Rare-earth free photoluminescent organic / inorganic hybrid material for application in LED lighting and as product marker

Abstract

Rare-earth free photoluminescent organic / Inorganic hybrid material for application in LED lighting and as product marker It relates to organic / inorganic hybrid material, which is the reaction product of a mixture of the following organic and inorganic precursor materials: a) a first organic and a second organic compound and a inorganic powder comprising at least one of the following compounds: specific metal chalcogen, metal halide, and P2O5; their preparation processes, their use as a light converter in white light emitting diodes (wLEDs), specifically for white light extraction in reflection mode; as a product marker / taggant, or as fluorescent marker in plastic sorting; as well as light emitting devices comprising them.

Description

[0001] Rare-earth free photoluminescent organic / lnorganic hybrid material for application in LED lighting and as product marker

[0002] This application claims the benefit of European Patent Application EP24192095 filed on July 31st, 2024.

[0003] Technical Field

[0004] The present invention relates to organic / inorganic hybrid materials, their preparation processes and their use as a light converter in white light emitting diodes (wLEDs). These materials can also be useful as a product marker in security inks, security papers, and as product markers for product sorting purposes.

[0005] Background Art

[0006] Photoluminescence is a process by which a material emits light of longer wavelength after absorbing higher energy radiations. Photoluminescent material, which is referred as a phosphor, has dominated the lighting industry since the introduction of energy saving fluorescence tubes but this particular light source has now been banned in many countries because they contain toxic mercury.

[0007] Light emitting diodes (LEDs) are semiconductor light emitters being the colour of the light produced dependent on the type of semiconductor material used in its manufacture. LEDs have taken centre stage as standard light sources. Unfortunately, current single LED chips do not directly emit white light. To achieve white light, either three red, green and blue (RGB) LED chips are combined or, alternatively, blue / UV LEDs are coated with a single or combination of phosphors. The former method of using RGB LEDs is expensive, hence, the use of phosphor converters is the most viable commercial method of producing white LEDs (wLEDs).

[0008] A phosphor absorbs radiation energy in a portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum. By interposing a phosphor excited by the radiation generated by the LED, light of a different wavelength may be generated. A combination of LED generated light and phosphor generated light may be used to produce white light. Specifically, blue emitting chips may be coated with a phosphor that converts some of the blue radiation to a complementary colour, e.g. a yellow-green emission. Thus, in wLEDs, the blue light from the LED excites the phosphor, which then emits light across the spectrum, combining to produce white light.

[0009] White LEDs are used in various applications including general lighting, automotive headlights, displays, backlighting for screens, medical devices, and more due to their efficiency, durability, and versatility.

[0010] The main problem is that the LED phosphors available in the market contain rare-earth elements which are facing supply risks, and their production also pollutes the environment. The LED phosphors are also synthesized at extreme temperature of above 1000 °C. Additionally, the current standard Cerium dopped Yttrium Aluminium Garnet (YAG:Ce) do not emit enough red light. For this reason, another rare-earth red emitting phosphor is always added in order to form warm white light. This also increases the cost of production. Another common problem of the phosphor of the prior art consisting of organic dyes is that they undergo photobleaching with continuous illumination.

[0011] Several phosphor compounds based on inorganic-organic structures have been disclosed in the art. For instance, Pangkuan Chen et al.; in “White Light Emitting Lanthanide Metal logels with Tunable Luminescence and Reversible Stimuli-Responsive Properties”, J. Am, Chem. Soc.2015, 137, 11590 discloses the use of materials based on metal-ligand coordination, more precisely, lanthanide metal -ligand (M-L) coordination complexes via a terpyridyl end-capped 4-Arm PEG polymer. According to the document these compounds are highly luminescent, and they emit white light. Furthermore, these compounds provide a broad variety of reversible stimuli- responsive properties (mechano-, vapo-, thermos-, and chemochromism).

[0012] W02009 / 120716A1 discloses a crystalline hybrid structure with repeating units comprising two organic ligand layers and a semiconducting inorganic double layer (ll-VI chalcogenide compound) sandwiched between them that can be used in semiconductor devices and lightemitting devices as they possess semiconducting properties and are capable of generating white light directly when used as a phosphor in light emitting diodes (LEDs).

[0013] The inorganic layer consists of two single-atom-thick layers. The organic layers are attached through covalent or coordinate covalent bonds to the inorganic layer, forming ordered crystal lattices. The ll-VI chalcogenide compound can be Cd or Zn with S, Se, or Te. Organic ligand layers include organic amines or diamines such as 1-ethylamine, aniline, and 4,4-bispyridine.

[0014] Yun, Xiangyan et al.; in “High-quality white photoluminescence of zero-dimensional hybrid metal halides with multiple optical polyhedral units”, Journal of Luminescence (2024), 268, 120379 discloses an organic-inorganic hybrid compound which is a zero-dimensional binary halide (TEA)2(MnCl4)i-x (SbCls)x (TEA+= tetraethylammonium, CsH2oN+) realizing warm white emission.

[0015] Finally, WO2016 / 058553A1 discloses a non-conjugated polymer composed of an oxygenic polymer capable of exhibiting fluorescence despite lacking conjugation. This polymer possesses luminogenic properties, enabling it to emit light. Clusters of carbonyl groups on its monomers form a chromophore that emits red light. This polymer can detect amines when introduced to a sample which is indicated by the formation of purple aggregates. This occurs due to the clustering of electron-rich atoms, such as carbonyl groups, within the polymer, forming a chromophore known as a clusteroluminogen. These clusters allow the polymer to emit light without requiring a conjugated system.

[0016] Despite from what is known in the art, there is still the need of finding new phosphors showing high intensity, high stability, and long lifetime, to be used in wLEDs, security inks, or product markers.

[0017] Summary of Invention

[0018] The present inventors have found a photoluminescent material which is rare-earth free broadband yellow emitting phosphor that produces a higher proportion of red-light component (600-700 nm maximum intensity), hence enabling conversion of blue LEDs directly to white LEDs (wLEDs) without relying on rare-earth element and which offer solutions to the above-mentioned problems. The material also emits yellow light under a wide range of UV radiations hence enabling its application in security inks.

[0019] The phosphor of the present invention is the result of the combination of three types of precursors that are non-toxic, readily available, and cheaper compared to the rare-earth elements. In addition, it is characterized by good thermal and photostability. These two critical properties have hindered the use of traditional organic dyes and other alternatives such as perovskites, quantum dots, and metal-organic-frameworks in many practical applications like solid-state lighting. In addition, these materials do not undergo bleaching.

[0020] The photoluminescence in the formed product of the present invention occurs due to a phenomenon referred to as clusteroluminescence. This enhances through space conjugation as opposed to through bond conjugation in traditional fluorophores. Clusteroluminogens are therefore suitable for solid state applications such as lighting where traditional conjugated fluorophores would suffer from aggregation induced quenching. Conversely, the phosphor of the present invention provides a light extraction in reflection mode that minimizes thermal quenching of the photoluminescent material when used as light converter in wLEDs.

[0021] Thus, the phosphor of the present invention can be used as light converter in white light emitting diodes (wLEDs) and can be useful in various lighting and display technologies.

[0022] It can also be used as a product marker for example in security inks, security papers, or for product sorting purposes. Accordingly, an aspect of the present invention relates to a phosphor material which is a photoluminescent organic / inorganic hybrid material, which is the reaction product of a mixture of the following organic and inorganic precursor materials: a) a first organic compound selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic) below, where: Ri is selected from the group consisting of -CH3, -OH, -COOR3, NH2 and -OOCR3; R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from -COOR3, -OOCR3, -COOR3-R4, and -OOCR3-R4; R3 is a linear, branched, or cyclic, saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; and R4 is selected from the group consisting of, mercapto, hydroxyl, alkene, and phosphoryl; where: the compound of formula (la) is a (Ci-Cw)-alkyl ester of citric acid; the compound of formula (lb) is a (Ci-Cio)-alkyl ester of pentaerythritol with an amino, mercapto, hydroxyl or alkene as end groups; and the compound of formula (Ic) is a (Ci-Cio)-alkyl linear or branched alkyl ester of an acid selected from malonic acid, succinic acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, with at least two ester groups;

[0023] (la) (lb) (Ic) b) a second organic compound which is either a linear or a branched structure of formula X- (Rs)m-(OR6)n-X (II); where: Rs is linear, branched, or cyclic, saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; Rs is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer which is 0 or 1 ; n is an integer ranging from 1 to 10.000, in particular from 2 to 10.000; X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl, an aldehyde, phosphoryl, and Boc-protected amino group; wherein the compound of formula (II) is either a compound of formula (Ila) wherein: R? is an amino group; Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4;

[0024] (Ila), or a compound of formula (lib) wherein: R9 is an amino group; and Rwis a side chain of a common amino acid; R9-CHR10-COOH (lib); and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5 (V); where: M is a metal which is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV), and c6) a glass frits (powder); and c7) mineral sand (zircon sand); and which is obtainable by a process which comprises subjecting a mixture of the organic and inorganic precursor materials to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; heating with or without condensation step; and mixing at room temperature.

[0025] The new rare-earth free phosphor in this invention can be produced from a single step reaction conducted at moderate temperatures using non-fluorescent mixture of organic and inorganic precursor materials that are non-toxic, readily available, and also cheaper compared to the rare- earth elements. The processes are advantageous because the reactants react without catalyst and without solvent, and without generating wastes, being environmentally friendly.

[0026] Thus, a second aspect of the present invention relates to a process for preparing the photoluminescent organic / inorganic hybrid material as defined above, which comprises submitting a mixture of the following organic and inorganic precursor materials: a) a first organic compound selected from a compound of formula (la), a compound of formula (lb), and a compound of formular (Ic), where: Ri is selected from the group consisting of -CH3, -OH, - COOR3, NH2 and -OOCR3; R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from -COOR3, -OOCR3, - COOR3-R4, and -OOCR3-R4; R3is a linear, branched, or cyclic, saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; and R4 is selected from the group consisting of, mercapto, hydroxyl, alkene, and phosphoryl;

[0027] (la) (lb) (Ic) wherein: the compound of formula (la) is a (Ci-Cio)-alkyl ester of citric acid, the compound of formula (lb) is a (Ci-Cio)-alkyl ester of pentaerythritol with a mercapto, hydroxyl or alkene as end groups; the compound of formula (Ic) is a (Ci-C2o)-alkyl linear or branched alkyl ester of an acid selected from malonic acid, succinic acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, with at least two ester groups; preferably (Ci-C2o)-alkyl linear or branched alkyl ester. b) a second organic compound which is either a linear or a branched structure of formula X- (Rs)m-(0R6)n-X (II); where: Rs is a linear, branched, or cyclic saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; Re is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1; n is an integer ranging from 2 to 10.000; X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and Boc-protected amino group; wherein: the compound of formula (II) is either a compound of formula (Ila), wherein: R? is an amino group, Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4, or a compound of formula (lib):

[0028] R9-CHR10-COOH

[0029] (Hb) wherein:Rg is an amino group; R10 represents side chains in common amino acids; and and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5 (V); where: M is a metal which is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); c6) a glass frits (powder) and c7) mineral sand (zircon sand); to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; heating with or without condensation step; and mixing at room temperature. Another aspect of the present invention relates to their applications as light converter in white light emitting diodes (wLEDs); specifically for white light extraction in reflection mode. It minimizes thermal quenching of the photoluminescent material when used as light converter in wLEDs. In addition, it can be used as a product marker, for example in security inks, security paper, or for product sorting purposes.

[0030] Another aspect of the present invention relates to a light emitting device for remote extraction of white light from blue / UV LEDs through reflection mode which comprises: a) a LED chip (1) to generate blue or UV light; b) a curved reflecting surface (3) to reflect light on to the phosphor coated curved surface and to redirect the light to the exit surface; c) optionally, a reflecting surface in form of an inverted pyramid or cone shape (6) and its support (7) to redirect LED light onto the curved surface; d) a phosphor (4) as defined above coated onto the reflective surface, which is configured to absorb blue or UV light emitted from the LED, and with the ability to emit light having a wavelength different from the absorbed light in the red, green and blue regions of the spectrum which combine to produce white light; and d) a transparent / translucent light diffusing cover (5).

[0031] Brief Description of Drawings

[0032] FIG. 1 XRD diffractogram for a more amorphous sample (a) and a more crystalline sample (b). (c) visualized structures done using Vesta software.

[0033] FIG. 2 shows the Mid Infra-red (IR) and NIR spectrum of sample LMS 05.

[0034] FIG. 3 shows photoluminescent spectra of the organic / inorganic product of the current invention in comparison with the YAG:Ce phosphor. The emission spectra are normalized with respect to the maximum intensity when excited at 470 nm. The full width at half maximum (FWHM) is slightly greater at 119 nm against that of YAG:Ce which is 113 nm. The spectrum of the product of the current invention is also red shifted by 20 nm in comparison to that of YAG:Ce. The intensity of the yellow and red components of the emitted light at wavelength of 600 nm and 625 nm is at 80 % and 60 % of the maximum intensity which is greater than that of the YAG:Ce by about 10% and 15% respectively.

[0035] FIG. 4 shows photoluminescence spectra of the prepared samples labelled LMS 01, LMS 02, LMS 03, LMS 04 and LMS 05 for excitation wavelengths of 312 nm (UV-B), 365 nm (UV A) and 470 nm (blue). At excitation of 470 nm, the emission intensity of the red component at 625 nm is between 40 % to 70% of the maximum intensity and the full width at half maximum (FWHM) is between 100-130 nm for all the samples. FIG. 5 shows photoluminescence spectra of the prepared samples labelled LMS 06, LMS 07 and LMS 08, LMS 09, LMS 10, LMS 11 , LMS 12, LMS 13 and LMS 14 for excitation wavelengths of 312 nm (UV-B), 365 nm (UV A) and 470 nm (blue).

[0036] FIG. 6 shows photoluminescence spectra recorded as the reaction of the precursor materials proceeds at room temperature.

[0037] FIG. 7 shows self-healing properties of the sample demonstrated by taking photos of the sample at specific time intervals after a hole is made on its surface.

[0038] FIG. 8 shows ESI mass spectrometry data for the selected samples.

[0039] FIG. 9 shows image showing printed invisible QR code under natural light and UV light

[0040] FIG. 10 shows the integrated photoluminescence emission of the organic / inorganic hybrid material as a function temperature. Notably, the phosphor still retains up to 80 % of the emission at 120 °C. Operating temperature of most LED is around 80 °C.

[0041] FIG. 11 shows the test for photostability. The sample was continuously illuminated with UV light of wavelength 340 nm and emission above 500 nm was recorded after every 5 hours a total duration of 920 hours, (a) show the integrated emission a function of illumination time, (b) Spectra of the emission at the start and at the end of the test.

[0042] FIG. 12 shows the spectrum of white light emitted after coating a blue LED (470 nm) with our photoluminescent (phosphor material).

[0043] FIG. 13 shows the spectrum of the white light emitted after coating a near UV LED (430 nm) with our photoluminescent (phosphor material).

[0044] FIG. 14 shows a lighting for remote extraction of white light from blue / UV LEDs through reflection mode. The device comprises: LED driver 1 and thermal management, LED chip 2, curved reflecting surface 3, phosphor coated onto the reflective surface 4, transparent / translucent light diffusing cover 5, inverted pyramid shape with apex facing down and all outer surfaces being reflective 6, support for the pyramid / cone 7, extracted white light 8.

[0045] FIG. 15 shows a lighting for remote extraction of white light from blue / UV LEDs through reflection mode, which comprises curved surface 10, curved reflecting surface 3, phosphor coated onto the reflective surface 4, LED chip 2, light from the LED chip 9, a beam of white light 8, LED and thermal management (heat sink) 1, and transparent / translucent light diffusing cover 5. Detailed description of the invention

[0046] All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the art. Other more specific definitions for certain terms as used in the present application are as set forth below and are intended to apply throughout the description and claims.

[0047] As used herein, the indefinite articles “a” and “an” are synonymous with “at least one” or “one or more.” Thus, as used herein, the singular forms ”a”, “an”, and also the definite article “the” include plural referents unless the context clearly dictates otherwise”.

[0048] As used herein, the terms “comprise”, “comprises”, “comprising”, “include”, “includes”, and “including” are meant to be non-limiting, i.e., they are used to specify the presence of the stated components but do not preclude the presence of additional components, unless the contrary is specifically stated. These terms also include the term “consisting essentially of” or “consisting of’.

[0049] Unless indicated otherwise, the percentages (%) used in the present description refer to weight percentages (weight / weight, w / w).

[0050] The term room temperature (RT) as used herein refers to room temperature, which is in a range between 20°C and 25°C.

[0051] Light emitting diodes (LEDs) are semiconductor light emitters often used as a replacement for other light sources, such as incandescent lamps. The colour of light produced by an LED is dependent on the type of semiconductor material used in its manufacture. WLEDs generate white light by using a blue LED chip to excite phosphors, which then emit yellow or red light. This combined emission produces the desired white light.

[0052] The term “thermal quenching” as used herein refers to the phenomenon that can affect the performance of white light-emitting diodes (WLEDs), particularly impacting their efficiency and lifespan. It refers to the decrease in light output of a WLED as its temperature increases. The decrease in light output due to thermal quenching may affects the brightness and efficacy of WLEDs and can also impact their colour stability. As the temperature affects the blue and phosphor-converted components differently, the colour of the emitted light might shift as well.

[0053] The term “photobleaching” as used herein refers to the degradation or deterioration of the phosphor materials used in these LEDs due to prolonged exposure to intense light. While closely related to thermal quenching, photobleaching specifically involves the chemical breakdown or change in the physical properties of the phosphors, leading to a permanent reduction in light output and colour shift over time.

[0054] The term “photostability” refers to the ability of the components within the WLED, especially the phosphors, to resist degradation or alteration due to exposure to light over time.

[0055] As mentioned above, the phosphor material of the present invention is a photoluminescent organic / inorganic hybrid material, which is the reaction product of a mixture of the following organic and inorganic precursor materials: a) a first organic compound independently selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic), below,

[0056] (la) (lb) (Ic) where: Ri is selected from the group consisting of -CHs, -OH, -COOR3, NH2 and -OOCR3; R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from -COOR3, -OOCR3, COOR3-R4, and -OOCR3-R4; R3 is a linear, branched, or cyclic saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; and R4 is selected from the group consisting of, mercapto, hydroxyl, alkene, and phosphoryl; wherein: the compound of formula (la) is a (Ci-Cio)-alkyl ester of citric acid; the compound of formula (lb) is a (Ci-Cio)-alkyl ester of pentaerythritol with a mercapto, hydroxyl or alkene as end groups; and the compound of formula (Ic) is a (Ci-Cw)-alkyl linear or branched alkyl ester of an acid selected from malonic acid, succinic acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, with at least two ester groups preferably (Ci-C2o)-alkyl linear or branched alkyl ester; b) a second organic compound which is either a linear or a branched structure of formula X-(Rs)m-(OR6)n-X (II); where: Rs is a linear, branched, or cyclic, saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms Rs is an alkyl group having 2- 4 linear or branched carbon atoms; m is an integer selected from 0 and 1 ; n is an integer ranging from 1 to 10.000; X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and Boc-protected amino group; wherein the compound of formula (II) is a compound of formula (Ila)

[0057] (Ha) wherein: R? is an amino group, Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4, or a compound of formula (lib): R9-CHR10-COOH, wherein: R9 is an amino group, and R10 is a side chain of a common amino acid; and c) a inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5 (V); where: M is a metal which is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); c6) a glass frits (powder); and c7) mineral sand (zircon sand).Boc means t-butoxycarbonyl protective group.

[0058] The chalcogen is selected from the following list: oxygen (O), sulphur (S), selenium (Se), and tellurium (Te).

[0059] The halogen is selected from the following list: Florine (F), Chlorine (Cl), Bromine (Br), and Iodine (I).

[0060] The metal with valency 2, 3, or 4 can be any of Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Ir, Zn, Cu, Al, Pt, Pd, Sn, Cr, Mn, Fe, Co, and Ni.

[0061] The phosphor material of the present invention is a powder, a paste or a gel. In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the first organic compound is either a compound of formula (la), or a compound of formula (la) and (Ic). In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the compound of formula (la) is selected from trimethyl citrate, triethyl citrate, tributyl citrate, triethyl acetyl citrate, and tributyl acetyl citrate.

[0062] In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the compound of formula (lb) is selected from pentaerythritol-tetraacrylate, trimethylolpropantriacrylate, pentaerythritol-tetrakis(3-mercaptopropionate), and trimethylolpropan-tris(3-mercaptopropionate)

[0063] In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the organic compound of formula (Ic) is selected from dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl sebacate, diethyl malonate, diethyl succinate, diethyl glutarate, diethyl adipate, diethyl pimelate, diethyl suberate, diethyl sebacate, dipropyl succinate, dipropyl glutarate, dipropyl adipate, dipropyl pimelate, propyl butyl pimelate, dipropyl suberate, dipropyl sebacate, dibutyl malonate, dibutyl succinate, dibutyl glutarate, dibutyl adipate, dibutyl pimelate, dibutyl suberate, and dibutyl sebacate; diethylmehoxymethylene malonate, diethyl 2-(2-cynoethyl) malonate, ethyl 2-(ethoxymethylene) acetoacetate, diethyl aminomethylene malonate, and ethyl 2-cyano -3- ethoxyacrylate, glyceryl triacetate.

[0064] In another particular embodiment, the organic / inorganic hybrid material as defined above is that where the (Ci-Cio)-alkyl ester of citric acid is selected from the group consisting of trimethyl citrate, triethyl citrate, triethyl acetyl citrate, tributyl citrate, and tributyl acetyl citrate; the (C1-C10)- alkyl linear or branched alkyl ester of an organic acid with at least two ester groups is selected from the group consisting of dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl sebacate, diethyl malonate, diethyl succinate, diethyl glutarate, diethyl adipate, diethyl pimelate, diethyl suberate, diethyl sebacate, dipropyl succinate, dipropyl glutarate, dipropyl adipate, dipropyl pimelate, propyl butyl pimelate, dipropyl suberate, dipropyl sebacate, dibutyl malonate, dibutyl succinate, dibutyl glutarate, dibutyl adipate, dibutyl pimelate, dibutyl suberate, and dibutyl sebacate; diethylmehoxymethylene malonate, diethyl 2-(2-cynoethyl) malonate, ethyl 2-(ethoxymethylene) acetoacetate, diethyl aminomethylene malonate, ethyl 2-cyano -3- ethoxyacrylate, glyceryl triacetate; diethylmehoxymethylene malonate, diethyl 2-(2-cynoethyl) malonate, ethyl 2-(ethoxymethylene) acetoacetate, diethyl aminomethylene malonate, ethyl 2-cyano -3- ethoxyacrylate, glyceryl triacetate; and the pentaerythritol derived esters with thiol, hydroxyl or alkene as end group is pentaerythritoltetra kis(3-mercarptopropionate, trimethylolpropantriacrylate, and trimethylolpropan-tris(3-mercaptopropionate.

[0065] In another particular embodiment, the organic / inorganic hybrid material as defined above is that where the (Ci-Cio)-alkyl ester of citric acid is selected from the group consisting of triethyl citrate, triethyl acetyl citrate, tributyl citrate, and tributyl acetyl citrate, the (Ci-Cw)-alkyl linear or branched alkyl ester of malonic acid with at least two ester groups is diethyl ethoxymethylene malonate and dimethyl succinate, and the pentaerythritol derived esters with thiol, hydroxyl or alkene as end group is pentaerythritoltetra kis(3-mercarptopropionate).

[0066] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the second organic compound of formula (II) is selected from polypropylene glycol)-bis(2-aminopropylether), 0,0- bis (2-aminopropyl)-polypopylene glycol-block-polyethylene glycol-block-polypropylene glycol; O- (2-aminopropyl)-O’-(2-methoxyethyl) propylene glycol; poy(ethylene oxide) 4-arm, amine terminated; poly(ethylenglycol) bis(3-aminopropyl); poly(ethylenglycol) bis (amine); 4,7,10 trioxa- 1,13-tridecandiamine; 2,2-(ethylendioxy) diethylamine; 1,11-diamino,3,6,9-trioxandecane; 1 ,13- diamino-4,7,10-trioxatridicane; 4,9-dioxa-1 ,12-dodean diamine; 1,8-diamino-3-6-dioxaoctane; 1,12-diamino-dodecane; poly(ethylenglycol) methyletherthiol; poly(ethylenglycol)methylether- maleimide; poly(ethylenglycol)-2-mercaptoethylehter acetic acid; and poly(ethylenglycol)-2-amino ethyl ether acetic acid.

[0067] Generally, the number average molecular weight is about 230--10.000 measured by Nuclear Magnetic Resonance1H NMR end-group analysis.

[0068] In a particular embodiment, in combination with any of the embodiments above or below, the organic compounds I and II are mixed with the inorganic compounds III, IV, V and glass powder according to, but not limited to the combinations in Table 1.

[0069] Table 1 : Possible combinations of the organic / lnorganic mixtures

[0070] The word ‘1 type’ as used in Table 1 means a single compound of a particular formula whereas ‘2 types’ means a mixture of two compounds of different formulae.

[0071] In the mixtures consisting of more than 1 type of inorganic compound, the powders of the inorganic compounds are first mixed by ball milling.

[0072] In a particular embodiment, in combination with any of the embodiments above or below, the photoluminescent organic / inorganic hybrid material as defined above, is that where the reaction product has an organic part comprising a polymer consisting of formula (1) and or formula (2), (1) (2) wherein: R10 is selected from the group consisting of mercapto, amino, methylene, hydroxyamine, oxime, hydrazine, hydrazone, hydrazide, nitroso, acetyl (Ci-Cw)-alkyl ester, hydroxyl and hydrogen atom; C is the central carbon atom on which R and at least one branch represented by the section in square parenthesis are attached; k is an integer ranging between 0-20, g is 0 or 1 ,0 is an oxygen atom; j is an integer between 1-4 and corresponds to the number of branches attached to the central carbon; Rn is independently selected from amide, thiol-ester, secondary or tertiary amino groups; and

[0073] R12 is an organic radical compound which is either of liner or branched structure comprising of formula (Ila’) or (lib’);

[0074] -CHR9-COOH

[0075] (Hb’) where: R’7 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; ‘a’ is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer between 2-4; and Rg represents side chains in common amino acids; and the inorganic part is as defined above.

[0076] In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the compound (Ila) is derived from amino terminated poly propylene glycol or amino terminated polyethylene glycol and compound of formular (lib) is L-arginine amino acid.

[0077] In another particular embodiment, the photoluminescent organic / inorganic hybrid material as defined above is that where the reaction product has an inorganic part as follows:

[0078] [f(MyCz) f(MyXz) f(P2O5)]T where M is a metal that is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; f is the percent mole fraction in the range, 0 < f < 100, of the inorganic mixture excluding the organic part; and 7" is the percent mole fraction in the range, 20 < T < 98, of the inorganic part of the organic / inorganic hybrid material. In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the inorganic part consists of metal oxides and or metal fluorides combined in the following percent mole fractions: [9(ZnO) 35(SnO) 56(P20s)]so; [43(ZnO) 57(MgF2)]s3; [49(ZnO) 51(CaF2)]7i; [100(ZnO)]79; [53(ZnO) 37(SnO)]76;[100(CaF2)]92; and [(65 (ZrO2) 35(SiO2)]s4.

[0079] In another particular embodiment, the organic / inorganic hybrid material of the present invention are those where the inorganic part comprises of either Tin Phosphate Sna(PO4)2 which crystalizes into Monoklin structure with phase group P21 / c (14) and lattice parameters: 11.09200 A, 4.83000 A, 16.40500 A, 94,280 ° or two phases of ZnO Zincite, syn Hexagonal, phase group: P63mc (186), lattice parameter: 3,24940 A 5,20380 A and MgF2 Sellaite, syn Tetragonal, phase group: P42 / mnm (136), lattice parameters: 4.62130 A, 3.01590 A.

[0080] In another particular embodiment, the organic / inorganic hybrid material of the present invention is that which is either amorphous, mono- or polycrystalline with average grain (crystallite) sizes in the range of 10 - 500 nm.

[0081] In another particular embodiment, the organic / inorganic hybrid material of the present invention is that which is able to exhibits self-healing properties. The self-healing is attributed to a supramolecular network within the matrix formed by non-covalent interactions selected from hydrogen bonding and the metal-ligand coordination wherein the supramolecular interactions enable reversible network formation such that, upon mechanical damage, the material autonomously restores its mechanical integrity without the need for external repair agents. The H-bonding network in this embodiment is possible to due the interactions between amide / amine moieties and the carbonyl groups. Additionally, self-healing is also enabled by reversible interaction between Zn+2and amide or amine groups in the sample.

[0082] In another particular embodiment, the organic / inorganic hybrid material of the present invention is that which comprises of parts that easily disperses or dissolves in polar solvents to from stable colloid / solution.

[0083] In another particular embodiment, the organic / inorganic hybrid material of the present invention is that wherein the colloidal solution in water forms water-based fluorescent ink which prints on different paper to from stable visible / invisible fluorescent marks.

[0084] In another particular embodiment, in combination with any of the embodiments above or below, the content in mole percent of the organic compounds in the mixtures described in Table 1 are, independently from each other in an amount selected from 0.1 to 15% by mole, in another particular embodiment, from 5 to 10% by mole, in still another particular embodiment, from 10 to 15% by mole.

[0085] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the content in mole percent of the individual inorganic compounds in the mixture is selected from 20% to 60% by mole, in another particular embodiment, from 25% to 50% by mole, still in another particular embodiment, from 35% to 50%.

[0086] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the inorganic powder is a glass powder. In a particular embodiment, the melting temperature of the glass powder should be less than 600 °C, in another particular embodiment less than 500 °C, still in another particular embodiment less than 400 °C.

[0087] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the inorganic glass powder consists of compound V, SnO, and ZnO in proportions of 30%, 60% and 10% by mole, respectively.

[0088] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the inorganic powder is a mixture of one compound (III) and one compound (IV). In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the MyCz (III) are selected from ZnO, SnO, SnO2, TiO2, and mixtures thereof. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those where the My’Xz’ (IV) are selected from MgF2, CaF2, and mixtures thereof. The inorganic powder of the present invention can be free of rare-earth metals, radioactive or highly toxic elements.

[0089] In a particular embodiment, in combination with any of the embodiments above or below, compound (III) and (IV) should be transparent / translucent or they can form transparent spinel with general formular MN2O4 where M is a 2 or 4 valency metal, N is a 2 or 3 valency metal, and O is oxygen.

[0090] In another particular embodiment, in combination with any of the embodiments above or below, any two compounds selected from a group belonging to compound (III) and mixed with compound (V) should be able to sinter into a transparent amorphous material. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those which are free of rare- earth elements.

[0091] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention are those which are a mixture of a first organic compound of formula (la) or (lb) or (Ic), a second organic compound of formula (II); one or two selections from compound (III) and a compound (IV).

[0092] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention is that which are a mixture of triethyl acetyl citrate, polypropylene glycol)-bis(2-aminopropylether), TiC>2, P2O5 and ZnO. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention is that which are a mixture of triethyl acetyl citrate, polypropylene glycol)-bis(2-aminopropylether), ZnO, and MgF2. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material of the present invention is that which are a mixture of triethyl acetyl citrate, polypropylene glycol)-bis(2-aminopropylether), ZnO, and CaF2.

[0093] This organic / inorganic hybrid material is in the form of a powder, specifically is an amorphous or crystalline powder. In a particular embodiment, this organic / inorganic hybrid material of the present invention is that which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 22.6, 26.2 and 27.3 degrees 2 theta at a Cu-Ka radiation A= 1.5406 Angstroms. In another particular embodiment, the organic / inorganic hybrid material of the present invention is that where, further characterized by an X-ray diffractogram as in FIG. 1 (a).

[0094] In a particular embodiment, this organic / inorganic hybrid material of the present invention is that which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 27.0, 31.8, 34.4, 36.2, 47.5, 56.5, and 62.8 degrees 2 theta at a Cu-Ka radiation A= 1.5406 Angstroms. In another particular embodiment, this organic / inorganic hybrid material of the present invention is that which exhibits an X-ray diffractogram that further comprises peaks at approximately 40.3; 43.7; 56.5; and 62.8; degrees 2 theta at a Cu-Ka radiation A= 1.5406 A. In another particular embodiment, the organic / inorganic hybrid material of the present invention is that where is further characterized by an X-ray diffractogram as in FIG. 1(b). In another particular embodiment, in combination with any of the embodiments above or below, this organic / inorganic hybrid material of the present invention is that which is characterized by a Mid infra-red (MIR) spectrum as in FIG. 2.

[0095] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material as defined above is able to emit broadband yellow light between wavelength of 500 to 700 nm when illuminated by light of various wavelengths from 250 to 490 nm.

[0096] In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material as defined above are the ones which the ‘y’ chromaticity coordinates according to the CIE 1931 chromaticity diagram range between 0.4 to 0.6 at excitation wavelength between 300 nm to 500 nm. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material as defined above or below are the ones in which the CIE 1931 photoluminescence emission colour chromaticity coordinates are shown in Table 3 in the examples. In another particular embodiment, in combination with any of the embodiments above or below, the organic / inorganic hybrid material as defined above is that whose photoluminescence emission is stable against temperature quenching up 200 °C and stable against photo bleaching for more than 1000 hours of continuous illumination.

[0097] The organic / inorganic hybrid material of the present invention may be prepared by a process which comprises subjecting a mixture of the several organic and inorganic precursor materials indicated above to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; heating with or without condensation step, and mixing at room temperature, specifically, the precursor materials are the following: a) a first organic compound selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic), where: Ri is selected from the group consisting of -CHs, OH, -COOR3, NH2 and - OOCR3; 2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from -COOR3, -OOCR3, COOR3-R4, and -OOCR3- R4; R3 is a linear, branched, or cyclic saturated or unsaturated hydrocarbon radical, containing 1 to 20 carbon atoms; and R4 is selected from:, mercapto, hydroxyl, alkene, and phosphoryl; wherein: the compound of formula (la) is a (Ci-Cio)-alkyl ester of citric acid; the compound of formula (lb) is a (Ci-Cio)-alkyl ester of pentaerythritol with a thiol, hydroxyl or alkene as end groups; and the compound of formula (Ic) is a (Ci-Cio)-alkyl linear or branched alkyl ester of an acid selected from malonic acid and succinic acid with at least two ester groups, preferably (C1- C2o)-alkyl linear or branched alkyl ester; b) a second organic compound which is either a linear or a branched structure of formula (II): X-R5-(ORe)n-X; where: Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; Rs is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1 ; n is an integer ranging from 1 to 10.000; X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and Boc-protected amino group; wherein: the compound of formula (II) is either a compound of formula (Ila)

[0098] (Ha) wherein: R? is an amino group, Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4, or a compound of formula (lib):

[0099] RcrCHR -COOH

[0100] (Hb) wherein:Rg is an amino group; R10 represents side chains in common amino acids; and and c) a inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5 (V); where: M is a metal which is not classified as rare-earth and has a with valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); and c5) a compound (IV); a c6) a glass frits (powder), and c7) mineral sand (zircon sand).

[0101] In a particular embodiment of the process, the reaction is a sonochemical reaction. In such embodiment, the mixture of the precursor materials mentioned above is submitted to high power ultrasonic waves to enable the in-situ sonochemical reaction in an open or in an autoclavable stainless steel reaction cell. In another particular embodiment of the process, in combination with any of the embodiments above or below, the sonochemical reaction comprises: (1a) mixing the precursors where in the mole percentage of the individual organic compounds in the mixtures is fromO.1% to 15% by mole and the mole percentages of the individual inorganic compounds are from 10 to 98% by mole, more particularly, 20% to 60% by mole; (1b) ultrasonicating the mixture for the necessary period of time; and (1c) cooling down to room temperature. In another particular embodiment of the process, the sonochemical reaction is conducted in an autoclave.

[0102] In another particular embodiment of the process, the sonication was conducted at a constant power between 100-900 W and vibration amplitude ranging between 20 to 100 % for a period of time between 0.5 to 3 hours. In another particular embodiment of the process, the sonication is conducted at a temperature comprised in a range from 70 to 300 °C.

[0103] In another embodiment of this process, in combination with any of the embodiments above or below, a mixture of one compound (III), one compound (IV), organic compound (la) or (lb) or (lc)), and organic compound (II) are used. Alternatively, two selections from the group described in compound (III) are mixed with organic compound (I) and organic compound (II). In yet another embodiment, either one of compound (III) or one of compound (IV) is mixed together with either organic compound (la) or (lb) or (lc) or (Id), and organic compound (II). In yet another embodiment, either organic compound (la) or (lb) is mixed with organic compound (II) any of the commercial glass frits powder or ordinary glass that is crushed into powder.

[0104] The sonochemical reaction method employed in the present invention is one of the green chemistry, where the reaction takes place within small hot spots or cavitation bubbles which experiences intense pressure and temperature while the bulk of the sample remains relatively at low temperature. This prevents release of volatile intermediates to the environment.

[0105] In another particular embodiment of the process, the reaction is a solvothermal reaction. In a particular embodiment of this process, the in organic powder consists of compound (V) and two selections from the group described in compound (III) are mixed together with organic compound (la) or (lb) or (lc) and organic compound (II). The mixture can be heated, for instance, in an autoclave. Once the organic / inorganic hybrid material of the present invention is obtained, it can be isolated, for instance, by filtration and then it can be dried.

[0106] In another particular embodiment of the process, in combination with any of the embodiments above or below, the reaction is conducted by heating with or without condensation step. The product of this invention can also be achieved by thermal agitation of the mixture described above by direct heating or by using microwave radiation in a pressurized or non-pressurized container with or without a condensation step.

[0107] In another particular embodiment of the process, in combination with any of the embodiments above or below, the first organic compound is a compound of formula (la), the second organic compound is a compound of formula (Ila) and the process is conducted by mixing at room temperature (20-25°C).

[0108] Any of the above preparation method enables the formation of the clusteroluminogens from organic compounds and gets them embedded in an inorganic matrix all in a single in-situ reaction step without additional catalysts or solvents. Notably, the product can be formed relatively fast in single step reaction with no wastes. This reaction would qualify to be referred to as click chemistry. This is mostly aided by the Schiff base intermediate radicals which could be presence in this case when the carbonyl groups react with amino groups.

[0109] The organic / inorganic hybrid material of the present invention obtainable by a process which comprises subjecting the mixture of the organic and inorganic precursor materials as defined above to reaction conditions selected from the group consisting of: a sonochemical reaction conditions; a solvothermal reaction conditions; and heating with or without condensation step is part of the invention. All the particular embodiment of the process are also particular embodiments for the organic / inorganic hybrid material of the present invention obtainable by such process.

[0110] The organic / inorganic hybrid material of the present invention may be a product which has an organic part comprising a polymer consisting of formula (1) and or formula (2)

[0111] (1) (2) wherein: Rio is selected from the group consisting of mercapto, amino, methylene, hydroxyamine, oxime, hydrazine, hydrazone, hydrazide, nitroso, acetyl (Ci-Cw)-alkyl ester, hydroxyl and hydrogen atom: C is the central carbon atom on which R and at least one branch represented by the section in square parenthesis are attached, k is an integer ranging between 0 - 20, g is 0 or 1 , O is an oxygen atom, j is an integer between 1-4 and corresponds to the number of branches attached to the central carbon, Rn is independently selected from amide, thiol-ester, secondary or tertiary amino groups, R12 is an organic radical compound which is either of liner or branched structure comprising of formula (Ila’) or (lib’);

[0112] -CHR9-COOH

[0113] (Hb’) where: R’7 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; ‘a’ is an integer selected from 0 and 1 ; m is an integer ranging from 1 to 4000; o is an integer between 2-4; and R9 represents side chains in common amino acids; and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III); - My’Xz’ (IV); and P2O5 (V); where M is a metal that is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; and the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); c6) a glass frits (powder); and c7) mineral sand (zircon sand).

[0114] The corresponding particular embodiments of this product defined by its preparation process disclosed above are also particular embodiments of the product defined here only by its final structure.

[0115] The organic / inorganic hybrid material of the present invention may be used as LED phosphor, i.e. as a light converter in white light emitting diodes (wLEDs). In a particular embodiment of this use, the organic / inorganic hybrid material of this invention is designed to be used in combination with blue LED chips. In another particular embodiment of this use, the organic / inorganic hybrid material of this invention may also be used with near UV LED chips. FIGs 1-5 shows that the product possesses characteristics / properties suitable for use in the production of white LEDs. In another particular embodiment of this use, the organic / inorganic hybrid material of this invention for white light extraction in reflection mode. The organic / inorganic hybrid material of the present invention may also be used as product marker / taggant. In a particular embodiment of this use, the use as product marker is in security inks. The photoluminescent material of this invention can be used as a pigment that is incorporated in security inks and printed onto sensitive documents such banknotes, cheques, certificates, tickets or any other important government document. The security ink may also be printed on other valuable products or on their labels in order to protect them against counterfeits.

[0116] The organic / inorganic hybrid material of the present invention may also be used as fluorescent marker in plastic sorting. Current method of plastic sorting employing near infra-red (IR) spectroscopy has limitation when it comes to sorting black plastics or plastics of the same material used for different purposes, for instance, it is important to differentiate plastic used for food and non-food packaging. In corporation of fluorescent marker (product of this invention) directly during the manufacture of the plastic containers or onto the plastic labels can solve this problem.

[0117] The applications described above used as product marker / taggant and as fluorescent marker in plastic sorting are feasible because the product of this invention emits stable yellow light when continuously illuminated by UV light over a long time (FIG. 10) and can also be excited by a wide range of UV wavelength e.g., UV A, UV B or UV C (FIG. 11). The advantage is that very few materials would emit long wavelength light (greater than 600 nm) under UV excitation. Such large stoke shift especially with UV C excitation is very rare. The emission is detectable by human eye, but it is also machine readable.

[0118] According to the present invention, the light emitting device to remotely convert LED light into white light which comprises the organic / inorganic hybrid material as defined above uses reflection mode to alleviate the problems of the state of the art as detailed in FIGs 12 and 13. Specifically, the common state of the art in the production of white LEDs is to mix the photoluminescent material or phosphor with transparent polymer binder and deposit the mixture directly on the blue LED chips. Part of the light from the LED chips is transmitted and part is absorbed and excites the phosphor to produce long wavelength radiations. The mix of the light from the LED chip and that from the phosphor produces white light. But part of the absorbed light from the LED chip is converted into heat and causes thermal quenching of the phosphor. Thus, with the light emitting device of the present invention, these problems of thermal quenching are minimized.

[0119] Finally, it is part of the invention a light emitting device for remote extraction of white light from blue / UV LEDs through reflection mode which comprises: a) a LED chip 1 to generate blue or UV light; b) a curved reflecting surface 3 to reflect light on to the phosphor coated curved surface and to redirect the light to the exit surface; optionally, c) a reflecting surface in form of an inverted pyramid or cone shape (6) and its support (7) to redirect LED light onto the curved surface; d) a phosphor 4 as defined above coated onto the reflective surface, which is configured to absorb blue or UV light emitted from the LED, and with the ability to emit light having a wavelength different from the absorbed light in the red, green and blue regions of the spectrum which combine to produce white light; and e) a transparent / translucent light diffusing cover 5.

[0120] The LED chip emits light. It is a semiconductor device that converts electrical energy into light. The efficiency and colour of the light emitted depend on the materials used in the LED chip. WLEDs generate white light by using a blue LED chip to excite phosphors, which then emit yellow or red light. This combined emission produces the desired white light.

[0121] In a particular embodiment, in combination with any of the embodiments above or below, the light emitting device of the present invention, further comprises: e) a LED driver to regulate the power to the LED chip. LEDs require a constant current to function properly, and the driver ensures that the LED receives this constant current. The driver can also provide dimming capabilities and protect the LED from voltage fluctuations and surges.

[0122] In another particular embodiment, in combination with any of the embodiments above or below, the light emitting device of the present invention further comprises f) a thermal management to manage and dissipate the heat generated by LEDs during operation to ensure they operate within safe temperature limits. LEDs generate heat during operation, and if this heat is not managed properly, it can degrade the LED chip and reduce its lifespan.

[0123] In another particular embodiment, in combination with any of the embodiments above or below, the light emitting device according the present invention, further comprises g) an inverted pyramid shape with apex facing down 6, wherein it has from 3 to 6 lateral faces with all outer surfaces being reflective; or alternatively, a cone with circular base; to reflect direct pointing light from the centre of LEDs chip on to the phosphor coated curved surface; and h) a support for the pyramid / cone 7 which is either reflective or is painted with reflective material.

[0124] In another particular embodiment, in combination with any of the embodiments above or below, the light emitting device according to the present invention is that where the light comes from: a) the centre of the LED chip; b) the inverted pyramid shape with apex facing down, or c) the cone with circular base.

[0125] FIG. 14 illustrates an example of a device for remote extraction of white light from blue / UV LEDs through reflection mode. The device comprises: LED driver 1 and thermal management, LED chip 2, curved reflecting surface 3, phosphor coated onto the reflective surface 4, transparent / translucent light diffusing cover 5, inverted pyramid shape with apex facing down and all outer surfaces being reflective 6. The pyramid may have any number of lateral faces from 3-6. Alternatively, it could also be a cone with circular base. The slanting edge is designed to reflect direct pointing light from the centre of LEDs chip on to the phosphor coated curved surface which then redirects the light to the exit surface, support for the pyramid / cone 7. The support is also a reflective or is painted with reflective material, extracted white light 8.

[0126] In another particular embodiment, in combination with any of the embodiments above or below, the light emitting device according to the present invention is that which is a semicircular coated reflecting surface insight led chip on the sites.

[0127] FIG. 15 illustrates another device for remote extraction of white light from blue / UV LEDs through reflection mode, which comprises: a curved surface which can be obtained by cutting through a longitudinal edge of the tube 10, a curved reflecting surface 3, a phosphor coated onto the reflective surface 4, a LED chip 2, a light from the LED chip 9, a beam of white light, 8, LED driver and thermal management (heat sink) 1, and transparent / translucent light diffusing cover 5.

[0128] A material for coating the reflective surface of a device for remote extraction of white light from blue / UV LEDs through reflection mode comprising the organic / inorganic hybrid material as defined above, and a transparent self-curing adhesive resin is part of the invention. In a particular embodiment, the coating in the reflective surface has a thickness in the range from 0.5 to 500 microns. In a particular embodiment, the transparent adhesive is an Acrifix 1s 00116.

[0129] Throughout the description and claims the word "comprise" and variations of the word, are not intended to exclude other technical features, additives, components, or steps. Furthermore, the word “comprise” encompasses the case of “consisting of”. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples and drawings are provided by way of illustration, and they are not intended to be limiting of the present invention. Reference signs related to drawings and placed in parentheses in a claim, are solely for attempting to increase the intelligibility of the claim and shall not be construed as limiting the scope of the claim. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein.

[0130] For reasons of completeness, various aspects of the invention are set out in the following numbered clauses:

[0131] Clause 1. A photoluminescent organic / inorganic hybrid material, which is the reaction product of a mixture of the following organic and inorganic precursor materials: a) a first organic compound independently selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic),

[0132] (la) (lb) (Ic) wherein: Ri is selected from the group consisting of -CHs, and OH, -COOR3, NH2 and -OOCR3; R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from -COOR3. -OOCR3, COOR3-R4, and -OOCR3-R4; R3 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; R4 is selected from: amino, mercapto, hydroxyl, and phosphoryl; and b) a second organic compound which is either a linear or a branched structure of formula (II):

[0133] X-(R5)m-(OR6)n-X (II) wherein: Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms Rs is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1; n is an integer ranging from 2 to 10.000;

[0134] X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and a Boc-protected amino group; and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III);

[0135] - My’Xz’ (IV); and P2O5 (V); wherein: M is a metal that is not classified as rare-earth and has a valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; and the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); and c6) a glass frits (powder).

[0136] Clause 2. The organic / inorganic hybrid material according to clause 1 , wherein the first organic compound is a compound of formula (la).

[0137] Clause 3. The organic / inorganic hybrid material according to any of the clauses 1-2, wherein the in organic powder is a mixture of one compound (III) and one compound (IV)

[0138] Clause 4. The organic / inorganic hybrid material according to any of the clauses 1-3, which is free of rare-earth elements.

[0139] Clause 5. The organic / inorganic hybrid material according to any of the clauses 1-4, which is a mixture of a first organic compound of formula (la) or (lb), a second organic compound of formula (II); a compound (III) and a compound (IV), where in the ratios in mole percentages of the individual organic compounds in the mixtures are from 0.1 % to 15% by mole while the individual inorganic compounds are from 20% to 60% by mole.

[0140] Clause 6. The organic / inorganic hybrid material according to clause 5, which is a mixture of triethyl acetyl citrate, polypropylene glycol)-bis(2-aminopropylether), SnO, TiO2ZnO, CaF2 and MgF2.

[0141] Clause 7. The organic / inorganic hybrid material according to clause 6, is selected from: a) an organic / inorganic hybrid material which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 22.6, 26.2, and 27.3 degree 2 theta at a Cu-Ka radiation A= 1.5406 Angstroms; and b) an organic / inorganic hybrid material which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 31.8; 34.4; 36.2; 47.5; 56.5; 62.8; 67;9 and 69.1 degrees 2 theta at a Cu-Ka radiation A= 1.5406 A.

[0142] Clause 8. The organic / inorganic hybrid material according to any of the clauses 1-7 which is able to emit broadband yellow light between wavelength of 500 to 700 nm when illuminated by light of various wavelengths from 250 to 490 nm.

[0143] Clause 9. The organic / inorganic hybrid material according to clause 8, whose photoluminescence emission is stable against temperature quenching up 200 °C and stable against photo bleaching for more than 1000 hours of continuous illumination.

[0144] Clause 10. A process for preparing the organic / inorganic hybrid material as defined in any of the clauses 1-9, which comprises subjecting a mixture of the following organic and inorganic precursor materials: a) a first organic compound independently selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic),

[0145] (la) (lb) (Ic) wherein: Ri is selected from the group consisting of -CHs, OH, NH2, -COOR3, and -OOCR3; R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; G is selected from the group consisting of -COOR3. -OOCR3, COOR3-R4, and - OOCR3-R4; Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; and

[0146] R4 is selected from the group consisting of mercapto, hydroxyl, alkene, and phosphoryl; and b) a second organic compound which is either a linear or branched structure of formula (II): X-(Rs)m- (ORe)n-X (II), wherein: Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; Rs is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1; n is an integer ranging from 2 to 10.000; X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and a Boc-protected amino group; and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5 (V); wherein: M is a metal which is not classified as rare-earth and has valency 2, 3, or 4; C is a chalcogen; X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; and the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); and c6) a glass frits (powder); to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; and heating with or without condensation step.

[0147] Clause 11. The process according to clause 10, wherein the reaction conditions are a sonochemical reaction which comprises: (1a) mixing the precursors where in the mole percentages of the individual organic compounds in the mixtures ais from 0.1% to 15% by mole, and the mole percentages of the individual inorganic compounds in the mixture are from 20% to 60% by mole. (1b) ultrasonicating the mixture for the necessary period of time; and (1c) cooling down to room temperature.

[0148] Clause 12. The process according to any of the clauses 10-11, wherein the sonication was conducted at a constant power ranging between 100 to 900 W and vibration amplitude between 20 to 100 % for a period of time between 0.5 to 3 hours at a temperature comprised in a range from 70 to 300 °C.

[0149] Clause 13. Use of an organic / inorganic hybrid material as defined in any of the clauses 1-9, as a light converter in white light emitting diodes (wLEDs).

[0150] Clause 14. Use of an organic / inorganic hybrid material as defined in any of the clauses 1-9, either as a product marker / taggant, or as fluorescent marker in plastic sorting.

[0151] Clause 15. A light emitting device for remote extraction of white light from blue / UV LEDs through reflection mode which comprises: a) a LED chip (1) to generate blue or UV light; b) a curved reflecting surface (3) to reflect light on to the phosphor coated curved surface and to redirect the light to the exit surface; c) optionally, a reflecting surface in form of an inverted pyramid or cone shape (6) and its support (7) to redirect LED light onto the curved surface; d) a phosphor (4) as defined in any of the clauses 1-9 coated onto the reflective surface, which is configured to absorb blue or UV light emitted from the LED, and with the ability to emit light having a wavelength different from the absorbed light in the red, green and blue regions of the spectrum which combine to produce white light; and e) a transparent / translucent light diffusing cover (5).

[0152] Examples

[0153] Example 1 : Sample (LMS 01) preparation method (Solvothermal reaction)

[0154] 5 ml of Triethyl acetyl citrate and 5 ml of Polypropylene glycol) bis(2-aminopropyl ether), Mn =230 (purchased from Sigma Aldrich) were mixed in a 20 ml PPL lined autoclave. 5 g of a low melting glass powder (supplied by Schott AG) consisting of 9% ZnO, 35% SnO and 56% phosphorous pentoxide was then added. Afterwards the autoclave was closed tightly and heated for 2 hours at 260 °C in a Baoshisha 25 ml hydrothermal synthesis reactor. The reaction mixture was allowed to cool to room temperature. The final organic / inorganic hybrid powdered material was obtained after filtering, drying and ball milling.

[0155] Example 2: Sample (LMS 02) preparation method (Sonochemical reaction) .

[0156] 30 ml of Triethyl acetyl citrate and 30 ml of Polypropylene glycol) bis(2-aminopropyl ether), 15 g of Calcium Fluoride and 15 g of Zinc oxide were mixed in a stainless-steel autoclavable reactor from Hielscher Ultrasonics. The reactor is equipped with stirrer and temperature sensor. Under continuous stirring, the mixture was ultrasonicated at constant power of 600 W and 100 % amplitude for 1 hour using UIP 1000 hdT (1000 W, 24 Hz) transducer that was connected to a BS4d34 sonotrode. The internal temperature increased to around 80 degrees Celsius and, in the end, the product was allowed to cool to room temperature before opening. A hard solid material was obtained. Notably, the product was formed relatively fast in single step reaction with no wastes. This reaction would qualify to be referred to as click chemistry which is one of the rare and important chemical reaction where reactant simply snap / click into to the structure of the final product. This is mostly aided by the Schiff base intermediate radicals which could be presence in this case when the carbonyl groups react with amino groups. It saves on energy and doesn’t produce environmental wastes. The sonochemical reaction method employed here is also one of the ‘green chemistry’ where the reaction takes place within small hot spots or cavitation bubbles which experiences intense pressure and temperature while the bulk of the sample remains relatively at low temperature. This prevents release of volatile intermediates to the environment. The hard solid material obtained in the end was manually crushed into powder. To reduce particle sizes, it was further ball milled in a Fritsch planetary micro mill pulverisette.

[0157] Example 3: Sample (LMS 03) preparation method: (heating with condensation step)

[0158] 15 g of Zinc oxide was added to a mixture consisting of 15 ml each of the organic molecules used in example 1. The mixture was stirred and poured into a drying tube of the Buchi B-580 glass oven. A complete drying tube was assembled and heated in the oven at 260 °C for 1 hour. The part of the tube used to collect the condensate was place in cold water bath. The obtained solid sample was ball milled at room temperature into powder.

[0159] Example 4: Sample (LMS 04) preparation method (Heating in open container)

[0160] A mixture consisting of 5 g of Titanium IV oxide 5 g of Zinc oxide (obtained from Laboratories discounter) and 5 ml each of the organic samples used in example 1, were mixed in a glass vial and placed in stainless steel vessel which was then heated at 260 °C for 1 hour in a Prometheus Pro 7 PRG oven.

[0161] Example 5: Sample (LMS 05) preparation method (Sonochemistry)

[0162] A mixture consisting of 180 g Magnesium fluoride, 180 g Zinc oxide and 180 ml of each of the organic samples in example 1 was placed in autoclavable reaction cell from Hielscher Ultrasonics. The method described in example 2 was used to prepare the final sample.

[0163] Example 6: Sample (LMS 06) preparation method (Heating in a closed container)

[0164] A mixture of 2.55 g Calcium fluoride, 0.255 ml of Diethyl ethoxymethylene malonate (DEEMM), and 0.255 ml of 2,2-(Ethylenedioxy) bis ethylamine (EEA) was placed in a 25 ml PPL lined stainless steel autoclave which was then closed and a heated at_260 °C in a Prometheus Pro 7 PRG oven for 20 minutes. The final product was obtained after ball milling at room temperature (20-25°C).

[0165] Example 7: Sample (LMS 07)

[0166] Procedure described in example 6 was followed except that DEEMM was replaced with Dimethyl succinate.

[0167] Example 8: Sample (LMS 08) Procedure described in example 6 was followed except that DEEMM was replaced with

[0168] Pentaerythritoltetra kis(3-mercaptopropionate)

[0169] Example 9: Sample (LMS 09)

[0170] Procedure described in example 6 was followed except that DEEMM was replaced with Triethyl citrate.

[0171] Example 10: Sample (LMS 10)

[0172] Procedure described in example 6 was followed except that Calcium fluoride and DEEMM were replaced with Bullseye glass frits powder and Triethyl citrate, respectively. The Bullseye glass frits, COE 90, crystal clear was purchased from Glasinsel.

[0173] Example 11 : Sample (LMS 11)

[0174] Procedure described in example 6 was followed except that DEEMM and EEA were replaced with Triethyl acetyl citrate and 4,7,0 Trioxa-1, 13 tridecane diamine, respectively.

[0175] Example 12: Sample (LMS 12)

[0176] Procedure described in example 6 was followed except that Calcium fluoride and DEEMM were replaced with micronized Zircon sand and Triethyl citrate, respectively. Zircon sand, (65 % ZrO2, 35% SiO2) was obtained from Helmut Kreutz Mahlwerke GmbH.

[0177] Example 13: Sample (LMS 13) Preparation method (Simple mixing at room temperature)

[0178] 5 ml of 4,7,0 Trioxa-1, 13 tridecane diamine and 5 ml of Triethyl acetyl citrate were mixed in a glass beaker and then 20 g of Calcium fluoride was added and continuously mixed manually with a wooded spatula for about 10 minutes. 37 g more of Calcium fluoride was additionally added step by step at room temperature. The sample was then stored in a closed glass vial. By observing the colour changes, and measurement of its fluorescence intensity, the reaction was determined to be complete after about 6 hours without heating or applying any other external energy. In order to further test this room temperature reaction, 200 iL of 4,7,0 Trioxa-1, 13 tridecane diamine and 200 iL of Triethyl acetyl citrate was mixed and poured in a special vial and mounts to the cuvette holder of the_Hamamatsu C9920-02 Absolute PL Quantum Yield Spectrometer. Fluorescence emission was recoded after every 1 minute at excitation wavelength of 365 nm. The data is plotted in Fig. 6. This shows that fluorescence starts to increase at wavelength of about 600 nm. After about 15 minutes, emission peaks at around 450 nm and 650 nm starts to grow. This implies that the emission at 600 nm (labelled B) is due to the new structures formed during the reaction and the emission at 450 nm (labelled A) and 650 nm (labelled C) are due to clusteroluminogens formed as molecular aggregation in the sample increases due to the formation of H-bonding network. The advantage with this method is that it saves on energy and the environment. This reaction between esters and amines proceeds this faster at room temperature due to the presence alkoxy groups which lowers the amidation activation energy and also stabilizes the intermediates. The sample also changes from colourless at the beginning to deep red colour at the end of the reaction meaning the method can also be used to form red dyes.

[0179] Example 14: Sample (LMS 14) preparation method (Heating in a closed container)

[0180] Procedure described in example 6 was followed except that DEEMM and EEA were replaced with Triethyl acetyl citrate and L-Arginate (amino acid), respectively.

[0181] Example 15: Powder X-ray diffraction (XRD)

[0182] The structural phases of the prepared sample were determined using Buker D8 advance powder diffractometer with Bragg Brentano geometry for phase and structural analysis. It had a LYNXEYE detector. CuKa radiation with a wavelength of A = 0,15406 nm was used for measurement. The diffraction pattern showed peaks at approximately 22.6; 26.2; and 27.3 (Fig 1a) and 27.0; 31.8; 34.4; 36.2; 40.3; 43.7; 47.5; 53.2; 56.5; 60.6; 62.8; 66.4; 72.5; 77.2; 81.4; degrees 2 theta at a Cu-Ka radiation A= 1.5406 A (Fig 1b. The analysis of the structures was done using the DIFFRAC.EVA software, version V5.2 and the PDF2021 database. By comparing the measured XRD diffraction spectrum with the database, the main structures found are monoclinic tin phosphate SnsPCL with lattice parameters 11.092 A, 4.830 A, 16.405 A; the tin II pyrophosphate Sn2P2O? with lattice parameters 5.277 A, 11.541 A,, 11.636 A; the hexagonal ZnO Zincite crystal space group P63mc and lattice parameters of 3.24940 A and 5.20380 A, and the tetragonal MgF2 sellaite of crystal space group P42 / mmm and lattice parameters of 4.62130 A and 3.01590 A. The grain size of the polycrystalline sample containing ZnO: MgF2 was determined from the Scherrer’s Equation written as: D=(kA) / p cos 0; where D is the grain size, k (= 0.941) is the constant, A (= 0.1506) nm is the radiation wavelength, p is the full wave at half maximum (FWHM) of the diffraction peak and 0 is the diffraction angle in radians. Making use of this Scherrer’s Equation, the average grain size of this sample was determined to be 130 nm.

[0183] Example 16: FTIR characterization

[0184] FTIR measurement was carried out in ATR mode using Nicolet iS 10 spectrometer, having a diamond -ATR smart endurance from Thermo Fisher Scientific which is equipped with DTGS detector and KBr beam splitter. The measurement was run with the following settings: resolution of 4 cm-1, number of scans 32, with aperture of 80 and gain of 4. Spectrum obtained is shown in FIG. 3. The dominant IR vibrational frequencies can be assigned to the following molecular moieties shown in the Table 2 below.

[0185] Table 2: Assignment for Mid IR vibrational frequencies information obtained from the IR spectroscopy, it was concluded that the main organic product of this invention is formed when the two organic precursors are joined through the formation of amide bond as a result of the reaction between carbonyl and amino groups. The structure of the product is shown in the molecular scheme 1 represents only the core part of the structure. The core structure of the organic product; Ra, Rb and Rc may be represented by the shown molecular groups. Rb is an optional group and can be removed / omitted without altering the intended functional properties of the product. For clarity purpose, not all hydrogen atoms are shown in the structures. The overall structure could consist of an extended supramolecular structure with extended chains that are connected by intra and inter molecular Hydrogen bonds Molecular scheme 1 : Core molecular structure of the organic product of this invention:

[0186]

[0187] Example 17: Electron Spray Ionization Mass Spectrometry (ESI-MS) Molecular masses of the smaller molecules formed during the sample preparation described in Examples 2, 6, 7, 9 and 13 above were determined using the Bruker Daltonics - micrOTOF - ESI- TOF MS. The micrOTOF shows a mass accuracy better than 3 ppm and is suitable for formular determination from the measured mass. The use of ESI orthogonal electrospray source (1 pl -1 ml / min) which is regarded as soft ionization, enables sensitive detection and accurate mass determination of intact molecules. For this measurement, the selected samples were dispersed in Mili-Q water. The undissolved part of the sample was allowed to completely settle at the bottom of the container. After a period of one day, 200 pL of the liquid at the top was drawn using a micro pipette and taken for MS measurement. MS acquisition parameters were set as follows; Source type: ESI, Ion polarity: positive, set capillarity: 4500 V, set end plate offset: -500 V, set nebulizer: 2.8 bar, Set Dry heater: 220 C, Set dry gas 4.5 L / min, Scan range 5 - 1700 m / z. The measure m / z data with their respective intensities are plotted in FIG: 8 for the different sample labelled LMS 02, LMS 06, LMS 07, LMS 09, and LMS 13. The measured m / z masses labelled 1- 7 are shown in Table 3.

[0188] Table 3: Molecular masses as obtained from ESI mass spectrometry corresponding [M+H]+of the m / z data shown in FIG. 8

[0189] Example 18: Photoluminescence characterization

[0190] The photoluminescence emission spectra of the obtained powder sample were measured using the Hamamatsu C9920-02 Absolute PL Quantum Yield Spectrometer. The spectrometer is equipped with Xenon lamp, integrating sphere unit, Photonic Multichannel Analyser C10027, Light guides, and basic software for quantum Yield measurement U6039-05. The sample was placed in a specialized provided laboratory dish with cap for powdered samples. This was then inserted inside the integrating sphere. The emission spectra for different samples (FIG. 3, FIG. 4, and FIG. 5) were obtained after subtracting the excitation spectrum.

[0191] Example 19: Temperature dependence photoluminescence measurement

[0192] In order to determine the extent of temperature quenching, we measured the emission spectra of the sample as function temperature. In this measurement, the powder sample was sandwiched between two pieces of microscope slide and placed onto a THMS 600 Linkam heating stage that was connected to Linkam TP 94 temperature controller. The sample was illuminated by fibre- coupled LED (wavelength of 455nm) connected to LED driver from Thorlabs. The optical fibre of core diameter of 600 .m and numerical aperture of 0.5 was used. The photoluminescence emission was collected through another optical fibre attached to a long pass filter with cut-off wavelength at 515 nm. The spectrum of the emitted light was recorded by the optical fibre spectrometer, Avaspec ULS2048 CL-RS-Evo obtained from Avantes. The temperature was manually adjusted, and the spectrum was recorded after stabilized set temperature was reached. The integrated intensity of each spectrum was calculated using MagicPIot programme and plotted as a function of temperature (FIG. 5). The results show that at higher temperatures, for instance at 120 °C, the sample still emits up to about 80 % of the original intensity at room temperature. This is comparable with the temperature dependence of the commercial YAG:Ce LED phosphor and shows that the sample is relatively stable against thermal quenching.

[0193] Example 20: Photostability measurement

[0194] Most organic dyes undergo photobleaching. This happens when the photon energy breaks the molecular bonds and as a result, the emissive moieties in the sample are destroyed and hence the photoluminescence is quenched. To test the stability of the prepared sample against photo quenching, the sample was sandwiched between inorganic slides and placed on the sample port of the Avasphere 50 integrating sphere from Avantes which has both the illuminating and measurement ports. The illuminating port couples external light into the sphere through a fibreoptic cable connected to a COL-UV / VIS collimating lens. The sample was illuminated by UV light 340 nm from LED coupled to fibre patch cable having core diameter of 600 .m and numerical aperture of 0.5. A similar fibre cable was connected to the measurement port and to Avaspec ULS2048 CL-RS-Evo spectrometer in order to record the emitted light. A long pass filter with cutoff wavelength 515 was connected directly to the spectrometer port having a slit of 200 .m.

[0195] Under continuously illumination, the emitted spectra were recorded after every 5 hours for a total of 920 hours. The integrated intensity of the recorded spectrum was plotted as a function time. (FIG. 6). The results show that the photoluminescence of the sample is very stable against photon energy.

[0196] Example 21 : Self-healing properties

[0197] The organic resin / binder formed by the process of this invention possess self-healing properties. This is shown in FIG. 7 where the sample obtained from example 5 was put in a glass beaker, a small part of a mm ruler was place on top of it and hole of about 3 mm diameter was made next to ruler using a cylindrical rod-like object. The set-up was left at room temperature as the size of the hole was monitored by taking picture at specific time intervals. The hole starts to seal by itself, and it completely disappeared after about 18 hours. The self-healing in this sample is attributed to a supramolecular network within the matrix formed by non-covalent interactions selected from hydrogen bonding and the metal-ligand coordination wherein the supramolecular interactions enable reversible network formation such that, upon mechanical damage, the material autonomously restores its mechanical integrity without the need for external repair agents.

[0198] The H-bonding network in this sample is possible due to the interactions between amide / amine moieties and the carbonyl. On the other hand, self-healing is also enabled by reversible interaction between Zn+2and amide or amine groups in the sample. This property is important for example if the sample is used to formulate fluorescent printing ink, the ink will form stable marks that are rub resistant.

[0199] Example 22: Use of the product of this invention as a marker / taggant on other products for anticounterfeeding or sorting purposes

[0200] The product of this invention can be used to formulate fluorescent inks for printing covert or overt security marks on other products so as to differentiate them from fake ones. By surprise, we found that the water solution part of the product of this invention forms stable prints on various type of printing papers using ordinary inkjet printers. We used this to print invisible QR code (FIG. 9) which becomes visible under UV light or when illuminated by blue / green light and viewed through an optical filter. This can be used as an anti-counterfeiting mark, for track and trace and also for product sorting purposes, e.g sorting letters and parcels or sorting plastics for recycling. Besides QR codes, any other artwork including microtext can be printed using this special ink to act as anti-counterfeiting marks. It is important to note that any polar solvent would work instead of water and the insoluble part or the whole of the organic / inorganic product material of this invention can be used to formulate fluorescent printing inks. UV printing as well as traditional printing technigues such as relief, intaglio, flexographic, offset, engraving, pad printing and stencil printing can be implemented. The product of this invention can also be used as a marker / taggant for plastic sorting employing the current technigue of near-infra-red (NIR) spectroscopy. This is enabled by the fact the sample e.g that obtained from example 5 exhibits unigue NIR absorption peaks where other common plastics do not absorb for instance at wavelength 1570 nm and 1696 nm (FIG. 2). Such peaks can be used as a signal to identify the plastics in the sorting process. Within this framework, the marker can be applied as label on plastics or incorporated into the plastics during manufacture e.g. by mixing the marker with the polymer / plastic granules at about 3-5 % by weight and feeding it into the injection or blow moulding or using the twin-screw extruder.

[0201] Example 23: Spectra of the prototype white LED

[0202] The prototype white LED was obtained by coating the phosphor powder on to the 5 mm cylindrical blue LEDs of wavelength 470 nm and 430 nm. The sample powder was first mixed with Acrifix 1s 0116 to form a past and then immediately painted on top of the transparent dome casing of the LEDs. The thickness of the coated layer was adjusted to allow appropriate transmission of both the blue and the yellow light emitted by the phosphor. The coated layer was allowed to cure at room temperature for one day. Additive mixing of the blue and yellow light forms the white light. The spectrum of the prepared white LED was measured using a calibrated Avantes LED light measurement bundle set-up. The set-up consists of an AvaSpec-ULS2048CL- EVO spectrometer, FC-U IR600-2-ME-FC / SMA fibre optic cable, AvaSphere-50-IRRAD integrating sphere, Navisphere LED adapter and the Avasoft irradiance software.

[0203] Citation List

[0204] Patent Literature

[0205] - W02009 / 120716A1

[0206] - WO2016 / 058553A1 Non-Patent Literature

[0207] - Pangkuan Chen et al.; in “White Light Emitting Lanthanide Metallogels with Tunable Luminescence and Reversible Stimuli-Responsive Properties”, J. Am, Chem. Soc.2015, 137, 11590

[0208] -Yun, Xiangyan et al.; in “High-quality white photoluminescence of zero-dimensional hybrid metal halides with multiple optical polyhedral units”, Journal of Luminescence (2024), 268, 120379

Claims

Claims1. A photoluminescent organic / inorganic hybrid material, which is the reaction product of a mixture of the following organic and inorganic precursor materials: a) a first organic compound independently selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic),(la) (lb) (Ic) wherein:R1 is selected from the group consisting of -CH3, and OH, -COOR3, NH2 and -OOCR3;R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms;G is selected from -COOR3. -OOCR3, COOR3-R4, and -OOCR3-R4;R3 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms;R4 is selected from: mercapto, hydroxyl, alkene, and phosphoryl; wherein: the compound of formula (la) is a (Ci-Cw)-alkyl ester of citric acid; the compound of formula (lb) is a (Ci-Cw)-alkyl ester of pentaerythritol with an amino mercapto, hydroxyl or alkene as end groups; and the compound of formula (Ic) is a (Ci-Cw)-alkyl linear or branched alkyl ester of an acid selected from malonic acid, succinic acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, with at least two ester groups, preferably (Ci-C2o)-alkyl linear or branched alkyl ester; b) a second organic compound which is either a linear or a branched structure of formula (II):X-(R5)m-(OR6)n-X(II) wherein:Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms Re is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1 ; n is an integer ranging from 1 to 10.000;X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and a Boc-protected amino group; and wherein the compound of formula (II) is either a compound of formula (Ila),wherein:R? is an amino group,Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4, or a compound of formula (lib):R9-CHR10-COOH(Hb) wherein:R9 is an amino group,R10 is a side chain of a common amino acid; c) an inorganic powder comprising at least one of the following compounds: MyCz, (III);- My’Xz’ (IV); and P2O5(V); wherein:M is a metal which is not classified as rare-earth and has a valency 2, 3, or 4;C is a chalcogen;X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; andthe inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); and c6) a glass frits (powder); and c7) mineral sand (zircon sand); and which is obtainable by a process which comprises subjecting a mixture of the organic and inorganic precursor materials to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; heating with or without condensation step; and mixing at room temperature.

2. The photoluminescent organic / inorganic hybrid material according to claim 1, wherein:The (Ci-Cw)-alkyl ester of citric acid is selected from the group consisting of trimethyl citrate, triethyl citrate, triethyl acetyl citrate, tributyl citrate, and tributyl acetyl citrate, the (Ci-Cw)-alkyl linear or branched alkyl ester of an organic acid with at least two ester groups is selected from the group consisting of dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl sebacate, diethyl malonate, diethyl succinate, diethyl glutarate, diethyl adipate, diethyl pimelate, diethyl suberate, diethyl sebacate, dipropyl succinate, dipropyl glutarate, dipropyl adipate, dipropyl pimelate, propyl butyl pimelate, dipropyl suberate, dipropyl sebacate, dibutyl malonate, dibutyl succinate, dibutyl glutarate, dibutyl adipate, dibutyl pimelate, dibutyl suberate, and dibutyl sebacate; diethylmehoxymethylene malonate, diethyl 2-(2-cynoethyl) malonate, ethyl 2-(ethoxymethylene) acetoacetate, diethyl aminomethylene malonate, and ethyl 2-cyano -3- ethoxyacrylate, glyceryl triacetate; and the pentaerythritol derived esters with thiol, hydroxyl or alkene as end group is pentaerythritoltetra kis(3-mercarptopropionate, trimethylolpropantriacrylate, and trimethylolpropan-tris(3-mercaptopropionate; and the second organic compound of formula (II) is selected from polypropylene glycol)- bis(2-aminopropylether), 0,0- bis (2-aminopropyl)-polypopylene glycol-block-polyethylene glycol-block-polypropylene glycol; O-(2-aminopropyl)-O’-(2-methoxyethyl) propyleneglycol; poy(ethylene oxide) 4-arm, amine terminated; poly(ethylenglycol) bis(3- aminopropyl); poly(ethylenglycol) bis (amine); 4,7,10 trioxa-1 ,13-tridecandiamine; 2,2- (ethylendioxy) diethylamine; 1 ,11 -diamino, 3, 6, 9-trioxandecane; 1 ,13-diamino-4,7,10- trioxatridicane; 4,9-dioxa-1 ,12-dodean diamine; 1 ,8-diamino-3-6-dioxaoctane; 1 ,12- diamino-dodecane; poly(ethylenglycol) methyletherthiol; poly(ethylenglycol)methylether- maleimide; poly(ethylenglycol)-2-mercaptoethylehter acetic acid; and poly(ethylenglycol)- 2-amino ethyl ether acetic acid.

3. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-2, wherein the reaction product has an organic part comprising a polymer consisting of formula (1) and or formula (2)(1) (2) wherein:R is selected from the group consisting of mercapto, amino, methylene, hydroxyamine, oxime, hydrazine, hydrazone, hydrazide, nitroso, acetyl (Ci-Cw)-alkyl ester, hydroxyl and hydrogen atom,C is the central carbon atom on which R and at least one branch represented by the section in square parenthesis are attached, k is an integer ranging between 0 - 20, g is 0 or 1 ,O is an oxygen atom, j is an integer between 1-4 and corresponds to the number of branches attached to the central carbon,R11 is independently selected from amide, thiol-ester, secondary or tertiary amino groups,R12 is an organic radical compound which is either of liner or branched structure comprising of formula (Ila’) or (lib’);-CHR9-COOH(Hb’) wherein:R’7 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms;‘a’ is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer between 2-4; andR9 represents side chains in common amino acids; and the inorganic part is as defined in claim 1.

4. The photoluminescent organic / inorganic hybrid material according to any of the claims1-3, wherein the reaction product has an inorganic part as follows:[f(MyCz) f(MyXz) f(P2O5)]T wherein:M is a metal which is not classified as rare-earth and has a valency 2, 3, or 4;C is a chalcogen;X is a halogen; f is the percent mole fraction in the range, 0 < f < 100, of the inorganic mixture excluding the organic part; andT is the percent mole fraction in the range, 20 < T < 98, of the inorganic part of the organic / inorganic hybrid material.

5. The photoluminescent organic / inorganic hybrid material according to claim 4, wherein the inorganic part is selected from the group consisting of [9(ZnO) 35(SnO) 56(P2Os)]5o; [43(ZnO) 57(MgF2)]83; [49(ZnO) 51 (CaF2)]7i; [100(ZnO)]79; [53(ZnO) 37(SnO)]76;[100(CaF2)]92; and [(65 (ZrO2) 35(SiO2)184.

6. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-5, wherein an organic compound of formula (la) is selected from Triethyl citrate, Triethyl acetyl citrate, Tributyl acetyl citrate, a compound of formula (lb) is Pentaerythritoltetrakis (3-mercaptopropionate), a compound of formula (Ic) is selected from dimethyl succinate and diethylethoxymethylene malonate, a compound of formula (Ila) is selected from polypropylene glycol bis(2-aminopropyl ether), 4,7,10 Trioxa-1 , 13 tridecanediamine, 2,2(ethylenedioxy) bis ethylamine and a compound of formular (lib) is L-arginine.

7. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-6, is selected from: a) a photoluminescent organic / inorganic hybrid material which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 22.6, 26.2, and 27.3 degree 2 theta at a Cu-Ka radiation A= 1.5406 Angstroms; and b) a photoluminescent organic / inorganic hybrid material which exhibits an X-ray diffractogram that comprises characteristic peaks of greater intensity than the rest at approximately 31.8; 34.4; 36.2; 47.5; 56.5; 62.8; 67;9 and 69.1 degrees 2 theta at a Cu- Ka radiation A= 1.5406 A.

8. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-7, wherein the inorganic part comprises of either Tin Phosphate Sn8(PC>4)2 which crystalizes into Monoklin structure with phase group P21 / c (14) and lattice parameters:11.09200 A, 4.83000 A, 16.40500 A, 94,280 ° or two phases of ZnO Zincite, syn Hexagonal, phase group: P63mc (186), lattice parameter: 3,24940 A 5,20380 A and MgF2Sellaite, syn Tetragonal, phase group: P42 / mnm (136), lattice parameters: 4.62130 A, 3.01590 A.

9. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-8, which is either amorphous, mono- or polycrystalline with average grain (crystallite) sizes in the range of 10 - 500 nm.

10. The photoluminescent organic / inorganic hybrid material according to any of the claims 1-9, which is a self-healing material wherein:a) the self-healing is enabled by non-covalent supramolecular interactions comprising of H-bonding network between amide, amine, carbonyl moieties and metal-ligand reversible interactions comprising of interaction between Zn+2and amide or amine groups b) upon a mechanical damage, the said material autonomously is able to restore its mechanical integrity at room temperature within a period of 18 hours without the need for external repair agents.11 . A process for preparing the photoluminescent organic / inorganic hybrid material as defined in any of the claims 1-10, which comprises subjecting a mixture of the following organic and inorganic precursor materials: a) a first organic compound independently selected from a compound of formula (la), a compound of formula (lb), and a compound of formula (Ic),(la) (lb) (Ic) wherein:Ri is selected from the group consisting of -CH3, OH, NH2, -COOR3, and -OOCR3;R2 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms;G is selected from the group consisting of -COOR3. -OOCR3, COOR3-R4, and -OOCR3-R4;R3 is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; andR4 is selected from the group consisting of amino, mercapto, hydroxyl, alkene, and phosphoryl; and wherein the compound of formula (la) is a (Ci-Cw)-alkyl ester of citric acid; the compound of formula (lb) is a (Ci-Cw)-alkyl ester of pentaerythritol with a mercapto hydroxyl or alkene as end groups; andthe compound of formula (Ic) is a (Ci-Cw)-alkyl linear or branched alkyl ester of an acid selected from malonic acid, succinic acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, with at least two ester groups, preferably (Ci-C2o)-alkyl linear or branched alkyl ester; b) a second organic compound which is either a linear or branched structure of formula (II):X-(R5)m-(OR6)n-X(II) wherein:Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms;Re is an alkyl group having 2-4 linear or branched carbon atoms; m is an integer selected from 0 and 1 ; n is an integer ranging from 1 to 10.000;X is selected from the group consisting of mercapto, hydroxyl, amino, carbonyl an aldehyde, phosphoryl, and a Boc-protected amino group; and the compound of formula (II) is either a compound of formula (Ila)wherein:R? is an amino group,Rs is a linear, branched or cyclic saturated or unsaturated hydrocarbon radical containing 1 to 20 carbon atoms; a is an integer selected from 0 and 1 ; b is an integer ranging from 1 to 4000; o is an integer ranging from 2 and 4, or a compound of formula (lib):R9-CHR10-COOH(Hb)whereinRg is an amino group;R represents side chains in common amino acids; and c) an inorganic powder comprising at least one of the following compounds: MyCz, (III); My’Xz’ (IV); and P2O5(V); wherein:M is a metal which is not classified as rare-earth and has valency 2, 3, or 4;C is a chalcogen;X is a halogen; y, y’, z, and z’ are integers independently selected from 1 to 6; and the inorganic powder being selected from the group consisting of: c1) a mixture of compound (V) and two different compounds of formula (III); c2) a mixture of one compound (III) and one compound (IV); c3) a mixture of two different compounds of formula (III); c4) a compound (III); c5) a compound (IV); c6) a glass frits (powder); and c7) mineral sand (zircon sand); to reaction conditions selected from the group consisting of: a sonochemical reaction; a solvothermal reaction; heating with or without condensation step; and mixing at room temperature.

12. The process according to claim 11 , wherein the reaction conditions are a sonochemical reaction which comprises:(la) mixing the precursors where in the mole percentages of the individual organic compounds in the mixtures ais from 0.1% to 15% by mole, and the mole percentages of the individual inorganic compounds in the mixture are from 20% to 60% by mole.(lb) ultrasonicating the mixture for the necessary period of time; and(lc) cooling down to room temperature.

13. The process according to any of the claims 11-12, wherein the sonication was conducted at a constant power ranging between 100 to 900 W and vibration amplitude between 20 to 100 % for a period of time between 0.5 to 3 hours at a temperature comprised in a range from 70 to 300 °C.5014. The process according to claim 11 , wherein the first organic compound is a compound of formula (la), the second organic compound is a compound of formula (Ila) and the process is conducted by mixing at_room temperature (20-30°C).

15. Use of a photoluminescent organic / inorganic hybrid material as defined in any of the claims 1-10, either as a product marker / taggant, or as fluorescent marker in plastic sorting.

16. Use of a photoluminescent organic / inorganic hybrid material as defined in any of the claims 1-10, as a light converter in white light emitting diodes (wLEDs).

17. A light converter according to claim 16, for remote extraction of white light from blue / UV LEDs through reflection mode which comprises: a) a LED chip (1) to generate blue or UV light; b) a curved reflecting surface (3) to reflect light on to the phosphor coated curved surface and to redirect the light to the exit surface; c) optionally, a reflecting surface in form of an inverted pyramid or cone shape (6) and its support (7) to redirect LED light onto the curved surface; d) a phosphor (4) as defined in any of the claims 1-12 coated onto the reflective surface, which is configured to absorb blue or UV light emitted from the LED, and with the ability to emit light having a wavelength different from the absorbed light in the red, green and blue regions of the spectrum which combine to produce white light; and e) a transparent / translucent light diffusing cover (5).

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