure 12A shows photographs of MA3 (2 cm x 2 cm) in the reduced (colored) and oxidized (bleached) states in 0.1M aqueous solution of LiCICh. Figure 12B shows absorption spectra corresponding to consecutive oxidation and reduction cycles of MA3. Bare FTO substrates were used for the baseline (black). Figure 12C shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s. The arrows indicate the increase in the current with an increase in the scan rate. Substrate dimension: 2 cm x 1 cm. Figure 12D shows exponential and linear correlations between the peak currents (I) vs scan rates (v) (left) and I vs v1 / 2(right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits). Figure 12Eshows SEC measurements of [MA3 |FTO / glass] (2 cm * 1 cm) using double potential steps: 0.2 V to 1.4 V at different switching times in 0.1 M LiCICh / FbO electrolyte. Figure 12F shows dependence of the contrast ratio (AT) on the switching time. Figure 12G shows SEC performance at the start and after 1800 cycles for MA3.

[0045] Figures 13A-13B show the fabrication of the electrochromic molecular assembly MA4 from water. Figure 13A shows the one example of steps in the fabrication of the electrochromic molecular assembly MA4 (this applies for complex 1 and / or complex 2, for 95% H2O). Figure 13B shows the MA4 was formed by depositing alternating layers of aqueous PdCh(py-3-SO3H)2 and aqueous solution of complex 2 by spin-coating (n = 16). Transparent conductive oxides (TCOs) on glass were used as substrates.

[0046] Figures 14A-14D show the surface characterization of [MA4|FTO / glasslO Q / n] after 16 deposition cycles. Figure 14A shows ex situ absorption spectra recorded during the formation of MA4by alternating deposition cycles of PdChfPy-S-SChEfhand complex 2. A bare FTO substrate was used for the baseline (black). Inset: Absorbance intensity of the MLCT band (kmax = 600 nm) vs the number of deposition cycles, showing a linear growth behavior. Figure 14A shows X-ray photoelectron spectroscopy (XPS) spectra showing the Fe2+2p, N Is, and Pd2+3d regions. Figure 14C and 14D show scanning electron microscopy (SEM) images: Figure 14C shows top view and Figure 14D shows cross section of [MA4|FTO / glass 10 Q / n] that was milled by a 30 keV Ga+focused ion beam (FIB). A Pt coating was used to prevent ion beam damage (the surface was first covered with a 3 nm thick layer of iridium).

[0047] Figures 15A-15G show results for molecular assembly MA4: complex 2 with Pd(Py- 3-SO3-H)2C12. Figure 15A shows photographs of MA4 (2 cm * 2 cm) in the reduced (colored) and oxidized (bleached) states in 0. IM aqueous solution of LiCICh. Figure 15B shows absorption spectra corresponding to consecutive oxidation and reduction cycles of MA4. Bare FTO substrates were used for the baseline (black). Figure 15C shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s. The arrows indicate the increase in the current with an increase in the scan rate. Substrate dimension: 2 cm * 1 cm. Figure 15D shows exponential and linear correlations between the peak currents (I) vs scan rates (v) (left) and I vs v1 / 2(right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits). Figure 15E shows SEC measurements of [MA4 |FTO / glass] (2 cm x 1 cm) using double potential steps: 0.0 V to 1.5 V at different switching times in 0.1 M LiCICh / EEO electrolyte. Figure 15F shows the dependence of the contrast ratio (AT) on the switching time. Figure 15G shows SEC performance at the start and after 2000 cycles for MA4.

[0048] Figures 16A-16D show ECD performance without the ion storage layer: MA4, complex 2 with Pd(Py-3-SO3H)2C12. Figure 16A shows a schematic representation of the ECD of [MA4 | FTO / glass], using bare FTO / glass as the counter electrode. FTO / glass is used as substrates for both electrodes, which are separated by a gel electrolyte (LiC104 / PMMA / ACN) and a spacer (double-sided tape). Figure 16B shows photographs of the colored and bleached states (2 cm x 2 cm). Figure 16C shows absorption spectra corresponding to consecutive oxidation and reduction cycles. Bare FTO substrates were used for the baseline (black). Figure 16D shows SEC performance using double potential steps: -1.2 V to +2.8 V at zma\ = 595 nm, start and after 1000 cycles.

[0049] Figures 17A-17D show ECD performance without ion storage layer: MA3: complex1 with Pd(Py-3-SO3H)2C12. Figure 17A shows a schematic representation of the ECD of [MA3 | FTO / glass], using bare FTO / glass as the counter electrode. FTO / glass is used as substrates for both electrodes, which are separated by a gel electrolyte (LiC104 / PMMA / ACN) and a spacer (double-sided tape) Figure 17B shows photographs of the colored and bleached states (2 cm x 2 cm). Figure 17C shows absorption spectra corresponding to two consecutive oxidation and reduction cycles. Bare FTO substrates were used for the baseline (black). Figure 17D shows SEC performance using double potential steps: -1.2 V to +2.6 V at zma\ = 570 nm, start and after 850 cycles.

[0050] Figure 18 shows one example of a water soluble linker with trans geometry providing a porous surface assembly for electrolyte mobility.

[0051] Figures 19A-19C show the fabrication of electrochromic molecular assemblies (MAs) by ultrasonic spray coating [MAs|FTO / glass 10 Q / n], The MAs were formed by depositing PdC12(Py-3-SO3H)2 linker and complexes 1 or 2 using two automatic spray guns. Thickness of the film depends on the number of layers. Figure 19A shows photograph of the ultrasonic spray coated electrochromic molecular assemblies MA3 (complex 1 with sulfate anion and PdCEfPy- 3-SO3H)2 linker) on transparent conductive oxides (TCOs) (2 cm x 2 cm), one layer (three passes): [MA3|FTO / glass]. Figure 19B shows a photograph of the ultrasonic spray coated electrochromic molecular assemblies MA3 (complex 1 with sulfate anion and PdC12(Py-3-SO3H)2 linker) on transparent conductive oxides (TCOs) (2 cm x 2 cm), six layers (three passes): [MA3|FTO / glass]. Figure 19C shows photographs of the ultrasonic spray coated electrochromic molecular assemblies MA4 and MA3 having different thicknesses [for the complex 2 (four samples on the left of the dotted line) and the complex 1 (four samples on the right of the dotted line) with sulfate anion and PdC12(Py-3-SO3H)2 linker] on transparent conductive oxides (TCOs) (2 cm x 2 cm), [MA4 and MA3 |FTO / glass]. The upward arrow indicated samples of increasingdecreasing layers. Thus, the samples have the following, from bottom to top: six layers (three passes), four layers (three passes), three layers (three passes), two layers (three passes).

[0052] Figures 20A-20F show results for water soluble spray-coated films for three-arm EC compound. Figure 20A shows photographs of FTO / Glass / [Fe]2+three arms (2 cm x 2 cm) in the reduced (colored) and oxidized (bleached) states in 0.1 M aqueous solution of LiCICh. Figure 20B shows absorption spectra corresponding to two consecutive oxidation and reduction cycles. Figure 20C shows SEC measurements of FTO / Glass / [Fe]2+three arms using double potential steps: 0.0 V to 1.3 V in 0.1 M LiCICU / FEO electrolyte. Figure 20D shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s. The arrows indicate the increase in the current with an increase in the scan rate. Figure 20E shows exponential correlations, and Figure 20F linear correlations, between the peak currents (I) vs scan rates (v) (left) and I vs v1 / 2(right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits).

[0053] Figures 21A-21F show results for water soluble spray-coated films for six-arm EC molecule. Figure 21A shows photographs of FTO / Glass / [Fe]2+six arms (2 cm * 2 cm) in the reduced (colored) and oxidized (bleached) states in 0.1M aqueous solution of LiCICE. Figure 21B shows absorption spectra corresponding to two consecutive oxidation and reduction cycles. Figure 21C shows SEC measurements of FTO / glass / [Fe]2+six arms using double potential steps: 0.2 V to 1.3 V in 0.1 M LiCICU / FEO electrolyte. Figure 21D shows cyclic voltammograms (CVs) with scan rates of 0.05-0.9 V / s. The arrows indicate the increase in the current with an increase in the scan rate. Figure 21E shows exponential correlation, and Figure 21F shows linear correlation, between the peak currents (I) vs scan rates (v) (left) and I vs vi / 2 (right), respectively, during oxidation (top) and reduction (bottom) (R2> 0.99 for all fits).

[0054] Figures 22A-22D show TEM-EDS of spray coated Fe “six arms” on FTO / Glass with High-Angle Annular Dark-Field (HAADF) imaging. Figure 22A shows Fe and Sn components. Figure 22B shows the Fe component of the EC compound. Figure 22C shows the S component of the linker+anion. Figure 22D shows the Pd component of the linker+anion.

[0055] Figures 23A-23F show structures of water soluble complexes. Fig. 23A shows the Fe- 3arms-Cl structure. Fig. 23B shows the Ru-3arms-Cl structure. Fig. 23C shows the Fe-6arms- DB-C1 structure (“DB” = double bond). Fig. 23D shows the Fe-6arms-SB-Cl structure (“SB” = single bond). Fig. 23E shows the OS-3arms-Cl structure. Fig. 23F shows the Fe-6arms-TB-Cl structure (“TB” = triple bond).

[0056] Figure 24A shows an initial photo of the various vials containing 1 mg of complexes of Figures 23A-23F in lOmL of water. Figure 24B shows the same vials but after 2 hrs, demonstrating a solubility check.

[0057] Figure 25A demonstrates the synthesis of the Fe-3arms-Cl complex. Figure 25B demonstrates the synthesis of the Ru-3arms-Cl complex. Figure 25C demonstrates the synthesis of the Os-3arms-Cl complex. Figure 25D demonstrates the synthesis of the Fe-6arms-SB-Cl complex. Figure 25E demonstrates the synthesis of the Fe-6arms-DB-Cl complex. Figure 25F demonstrates the synthesis of the Fe-6arms-TB-Cl complex.

[0058] Figures 26A-26D shows the solubility of various complex in different solutions.

[0059] Figure 27A shows a solubility test for the Fe-3arms-Cl complex in water, methanol, ethanol, and 1-butanol. Figure 27B shows a solubility test for the Fe-3arms-PFe complex in water, methanol, ethanol, and 1-butanol.

[0060] For simplicity and clarity of illustration, elements shown in the figures are not necessarily drawn to scale, and the dimensions of some elements may be exaggerated relative to other elements. In addition, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.DETAILED DESCRIPTION

[0061] In the presently disclosed subject matter, a strategy is provided, with iron polypyridyl complexes (1 and 2) with different counter anions, that possess superior solution processability in eco-friendly solvents such as water, or methanol. In one embodiment the eco-friendly solvent is water and / or methanol. Two water-soluble, iron complexes have been synthesized using nitrate (NOT) and sulfate (SCU2') as counter anions (Figures 2A-2B). In some embodiments MAs were prepared by layer-by-layer deposition of aqueous solutions of polypyridyl iron complex (1 or 2) and palladium salt using spin-coating (Figure 1C). The formed MAs are colored, purple (MAI) and grey (MA2) in the ground state.

[0062] One electron electrochemical oxidation of iron complex (II) gives a transparent state due to unfavorable metal -to-ligand charge transfer (MLCT) in the formed iron (III) complex. The present disclosure also shows the effect of the coordinating linker (= cross-linker) on electrochromic properties. The variations in palladium cross linker structure (PdCU2' or [(Pd(Py- 3-SO3H)2C12]) leading to diversification in spectroelectrochemical (SEC) properties (cycling stability, response time, etc.) in films and laminated devices. The diversifications in SEC properties might be due to different molecular arrangement within MAs. The coloration efficiencies up to 258 cm2 / C, ECDs switching stabilities up to — 1000 cycles, and high optical contrast (up to 47%) with relatively low response times (0.8-1.05 s).

[0063] Two different types of water soluble Pd(II) linkers are presented: one is commercially available Na2PdCU, and another one is Pd(Py-3-SO3H)2Ch. These two Pd(II) linkers provide significant effects on the ECDs performance. Electrochromic molecular assemblies were formed by depositing alternating layers of an aqueous solution of Pd-linkers and complexes 1-2 by spincoating (n = 16-26). Fluorine-doped transparent conductive oxides (FTO) on glass were used as substrates. These commercially available doped metal oxides were supported on glass substrates (2 cm x 2 cm). The principle of using a water-soluble linker can be extended to any other water- soluble linker that are not specifically these two linkers.

[0064] As aqueous solution of Pd(II) linker (1.0 mM) is first drop-casted onto a freshly cleaned and activated FTO substrate that was subsequently spun at 500 rpm for 10 s and then at 1000 rpm for 60 s. Metal-complex (1 and 2) deposition step on the TCO is crucial. In one example, complexes (1-2) are directly spin coated on FTO. It is noted that d8palladium centers can bind through the surface hydroxyl groups onto the metal-oxide substrate to form a dense layer. This layer can be used for successive binding of the polypyridyl complexes 1 and 2. Excess palladium on the surface is likely to induce immediate cross-linking of the polypyridyl complexes. A total four number of MAs (MA1-MA4) were formed: MAI an MA2 were formed using aqueous solution of Na2PdCh with complex 1 and 2, respectively (Figures 3 A and 6A), whereas MA3 and MA4 were formed using aqueous solution of Pd(Py-3-SO3H)2C12 with complex 1 and 2, respectively (Figures 10A-10B and 13A-13B).

[0065] All the MAs (MA1-MA4) were characterized in detail by scanning electron microscopy (SEM), focused ion beam (FIB)-SEM, angle-resolved X-ray photoelectron spectroscopy (XPS), transmission UV-vis spectroscopy, electrochemistry, and spectroelectrochemistry (SEC) (Figures 4A-4B, 7A-7B, 11A-11B and 14A-14B). The homogeneity and continuity of the grainy surfaces of [MAl-MA4|FTO / glass], were illustrated at the microscale by SEM measurements (Figures 4C-4D, 7C-7D, 11C-11D, 14C-14D). Information about the thickness and inner structure of the MAs was obtained by FIB measurements. SEM measurements of a cross section of [MAl-MA4|FTO / glass] was obtained by milling with a focused ion beam (FIB). Prior to this milling process, the region of the cross section was locally coated with a layer (0.6-0.8 z / m) of Pt to prevent damage caused by the ionbeam bombardment of MA1-MA4. The SEM image of the cross section shows the glass support, FTO, MAs, and the Pt layer. The top view shows the grainy nature of MA1-MA4 (Figures 4c, 7c, 11c, 14c) The thickness of the metallo-organic assembly was found to be 245-295 nm (depends on the number of deposition layers), which was much higher than the interfacial roughness of [MAs|FTO / glass], No defects were observed.

[0066] X-ray photoelectron spectroscopy (XPS) data for [MAl-MA4|FTO / glass], confirmed the presence of the divalent iron complex 1 or 2, as judged by the two peaks of the 2p orbitals of Fe2+at 710 eV (2p3 / 2) and 725 eV (2pi / 2). Two distinctive peaks of the 3d orbitals of Pd(II) are observed at 337 eV (3ds / 2) and 345 eV (3ds / 2) (Figures 4b, 7b, 11b, 14b). The MAs are formed with retention of the metal oxidation states of the starting materials. The Nissignal is observed at 402 eV. The Pd / Fe ratio was found to be ~3.6-3.7 (MA2-MA4) and -1.7-1.8 (MA1-MA3) The expected Pd / Fe ratios are 3 (MA2 and MA4) and 1.5 (MAI and MA3) for a fully formed network, where the palladium centers are bound by two pyridine groups (i.e., py'-Pd-py"). This suggests that the MAs contain an excess of the palladium salt or are not fully cross-linked.

[0067] The UV-vis spectra of MA1-MA4 show the characteristic metal-to-ligand chargetransfer (MLCT) bands, at kmaxi = 455 nm and kma\2 = 598 nm for MA2 and MA4, and at kmax = 579 nm for MAI and MA3. An intense 7t-7t* transition band is also present at kmax - 330 nm, which is due to the presence of TI stacked ligand structures in the complexes. Assuming that the absorption coefficients of complexes 1 (a = 2.2 * 104L mol-1cm-1) and 2 (a = 3.6 x 104L mol-1cm-1) are similar to their coefficients as thin films, the molecular densities are calculated as — 1.76 x 1016molecules / cm2(MAI), — 1.85x l016molecules / cm2(MA2), — 8.75x l015molecules / cm2(MA3), and — 10.3x 1015molecules / cm2(MA4).

[0068] The electrochemical and SEC properties of MAI- MA4 assembled on FTO / glass were assessed using a three-electrode cell configuration consisting of the coated TCOs as the working electrode and the Pt and Ag / Ag+wires as the counter and quasi-reference electrodes, respectively. Aqueous solution of LiCICU (0.1M) was used as the electrolyte solution. The colour changes of the MAs, upon oxidation and reduction of the iron complexes, are clearly visible to the naked eye, as shown in the photographs (Figures 5A, 8A, 12A, 15A). MAI and MA3 are purple in colour whereas MA2 and MA4 are grey in the ground state, respectively, and transparent when oxidized. The cyclic voltammograms (CVs) of MA1-MA4 show reversible one-electron redox processes as expected for the Fe2+ / 3+couple with half-wave potentials E1 / 2) of 0.607V for [MAl|FTO / glass], 0.723V [MA2|FTO / glass], 0.720V [MA3|FTO / glass], 0.668V [MA4|FTO / glass] (Figures 5C, 8C, 12C, 15C). The molecular densities were found to be - 1.05x l016molecules / cm2for [MAl|FTO / glass], ~1.21 x l016molecules / cm2[MA2|FTO / glass], - 7.25 x lO15molecules / cm2[MA3|FTO / glass], and 9.15x l015molecules / cm2[MA4|FTO / glass], These values are in good agreement with the values derived from the UV-vis data (vide supra). The UV-vis spectra show the decrease in the MLCT band upon one-electron oxidation of Fe2+(Figures 5B, 8B, 12B, 15B) SEC measurements showed that the maximum AT% lies between39% to 47% for MA1-MA4. MA2, MA3 and MA4 shows >95% retention of the initial AT% for ~ 2000 cycles. For MAI >95% retention of the initial AT% is possible for at least 100 cycles only.

[0069] Diffusion of the electrolyte plays a key role in the electron transfer processes, as can be seen by varying the scan rate (v) from 0.05 to 0.9 V / s (Figure 5C-5D, Figure 8C-8D, Figure 12C-12D, Figure 15C-15D)

[0070] The anodic and cathodic peak currents (Ipaand Ipc) versus v and V7 / 2 show an exponential and linear correlation, respectively (Figures 5D, 8D, 12D, 15D). Such electrochemical properties are expected for electron transfer processes, which are limited by the diffusion of the electrolyte. The calculated diffusion coefficient (Df) for counter ion diffusion associated with the oxidation and reduction processes for [MA1-MA4 |FTO / glass] lies between 1.17* 10'9cm2 / sec to 2.35>< 10'9cm2 / sec (see Table 2). The differences in these Df values might imply that the molecular packing of the structurally different complexes (1, 2) with different Pd(II) linkers affects the diffusion of anions in aqueous LiCICh solution.

[0071] The effectiveness of the water processable MAs coating and the function of the assemblies are further demonstrated by the excellent performances of the corresponding laminated ECDs. For fabrication of laminated ECDs, [MAl-MA4|FTO / glass], were used as working electrodes. An example of these successful switching devices with the MA3-MA4 having an active surface area of 1.7 cm * 1.3 cm is shown in Figures 16A-16D and 17A-17D. Examples of lamination materials include, but not limited to: polyethylene terephthalate (PET), indium tin oxide (ITO) coated PET, polyethylene naphthalate (PEN), polymer electrolyte membranes (PEM), polyvinyl butyral (PVB), glass, epoxy resins, polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylics (PMMA), silicone rubber, fluoropolymers (e.g., PTFE, FEP), etc.

[0072] Here, it is shown that the geometry of the Pd(II) linker plays a key role on the switching performance of the ECDs (vide infra). For commercially available Na2PdCh linker, all the labile chlorine atoms are cis- to each other’s, which results a very compact and dense molecular assembly formation with complex 1 and 2, that cannot be freely penetrated by the electrolyte under ECD’s condition, hence resulted into poor or no switching of MAI and MA2 based devices. MA2 with higher number of binding pyridine groups are expected to form more dense assembly than MAI, hence no switching takes place (Figure 9B). Thus, the present invention provides a design and synthesis of a water soluble Pd(II) linker with trans geometry with respect to the labile groups. Therefore, the resulting water soluble Pd(Py-3-SO3H)2Ch linker (Scheme 3) has been synthesized and characterized, where the leaving groups are trans to each other. Suchgeometry provides a better void in the molecular assembly on surface and allow to penetrate the electrolyte successfully under ECDs conditions. Our assumption proves to be correct after successful switching of MA3 an MA4 with significant stability (Figure 16 and 17). This setup consisted of (z) [MA|FTO / glass] as the working electrode (bottom), (zz) FTO / glass as the counter and reference electrodes (top), (iii) a poly(methyl methacrylate)- (PMMA-) based gel electrolyte, and (iv) double-sided tape (3M 9088) as an insulating spacer (Figure 16A and 17A). The electrochromic properties of the devices are evident from the absorption spectra (Figure 16C and 17C) and clearly visible to the naked eye (Figure 16B and 17B). EC switching between the coloured and transmissive states was observed using potential steps of -1.8 to +2.8 V with a pulse width of 8 s. Photographs of the ECDs (MA4 and MA3 with Pd Py-S-SChEfhCh demonstrate the consistency of the change in the colour intensity upon 1000 redox cycles for MA4 and 850 cycles for MA3 (Figure 16D and 17D).UV-vis measurements of this device clearly show the reversible intensity changes in the characteristic MLCT band at +ma\ = 595 nm for MA4 and +ma\ = 570 nm for MA3.

[0073] The water processable high-quality coatings were used for device fabrication, as exemplified here by demonstrating two ECDs. For the assemblies, no other processing steps (e.g., preassembly in solution, thermal curing) are needed to acquire the desired redox and electrochemical activities. The thermally robust assemblies readily allow device integration in air. No strictly inert glovebox environment is required. 3D molecular assemblies were fabricated using water soluble molecular building blocks. Water soluble Pd(II) linker are synthesized and prove the importance of linker composition in device switching and stability.Methods of producing electrochromic films with water, green solvents or a combination thereof

[0074] A general method is now described which incorporates the use of water, green solvents, or a combination thereof, required for the production of electrochromic films.

[0075] As understood herein, “green solvents” are solvents that are environmentally friendly and / or sustainable solvents. In some embodiments “green solvents” also include “green resins”. “Green resins” are resins derived from renewable resources, often plant-based, with reduced environmental impact compared to traditional petroleum-based resins. In various embodiments the green solvents and / or green resins are comprised within ink and / or spray-coating solutions for use in printing and / or producing films. Examples of resins include: photopolymer, thermoplastic, UV-curable, epoxy, acrylic, polyester, polymer, etc. In some embodiments the resin comprises any of the following selected from: acrylonitrile butadiene styrene (ABS),polycarbonate, epoxy, nylon, PETG (polyester derived from glycol and terephthalic acid), lactic- acid (LA) resin, biopolymer and nylon. Other examples include biopolymer resins, such as polylactic acid (PLA) and polyhydroxyalkanoates (PHA), which are derived from renewable resources like corn starch, sugarcane, or vegetable oils. These resins are biodegradable and have low VOC emissions, making them suitable for environmentally friendly printing applications. Lactic-acid (LA) based resins are a biodegradable plastic made from renewable resources: sugarcane, com starch, and the roots of tapioca. These green solvents are typically characterized by their low toxicity, renewable sourcing, and biodegradability, amongst other characteristics. For example, the use of green solvents aims to minimize the environmental impact and contribute sustainable practices in chemical processes for a variety of industrial applications. In some embodiments, “green solvents” are any solvents that reduce the carbon footprint of a process. In some embodiments “green solvents” are also understood as any solvent that are environmentally sustainable. For example, sustainability is understood in the sense that pollution is minimized by using green solvents and / or natural resources are managed more effectively and / or efficiently. For example, replacing one conventional solvent with a different solvent within a process thereby improving a measure of sustainability and / or a measure of environment is considered a green solvent. In various embodiments water is a green solvent. In some embodiments green solvents comprise water. In some embodiments the green solvent consists of water.

[0076] In some embodiments solvents green solvents are selected from: waste materials, solvents derived from carbohydrates, solvents derived from lipids, deep eutectic solvents, terpenes, ionic liquids, switchable solvents, petrochemical solvents or a combination thereof.

[0077] In some embodiments the solvents derived from waste materials are selected from: renewable diesel, bio-based solvents, waste cooking oil-based solvents, terpenes from citrus waste, ethanol from agricultural waste, acetone from biomass, glycerol-based solvents from biodiesel production, furfural-based solvents, 2-methyltetrahydrofuran, recycled solvent blends or any combination thereof.

[0078] In some embodiments the solvents derived from carbohydrates are selected from: ethyl lactate, ethyl acetate, methyl lactate, isopropyl alcohol, acetone, butanol, glycerol, methanol, ethanol, propanediol or any combination thereof.

[0079] In some embodiments the solvents derived from lipids are selected from: esters, methyl esters, fatty acid methyl esters (FAME), glycerides, triglycerides, glycerol-based solvents, fatty alcohols or any combination thereof.

[0080] In some embodiments the deep eutectic solvents are selected from: urea, glycerol, ethylene glycol, malonic acid, acetic acid, lactic acid, oxalic acid, succinic acid, choline chloride, levulinic acid or any combination thereof.

[0081] In various embodiments at least one of the solutions used for the production of the electrochromic films disclosed herein comprises water, green solvents or a combination thereof. In some embodiments at least two separate aqueous solutions comprise water, green solvents, or a combination thereof, for the production of electrochromic films. For example, metal- coordinated organic complexes are typically used as the EC material, the solution within which it is dissolved can comprise: water, green solvents, or a combination thereof. Otherwise, the linker solution can comprise: water, green solvents, or a combination thereof. Furthermore, for multi-layers of different metal-based EC layers, some of the metals may be water based whereas others aren’t.

[0082] As defined herein, in metal -coordinated organic complex, a metal ion is coordinately bonded to at least one organic molecule (a ligand). In some embodiments, the metal -coordinated organic complex is referred to in short as “metal-complex”.

[0083] The processes of producing electrochromic films will now be disclosed. In one embodiment the invention provides a method of producing an electrochromic film, the method comprising: providing a substrate; depositing at least one metal linker; depositing at least one metal -coordinated organic complex to form an electrochromic (EC) layer; repeating the depositing steps to obtain an electrochromic film disposed on the substrate; wherein the at least one metal linker and / or the at least one metal -coordinated organic complex are comprised within aqueous solutions that comprise: water, green solvents or a combination thereof.

[0084] In one embodiment only the at least one metal-coordinated organic complex comprises water, green solvents or a combination thereof. In one embodiment only the at least one metal linker comprises: water, green solvents or a combination thereof. When EC multi-layers of different metals are produced in a stack, at least one of the aqueous solutions comprising the at least one metal-coordinated organic complex comprises: water, green solvents or a combination thereof. In one embodiment the green solvent is water.

[0085] In some embodiments the water comprises deionized water. In one embodiment the water comprises ultra-pure water (UPW). In one embodiment the water comprises distilled water. In one embodiment the water is selected from: deionized water, ultra-pure water, distilled water, purified water, nanopore water, tap water, desalinated water, filtered water, or a combination thereof. The various options for ‘water’ as detailed herein applies equally for water comprised within aqueous solutions (e.g., for aqueous solutions comprising at least one metal-coordinated organic complex, linkers, etc) and / or for water used for cleaning / washing purposes.

[0086] In one embodiment the at least one metal linker and / or the at least one metal- coordinated organic complex are comprised within aqueous solutions that comprises water. In one embodiment the at least one metal linker and / or the at least one metal-coordinated organic complex are comprised within aqueous solutions that comprises green solvents.

[0087] The steps for depositing at least one metal linker and / or the at least one metal- coordinated organic complex result in a continuous film. In one embodiment, “continuous” is understood as being continuous throughout the thickness of the EC layer / film (i.e., in the z-axis). In another embodiment “continuous” refers to continuity of the EC layer / film across the substrate. The continuous film is characterized in that the linker and metal-coordinated organic complex materials are interspersed throughout the film. Such a continuous film comprises a 3D network, as described herein. Within such a 3D network ions are able to move. When multilayers comprising different metal-based EC complexes are made, each metal-based layer comprises a 3D network of its own, each with its own interspersion of its linker and metal -based EC complex materials. In some embodiments the linker is the same for any of the metal -based EC complex layers. In some embodiments the linker molecule for each of the metal-based EC complex layers is different for at least one other metal-based EC complex layer. In various embodiments the continuous film is characterized by at least one of the following: its uniform thickness, smooth surface, minimal defects and / or discontinuities. The coverage of a continuous film is such that the continuous film forms a complete cover on the layer onto which it is deposited. Therefore, in one embodiment, the continuous film is continuous across the layer onto which it is deposited (e.g., the substrate) and / or also continuous throughout the thickness of the film itself.

[0088] In various embodiments the method further comprises washing the layer, drying the layer or a combination thereof, after the depositing of at least one metal linker, depositing at least one metal-coordinated organic complex, or a combination thereof. As used herein “cleaning” and “washing” are understood interchangeably. The washing and / or drying steps can be carried out in between each deposition as well as at the end of the entire deposition process.

[0089] In some embodiments the drying is selected from: stream of air, stream of nitrogen, heating and vacuum drying, or a combination thereof. In various embodiments the substrate is heated during the deposition of any one of the layers. Thus heating can be a post-deposition process or during the deposition process. In some embodiments the heating is carried out between 30 - 200 °C. In some embodiments the heating is carried out between 30 - 100 °C. In some embodiments the heating is carried out between 50 - 100 °C. In some embodiments the heating is carried out between 80 - 100 °C. In some embodiments the heating is carried out between 80 - 150 °C. In one embodiment the process is carried out at room temperature.

[0090] In one embodiment the metal -coordinated organic complex comprises at least one functional group, the functional group capable of binding to the at least one metal linker. In one embodiment the binding comprises a coordination bond between the functional group and the at least one metal linker. In various embodiments the terms “linker” and “metal linker” are understood interchangeably. In one embodiment the metal-coordinated organic complexis a polypyridyl complex. Furthermore, in various embodiments “metal linker” and “at least one metal linker” can be used interchangeably. This is because the principle of a single metal linker layer can be extended to any number of different types of metal linkers. Correspondingly, in various embodiments the “metal -coordinated organic complex” and “at least metal -coordinated organic complex” can be used interchangeably. This is because the principle of a single metal- coordinated organic complex layer can be extended to any number of different types of metal- coordinated organic complex layers.

[0091] The metal linker and the metal -coordinated organic complex material can be applied in any number of ways. In some embodiments the application of the metal linker and the metal - coordinated organic complex are the same, and in other embodiments they are different. Different layers that require different materials (e.g., different linkers, or different metal-bases for the metal-coordinated organic complex) require a particular application or deposition type. As understood herein “depositing” refers to method of making a layer and can be understood interchangeably with “applying”. In one embodiment the depositing steps comprise any of the following selected from: roll-to-roll, spin coating, dip coating, spray coating, ultrasonic coating, drop casting, blade-coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) and Meyer bar coating or a combination thereof.

[0092] As understood herein, spray-coating and / or ultrasonic spray coating of the invention can be used for printing purposes. In various applications described herein, “spray coating” and “ultrasonic spray coating” are used interchangeably. Furthermore, spray coating can be used in various printing applications, such as screen printing, inkjet printing, and even 3D printing, toapply coatings, inks, or other materials onto the printing substrate. The spray coating methods of the present application are thus used for printing, in various embodiments.

[0093] In various embodiments, spray coating of water-based aqueous solutions comprising metal linkers and / or metal -coordinated organic complexes requires heating. In one embodiment the substrate is heated to between 50 to 100 °C. In one embodiment the substrate is heated to between 60 to 90 °C. In one embodiment the substrate is heated to between 80 to 90 °C. The sample stage height can be adjusted for spray coating to control the deposition height. In one embodiment the sample to spray-coating nozzle distance ranges between 1 to 10 cm. In one embodiment the sample to spray-coating nozzle distance is about 5 cm.

[0094] In one embodiment the metal linker, the organic complex, or a combination thereof, is carried out by spray coating In one embodiment, the spray coating steps for applying the metal linker and the metal-organic complex are conducted at atomization pressure ranging between 0.5 kPa and 2.00 kPa. In one embodiment, the spray coating steps for applying the metal linker and the organic complex are conducted at atomization pressure ranging between 0.75 kPa and 1.50 kPa.

[0095] In one embodiment, the spray coating steps for applying the metal linker and the metalorganic complex are conducted at a nozzle to substrate distance ranging between 2.0 and 10.0 cm. In one embodiment, the spray coating steps for applying the metal linker and the metalorganic complex are conducted at a nozzle to substrate distance ranging between 4.0 and 8.0 cm.

[0096] In one embodiment, the spray coating steps for applying the metal linker and the metalorganic complex are conducted at a spraying solution flow rate ranging between 0.4 and 0.8 mL / min. In one embodiment the spray coating is carried out at room temperature. In one embodiment the spray coating is carried out with the substrate at room temperature. In one embodiment the spray coating is carried out at an elevated temperature. The elevated temperature ranges between 50 to 200 °C. In one embodiment the elevated temperature ranges between 40 to 150 °C. In one embodiment the elevated temperature ranges between 50 to 100 °C. Any combination of the above-mentioned parameters is included in embodiments of this invention.

[0097] In one embodiment, spraying is conducted such that the spraying nozzle is moved parallel to the substrate in a pattern along the X-Y substrate directions at a speed ranging between 3 and 7 mm / s. In one embodiment, spraying is conducted such that the spraying nozzle is moved parallel to the substrate in a pattern along the X-Y substrate directions at a speed ranging between 1 and 10 mm / s X-Y substrate directions are the substrate directions parallel to the sprayed surface.

[0098] Other spraying parameters and other combinations of spraying parameters are possible and are compatible with embodiments of this invention as known to a person of ordinary skill in the art. Spraying parameters can be modified to fit a certain spraying apparatus. Different spraying apparatuses can be used in embodiments of this invention. Spraying parameters can be modified to fit certain spraying solution contents and spraying solution concentrations.

[0099] In one embodiment, the number of passes (spray passes) ranges between 1 and 5 or between 1 and 10 or between 2 and 7 or between 1 and 20. “Pass” means a spray event. For example, 3 spray passes refer to a substrate that was sprayed 3 consecutive times with a solution of a certain compound.[000100] Each complete spray-deposition of a linker and a complex provides one deposition cycle. Repetition means how many deposition cycles have been performed. For example, 3 repetitions mean 3 layers of (linker + complex).[000101] In one embodiment, the number of repetitions ranges between 1 and 5 or between 1 and 10 or between 2 and 7 or between 1 and 20 or between 1 and 100 or between 1 and 1000 or between 1 and 10,000. Any number of repetitions is possible in embodiments of this invention. [000102] In one embodiment, the spraying is conducted such that the spraying nozzle is moved parallel to the substrate in a pattern along the X-Y substrate directions at a speed ranging between 3 and 7 mm / s.[000103] The pattern of a pass can also be modified as required (e.g. left-right, zigzag, circular, oval, spiral) or any other pattern that will cover the surface in an efficient manner. Nozzle speed can also be changed according to some embodiments. In some embodiments, the nozzle is moved, and the substrate is stationary. In another embodiment, the nozzle is stationary, and the substrate is moved.[000104] In one embodiment, the concentration of said linker in said solution and / or the concentration of said metal-coordinated organic complex in the solution used for spraydepositing is ranging between 1 mM to 50 mM, or between 1 mM and 12 mM, or between 1 mM and 100 mM, or between 0.1 mM and 100 mM, or between 1 mM and 10 mM, or between 10 mM and 40 mM, or between 0.01 mM and 10 mM, or between 0.001 mM and 500 mM. In one embodiment, the concentration of said linker in said solution and / or the concentration of said metal-coordinated organic complex in the solution used for spray-depositing is selected from 0.05 mM, 0.1 mM, 0.2 mM, 1 mM, 2, mM, 5 mM or any concentration in the range between these values.[000105] In one embodiment the invention provides a method of preparation of an EC film by spray coating comprising: spray coating steps for applying the metal linker and the organiccomplex are conducted at atomization pressure ranging between 0.75 kPa and 1.50 kPa and at a nozzle to substrate distance ranging between 3.0 and 8.0 cm, and at a spraying solution flow rate ranging between 0.4 and 0.8 mL / min.[000106] Deposition methods can be considered “dry” or “wet”, both are considered within the scope of the methods disclosed herein. In some embodiments “dry” deposition relates to a deposition step which requires minimal time for the deposited layer to dry before the next deposition step is carried out. In some embodiments “wet” deposition relates to a deposition step which requires a more substantial time for the deposited layer to dry before the next deposition step is carried out. In a ‘wet’ deposition step, additional drying stages may be required, in various embodiments, before a subsequent layer deposition is carried out. For example, the concentration, wettability, required thickness, all determine whether additional drying steps would be required before the subsequent layer deposition is carried out.[000107] In one embodiment, the metal -coordinated organic complex comprises one or more isomers of the same compound. In one embodiment, the metal -coordinated organic complex comprises any mixture of isomers of the same compound. In one embodiment, the isomers are enantiomers. In one embodiment, the metal -coordinated organic complex comprises one or two enantiomers of the same compound. In one embodiment, the metal -coordinated organic complex comprises a mixture of the one or two enantiomers. In one embodiment, the enantiomer mixture is a racemic mixture. In one embodiment, the applying step(s) comprise spin coating.[000108] Deposition methods may include spin coating. Deposition steps are considered for the application of the metal linker and / or the metal -coordinated organic complexes of the invention. Typically, the spin coating steps to apply the at least one metal linker, the metal -coordinated organic complex, or a combination thereof, has a first spin rate and a first spin time. Typically programming the spin coating process in two steps allows differentiation between two subsequent processes that are occurring during the spinning: the first process is the spreading of the material and the attachment of it to the substrate. This step requires relatively longer time, and therefore performs at slower rates. The subsequent step involves disposal of unattached molecules. This step requires higher speeds, as one has to overcome physical adsorption in order to dispose unattached material.[000109] In some embodiments the first spin rate ranges between about 100 to about 2000 rpm. In some embodiments the first spin rate ranges between about 100 to about 1000 rpm. In some embodiments the first spin rate ranges between about 100 to about 500 rpm. In some embodiments the first spin time ranges between about 0.3 sec to about 60 sec. In someembodiments the first spin time ranges between about 0.3 sec to about 30 sec. In some embodiments the first spin time ranges between about 0.3 sec to about 10 sec.[000110] In one embodiment the spin coating step to deposit the metal linker, the metal- coordinated organic complex, or a combination thereof, further comprises a second spin rate and a second spin time. In one embodiment the second spin rate ranges between about 200 to about 5000 rpm. In one embodiment the second spin rate ranges between about 200 to about 3000 rpm. In one embodiment the second spin rate ranges between about 200 to about 2000 rpm. In one embodiment the second spin rate ranges between about 200 to about 1000 rpm. In one embodiment the second spin time ranges between about 1 second to about 240 seconds. In one embodiment the second spin time ranges between about 1 second to about 120 seconds. In one embodiment the second spin time ranges between about 1 second to about 60 seconds.[000111] In one embodiment the washing is carried out with any of the following selected from: water, alcohols, ethers, esters, hydrocarbons, ketones, or a combination thereof. In one embodiment the alcohol is selected from: isopropanol, ethanol, methanol, ethyl acetate, acetone, or a combination thereof. Examples of ketones include, but are not limited to: acetone, cutanone, acetophenone, cyclohexane, benzophenone, methyl isobutyl ketone (MIBK), diethyl ketone, hexan-2-one, etc. As stated herein, the washing stage can be carried out after every deposition step, or at selected step. Washing can include direct washing under a stream of the various solvents described herein and / or dipping / immersion the sample within those solvents. Postfabrication processes can also include sonication.[000112] The repeated deposition of metal linkers and metal -coordinated organic complex layers forms thicker layers with every additional deposition. As stated herein, although each deposition (e.g., linker and metal -coordinated organic complex) comprises a single step which contributes ‘a layer’, it is understood that the linker and metal-coordinated organic complex form a continuous layer, resulting in a 3D network. In some embodiments the deposition steps (e.g., for linker and metal -coordinated organic complex) are each repeated from about 2 to 80 times. In one embodiment both depositing steps are repeated between about 2 to about 50 times. In one embodiment both depositing steps are repeated between about 2 to about 20 times. In one embodiment both depositing steps are repeated between about 2 to about 10 times. Generally, one metal-linker deposition step is followed by one metal-coordinated organic complex deposition step, and the process is repeated. In some embodiments, the metal-linker deposition step, and / or the metal-coordinated organic complex deposition step is carried out more than one time in succession. For example, two metal-linker deposition steps can be followed by three metal-coordinated organic complex deposition steps, followed by one metal-linker depositionstep, followed by four metal-coordinated organic complex deposition steps. All combinations of deposition repetitions are considered within the scope of the invention. The relevant thickness and film characteristics result from the methods and sequence of the deposition processes.[000113] The invention encompasses methods of depositing multiple layers of electrochromic materials onto a substrate thereby creating a multilayered EC assembly. The invention also encompasses multilayered EC materials composed of mixtures of at least two metal polypyridyl complexes. The combination of Layer by Layer principles with spin coating layering techniques achieves well-designed nanostructures. For example, it was shown that in one case, the different layers constructed of Fe-polypyridyl-complex and Pd metal linker form a 3D coordination network with particular advantageous properties.[000114] The method of the invention produces EC material that is thermally and electrochemically robust in air with very high contrast ratios (ON / OFF ratios). The EC material may operate under low voltage and have practical switching times. Thus, an EC material that has very high ON / OFF ratios, homogenous coating, low-voltage operations, high electrochemical stability and durability (such as light and thermal durability), color versatility, and low switching times, is useful in a variety of applications. The multilayered EC material has unique electrical properties suitable in applications such as smart windows, electrochromic windows, smart mirrors, optical filters, frequency doubling devices, spatial light modulators, pulse shapers, displays, signs, plastic electronics, lenses, sensors, to name a few. The method of the invention may be used for the formation of electrochromic coatings such as films.[000115] As used herein, unless otherwise defined, the term “high electrochemical stability” refers to the capability of the EC material to retain high values of %AT, z.e., >90%, >95%, or >97%, after at least 1000, but preferably more than 3,000, 5,000, or 10,000 electrochemical switching cycles as immersed in an electrolyte solution / exposed to electrolyte gel, and exposed to air and to visible / UV light over a period of a few hours to a few days. In one embodiment, high electrochemical stability refers to the capability of the EC material to retain high values of %AT, i.e., >80%, >90%, >95%, or >97% or >99%, after at least 1000, but preferably more than 3,000, 5,000, 10.000 or 100,000 electrochemical switching cycles when immersed in an electrolyte solution or being in contact with electrolyte gel or solid electrolyte and exposed to air, to extreme atmosphere temperatures and to visible / UV light over a period of a few hours to a few years.[000116] In one embodiment, the EC materials of this invention retained >90% of the original value of their contrast ratio after >1000 switching cycles.[000117] The layer-by-layer (LBL) film-construction approach is an approach, based on the use of different kinds of inter-layers interactions such as electrostatic interactions and hydrogen bonding for the purpose of adhering layers of different materials to each other to form a film. The LBL approach relates to cases where films are formed by depositing alternating layers of materials that are known to have a certain type of interactions between them. In one embodiment the interaction is covalent between a pyridine group of the metal complex with Pd. In another embodiment the interaction is a metal-ligand coordination.[000118] Typically, the step of applying the polypyridyl compound or complex by spin coating requires applying either a polypyridyl compound or a polypyridyl metal complex to the substrate coated with the metal linker, optionally, these materials may be in solution. Suitable solvents for the solution include, but are not limited to, tetrahydrofuran, ethyl ether, dichloromethane, methanol, acetonitrile others. Similar solvents may be used to dissolve / disperse the metal linkers; for example, the PdCh based linker is soluble in THF. However, depending on the metal linker and the metal complex, other solvents may be used as long as the metal-linker or metal complex are dissolved or dispersed in such solvent.[000119] Preferably, the substrate is transparent and has conducting properties. The substrate can be an n-type semiconductor with high carrier concentration, which leads to low electrical resistivity. High transmission in the visible and near-IR regions of the electromagnetic spectrum due to a wide band gap is also a desirable property of the substrate.[000120] Metals used in the invention include those that can work as a metal linker between the substrate and the pyridyl compound or complex material or between two pyridyl compounds or complex materials. In the latter case, the pyridyl complex may be the same or different. Typical metals include, but are not limited to, transition metals, lanthanides, actinides, or main group elements. Transition metals include Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y. Lanthanides include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu. Actinides include Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, or Lr. Main group elements include Zn, Ga, Ge, Al, Cd, In, Sn, Sb, Hg, Tl, or Pb. Preferably, the metal is Pd. The metal may be applied as a coordinate metal in either neutral or in an oxidation state. For instance, Pd can be applied as Pd or a Pd(II)-based complex. An example of Pd(II)-based complex is PdCh(PhCN)2. Further, the metals or metal complexes are applied from solution. Suitable solutions can include, but are not limited to, ethers such as tetrahydrofuran and ethyl ether. Metals in the metal -coordinated organic complexes of the invention can be any of the metals described herein above.[000121] As used herein, unless otherwise defined, the term “pyridyl complex” refers to a metal having one or more e.g., two, three, or four pyridyl compounds coordinated therewith.[000122] The bipyridyl complexes used in the invention are generally tris-bipyridyl complexes of the general formula (I):whereinM is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, or Ir; n is the formal oxidation state of the transition metal, wherein n is 0-6;X is a counter ion; m is a number ranging from 0 to 6;Ri to Ris each independently is selected from H, halogen, -OH, -N3, -NO2, - CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci- Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, - OR20, -COR20, -COOR20, -OCOOR20, -OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2O)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R2o)2, or - SO3H;[000123] Ai to Ae each independently is a group of Formula III, z.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula I via R19R19 each independently is selected from a covalent bond, C-C, C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, - Si(R2o)2-, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,’Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, - CN, -N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci- Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, - OR20, -COR20, -COOR20, -OCOOR20, -OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R20)2, or - SO3H; andR2O each independently is H, (Ci-Ce)alkyl, or aryl.[000124] In some embodiments X is a counterion and may be any suitable anion having a negative charge, e.g., -1 or -2. In various embodiments counterions include, but are not limited to, from (NO3)' and (SC )2’.[000125] Another pyridyl complex used in the invention is an iron-based tris-bipyridyl complex of the general Formula II:wherein n is the formal oxidation state of Fe, wherein n is 0-6;X is a counter ion; m is a number ranging from 0 to 6;Ri to Ri8 each independently is selected from H, halogen, -OH, -N3, -NO2, - CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci- Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, - OR20, -COR20, -COOR20, -OCOOR20, -OCON(R2o)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2O)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R2o)2, or - SO3H;Ai, A3, and A5 each independently is a group of Formula III, z.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula II via R19Ri9 each independently is selected from a covalent bond, C-C, cis / tran C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, - Si(R2o)2- an alkylene optionally interrupted by one or more heteroatoms selectedfrom O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, - CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci- Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, - OR20, -COR20, -COOR20, -OCOOR20, -OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2O)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R2o)2, or - SO3H;Bi to B3 each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, -N(R2O)2, -CON(R2O)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, - OR20, -COR20, -COOR20, -OCOOR20, -OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2O)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R2o)2, or - SO3H; andR20 each independently is H, (Ci-Ce)alkyl, or aryl.[000126] X is a counterion and may be any suitable anion having a negative charge, e.g., -1 or - 2. Counterions include, but are not limited to, from (NO,)' and (SCU)2'. The value of “m” represents the ratio between the oxidation state of the metal and the valence of the anion. Values of “m” include, but are not limited to, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, or 6. In one embodiment n is the formal oxidation state of Fe, wherein n is 0-3.[000127] One method of the invention creates EC materials, such as thin films, based on compounds where M=Fe made by a method comprising providing a substrate, applying in a stepwise manner palladium dichloride and the pyridyl complexes using spin coating with LBL to form a layer, washing and drying the layer, and repeating the applying steps until the EC material has the desired number of layers or thickness. The combination of spin coating and LBL is referred to as a single deposition cycle. The invention encompasses methods where thedeposition cycle is repeated to obtain an EC material with 2 to 40 layers, preferably 5 to 30 layers, and more preferably 10 to 20 layers. In one particular case, such as a film, the method includes 18 deposition cycles, where after every deposition cycle, the modified substrates were washed using acetone, and dried under N2 stream. The fabrication process of the films occurs at ambient conditions.[000128] In one particular embodiment, the method of the invention comprises providing a substrate, applying a metal-linker complex solution by spin coating to form a metal-linker layer, applying a pyridyl compound or complex by spin coating to form a pyridyl layer, washing the pyridyl layer, drying the washed pyridyl layer, and repeating the applying steps to obtain an EC material with 2 to 80 layers.[000129] The metal-linker solution and pyridyl compound or complex are described above. Typically, the rinsing step is performed with at least one volatile organic solvent. Such volatile organic solvents include those capable of evaporating at room temperature. Typical volatile organic solvents include, but are not limited to, CH2CI2, acetone, methanol, ethanol, THF, acetonitrile, among others.[000130] Gasses suitable for use in the invention for the drying step, include, but are not limited to, nitrogen, argon, helium, neon, xenon, and radon. Preferably, the gas is nitrogen. Alternatively, the drying step can be air drying.[000131] One embodiment of the invention encompasses a method for making an EC material comprising providing a substrate, applying at least one metal linker, applying at least one metal- coordinated organic complex to form a layer, washing the layer, drying the layer, and repeating the applying steps to obtain a multiple layer EC material.[000132] In one embodiment, the metal-organic complex comprises at least one functional group, the functional group capable of binding to the metal linker. In one embodiment, the binding comprises a coordination bond between the functional group and the metal linker. In one embodiment, the metal complex is a polypyridyl complex.[000133] In one embodiment, no template or coupling layer is used or is present between the substrate and the metal linker layer in EC materials of this invention. In one embodiment, the layer-application steps are performed manually. In one embodiment, the layer-application steps are performed in a partially automated manner or in a fully automated manner. Automation of the layer application technique results in fast fabrication of the EC materials in one embodiment. [000134] Embodiments that are described herein for polypyridyl complexes are suitable for other metal-coordinated organic complexes as well. Embodiments that are described herein for Pd metal linkers are suitable for other metal linkers as well. Counter ions in metal-coordinatedorganic complexes of this invention can be any counter ion as known to the skilled artisan. In one embodiment, the growth of the layers in assemblies of this invention is such that the thickness of each layer is the same or is similar to the thickness of other layers in the assembly. In other embodiments, various layer thicknesses can be obtained for different layers in an EC material of this invention.[000135] In some embodiments the terms “working electrode” and “substrate” are used interchangeably. In some embodiments the substrate is transparent. In some embodiments the substrate is conductive. In some embodiments the substrate is crystalline. In some embodiments the substrate is amorphous or polycrystalline. In some embodiments the substrate is transparent, conductive or a combination thereof. The substrate of the EC device is selected according to a particular application. In one embodiment the substrate comprises any of the following selected from: glass, doped glass, metal-oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si(l l l), SiCh, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, carbon-based materials, graphene, carbon nanotubes, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically-conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminum or any combination thereof. In one embodiment the substrate comprises: glass, doped glass, metal-oxide, indium tin oxide (ITO)- coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon or zinc oxide (ZnO). In one embodiment the substrate is flexible.[000136] In some embodiments the substrate further comprises a conductive polymer. Examples of conductive polymers include, but are not limited to: polyaniline (PANI), polyacetylene (PA), polythiophene, polyphenylene vinylene (PPV), poly(3,4-ethylenedi oxythiophene) (PEDOT), polypyrrole (Ppy), polyfluorene, poly(3 -hexylthiophene) (P3HT), poly(phenylene sulfide) (PPS), poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), or combinations thereof, etc.[000137] In some embodiments the working electrode comprises ITO / PET. In some embodiments the working electrode consists of ITO / PET. In some embodiments the working electrode is functionalized. In some embodiments the working electrode comprises any of the following selected from: ITO, polymer, fluorine-doped tin oxide (FTO) on glass, zinc oxide (ZnO), or any combination thereof. In some embodiments the polymer is selected from: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyacrylamide (PAM), polystyrene (PS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride(PVC), polyethylene terephthalate glycol-modified (PETG), polyimide (PI), polyester elastomersa nd polymethyl methacrylate (PMMA) or any combination thereof. In one embodiment the working electrode comprises any of the following selected from: gold, silver, platinum, copper, zinc, aluminum or any combination thereof.[000138] In one embodiment the polymer is selected from: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyacrylamide (PAM), polystyrene (PS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate glycol-modified (PETG), polyimide (PI), polyester elastomers, polymethyl methacrylate (PMMA) or any combination thereof.[000139] In one embodiment the at least one metal linker is selected from Na2 dCE or (SO3II- 3-Py)2Pd(Cl)2. In various embodiments linker comprises any of the following selected from: 3- pyridinesulfonic acid, 2-pyridinesulfonic acid, 4-pyridinesulfonic acid, 2-pyridinecarboxylic acid, 3 -pyridinecarboxylic acid, 4-pyridinecarboxylic acid, 2-pyridinephosphonate, 3- pyridinephosphonate and 4-pyridinephosphonate. In one embodiment the linker comprises PdCh(PhCN)2. In one embodiment the concentration of the at least one linker in the corresponding the aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding the aqueous solution ranges between 0.1 mM and 10 mM. In one embodiment the concentration of the at least one linker in the corresponding the aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding the aqueous solution ranges between 0.1 mM and 5 mM. In one embodiment the concentration of the at least one linker in the corresponding the aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding the aqueous solution ranges between 0.1 mM and 1 mM. In one embodiment the concentration of the at least one linker in the corresponding the aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding aqueous solution ranges between 0.1 mM and 10 mM. In one embodiment the concentration of the at least one linker in the corresponding aqueous solution and / or the concentration of the metal-coordinated organic complex in the corresponding aqueous solution ranges between 5 mM and 10 mM. In one embodiment the concentration of the at least one linker in the corresponding the aqueous solution and / or the concentration of the metal- coordinated organic complex in the corresponding aqueous solution is about 1 mM.[000140] The aqueous solutions of the invention pertain to the metal linker solution, the metal - coordinated organic complex solution, or both. In some embodiments the aqueous solution further comprises a water-miscible solvent. In one embodiment the water-miscible solvent comprises: alcohol, glycol, glycol ethers, amides, ketones, carboxylic acid, amines, sulf-containing solvents, ethers, or a combination thereof. In one embodiment the aqueous solutions further comprise a water-miscible solvent selected from: acetaldehyde, acetic acid, acetone, acetonitrile, 1,2-butanediol, 1,3 -butanediol, 1,4 -butanediol, 2-butoxyethanol, butyric acid, dihydrolevoglucosenone, diethanolamine, diethylenetriamine, dimethoxyethane, dimethylformamide, 1,1 -dimethylhydrazine, 1,2-dimethylhydrazine, dimethyl sulfoxide, 1,4- dioxane, ethanol, ethylamine, ethylene glycol, ethyl lactate, formic acid, furfuryl alcohol, glycerol, methanol, methyl diethanolamine, methyl isocyanide, 2-methyltetrahydrofuran (2- MeTHF), N-methyl-2-pyrrolidone, 1-propanol, 1,3-propanediol, 1,5-pentanediol, 2-propanol, propanoic acid, propylene glycol, pyridine, sulfolane, tetrahydrofuran and triethylene glycol, or any combination thereof.[000141] In one embodiment the aqueous solutions further comprise at least one solvent selected from: acetone, ethanol, methanol, 2-propanol, ethyl acetate, isopropyl acetate, ethyl lactate, methyl ethyl ketone, 2-methyltetrahydrofuran (2-MeTHF), 1 -butanol, tert-butanol, supercritical carbon dioxide (scCCh), dihydrolevoglucosenone, limonene, propylene carbonate, formic acid, gamma-valerolactone (GVL) and ionic liquids, or any combination thereof.[000142] The methods to produce electrochromic films are readily suited towards making electrochromic devices and systems that incorporate electrochromic (EC) devices. There are numerous ways of coupling an EC film within an EC device. In some embodiments the EC film is comprised within a solid-state device. In some embodiments the EC is comprised within a wet cell.[000143] In one embodiment the EC device comprises: the substrate and EC films produced by methods of the invention; an electrolyte in contact with the EC film; an ion storage layer; and a counter electrode in contact with the ion storage layer; wherein the electrolyte is disposed between the substrate and the counter electrode.[000144] In one embodiment the EC device comprises: the substrate and EC films produced by methods of the invention; an electrolyte in contact with the EC film; an ion storage layer; and a counter electrode in contact with the ion storage layer; wherein the electrolyte is disposed between the EC film and the ion storage layer.[000145] In one embodiment the electrolyte is selected from: solid-state electrolyte, gel, liquid, transparent electrolyte and non-transparent electrolyte or any combination thereof. In some embodiments the “EC film” is referred to interchangeably as an “EC multi-layer”.[000146] In one embodiment the electrolyte comprises a compound with the formula NR4X wherein:R is selected from an alkyl or an aryl; andX is a counterion selected from: halides, sulfate, nitrate, perchlorate, carbonate, hexafluorophosphate, BF4, BR4 with R being aryl, alkyl, or fluorocarbon and ArFs.[000147] In one embodiment the electrolyte is a metal salt. In one embodiment the electrolyte is selected from: a sodium salt, a lithium salt, a potassium salt, a calcium salt, a cesium salt, an organic salt, an inorganic salt, an ammonium salt, organic solvents, ionic liquids (IL), alcohols and nitriles or any combination thereof.[000148] In one embodiment the electrolyte comprises any of the following selected from: NaCl, NaBr, NaOH, KC1, KBr, KOH, CaCl, CaBr, CaCO3, CsCl, CsBr, LiPF6, LiClO4, LiBF4, LiAsF6, LiSbF6, LiTaF6, LiNbF6, LiCF3SO3, LiC4F9SO3, LiC4F9SO3, Li(C2F5SO2)2N, Li(CF3SO2)3C, LiBF3(C2F5), LiB(C2O4)2, LiB(C6F5) and LiPF3(C2F5)3.[000149] In one embodiment the electrolyte is selected from: ACN / PC / PMMA / trifluoromethylsulfonamide lithium salt, polymethyl methacrylate (PMMA), propylene carbonate (PC), LiCF3SO3, LiBF4, Li2+2xZni-xGeO4 (LiSICON), glassy lithium phosphorus oxynitride (LIPON) and LiClO4 or any combination thereof.[000150] In some embodiments the electrolyte is disposed on top of the electrochromic layer. In some embodiments the electrolyte is disposed between the electrochromic layer and the counter electrode. In some embodiments the electrolyte is disposed between the electrochromic layer and the ion storage layer. For example, the layers of the device can be in the following order: substrate, linker, electrochromic film, electrolyte, ion storage layer and counter electrode. In various embodiments the electrochromic film can comprise linker and electrochromic material in a 3D network i.e., the linker is interspersed within the electrochromic film. In some embodiments the electrolyte is interspersed between the substrate and the counter electrode. Once the electrolyte is applied it diffuses through various layers between the working and counter electrodes, in various embodiments.[000151] In one embodiment the ion storage layer comprises any of the following selected from: polymers, copolymers, metal-organic polymer, coordination polymer, molecular film, metallic coating, transparent conducting oxides, metal oxides, metal fluorides, metal nitrides, metal sulfides, nanocrystalline metal oxides, mixed metals oxides, redox-active species, carbon-basedmaterials, graphene-based materials, buckminsterfullerenes, nanotubes, 2D materials, biomolecules, nanowires, polymethyl methacrylate (PMMA), benzocyclobutene (BCB) based polymers, poly(3,4-ethylenedioxythiophene), poly(styrenesulfonate), conjugated dithiolenes, polyelectrolytes, organic salts, inorganic salts, quinone-based compounds, viologen-based compounds, antimony-doped tin oxide (ATO), pyridine blue (PB), polyaniline, polypyrrole, lithium cobalt oxide, lithium cobalt oxide, indium tin oxide, fluorine doped tin oxide, niobium oxide, molybdenum oxide, zinc oxides, aluminum oxide, nickel oxides, ceric oxide, metal doped nickel oxides, lithium doped nickel oxides, lithium doped titanium oxides, polymetal oxides, nanoparticles, metallic nanoparticles, nickel hexacyanoferrate, iron hexacyanoferrate, lithium hexacyanoferrate, sodium hexacyanoferrate, manganese hexacyanomanganate, halogen-doped metal oxides, lithium sulfide, lithium garnet, lithium phosphorous oxynitride, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, sodium nickel chloride and activated carbon.[000152] In one embodiment the ion storage layer has a thickness ranging between 2 nm - 600 nm. In one embodiment the ion storage layer is disposed on the working electrode, counter electrode, or a combination thereof. In various embodiments the ion storage layer is in contact with the counter electrode. As used herein “in contact” can be understood interchangeably with “disposed on” and “bound to”. As such, the contact of such a layer can be understood to be fully in contact or partially in contact.[000153] In one embodiment the substrate and the counter electrode comprise any of the following selected from: glass, doped glass, metal-oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si( 111), SiCh, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically- conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminium or any combination thereof.[000154] The electrochromic films produced by the methods of the present invention can be incorporated into corresponding devices and systems. In its basic form, an EC film / device / system is configured to change its optical properties, e.g., color and / or opacity, in response an applied voltage or current.[000155] In one embodiment the EC device system comprises: an EC device produced in the methods of this invention; at least one sensor configured to detect an optical state;a power supply; and a controller configured to control the colored state of the electrochromic device by means of an applied potential; wherein the controller and the power supply are configured to apply a bias potential across the EC film thereby inducing at least one change in the optical state of the EC film and wherein the at least one sensor is configured to communicate the optical state to the controller.[000156] In some embodiments the system is configured such that the electrochromic device is in a bleached state when a bias potential is applied. In some embodiments the applied potential for the bleached state ranges between 0.1 to 10 V. In some embodiments the applied potential for the bleached state ranges between 1 to 10 V. In some embodiments the applied potential for the bleached state ranges between 2 to 10 V. In some embodiments the applied potential for the bleached state ranges between 5 to 10 V. In some embodiments the applied potential for the bleached state ranges between 0.1 to 5 V. In some embodiments the applied potential for the bleached state ranges between 0.1 to 2 V. In some embodiments the applied potential for the bleached state ranges between 0.1 to 1 V.[000157] In one embodiment the at least one sensor is an electro-optic sensor. In one embodiment the at least sensor is selected from: photodetector, photodiode, phototransistor, photomultiplier tube (PMT), spectrophotometer, reflectance spectrometer, transmittance spectrometer, colorimeter, color sensor, UV-vis spectrophotometer, UV sensor, infrared sensor, image sensor, complementary metal-oxide semiconductor (CCD) sensor, charge-coupled device (CCD) sensor, polarimeter, photoluminescence sensor, fluorescence sensor, optical sensor, ammeter, voltmeter, ohmmeter, multimeter, potentiometer, galvanometer, magnetometer, hall effect monitor and light dependent resistor (LDR), or a combination thereof.[000158] In one embodiment the multi-layer maintains the optical state for between 1 second to 24 hours. In one embodiment the system further comprises a display configured to output data from components of the system. In one embodiment the system further comprises an encapsulation layer. In one embodiment the encapsulation layer comprises any of the following selected from: polymers, plastics, organic / inorganic hybrid materials, glue, wax, epoxy, ceramics, carbon-based materials, bio-inspired materials and silicon-based materials or any combination thereof. In one embodiment the optical state corresponds to an electronic readout selected from: current, voltage, charge, conductance and impedance or a combination thereof. In one embodiment optical state of the at least one change in optical state is exhibited at a different time.[000159] The linkers of the invention are generally water soluble with a geometry that provides a porous surface assembly for electrolyte mobility.[000160] In one embodiment the linkers of the invention are metal -based complexes. As used herein the terms “metal-based complex” and “metal-based linker complex” can be used interchangeably. In one embodiment the metal-based complex is represented by a compound of Formula VIII:whereinA and A’ are each independently a nitrogen binding, single or fused, 5-10 membered heteroaromatic ring, or a single or fused, 5-10 membered aromatic ring, which comprises at least one metal binding group, covalently bound to the ring;L and L’ are each independently an anionic ligand;M is Pd, Pt, Cu, Zn, Fe, or Ru;LI and LI’ are each independently absent, or are metal binding groups, covalently bonded to the A and A’ rings respectively, wherein if LI and / or LI’ are absent then ring A and / or A’ are heteroaromatic; n, m are each independently an integer number between 1-5; W and W’ are each independently water soluble groups; and R is linear, branched or cyclic.[000161] In some embodiments M is a first row metal. In one embodiment M is a transition metal. In one embodiment the A and A’ are selected from: pyridine, pyrimidine, pyrazine, pyridazine, imidazole, pyrrole, quinoline, oxazole and indole. In one embodiment the Lland LI’ are selected from: nitrile, phosphine or amine. In one embodiment the L and L’ are selected from: Cl", Br", I", [NO3]’, [SO4]2’, [PO4]3’, [PFe]', [BF4]', tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (= BARF), borane anions and [BCAN4]’. In one embodiment the W and W’ are selected from: SO3H, COOH, PO(OR)2, NHC(O)H, NHC(O)R, NH2, NHCAN, NCAN2, C(O)NH2, C(O)NHCAN, SO2-NH2, SO2-NHCAN, SO2-NCAN2, CN and NO2. In one embodiment R is a selected from a C1-C8 alkyl group. In some embodiments the water-solubilizing group is selected from: amides, amides, acids, carboxylic acid, phosphonates, pyridine, nitriles, phosphines, etc.[000162] Other examples of anionic ligands include: chloride ion (CF), bromide ion (Br), iodide ion (F), fluoride ion (F‘), cyanide ion (CN’), hydroxide ion (OH"), nitrate ion (NO3‘), nitriteion (NO2’), sulfate ion (SCU2'), sulfite ion (SCE2'), thiosulfate ion (S2O32'), carbonate ion (CCE2' ), oxalate ion (C2O42'), phosphate ion (PCU3'), acetate ion (CEECOO' or C2H3O2‘), formate ion (HCOO"), citrate ion (CeEEO?3') and ethylenediaminetetraacetate ion (EDTA4').[000163] In one embodiment the metal -based complex is represented by the structure of Formula V:Wherein Xi, X2, X3, X4, X5, Xe, X7, Xs, X9 and X10 are each independently a carbon atom or nitrogen atom; wherein at least one of Xi, X2, X3, X4 and X5 is carbon; and wherein at least one of Xe, X7, Xs, X9 and X10 is carbon.[000164] In one embodiment at least two of at least one of Xi, X2, X3, X4 and X5 is carbon. In one embodiment at least three of Xi, X2, X3, X4 and X5 are carbon. In one embodiment at least four Xi, X2, X3, X4 and X5 are carbon. In one embodiment at least two of Xe, X7, Xs, X9 and X10 are carbon. In one embodiment at least three of Xe, X7, Xs, X9 and X10 is carbon. In one embodiment at least four of Xe, X7, Xs, X9 and X10 is carbon.[000165] Molecular assemblies facilitated with different metal linkers are shown in Table 1 and Table 2 below.[000166] Table 1 -Summary of the molecular assemblies (MA1-MA4) of the complex 1 and 2 with two different Pd-linker and their stability as EC film and ECD[000167] Table 2 - Compare various parameters for the molecular assemblies MA1-MA4 of the complex 1 and 2 with Pd-linkers.[000168] Methods for producing the (SO3H-3-Py)2Pd(Cl)2-based linker solution are provided. The present invention provides a method for producing a (SO3H-3-Py)2Pd(Cl)2 solution, the method comprising: reacting an aqueous solution of pyridine-3 -sulfonic acid in water with an aqueous solution of palladium (II) chloride, producing a solution comprising (SO3H-3- Py)2Pd(Cl)2.[000169] In one embodiment reacting is carried out between 20 and 100 °C. In one embodiment reacting is carried out between 20 and 50 °C. In one embodiment reacting is carried out between 50 and 100 °C.[000170] In one embodiment the reacting is carried out for between 0.5 to 5 hours. In one embodiment the reacting is carried out for between 1 to 5 hours. In one embodiment the reaction is carried out for between 2 to 5 hours. In one embodiment the reaction is carried out for between 3 to 5 hours. In one embodiment the reaction is carried out for between 0.5 to 24 hours. In one embodiment the reaction is carried out for between 0.1 to 0.5 hours. In one embodiment the reaction is carried out for between 0.5 to 3 hours. In one embodiment the reaction is carried out for between 0.5 to 2 hours.[000171] In one embodiment the method further comprises filtering the solution comprising (SO3H-3-Py)2Pd(Cl)2. In some embodiments the method further comprises drying the solution to increase the concentration of the solution. In some embodiments the drying is carried out under vacuum.Solubility of Electrochromic Complexes[000172] The solubility of the electrochromic complexes of the invention can be modified by selecting the appropriate counter ion in solution. Figures 26A-26D show difference in solubility of the electrochromic complexes when using Cl", PFe, SO4, as a counter ions.[000173] Figure 26A shows the results of a solubility test for Fe-3arm-DB-Cl, Fe-3arm-DB-PFe and Fe-3arm-DB-SO4 in: water, methanol, ethanol, butanol, ethyl lactate, propylene carbonate, acetonitrile, and acetone. Figure 26B shows the results of a solubility test for Ru-3arm-DB-Cl versus Ru-3arm-DB-PFe, and Os-3arm-DB-Cl versus Os-3arm-DB-PFe. Figure 26C shows the results of a solubility test for Fe-6arm-DB-Cl, Fe-6arm-DB-PF6, and Fe-6arm-DB-SO4. Figure 26D shows the results of a solubility test for Fe-6arm-TB-Cl versus Fe-6arm-TB-PF6, and Fe- 6arm-SB-Cl versus Fe-6arm-SB-PFe. These results are summarized as follows in Table 4:Table 4 - solubility test for various complexes in different solvents. ‘ Y’ denotes that the complex is soluble, ‘N’ denotes that it is insoluble.[000174] In one embodiment the invention provides a soluble electrochromic complex. The solubility of the electrochromic complex being dictated, at least in part, by the counter ion in the solution. In one embodiment the counter ion comprises any of the following selected from: CT, PFe', NCL', and SCU2'. In one embodiment the counter ion consists of any of the following selected from: Cl", PFe', NCL', and SCU2'. In one embodiment a combination of counter ions is comprised within the solution. Therefore, any of the soluble complexes (together with their counter ions) found in Table 4 can be used for making any of the electrochromic films of the invention.[000175] Figures 27A-27B show the solubility of complexes in solvent. In some cases, such as Fe-3arms-PF6 in ethanol (Figure 27B) the complex is sparingly soluble i.e., partly soluble.EXAMPLESEXAMPLE 1 Materials and Methods[000176] Solvents (AR grade) were purchased from Bio-Lab (Jerusalem), Frutarom (Haifa, Israel), or MallinckrodtBaker (Phillipsburg, NJ). Ferrous sulfate heptahydrate, Palladium dichloride, Sodium tetrachloropalladate, Lithium perchlorate, and Poly(methyl methacrylate) (PMMA) were purchased from Sigma- Aldrich. Mili Q water was taken from Synergy® UV Remote Water Purification System (Type 1) provided by Merck. Fluorine-doped tin oxide (FTO)-coated glass substrates (6 cm * 6 cm, Rs = 8-12 Q / n) was purchased from Xinyan Technology Ltd. (Hong Kong, China). FTO-coated glass substrates were cleaned by sonication in ethanol for 10 min, dried under a stream of N2, and subsequently cleaned for 20 min with UV and ozone in a UVOCS cleaning system (Montgomery, PA). The substrates were then rinsed with tetrahydrofuran (THF), dried under a stream of N2, and oven-dried at 130 °C for 2 h. A Laurell spin-coater, model WS-400A-6NPP / LITE, was used for the formation of the molecular assemblies (MAs).[000177] UV / Vis Spectroscopy: UV / vis spectra were recorded on a Cary 100 spectrophotometer. The absorbance was measured using the CaryWinUV-Scan application program, version 3.00 (182) by Varian(200-800 nm), whereas the transmittance was measured using the CaryWinUV-Kinetics application program, version 3.00 (182) by Varian. Bare substrates were used to compensate for the background absorption.[000178] X-ray Photoelectron Spectroscopy: XPS measurements were carried out on FTO / glass substrates (1.0 cm x 1.0 cm) with a KratosAXIS ULTRA system, using a monochromatic Al Ka X-ray source (hu =1486.6 eV) at 75W and detection pass energies ranging between 20 and 80 eV. Curve-fitting analysis was based on Shirley or linear background subtraction and application of Gaussian-Lorenzian line shapes.[000179] Atomic Force Microscopy: AFM imaging was carried out by using a JPK AFM (JPK Nanowizard III, Berlin, Germany). Scans were made in AC mode using a silicon probe (Olympus Co. AC240) with a nominal resonance frequency and a spring constant of 70 kHz and 2 N / m.[000180] Focused Ion Beam Microscopy: SEM images were recorded using a Helios 600 FIB / SEM dual-beam microscope (FEI), operating at 5 keV. The images were taken at the surface of the samples and at cross sections that were milled with a 30 keV Ga+focused ion beam (FIB). The sample was first locally coated with a 150-200-nm-thick layer of Pt using electron-beam- assisted deposition, which was followed by the ion-beam-assisted deposition of a 500-600-nm- thick layer of Pt. The Pt coating protects the MA layer from ion-beam damage, providing a clean edge of the cross section.[000181] Electrochemical Characterization: Electrochemical experiments were carried out using a CHI660A or CHI760E electrochemical workstation. The following configuration of the electrochemical cell was used: FTO-coated glass substrates (size of 2 cm x 2 cm) served as the working electrode, Ag / Ag+was used as the reference electrode, and a Pt wire was used as the counter electrode. Lithium perchlorate (LiCICh) in water (0.1 M) was used as the supporting electrolyte. The electrochemical measurements of the devices were carried out with FTO-coated glass (2 cm x 2 cm) serving as the working electrode and a corresponding bare substrate as the reference and counter electrodes.EXAMPLE 2Synthesis of ligand LI and L2[000182] Preparation of complex 1:Scheme 1: Synthetic route to prepare complex 1 from ligand LI.[000183] A solution of the (E)-4-methyl-4’-(2-(- 50 -yridine-4-yl)vinyl)-2,2’-bipyridine LI (2.73 g, lO mmol) in MeOH (lO mL) was added to a solution ofFeSCL JLO (0.925 g, 3.3 mmol) in H2O (10 mL). The solution was then stirred for 30 min, with occasional warming to 50 °C (every 10 min); thereafter, filter the solution and excess diethyl ether was added. The formed precipitate was filtered and washed diethylether (200 mL), and was dried under vacuum to yield complexl. Yield 3.9 g (82 %).[000184] Preparation of complex 2:Complex 2Scheme 2: Synthetic route to prepare complex 1 from ligand L2.[000185] A solution of 4,4’ -bis[(E)-2-(4-pyridyl)vinyl]-2, 2’ -bipyridine (L2) (3.6 g, 10 mmol) in MeOH (15 mL) was added to a solution of FeSCL 7H2O (0.925 g, 3.3 mmol) in H2O (10 mL). The solution was then stirred for 30 min, with occasional warming to 50 °C (every 10 min); thereafter, filter the solution and excess diethyl ether was added. The formed precipitate wasfiltered and washed with diethylether (200 mL), and was dried under vacuum to yield complex 2. Yield 3.6 g (80 %).[000186] Preparation of linker PdC12(Py-3-SO3H)2(complex 3):Scheme 3: Synthetic route to prepare the water soluble linker complex.[000187] Figure 18 shows a precise design of a Pd-linker with trans pyridine-based groups, which will provide more porous surface assembly.[000188] To an aqueous solution of pyridine-3 -sulfonic acid (1.60 g, 10 mmol) in water (10 ml), an aqueous solution of palladium (II) chloride (0.88g, 5 mmol) was added. The reaction mixture was then heated at 80°C for 2 hours. After that the solution was filtered and dried under vacuum to obtain a brown liquid.[000189] 1H-NMR:XH NMR (400 MHz, D2O) 5 9.048 (d), 8.81 (d), 8.25 (d), 7.59(dd) [000190] 13C-NMR: °C NMR (400 MHz, D2O) 5 154.62, 149.66, 141.22, 137.12, 126.19 [000191] ESI-MS: 460.87 [M-C1]+, 478. 86 [{M-C1}+H2O]+EXAMPLE 3 Formation of Unimolecular Assemblies[000192] MA1-MA4 were obtained by iterative spin-coating of the aqueous solutions of Na2PdCU and PdCh(Py-3-SO3H)2 and aqueous solution of the complexes 1 and 2. Complex 1 is completely soluble in water at room temperature, whereas 5% MeOH (95% H2O) was used for complex 2. An aqueous solution of PdCh(Py-3-SO3H)2 or ISfePdCh (4.0 mM) was used for the formation of molecular assemblies MA1-MA4. MAI and MA2 was obtained by iterative spincoating of aqueous solutions of ISfePdCU and aqueous solution of complex 1 and 2, whereas MA3 and MA4 was obtained from the aqueous solution of PdCh(Py-3-SO3H)2 with complex 1 and 2 respectively.Table 3 - complexes and linkers.[000193] The aqueous solution of the linker Na2PdCh or PdC12(Py-3-SO3H)2 was drop-casted onto the FTO / glass substrates (2 cm * 2 cm). Subsequently, the substrate was spun at 500 rpm for 10 s and then at 1000 rpm for 30 s. Next, a solution of the corresponding complex 1-2 was drop-casted after 80 s onto the substrates, which were spun as above. The substrates were then immersed in methanol for 30 s and were dried under a gentle stream of air. The linker deposition and subsequent complex (1-2) deposition step is referred to as a single deposition cycle. For the formation of MAI and MA3, the deposition cycle was repeated 26 times. For the formation of MA2 and MA4, the deposition cycle was repeated 16 times. The deposition of the first layer of Pd(II) linker was found to be necessary for the binding of metal complexes 1-2 to the substrate surface.EXAMPLE 4Fabrication of Laminated Electrochromic Devices[000194] A layered architecture was used to construct laminated sandwich cells based on MA1- MA4 on FTO / glass substrates. The modified FTO-coated glass substrates served as the working electrode, and a corresponding bare substrate served as the reference and counter electrodes. A frame of 2 I O- / m-thick double-sided tape (3M 9088) was attached to the working electrode (2 cm x 2 cm) for FTO / glass substrates leaving an exposed edge (1-2 mm) for silver paste or copper tape contacts. Contacts were also connected to an edge (1-2 mm) of the counter electrode. The two electrodes were placed with the two conducting faces facing each other. The electrolyte gel (70:20:7:3 wt% ACN / PC / PMMA / lithium perchlorate salt) was injected using a syringe between the two electrodes. The edges of the devices were sealed using epoxy glue. The device was then connected to a potentiostat, and the electrochromic properties were investigated.EXAMPLE 5Fabricating EC devices from Spray Coating[000195] To produce EC films and their derivative devices, spray coating was sometimes used for various deposition processes. Spray coating was carried out for the complex 1 at a concentration of 0.2 mM and for the complex 2 at a concentration of 0.3 mM. The water soluble Pd linker was deposited by a solution with a 1 mM concentration. The PdCh(PhCN)2 linker was deposited by a solution with a concentration of 1 mM. These precise concentrations are deemed essential for achieving the desired outcomes in the spray coating technique, ensuring optimal performance and reproducibility in experiments.[000196] Spray coated EC films are shown in Figures 19A-19C. Spray coating from methanolbased solution was carried out at 40 °C. Spray coating from water-based (only) solutions were heated up to 80-90 °C. However spraying at higher temperature decreased the stability of the films during switching. The temperature and the concentration were therefore optimized to ensure the highest quality films and optimized switchability.[000197] In depositing the EC complexes and the palladium salts (linkers) each was spray- coated onto the substrate in three consecutive passes. An automated spray-coating deposition instrument was used. The instrument is set up to perform three consecutive passes without any time lapses for one layer of coating i.e., for both the EC complex material and the palladium salt linker material. This process is repeated 5-6 times for 5-6 layers depending on the target thickness. Typically, the greater the number of deposition layers the larger the thickness. However, other factors like concentration, wettability, volatility also determine the final thickness. Such considerations are optimized for each application.[000198] For highly volatile solvents (e.g., DCM), no waiting time is required between any passes. However, for methanol at 40 °C, a five second waiting time was pre-programmed between consecutive passes. For water-based depositions at elevated temperature, a ten second waiting time was set for consecutive spray-coating deposition cycles to ensure the complete dryness of the sample before the subsequent deposition i.e., to ensure that no droplets remained. [000199] After completion of the spray coating deposition, the sample was washed gently in acetone (or other alcohols) and dried.[000200] Spray coating of the complex 1 and complex 2 electrochromic complexes were also carried out with sulphate anions, using both Pd(PhCN)2Ch and PdChQ-PhSOsH^ linkers which produced the EC films of the present invention.[000201] Further examples of spray coating films are shown in Figures 20A-20F, Figures 21 A- 21F and Figures 22A-22D.EXAMPLE 6Synthesis of Water soluble Cl complexes[000202] The structures of a variety of water soluble complexes are shown in Figures 23 A-23F. The solubility of the complexes is tested in water for 1 mg of each complex in 10 mL of water, as shown in Figures 24A-24B.[000203] Synthesis of Fe-3arms-Cl: A solution of ligand (1 mmol, 3 eq.) in MeOH (5 mL) was added to a solution of the FeC12.4H2O (0.33 mmol, 1 eq.) in MeOH (1 mL). The solution was then stirred for 30 min, with occasional warming to 50 °C (every 10 min). After that, the solventwas removed by rotary evaporator, and excess diethyl ether was added. The formed precipitate was filtered and washed with excess diethyl ether (20 mL) and was dried under vacuum to result in the required complex.1H NMR (500 MHz, MeOD): 59.02 (bs, 3H), 8.83 (s, 3H), 8.60 (s, 6H), 7.86 (d, J= 16.2 Hz, 3H), 7.71 (d, J= 16.4 Hz, 12H), 7.62 - 7.48 (m, 3H), 7.37 (m, 6H), 2.66 (s, 9H). A schematic of the process is shown in Figure 25A.[000204] Synthesis of Ru-3arms-Cl: The synthesis of Ru-3arms-Cl was performed using the corresponding Ru-3arms-PF6 complex analog. Then the Ru-3arms-PFe complex (0.2 mmol) was dissolved completely in acetone (50 mL). Excess amount of tetrabutylammonium chloride (1.0 mmol) was dissolved separately in acetone (10 mL). These two-mixture are mixed properly and stirred for 1 h. Red color precipitate was observed which was filtered and washed properly by acetone followed by ether. 'H NMR (500 MHz, MeOD): 5 9.02 (s, 3H), 8.81 (s, 3H), 8.69 (d, J = 5.2 Hz, 6H), 7.89 (dd, J = 15.6, 7.9 Hz, 11H), 7.80 (s, 3H), 7.75 - 7.67 (m, 7H), 7.40 (d, J = 5.7 Hz, 3H), 2.65 (s, 9H). A schematic of the process is shown in Figure 25B.[000205] Synthesis of Os-3arms-Cl: The synthesis of Os-3arms-Cl was performed using the corresponding Os-3arms-PF6 complex analog. Then the Os-3arms-PFe complex (0.2 mmol) was dissolved completely in acetone (50 mL). Excess amount of tetrabutylammonium chloride (1.0 mmol) was dissolved separately in acetone (10 mL). These two-mixture are mixed properly and stirred for 1 h. Dark brown color precipitate was observed which was filtered and washed properly by acetone followed by ether. 'H NMR (500 MHz, MeOD): 5 9.04 (d, J= 3.9 Hz, 3H), 8.81 (d, J= 3.9 Hz, 3H), 8.77 (d, J= 5.4 Hz, 6H), 8.14 (d, J= 5.4 Hz, 6H), 7.94 (d, J= 5.9 Hz, 5H), 7.89 - 7.77 (m, 4H), 7.67 - 7.55 (m, 6H), 7.34 (d, J= 6.2 Hz, 3H), 2.75 (s, 9H). A schematic of the process is shown in Figure 25C.[000206] Synthesis of Fe-6arms-SB-Cl: A solution of ligand (1 mmol, 3 eq.) in MeOH (5 mL) was added to a solution of the FeC12.4H2O (0.33 mmol, 1 eq.) in MeOH (1 mL). The solution was then stirred for 4 h. After that, the solvent was removed by rotary evaporator, and excess diethyl ether was added. The formed precipitate was filtered and washed with excess diethyl ether (20 mL) and was dried under vacuum to result in the required complex. 'H NMR (500 MHz, MeOD): 5 8.62 (s, 1H), 8.41 (d, J= 5.2 Hz, 2H), 7.37 - 7.30 (m, 3H), 7.20 (d, J= 5.8 Hz, 1H), 3.29 - 3.23 (m, 2H), 3.20 - 3.13 (m, 2H). A schematic of the process is shown in Figure 25D.[000207] Synthesis of Fe-6arms-DB-Cl: A solution of ligand (1 mmol, 3 eq.) in MeOH: DCM (1 : 1, 5 mL) was added to a solution of FeCLA^O (0.33 mmol, 1 eq.) in MeOH (1 mL). The solution was then stirred for 30 min, with occasional warming to 50 °C (every 10 min). After that, the solvent was removed by rotary evaporator, and excess diethyl ether was added. The formed precipitate was filtered and washed with excess diethyl ether (20 mL) and was driedunder vacuum to result in the complex with the counter anion of Cl.1H NMR (500 MHz, MeOD): 5 9.20 (s, 6H), 8.63 (s, 12H), 7.91 (d, J = 16.4 Hz, 6H), 7.72 (dd, J= 21.8, 10.6 Hz, 24H), 7.63 (d, J= 6.0 Hz, 6H). A schematic of the process is shown in Figure 25E.[000208] Synthesis of Fe-6arms-TB-Cl: A solution of ligand (1 mmol, 3 eq.) in MeOH: DCM (1 : 1, 15 mL) was added to a solution of FeCLAftO (0.33 mmol, 1 eq.) in MeOH (1 mL). The solution was then stirred for 4 h. After that, the solvent was removed by rotary evaporator, and excess diethyl ether was added. The formed precipitate was filtered and washed with excess diethyl ether (20 mL) and was dried under vacuum to result in the complex with the counter anion of Cl. 'H NMR (500 MHz, MeOD): 5 9.09 (d, J= 0.7 Hz, 6H), 8.68 (d, J= 4.7 Hz, 12H), 7.67 (dd, J= 15.4, 6.7 Hz, 24H). A schematic of the process is shown in Figure 25F.[000209] Figures 26A-26D show a Table representing the solubility of various complexes in different solvents with (“Y” = soluble, “N” = insoluble). The solutions tested were: water, methanol, ethanol, butanol, ethyl lactate, propylene carbonate, acetonitrile, and acetone. The Table shows the comparative solubility when using Cl" versus PFe counter ions for each complex (placed in a thick rectangular for convenience). For example, the Fe-3arm-Cl structure is soluble in water whereas the Fe-3arm-PFe structure is not. Thus, the solubility of the electrochromic complexes can be tuned by selecting the appropriate counter ion. Subsequently, electrochromic coatings and layers can be deposited using aqueous solvents (also mixed with green solvents).[000210] In one embodiment, the term “a” or “one” or “an” refers to at least one. In one embodiment the phrase “two or more” may be of any denomination, which will suit a particular purpose. In one embodiment, “about” or "approximately" may comprise a deviance from the indicated term of + 1 %, or in some embodiments, - 1 %, or in some embodiments, ± 2.5 %, or in some embodiments, ± 5 %, or in some embodiments, ± 7.5 %, or in some embodiments, ± 10 %, or in some embodiments, ± 15 %, or in some embodiments, ± 20 %, or in some embodiments, ± 25 %.[000211] Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations, and modifications can be made without departing from the scope of the presently disclosed subject matter, mutatis mutandis.

Claims

CLAIMS1. A method of producing an electrochromic (EC) film, the method comprising: providing a substrate; depositing at least one metal linker; depositing at least one metal-coordinated organic complex to form an electrochromic (EC) layer; repeating the depositing steps to obtain an EC film disposed on the substrate; wherein the at least one metal linker and / or the at least one metal -coordinated organic complex are comprised within solutions that comprise: water, green resins, or a combination thereof.

2. The method of claim 1 wherein the water is selected from: deionized water, ultra-pure water, distilled water, purified water, nanopore water, tap water, desalinated water, filtered water, or a combination thereof.

3. The method of claim 1 wherein said green resins are selected from: acrylonitrile butadiene styrene (ABS), polycarbonate, epoxy, nylon, PETG (polyester derived from glycol and terephthalic acid), lactic-acid (LA) resin, biopolymer and nylon.

4. The method of claim 1 wherein the EC film is continuous.

5. The method of claim 1 further comprising washing the layer, drying the layer or a combination thereof, after the depositing at least one metal linker, depositing at least one metal-coordinated organic complex, or a combination thereof.

6. The method of claim 1, wherein the at least one metal-coordinated organic complex comprises at least one functional group, the functional group capable of binding to the at least one metal linker.

7. The method of claim 6, wherein the binding comprises a coordination bond between the functional group and the metal linker.

8. The method of claim 1, wherein the at least one metal-coordinated organic complex is a polypyridyl complex.

9. The method of claim 1, wherein the depositing steps comprise any of the following selected from: roll-to-roll, spin coating, dip coating, spray coating, ultrasonic spray coating, drop casting, blade-coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) and Meyer bar coating or a combination thereof.

10. The method of claim 9 wherein said ultrasonic spray coating is conducted at an atomization pressure ranging between 0.75 kPa and 1.50 kPa and at a nozzle to substratedistance ranging between 3.0 and 8.0 cm, and at a spraying solution flow rate ranging between 0.4 and 0.8 mL / min.

11. The method of claim 10 further comprising said substrate being held at temperature ranging between 40 to 150 °C.

12. The method of claim 1 wherein the polypyridyl complex comprises one or more isomers of the same compound, or a mixture thereof.

13. The method of claim 12, wherein the isomers are enantiomers and wherein the polypyridyl complex comprises one or two enantiomers of the same compound or a mixture of the one or two enantiomers.

14. The method according to claim 8, wherein the spin coating step to deposit the at least one metal linker, the at least one metal-coordinated organic complex, or a combination thereof, has a first spin rate and a first spin time.

15. The method according to claim 14, wherein the first spin rate ranges between about 100 to about 2000 rpm.

16. The method according to claim 14, wherein the first spin time ranges between about 0.3 sec to about 60 sec.

17. The method according to claim 14, wherein the spin coating step to deposit the at least one metal linker, the at least one metal-coordinated organic complex, or a combination thereof, further comprises a second spin rate and a second spin time.

18. The method according to claim 17, wherein the second spin rate ranges between about 200 to about 5000 rpm.

19. The method according to claim 17, wherein the second spin time ranges between about 1 second to about 240 seconds.

20. The method according to claim 4, wherein the washing is carried out with any of the following selected from: water, alcohols, ethers, esters, hydrocarbons, ketones, or a combination thereof.

21. The method according to claim 1, wherein both depositing steps are repeated between about 2 to about 80 times.

22. The method according to claim 1, wherein the metal of the at least one metal linker is selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y.

23. The method of claim 1 wherein the at least one metal linker is selected from ISfePdCU,(SO3H-3-Py)2Pd(Cl)2.

24. The method of claim 1 wherein the at least one metal linker comprises any of the following selected from: 3 -pyridinesulfonic acid, 2-pyridinesulfonic acid, 4-pyridinesulfonic acid, 2- pyridinecarboxylic acid; 3 -pyridinecarboxylic acid; 4-pyridinecarboxylic acid; 2- pyridinephosphonate; 3 -pyridinephosphonate; 4-pyridinephosphonate.

25. The method according to claim 8, wherein the polypyridyl complex is represented by Formula I:whereinM is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh,Os or Ir; n is the formal oxidation state of the transition metal, wherein n is 0-6;X is a counter ion selected from (NCh)' and (SC )2'; m is a number ranging from 0 to 6;Ri to Ri8 each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R2O)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, - (C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, - O-(Ci-C8)alkyl, -CON(R20)2, or -SO3H;Ai to Ae each independently is a group of Formula III, selected from a pyridine or pyridine derivative moiety, or of Formula IV, selected from pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula I via R19R19 each independently is selected from a covalent bond, C-C, C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, - Si(R2o)2-, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,or 'Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, - (C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, - O-(Ci-C8)alkyl, -CON(R20)2, or -SO3H; andR2O each independently is H, (Ci-Ce)alkyl, or aryl.

26. The method according to claim 8, wherein the polypyridyl complex is represented by Formula II:wherein n is the formal oxidation state of Fe, wherein n is 0-6;X is a counter ion selected from (NCh)" and (SC )2";m is a number ranging from 0 to 6;Ri to Ris each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R2O)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, - (C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R20)2, or -SO3H;Ai, A3, and A5 each independently is a group of Formula III, selected from a pyridine or pyridine derivative moiety, or of Formula IV, selected from pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula II via R19R19 each independently is selected from a covalent bond, C-C, cis / trans C=C, C=C, N=N, C=N, N=C, C-N, N-C, -COO-, -CONH-, -CON(OH)-, -NR20-, -Si(R20)2- an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,Rxand Ryeach independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, - (C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR2o, -COR2o, -COOR2o, -OCOOR2o, - OCON(R20)2, -(Ci-C8)alkylene-COOR20, -CN, -N(R20)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R20)2, or -SO3H;Bi to B3 each independently is selected from H, halogen, -OH, -N3, -NO2, -CN, - N(R20)2, -CON(R20)2, -COOR20, -SR20, -SO3H, -CH=CH-pyridyl, -(Ci-Cio)alkyl, -(C2-Cio)alkenyl, -(C2-Cio)alkynyl, -(Ci-Cio)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (Ci-Cio)alkyl, (C2-Cio)alkenyl, (C2-Cio)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, -OR20, -COR20, -COOR20, -OCOOR20, - OCON(R2O)2, -(Ci-C8)alkylene-COOR2o, -CN, -N(R2o)2, -NO2, -SR20, -(Ci-C8)alkyl, -O-(Ci-C8)alkyl, -CON(R2o)2, or -SO3H; andR20 each independently is H, (Ci-Ce)alkyl, or aryl.

27. The method according to claim 1, wherein the substrate comprises any of the following selected from: glass, doped glass, metal -oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si(l l l), SiCh, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, carbon-based materials, graphene, carbon nanotubes, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically-conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminium or any combination thereof.

28. The method of claim 27 wherein the polymer is selected from: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyacrylamide (PAM), polystyrene (PS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate glycol-modified (PETG), polyimide (PI), polyester elastomers, polymethyl methacrylate (PMMA) or any combination thereof.

29. The method of claim 1, wherein the concentration of the at least one metal linker in the corresponding the aqueous solution and / or the concentration of the metal -coordinated organic complex in the corresponding aqueous solution ranges between 0.1 mM and 10 mM.

30. The method of claim 1 wherein the aqueous solutions further comprise a water-miscible solvent.

31. The method of claim 1 wherein the water-miscible solvent selected from: acetaldehyde, acetic acid, acetone, acetonitrile, 1,2-butanediol, 1,3 -butanediol, 1,4-butanediol, 2- butoxyethanol, butyric acid, diethanolamine, diethylenetriamine, dimethoxyethane, dimethylformamide, 1,1 -dimethylhydrazine, 1,2-dimethylhydrazine, dimethyl sulfoxide, 1,4-di oxane, ethanol, ethylamine, ethylene glycol, formic acid, furfuryl alcohol, glycerol, methanol, methyl diethanolamine, methyl isocyanide, N-methyl-2-pyrrolidone, 1 -propanol,1,3-propanediol, 1,5-pentanediol, 2-propanol, propanoic acid, propylene glycol, pyridine, sulfolane, tetrahydrofuran andtri ethylene glycol, or any combination thereof.

32. The method of claim 1 wherein the aqueous solutions further comprise at least one solvent selected from: acetone, ethanol, methanol, 2-propanol, ethyl acetate, isopropyl acetate, methyl ethyl ketone, 1 -butanol, tert-butanol, supercritical carbon dioxide (scCCh), limonene, propylene carbonate, formic acid, gamma-valerolactone (GVL) and ionic liquids, or any combination thereof.

33. The method of claim 4 wherein the drying is selected from: stream of air, stream of nitrogen, heating and vacuum drying, or a combination thereof.

34. An electrochromic device comprising: the substrate and electrochromic (EC) film produced by the method of claim 1; an electrolyte disposed on the EC film; an ion storage layer; and a counter electrode in contact with the ion storage layer; wherein the electrolyte is disposed between the EC film and the ion storage layer.

35. The device of claim 34 wherein said electrolyte is selected from: ACN / PC / PMMA / trifluoromethylsulfonamide lithium salt, polymethyl methacrylate (PMMA), propylene carbonate (PC), LiCFsSCE, LiBF4, Li2+2xZ -xGeO4 (LiSICON), glassy lithium phosphorus oxynitride (LIPON) and LiCICh or any combination thereof.

36. The device of claim 34 wherein said ion storage layer comprises any of the following selected from: polymers, copolymers, metal-organic polymer, coordination polymer, molecular film, metallic coating, transparent conducting oxides, metal oxides, metal fluorides, metal nitrides, metal sulfides, nanocrystalline metal oxides, mixed metals oxides, redox-active species, carbon-based materials, graphene-based materials, buckminsterfullerenes, nanotubes, 2D materials, biomolecules, nanowires, polymethyl methacrylate (PMMA), benzocyclobutene (BCB) based polymers, poly(3,4- ethylenedioxythiophene), poly(styrenesulfonate), conjugated dithiolenes, polyelectrolytes, organic salts, inorganic salts, quinone-based compounds, viologen-based compounds, antimony-doped tin oxide (ATO), pyridine blue (PB), polyaniline, polypyrrole, lithium cobalt oxide, lithium cobalt oxide, indium tin oxide, fluorine doped tin oxide, niobium oxide, molybdenum oxide, zinc oxides, aluminum oxide, nickel oxides, ceric oxide, metal doped nickel oxides, lithium doped nickel oxides, lithium doped titanium oxides, polymetal oxides, nanoparticles, metallic nanoparticles, nickel hexacyanoferrate, iron hexacyanoferrate, lithium hexacyanoferrate, sodium hexacyanoferrate, manganesehexacyanomanganate, halogen-doped metal oxides, lithium sulfide, lithium garnet, lithium phosphorous oxynitride, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, sodium nickel chloride and activated carbon.

37. The device of claim 34 wherein said counter electrode comprises any of the following selected from: glass, doped glass, metal -oxide, indium tin oxide (ITO)-coated glass, fluorine-doped tin oxide (FTO)-coated class, silicon, doped silicon, zinc oxide (ZnO), Si(100), Si(l l l), SiCh, SiH, silicon carbide mirror, quartz, metal, metal oxide, mixture of metal and metal oxide, group IV elements, mica, graphite comprising intercalated metal cations, polymer, plastic, zeolite, clay, membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically-conductive material, semiconductor, steel, and stainless steel, gold, silver, platinum, copper, zinc, aluminium or any combination thereof.

38. The electrochromic device of claim 34 further comprising a lamination.

39. An electrochromic device system comprising; the electrochromic (EC) device of claim 34; at least one sensor configured to detect an optical state; a power supply; and a controller configured to control the colored state of the EC device by means of an applied potential; wherein the controller and the power supply are configured to apply a bias potential across the EC film thereby inducing at least one change in the optical state of the EC film and wherein the at least one sensor is configured to communicate the optical state to the controller.

40. The system of claim 39 configured such that the EC device is in a bleached state when a bias potential is applied.

41. The system of claim 40 wherein the applied potential for the bleached state ranges between 0.1 to 10 V.

42. The system of claim 39 wherein at least one sensor is an electro-optic sensor.

43. The system of claim 39 wherein at least sensor is selected from: photodetector, photodiode, phototransistor, photomultiplier tube (PMT), spectrophotometer, reflectance spectrometer, transmittance spectrometer, colorimeter, color sensor, UV-vis spectrophotometer, UV sensor, infrared sensor, image sensor, complementary metal -oxide semiconductor (CCD) sensor, charge-coupled device (CCD) sensor, polarimeter, photoluminescence sensor, fluorescence sensor, optical sensor, ammeter, voltmeter, ohmmeter, multimeter,potentiometer, galvanometer, magnetometer, hall effect monitor and light dependent resistor (LDR), or a combination thereof.

44. A metal -based complex represented by a compound of Formula VIII:whereinA and A' are each independently a nitrogen binding, single or fused, 5-10 membered heteroaromatic ring, or a single or fused, 5-10 membered aromatic ring, which comprises at least one metal binding group, covalently bound to the ring;L and L' are each independently an anionic ligand;M is Pd, Pt, Cu, Zn, Fe, or Ru;LI and LI' are each independently absent, or are metal binding groups, covalently bonded to the A and A' rings respectively, wherein if LI and / or LI' are absent then ring A and / or A' are heteroaromatic; n, m are each independently an integer number between 1-5;W and Ware each independently water soluble groups; andR is linear, branched or cyclic.

45. The metal-based complex of claim 44 wherein the A and A' are selected from: pyridine, pyrimidine, pyrazine, pyridazine, imidazole, pyrrole, quinoline, oxazole and indole.

46. The metal-based complex of claim 44 wherein the L and L' are selected from: Cl, Br, I, [NCh]', [SO4]2’, [PO4]2', [PFe]', [BF4]', tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (= BARF), borane anions and [B(R)4]'.

47. The metal-based complex of claim 44 wherein the W and W' are selected from: SO3H, COOH, PO(OR)2, NHC(O)H, NHC(O)R, NH2, NH(R), N(R)2, C(O)NH2, C(O)NH(R), SO2-NH2, SO2-NH(R), SO2-N(R)2, CN and NO2.

48. The metal-based complex of claim 44 wherein the R is a selected from a C1-C8 alkyl group.

49. The metal-based complex of claim 44, represented by the structure of Formula V:whereinXi, X2, X3, X4, X5, Xe, X7, Xs, X9 and X10 are each independently a carbon atom or nitrogen atom; wherein at least one of Xi, X2, X3, X4 and X5 is carbon; and wherein at least one of Xe, X7, Xs, X9 and X10 is carbon.

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