Method for preparing robust supramolecular assemblies

Abstract

A robust bundle of single-walled nanotubes (b-NTs) comprising a monomer that forms a supramolecular structure and a cationic amino acid.

Description

03284.0398W001METHOD FOR PREPARING ROBUST SUPRAMOLECULAR ASSEMBLIESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and is a non-provisional of, U.S. Patent Application 63 / 770,075 (filed March 11, 2025), the entirety of which is incorporated herein by reference.STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under grant numbers HRD-1547830, 1752475 and 1531859 awarded by the National Science Foundation (NSF) and grant number DE-SC0018142 awarded by the United States Department of Energy Office of Basic Energy Sciences (DOE-BES). The government has certain rights in the invention.BACKGROUND OF THE INVENTION

[0003] The future of sustainable energy and information technologies requires efficient and, more importantly, robust solutions, especially as more frequent extreme weather events (e.g. climate change) threaten existing information technology and energy architectures. Robustness, that is, a system’s ability to maintain its function in the face of external and internal perturbations, is a key property of living systems. In nature, highly robust lightharvesting (LH) complexes found in photosynthetic bacteria are responsible for harvesting light energy (electronic excitation energy) and transferring it to the bacteria’s reaction centers where it is then converted into chemical energy (charge-separated state). These LH complexes contain close-packed photosynthetic pigments that self-assemble into hierarchical supramolecular assemblies with a delicate structure-function relationship.

[0004] As the pigments within the supramolecular assembly are held together by non-covalent interactions that allow for self-assembly and reversible assembly, the assembly easily undergo significant structural changes upon even minor changes of environmental conditions (for example, driving forces, temperature, solvent conditions, ion concentration, impurities, and deposition onto solid substrates). Thus, the assembly’s structure is intrinsically unstable. This is a pivotal property for the assembly’s robustness because the low stability allows the assembly to dynamically respond to external stimuli while maintaining its functionality.03284.0398W001

[0005] However, the assembly’s structural fragility is the limiting factor for translating nature’s successful design principle to applications ranging from renewable energy (e.g., solar energy harvesting & conversion) to nanomedicine (e.g., sensing and drug delivery) or information technology e.g., molecular electronics & spintronics). In nature (in LH complexes of photosynthetic bacteria, for example) the fragile supramolecular assemblies are embedded in a complex protein scaffold. The role the scaffold plays in the bacteria’s overall function is unclear, but nature may have evolved these sophisticated protein environments to structurally stabilize their fragile supra-molecular assemblies. In the bacteria’s LH complexes, their hierarchical supramolecular assembly design is responsible for not only their impressive light harvesting efficiency (approximately 90% and above) but also for their remarkable robustness against environmental stress (such as extreme temperature fluctuations). Translating nature’s successful design principle to broad applications requires both (1) control over the hierarchical self-assembly process and (2) robust supramolecular structures. To date, no such commercial system is available. Accordingly, an improved system would be commercially desirable.

[0006] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.SUMMARY

[0007] This disclosure provides a robust bundle of single-walled nanotubes (b-NTs) comprising a monomer that forms a supramolecular structure and a cationic amino acid. This disclosure also provides a method for forming the same. An advantage that may be realized in the practice of some disclosed embodiments an increase in the thermal robustness and / or decrease is the emissive lifetime of the resulting b-NTS relative to a corresponding b-NT that lacks the cationic amino acid.

[0008] In a first embodiment, a bundle of single-walled nanotubes (b-NTs) is provided. The b-NTs comprising: a monomer that forms a supramolecular structure in water; an amino acid selected from the group consisting of arginine, lysine and combinations thereof; and wherein the bundle of single-walled nanotubes (b-NTs) exhibits at least a 25% reduction in emission lifetime relative to a corresponding bundle of single-walled nanotubes (b-NTs) that lacks the amino acid.

[0009] In a second embodiment, a method for preparing bundles of single-walled nanotubes (b-NTs) is provided. The method comprising: preparing a monomer stock solution03284.0398W001by dissolving a monomer in an organic solvent such that the monomer is present at a concentration from about 3.1 mM to about IM, thereby producing a first solution, wherein the monomer is a supram olecular structure forming monomer; preparing nanotubes (NTs) by combining the first solution with water such that the monomer is present at a concentration greater than or equal to 0.048 mM, thereby producing a second solution; preparing bundles of single-walled nanotubes (b-NTs) by adding an amino acid selected from the group consisting of arginine, lysine and combinations thereof to the second solution such that the amino acid has a concentration between from about 0.45mM to about IM, thereby producing a third solution; and storing the third solution in darkness for at least 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs).

[0010] In a third embodiment, a method for preparing bundles of single-walled nanotubes (b-NTs) is provided. The method comprising: preparing a monomer stock solution by dissolving a cyanine dye in an organic solvent such that the cyanine dye is present at a concentration greater than or equal to about 3.1 mM, thereby producing a first solution; preparing nanotubes (NTs) by combining the first solution with water such that the cyanine dye is present at a concentration greater than or equal to about 0.048 mM, thereby producing a second solution; preparing bundles of single-walled nanotubes (b-NTs) by adding an amino acid selected from the group consisting of arginine, lysine and combinations thereof to the second solution such that the amino acid has a concentration greater than or equal to about 0.45mM, thereby producing a third solution; and storing the third solution in darkness for at least 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs).

[0011] This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.03284.0398W001BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which:

[0013] FIG. l is a flow diagram showing steps in one method of the invention.

[0014] FIG. 2 is a graph showing steady-state absorption spectra of cyanine dye monomer, double-walled nanotube (NTs) and neat bundled single-walled nanotube (b-NTs).

[0015] FIG. 3A shows a steady-state absorption spectra and Cryo-TEM images of NTs and neat b-NTs are shown.

[0016] FIG. 3B shows steady state absorption spectra and a Cryo-TEM image of NTS, b-NTS and b-NTS in the presence of arginine.

[0017] FIG. 4A shows a steady-state absorption spectra of conventional NTs during heat stress at 95°C and cooling to room temperature at about 23°C (Annealed).

[0018] FIG. 4Bshows a steady-state absorption spectra of conventional b-NTs during heat stress at 95°C and cooling to room temperature at about 23°C (Annealed).

[0019] FIG. 4C shows a steady-state absorption spectra of b-NTs made according to this disclosure during heat stress at 95°C and cooling to room temperature at about 23°C (Annealed).

[0020] FIG. 4D shows a steady-state absorption spectra of conventional b-NTs in the presence of NaOH (control) during heat stress at 95°C and cooling to room temperature at about 23 °C (Annealed).

[0021] FIG. 4E shows a steady-state absorption spectra of b-NTs made according to this disclosure after boiling in water for 30 minutes.

[0022] FIG. 5A shows a steady-state absorption spectra of conventional b-NTs and b-NTs in presence of lysine before heat stress cycling and after cooled to room temperature at about 23 °C (Annealed).03284.0398W001

[0023] FIG. 5B shows a steady-state absorption spectra of b-NTs in presence of arginine before heat stress cycling and after cooled to room temperature at about 23 °C (Annealed).

[0024] FIG. 5C shows a steady-state absorption spectra of b-NTs in presence of arginine before heat stress cycling and after cooled to room temperature at about 23 °C (Annealed).

[0025] FIG. 6A shows a steady-state absorption spectra of conventional NTs diluted with methanol at different dilution factors (DF).

[0026] FIG. 6B shows a steady-state absorption spectra of conventional b-NTs diluted with methanol at different dilution factors (DF).

[0027] FIG. 6C shows a steady-state absorption spectra of NTs in presence of arginine diluted with methanol at different dilution factors (DF).

[0028] FIG. 7A shows a steady-state absorption spectra of conventional b-NTs exposed to visible light of 5 min, 30 min and 60 min.

[0029] FIG. 7B shows a steady-state absorption spectra of b-NTs in the presence of arginine exposed to visible light of 5 min, 30 min and 60 min.

[0030] FIG. 8 A shows a steady-state emission spectra of conventional NTs in solution and after dried on a solid substrate.

[0031] FIG. 8B shows a steady-state emission spectra of conventional b-NTs in presence of arginine in solution and after dried on a solid substrate.

[0032] FIG. 8C shows a steady-state emission spectra of b-NTs in presence of arginine in solution and after dried on a solid substrate.

[0033] FIG. 9A depicts a graph of the radiative lifetime of monomeric C8S3.

[0034] FIG. 9B depicts a graph of the radiative lifetime of conventional NTs.

[0035] FIG. 9C depicts a graph of the radiative lifetime of conventional b-NTs.

[0036] FIG. 9D depicts a graph of the radiative lifetime of b-NTs in presence of arginine.

[0037] FIG. 9E depicts a graph of the radiative lifetime of b-NTs in presence of NaOH.

[0038] FIG. 9F depicts a graph of the radiative lifetime of b-NTs in presence of lysine.

[0039] FIG. 10A shows a steady-state absorption spectra of NTs in the presence of various concentrations of arginine.

[0040] FIG. 10B shows a steady-state absorption spectra of NTs in the presence of various concentrations of lysine.

[0041] FIG. 10C shows a steady-state absorption spectra of NTs in the presence of various concentrations of NaOH.

[0042] FIG. 11 A shows a steady-state absorption spectra of NTs in the presence of various arginine exposure times.03284.0398W001

[0043] FIG. 1 IB shows a steady-state absorption spectra of NTs in the presence of various lysine exposure times.

[0044] FIG. 11C shows a steady-state emission spectra of NTs in the presence of various NaOH exposure times.DETAILED DESCRIPTION OF THE INVENTION

[0045] This disclosure provides a controlled the hierarchical self-assembly process that produces highly robust hierarchical supramolecular assemblies. A Frenkel excitonic supram olecular double-walled nanotubes (NTs) self-assembles in solution from a monomer. Upon the addition of a cationic amino acid (e.g. arginine, lysine) these NTs hierarchically self-assemble into bundles of single-walled nanotubes (b-NTs). Without wishing to be bound to any particular theory, the cationic amino acids are believed to provide intermolecular electrostatic interactions that facilitate hierarchical self-assembly and stabilize the resulting b-NTs.

[0046] The disclosed b-NTs are highly robust even under extreme fluctuating environmental conditions. The disclosed method is applicable to dye supramolecular assemblies, polymer assemblies as well as to colloidal nanoparticles (metal, metal oxides, semiconductor, carbon-based, silica-based). This disclosure provides solution-based hierarchical supramolecular assemblies that are suitable for robust non-covalently bonded materials and related applications.

[0047] Referring to FIG. 1 and method 100 depicted therein, step 102 is executed wherein a monomer stock solution in an organic solvent is prepared. In one embodiment, the monomer concentration is from 3.1 mM to IM. For example, suitable concentrations include from 3.1 mM to 500 mM, from 3.1 mM to 100 mM, from 3.1 mM to 50 mM, from 3.1 mM to 25 mM and from 3.1 mM to 10 mM.

[0048] Different organic solvent classes can be employed to prepare supramolecular assemblies such as protic, aprotic, nonpolar and fluorinated solvents, and ionic liquids such as chloride and bromide solutions. The organic solvent is chosen to both dissolve the monomer and, in some embodiments, also be water-miscible when NTs are prepared in aqueous solution in the subsequent step (step 104). In some embodiments, an organic alcohol solvent is used, such as methanol, ethanol, propanol (including isopropanol or n-propanol) or butanol.03284.0398W001In some embodiment, the organic solvent is acetonitrile, acetone, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), tetrahydrofuran (THF), ethyl acetate or toluene.

[0049] Various types of monomers may be used to form supramolecular assemblies such as dye supramolecular assemblies, polymer assemblies, colloidal nanoparticles (metal, metal oxides, semiconductor, carbon-based, silica-based).

[0050] Examples of organic monomers that form dye supramolecular assemblies include pseudoisocyanine, 5,5',6,6'-tetrachlorobenzimidazolocarbocyanine, l,l'-diethyl-2,2'-cyanine iodide, l,l'-diethyl-2,2'-carbocyanine iodide, thiacarbocyanine dyes (e.g., 3,3'-diethylthiacarbocyanine iodide, MC-540 (Merocyanine 540), phenyl -substituted merocyanines, perylene bisimide (PBI), naphthalene diimide (NDI) and perylene tetracarboxylic diimide (PTCDI).

[0051] In one such embodiment, the organic dye is amphiphilic cyanine dye 3,3 '-bis(2-sulfopropyl)-5,5',6,6' -tetrachl oro-1, 1 '-dioctylbenzimidacarbo-cyanine, commonly abbreviated as C8S3. For example, a monomer stock solution of NTs may be prepared by dissolving a solid cyanine dye (e.g. C8S3, CAS number 191032-02-7) in an organic solvent. As used in this specification, a cyanine dye is a dye molecule that has two nitrogen atoms, at least one of which is quaternary, that are separated by a conjugated polymethine bridge. One such example is shown in Formula A.Formula A

[0052] In Formula A, n is a non-zero integer. In some embodiments, n is selected from 1, 2, 3, 4, 5 or 6. R1, R2, R3and R4may be independently selected groups such as methyl, ethyl or other conventional cyanine dye substitutions (e.g. nitro-containing heterocycles like indole, benzothiazole, benzimidazole). Examples include Cy2, Cy3, Cy3.5, Cy5, Cy5.5, Cy7, Cy7.5. Further examples include l,l'-diethyl-2,2'-cyanine, carbocyanines, and dicarbocyanines.

[0053] In another embodiment, the dye is a porphyrin derivative. In one such example, the porphyrin derivative is shown in Formula B.03284.0398W001Formula B

[0054] In Formula B, R1to R12are independently selected groups that are conventional porphyrin dye substitutions. Examples include heme / hemin, protoporphyrin IX, chlorophylls (e.g. chlorophyll a, b), tetraphenylporphyrine (TPP, H2TPP), octaethylporphyrin (EOT, H2OEP), phthalocyanines (e.g. copper phthalocyanine), cobalamin (B12). Also see Jin et al., “Biomimetic Self-assembling acylphthalocyanines” Chem. Commun., 2015, 51, 11884-11887; Balaban et al.; “Tailoring Porphyrins and Chlorins for Self-Assembly in Biomimetic Artificial Antenna System” acc. Chem. Res. 2005, 38, 612-62; Hecht et al.;“ Supramol ecularly Engineered J-Aggregates Based on Perylene Bisimide dyes” Acc. Chem. Res. 2021, 54, 642-653; Wurthner et al.; J-Aggregates: From Serendipitous Discovery to Supramol ecul ar Engineering of Functional dye Materials” Angewandte Chemie International Edition, Vol. 50, Issue 15, pp 3376-3410, 25 March 2011. The content of each of the aforementioned articles is hereby incorporate by reference.

[0055] Examples of polymer assemblies include micelles, block copolymer micelles -formed PEG-PLA, PEG-PCL, polymeric micelles, poly(amidoamine) (PAMAM) dendrimers, polypropylene imine (PPI) dendrimers, hydrogels, natural polymer-based hydrogels, alginate, chitosan, hyaluronic acid, polylactic acid (PLA), Poly(lactic-co-glycolic acid (PLGA), and polycaprolactone (PCL) nanoparticles, synthetic hydrogels - polyacrylamide, polyethylene glycol (PEG) hydrogels, polystyrenes (PS), poly(methyl methacrylate) (PMMA), polyaniline (PANI), polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT).

[0056] Examples of colloidal nanoparticles include metal nanoparticles e.g. silver nanoparticles, gold nanoparticles, platinum nanoparticles, palladium nanoparticles, copper nanoparticles, nickel nanoparticles), metal oxide nanoparticles e.g. zinc oxide, titanium oxide, selenium oxide, iron oxide (e.g. Fe20s, FesCh), aluminum oxide, copper oxide, cobalt oxide, cerium oxide, manganese oxide), semiconductor nanoparticles e.g. CdSe, CdS, CdTe,03284.0398W001ZnS, ZnSe, PbS, PbSe), carbon-based nanoparticles (e.g. carbon nanotubes (single-walled or multi -walled), graphen-based nanoparticles, reduced graphene oxide (rGO), fullerenes, carbon quantum dots) and silica-based nanoparticles (e.g. mesoporous silica nanoparticles, Stober silica nanoparticles, organosilica nanoparticles).

[0057] In step 104 of method 100, nanotubes (NTs) are prepared from the monomer stock solution. The monomer stock solution is combined with water such that the monomer is present at a concentration greater than or equal to 0.048 mM. In some embodiments, the water is added in two or more batches with the solution being stored in the dark between additions. For example, after a first addition of the water, the solution may be stored in the dark for at least 12 hours or at least 24 h before adding an additional 500 pL ultrapure water (monomer concentration is ranging from 0.048 mM to concentrations as high as 20 mM). For example, suitable monomer concentrations include from 0.048 mM to 20mM, from 0.048 mM to 15 mM, from 0.048 mM to 10 mM, from 0.048 mM to 5 mM, from 0.048 mM to 1 mM, from 0.048 mM to 0.1 mM.

[0058] In step 106 of method 100, a cationic amino acid (e.g. arginine, lysine) is added into the NTs. Sufficient amino acid is added to result in an amino acid concentration from 0.45mM to IM. For example, suitable amino acid concentrations include from 0.45 mM to 500 mM, from 0.45 mM to 250 mM, from 0.45 mM to 100 mM, from 0.45 mM to 50 mM, from 0.45 mM to 25 mM, from 0.45 mM to 10 mM and from 0.45 mM to 1 mM. In some embodiments, the amino acid and the monomer are present in the solution at a molar ratio (amino acid:monomer) of at least 1:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:l, atleast 8:1, atleast 9:l, atleast 10:1, at least 11:1, atleast 13:1 or atleast 14:1.

[0059] In step 108, the resulting solution is stored in darkness for at least 24 hours. The b-NTs are obtained within 48 hours. In some embodiments, b-NTs are obtained with arginine in less than 24 hours.

[0060] In step 110, the solution of b-NTs is dried to provide a solid product. The solid product may be rehydrated, and the integrity of the b-NTs is maintained.

[0061] Example 1: Comparative example03284.0398W001

[0062] 14.4 mg of C8S3 was dissolved in 5 mL of methanol to produce a monomer stock solution with a concentration of 3.1 mM (step 102). 130 pL of the monomeric stock solution was then added into 500 pL ultrapure water (greater than 18.2M Q cm Bamstead). (step 104). After the NTs formed, no arginine added (i.e. step 106 was omitted). The solution was stored in darkness for 4 weeks, thereby preparing bundles of single-walled nanotubes (b-NTs) (step 108). NTs are stored in glass vials, in the dark for about one month.

[0063] Example 2: NaOH control

[0064] 14.4 mg of C8S3 was dissolved in 5 mL of methanol to produce a monomer stock solution with a concentration of 3.1 mM (step 102). 130 pL of the monomeric stock solution was then added into 500 pL ultrapure water (greater than 18.2M Q cm Bamstead). (step 104). After the NTs formed 25 pl of 100 mM NaOH was added, resulting in an ion concentration of 9 mM (step 106). The solution was stored in darkness for 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs) (step 108).

[0065] Example 3: arginine

[0066] 14.4 mg of C8S3 was dissolved in 5 mL of methanol to produce a monomer stock solution with a concentration of 3.1 mM (step 102). 130 pL of the monomeric stock solution was then added into 500 pL ultrapure water (greater than 18.2M Q cm Bamstead). (step 104). After the NTs formed, 25 pl of 100 mM arginine was added, resulting in an arginine concentration of 9 mM (step 106). The solution was stored in darkness for 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs) (step 108).

[0067] Example 4: lysine

[0068] 14.4 mg of C8S3 was dissolved in 5 mL of methanol to produce a monomer stock solution with a concentration of 3.1 mM (step 102). 130 pL of the monomeric stock solution was then added into 500 pL ultrapure water (greater than 18.2M Q cm Bamstead). (step 104). After the NTs formed, 25 pl of 100 mM lysine was added, resulting in a lysine concentration of 9 mM (step 106). The solution was stored in darkness for 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs) (step 108).

[0069] Rapid Hierarchical Self-Assembly Process: In general, upon initiation of the self-assembly process, the broad absorption spectrum of the C8S3 monomers undergoes a03284.0398W001large spectral red-shift accompanied with a substantial narrowing of the absorption bands; both features characteristic of so-called J-aggregates or Scheibe aggregates. These spectral changes are caused by the close-packing arrangement of the C8S3 monomers within the NTs, which causes excitation transfer interactions (resonant coupling) between the monomers’ transition dipole moments resulting into new electronic states, delocalized Frenkel excitons (J-bands). The assembly’s optical properties are highly sensitive to the details of the molecular packing within the supramolecular assembly.

[0070] FIG. 2 shows a typical absorption spectrum taken from a solution of C8S3 monomers (monomer transitions) in methanol. When the monomer stock solution is added to a polar solvent the monomers self-assemble into double-walled NTs (FIG. 2, dotted line), exhibiting well-defined and well-characterized spectroscopic signatures. The narrow exciton band at 599 nm and broad exciton band at 589 nm are originated by parallel polarized exciton transitions of the NT’s inner- wall and outer- wall cylinder, respectively. The shoulder around 580 nm and features at higher energies result from perpendicular polarized exciton transitions from both the NT’s inner-wall and outer- wall cylinders. FIG. 2 also shows (solid line) the spectroscopic signature of bundled NTs in aqueous solution. The narrow exciton band at 603 nm and a broad absorption feature around 580 nm mainly originated by parallel polarized and perpendicular polarized exciton transitions of the bundled NTs, respectively. These spectral features permit one to identify the formation of NTs and b-NTs from monomers.

[0071] Conventionally, to form b-NTs from NTs, the hierarchical self-assembling process can take from time ranging from 3 weeks, to 1 month or even up to 3 months and beyond. In stark contrast, b-NTs can be obtained in less than 48 hours of exposure to the cationic amino acid (step 108). For example, b-NTs can be obtained in less than 24 hours. The cationic amino acid interactions with NTs significantly accelerate the hierarchical assembling (bundling) process, providing control of the hierarchical supramolecular selfassembly process.

[0072] Referring to FIG. 3A, a steady-state absorption spectra of NTs and neat (conventional) b-NTs are shown. Referring to FIG. 3B, a sample of b-NTs was prepared according to Example 1. Absorbance spectra showed the formation of NTs (dotted line), b-NTs (dashed line, comparative example 1) and b-NTs (solid line, inventive example 3). The long-range morphology of the b-NTs in the presence of arginine was also characterized via Cryo-TEM.03284.0398W001

[0073] Bundled NTs prepared with arginine are robust against heat stress: Light harvesting materials should be robust against heat stress to maintain their stability and efficiency in converting light into energy, even under extreme heat conditions. This is important for maintaining their performance in various applications such as light-emitting devices, solar cells and etc.

[0074] FIG. 4A, FIG. 4B and FIG. 4C depict absorption spectra taken after heat stress was applied to NTs, neat b-NTs (control example 1) and b-NTs with arginine (example 3). The three samples were treated as follows: solution was heated to 95°C and incubated at that temperature for 5 minutes, then cooled (annealed) to room temperature at 23 °C. FIG. 4 A shows that conventional NTs are not robust under heat stress. The increase of monomer signature shows the disassembly of NTs into monomers. In FIG. 4B, the neat b-NTs were prepared by storing NTs solution under dark conditions for a month. After the heat treatment, a minor degradation was observed from and there was no significant increase in free monomer signature. In contrast with these two conventional materials, arginine interacting with NTs and forming b-NT provides significant robustness of excitonic properties. Robustness of supramolecular structure (see FIG. 4C) remarkably had no significant change in overall spectral shape and energy positions of exciton bands was observed after heat stress.

[0075] Similarly, FIG. 4D depicts an absorption spectra taken after heat stress was applied to b-NTs with NaOH as a control (FIG. 4D, control example 2). In FIG. 4D, a dramatic degradation of the NT’s exciton bands is shown. This indicates NaOH interactions with nanotubes do not produce robust b-NTs. In contrast, in FIG. 4C, arginine interactions with nanotubes significantly increases the robustness of excitonic properties under heat stress. This shows robust Frenkel excitons in b-NTs produced in accordance with this disclosure.

[0076] A sample of b-NTs with arginine was produced in accordance with example 3. This sample was boiled in water for 30 minutes and then cooled to room temperature (about 23°C). The stead-state absorption spectra (FIG. 4E) showed the b-NTs were still robust despite such extensive heating.

[0077] In addition, increased heat stress was applied to neat b-NTs (comparative example 1) and b-NTs prepared with arginine (inventive example 3). The samples were incubated under repeated heating cycles (95°C-23°C-95°C for full 10 cycles). After repeated03284.0398W001heating cycles, conventional b-NTs significantly lost their excitonic character (FIG. 5B). In contrast, there was no significant different in spectroscopic signature of the b-NTs prepared with arginine (FIG. 5C). Arginine provides robustness to Frenkel excitonic materials even under extreme temperature fluctuations.

[0078] Similarly, and with reference to FIG. 5 A, b-NTs were prepared with lysine in accordance with example 4. The sample was incubated under repeated heating cycles (95°C-23°C-95°C for full 10 cycles). Like arginine, lysine interactions with the NTs significantly increased the robustness of excitonic character.

[0079] Bundled NTs prepared with arginine are robust against disassembly upon dilution: Light harvesting materials should be robust against disassembly to maintain their stability and efficiency at varying environmental conditions to allow for integration into devices. To demonstrate the disclosed materials are suitable as light harvesting materials, samples of b-NTs were prepared conventionally (example 1) and in presence of arginine (example 3). The inventive samples show significantly increased robustness upon concentration changes (for example, dilution) and changes in conditions driving the selfassembling process (for example, solvent polarity) compared to conventional NTs and conventional (arginine-free) b-NTs. For example, and with reference to FIG. 6A and FIG. 6B, at a dilution factor of 1.72 (concentration change) with methanol (reduction in solvent polarity) NTs and b-NTs completely disassemble into monomers with a complete loss of the NTs’ excitonic properties. In contrast b-NTs prepared with arginine maintain the basic features of their optical properties (FIG. 6C).

[0080] Bundled NTs prepared with Arginine are robust against light exposure: The photostability experiment of conventional, conventional b-NTs and b-NTs in presence of arginine was carried out by measuring the change on their absolute peak heights under increasing exposure of visible light from 5 to up to 60 minutes.

[0081] The absorbance of conventional b-NTs (example 1) decreased by around 72% after 60 minutes of exposure compared to a corresponding sample that was unexposed to light (dotted spectra), as seen in FIG. 7A. In contrast, the absorbance of b-NTs with arginine (example 3) decreased by 43% after 60 minutes of exposure compared to a corresponding unexposed to light (dotted spectra), as seen in FIG. 7B. Arginine interaction during the03284.0398W001hierarchical supramolecular self-assembling process significantly improved the photostability of b-NTs, that is, 40% more robust against light exposure compared to conventional b-NTs.

[0082] Bundled NTs prepared with arginine are robust against both immobilization and drying on solid substrates: As conventional supramolecular assemblies are held together by weak, non-covalent interactions, the main challenge in employing supramolecular Frenkel excitonic materials in device applications lies in their instability upon immobilization out of solution onto solid substrates as well as upon the accompanied drying processes.Conventional NTs, conventional b-NTs (example 1) and b-NTs prepared with arginine (example 3), each were deposited on a glass slide and air-dried overnight. NTs and neat b-NTs are not robust upon immobilization onto solid substrates under drying conditions. The spectroscopic features of monomers are dominant, that is, broad absorption bands at lower wavelengths, demonstrating the loss of excitonic character (FIG. 8A and FIG. 8B).Conversely, b-NTs prepared with arginine are robust against drying on a solid substrate (FIG.8C), representing a key breakthrough achievement for device-ready Frenkel excitonic materials.

[0083] Radiative lifetime of Frenkel excitonic supramolecular assemblies: Radiative lifetime of Frenkel excitonic materials was determined by means of time-resolved spectroscopy. Time-resolved emission was collected using a custom-built apparatus with a Hamamatsu Streak Scope (C4334). Briefly, a chirped-pulse regenerative amplifier (Spectra-Physics Spitfire F) is pumped using the output of a Ti: sapphire Oscillator (Spectra-Physics Tsunami) to produce 800 nm laser pulses at a 1 kHz repetition rate. In FIG. 9 A cyanine dye monomer has a 129± 1.75 ps radiative lifetime. As expected, upon the assembling of the free monomers into double-walled NTs (FIG. 9B), the radiative lifetime significantly reduced to 63.62±0.65 ps. As a further step, double-walled nanotubes hierarchically self-assembled into the neat b-NTs (over 2 months, example 1) with a radiative lifetime (81 ,85± 1.57) ps (FIG.9C). While double-walled nanotubes hierarchically self-assembled into bundles of singlewalled nanotubes in the presence of arginine (example 3), the radiative lifetime dramatically reduced to (40.58 ± 0.56) ps (FIG. 9D), which offers significant benefits for high-speed devices in optical communication. FIG. 9E is a graph showing the lifetime data of b-NTs in NaOH while FIG. 9F is a graph showing the lifetime data of b-NTS in the presence of lysine.

[0084] Rapid changes observed in Radiative lifetime: Changes in radiative lifetime were observed within 24 hours. See Table 1.03284.0398W001

[0085] In one embodiment, the inventive b-NTs exhibit at least a 25% reduction, at least a 30% reduction, at least a 35% reduction, at least a 40% reduction, at least a 45% or at least 50% reduction in emission lifetime relative to a corresponding bundle of single-walled nanotubes (b-NTs) that lacks the amino acid.

[0086] Concentration Dependent Effect of Cationic Amino Acid; Referring to FIG.10A and FIG. 10B, the interaction of cationic amino acids with NTs across different concentrations was examined. FIG. 10A provides absorbance data for NTS formed in the presence of various concentrations of arginine. At a concentration of 9.00 mM, arginine facilitates the efficient incorporation of free monomers into the nanotubular assembly within 5 min. This is evidenced by a reduction in the monomer-associated broad peak at around 520 nm (highlight), along with a corresponding increase in the intensity of peaks at 589 nm and 599 nm, which are characteristic of the outer and inner cylinders, respectively. FIG. 10B provides similar absorbance data for lysine. At 9.00 mM lysine, free monomers are driven to participate in the nanotubular assembly within 5 min interaction of lysine with NTs most efficiently compared to lower concentrations (0.18, 0.45. 0.90, 4.50 mM). This is evidenced by a decrease in the peak intensity corresponding to the broad monomer peak at approximately 520 nm, accompanied by an increase in the intensity of the peaks associated with the outer and inner cylinders at 589 nm and 599 nm, respectively. FIG. 10C is a NaOH control (control Example 2). For sodium hydroxide, at a concentration of 9.00 mM, they supported contribution of free monomers into the nanotubular assembly within 5 min. The intensity of monomer-associated peak at around 520 nm decreased significantly, along with an increase in the intensity of peaks at 589 nm and 599 nm belong to the outer and inner03284.0398W001cylinders, respectively. In each case, absorbance data was measured after 5 minutes at concentrations of 0.18, 0.45, 0.90, 4.50, 9.00 mM.

[0087] Time Dependent Effect of Cationic Amino Acid: Referring to FIG. HA and FIG. 1 IB, the incubation duration of the amino acid was found to play a role in the bundling process. The NTs were incubated with 9.00 mM arginine (FIG. 11 A), lysine (FIG. 1 IB) or NaOH (FIG. 11C) for 5min, 15min, 30min, Ih and 24h. In FIG. 11 A, the NTs were incubated with 9.00 mM arginine for 5min, 15min, 30min, Ih and 24h. After 24 h of incubation at 9.00 mM arginine, the formation of bundled NTs was observed. Spectroscopic analysis of NTs interacting with arginine further confirms this structural transformation, as indicated by the presence of a narrow exciton band at 603 nm and a broad absorption feature around 580 nm in aqueous solution. In FIG. 1 IB, at a lysine concentration of 9.00 mM, the formation of bundled nanotubes (NTs) was observed after 24 hours of incubation. NTs interacted with lysine shows the evidence of spectroscopic signature of bundled NTs in aqueous solution: the narrow exciton band at 603 nm and a broad absorption feature around 580 nm. In FIG. 11C, after 24 hours of incubation at 9.00 mM NaOH, the formation of bundled NTs was observed by the presence of a narrow exciton band at 603 nm and a broad absorption feature around 580 nm in aqueous solution.

[0088] Solar Cells In one embodiment, the disclosed materials are incorporated into a solar cell. The low efficiency of current solar cell designs restricts their widespread adoption in the energy production sector. This inefficiency limits the energy output from solar resources, reducing the viability and appeal of solar technology for large-scale energy generation projects. The power conversion efficiency of dye-synthesized solar cells is to around 14%, where the conversion efficiency of the organic solar cells has been reached nearly 20% using the slip-stacked molecular packing effect of non-fullerene electron acceptors. As with non-fullerene electron acceptors, both the orientation and the aggregation / assembly of the dye molecules (chromophores) also have a potential impact to generate more free charge carriers and facilitate charge transport, which resulted with a higher efficiency. Frenkel exciton nano-assemblies — also known as J-aggregates or Scheibe aggregates — is a material group presenting a high potential to increase the efficiency of solar cells with their head-to-tail or slip-stacked packing arrangements. This disclosure allows for (1) effectively controlling hierarchical self-assembly process as well as for utilizing (2) robust Frenkel exciton materials derived from arginine. This disclosure provides03284.0398W001a method for tuning various materials properties pivotal for solar cell efficiency — for example, light absorption, energy transfer efficiency, exciton diffusion length, charge carrier mobility, etc.

[0089] High-speed light emitting devices. In one embodiment, the disclosed material is incorporated into a high-speed light emitting device. Short radiative lifetime is a requirement to develop high-speed light emitting devices. Achieving and maintaining a short radiative lifetime requires advanced material engineering and precise control of the material properties. The lifetime of inorganic materials such as semiconducting nanocrystals (quantum dots) can be reduced only to a few nanoseconds through very complex synthesis methods. In contrast, Frenkel excitonic materials — also known as J-aggregates or Scheibe aggregates — exhibit lifetimes at the picosecond scale as short as 100 ps. This disclosure shows how a cationic amino acid significantly reduces the radiative lifetime of Frenkel excitonic nanotubes, highlighting the potential of these materials for efficient energy transfer in optoelectronics, optical communications, and display technologies etc.

[0090] As used herein, the term “approximately” or “about,” as applied to one or more values of interest, refers to a value that is similar to a stated reference value. In certain embodiments, the term “approximately” or “about” refers to a range of values that fall within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0091] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

03284.0398W001What is claimed is:

1. A bundle of single-walled nanotubes (b-NTs) comprising:a monomer that forms a supramolecular structure in water;an amino acid selected from the group consisting of arginine, lysine and combinations thereof; andwherein the bundle of single-walled nanotubes (b-NTs) exhibits at least a 25% reduction in emission lifetime relative to a corresponding bundle of single-walled nanotubes (b-NTs) that lacks the amino acid.

2. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the monomer is a cyanine dye.

3. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the bundle of single-walled nanotubes (b-NTs) exhibits at least a 50% reduction in emission lifetime relative.

4. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the bundle of single-walled nanotubes (b-NTs) consists essentially of water, the monomer and the amino acid such that the bundle of single-walled nanotubes (b-NTs) exhibits at least a 25% reduction in emission lifetime relative to a corresponding bundle of singlewalled nanotubes (b-NTs) that lacks the amino acid.

5. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the bundle of single-walled nanotubes (b-NTs) consists essentially the monomer and the amino acid such that the bundle of single-walled nanotubes (b-NTs) exhibits at least a 25% reduction in emission lifetime relative to a corresponding bundle of single-walled nanotubes (b-NTs) that lacks the amino acid.

6. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the bundle of single-walled nanotubes (b-NTs) consists essentially of water, the monomer and the amino acid such that the bundle of single-walled nanotubes (b-NTs) exhibits at least a 50% reduction in emission lifetime relative to a corresponding bundle of singlewalled nanotubes (b-NTs) that lacks the amino acid.03284.0398W0017. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the bundle of single-walled nanotubes (b-NTs) consists essentially of the monomer and the amino acid such that the bundle of single-walled nanotubes (b-NTs) exhibits at least a 50% reduction in emission lifetime relative to a corresponding bundle of single-walled nanotubes (b-NTs) that lacks the amino acid.

8. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the cationic amino acid is arginine.

9. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the cationic amino acid is lysine.

10. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the amino acid is present in the water at a concentration from 0.45mM to IM.

11. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the monomer is present in the water at a concentration from 0.048 mM to IM.

12. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the amino acid and the monomer are present in the water at a molar ratio of at least 1:1.

13. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the amino acid and the monomer are present in the water at a molar ratio of at least 3:1.

14. The bundle of single-walled nanotubes (b-NTs) as recited in claim 1, wherein the amino acid and the monomer are present in the water at a molar ratio of at least 14:1.

15. A method for preparing bundles of single-walled nanotubes (b-NTs), the method comprising:preparing a monomer stock solution by dissolving a monomer in an organic solvent such that the monomer is present at a concentration from about 3.1 mM to about IM, thereby producing a first solution, wherein the monomer is a supramolecular structure forming monomer;preparing nanotubes (NTs) by combining the first solution with water such that the monomer is present at a concentration greater than or equal to 0.048 mM, thereby producing a second solution;preparing bundles of single-walled nanotubes (b-NTs) by adding an amino acid03284.0398W001selected from the group consisting of arginine, lysine and combinations thereof to the second solution such that the amino acid has a concentration between from about 0.45mM to about IM, thereby producing a third solution; andstoring the third solution in darkness for at least 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs).

16. The method as recited in claim 15, wherein the storing occurs for less than 48 hours.

17. The method as recited in claim 15, wherein the bundles of single-walled nanotubes (b- NTs) form within 48 hours of the step of preparing bundles of single-walled nanotubes (b-NTs) by adding the amino acid.

18. A bundle of single-walled nanotubes (b-NTs) produced by the method of claim 15.

19. A method for preparing bundles of single-walled nanotubes (b-NTs), the method comprising:preparing a monomer stock solution by dissolving a cyanine dye in an organic solvent such that the cyanine dye is present at a concentration greater than or equal to about 3.1 mM, thereby producing a first solution;preparing nanotubes (NTs) by combining the first solution with water such that the cyanine dye is present at a concentration greater than or equal to about 0.048 mM, thereby producing a second solution;preparing bundles of single-walled nanotubes (b-NTs) by adding an amino acid selected from the group consisting of arginine, lysine and combinations thereof to the second solution such that the amino acid has a concentration greater than or equal to about 0.45mM, thereby producing a third solution; andstoring the third solution in darkness for at least 24 hours, thereby preparing bundles of single-walled nanotubes (b-NTs).

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