Nanocomposite material made of a polymer-matrix comprising PEO- containing polymers and salts of luminescent polyanionic metal clusters

Abstract

The present invention concerns a solid nanocomposite material consisting of a polymer-matrix in which are dispersed alkali metal, hydronium or ammonium salts of polyanionic components, wherein the polymer-matrix comprises at least a linear or branched polymer or copolymer containing one or several poly(ethylene oxide) (PEO) chains, said polymer or copolymer being optionally crosslinked and each PEO chain having at least 4 ethylene oxide monomer units. The present invention relates also to a photonic, e.g. optoelectronic, device comprising such a nanocomposite material. Such material and device can be used as phosphorescence emitter, for crop growth lighting or for generating singlet oxygen.

Claims

1. A solid nanocomposite material consisting of a polymer-matrix in which are dispersed alkali metal, hydronium or ammonium salts of polyanionic metal clusters, wherein the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters are salts or a mixture of salts of the general formula A.sub.nM.sub.6X.sup.i.sub.8L.sup.a.sub.6, wherein: A represents Cs, Na, K, a hydronium or NR.sub.1R.sub.2R.sub.3R.sub.4, wherein R.sub.1 to R.sub.4 represent, independently of each other, a hydrogen atom or a C.sub.1-C.sub.6 alkyl group; n ranges from 2 to 5; M represents Mo, W, Re or a mixture thereof; X.sup.i is an inner ligand and represents a halogen atom or a mixture thereof; and L.sup.a is an apical ligand and represents a halogen atom, an organic ligand or a mixture thereof, wherein the polymer-matrix comprises at least a linear or branched polymer or copolymer containing one or several poly(ethylene oxide) (PEO) chains, said polymer or copolymer being optionally crosslinked and each PEO chain having at least 4 ethylene oxide monomer units, and wherein the salts of polyanionic metal clusters interact with the polymer-matrix solely by means of weak interactions in between the alkali metal, hydronium or ammonium cation and the PEO chains of polymer or copolymer.

2. The nanocomposite material according to claim 1, wherein: X.sup.i represents Cl, Br, I or a mixture thereof; and L.sup.a represents Cl, Br, I, CN, SCN, a carboxylate or a mixture thereof.

3. The nanocomposite material according to claim 1, wherein the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters are selected from the group consisting of Cs.sub.2Mo.sub.6Br.sub.14, Cs.sub.2Mo.sub.6Cl.sub.14, Cs.sub.2Mo.sub.6I.sub.14, Cs.sub.2Mo.sub.6Br.sub.8C.sub.16, Cs.sub.2Mo.sub.6Br.sub.8I.sub.6, Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6, Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6, (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6, K.sub.2Mo.sub.6Cl.sub.14, Cs.sub.2W.sub.6I.sub.14, (H.sub.3O).sub.2Mo.sub.6Cl.sub.14, (H.sub.3O).sub.2W.sub.6Cl.sub.14 and mixtures thereof.

4. The nanocomposite material according to claim 1, wherein the polymer or copolymer is: at least a linear PEO polymer, at least a branched copolymer containing PEO chains grafted as side-chains onto the backbone chain of the copolymer, or at least a linear or branched copolymer containing one or several PEO chains that are part of the backbone chain of the copolymer.

5. The nanocomposite material according to claim 1, wherein the polymer-matrix comprises at least a linear PEO polymer, optionally with one or two identical or different light-emitting moieties grafted on its extremities.

6. The nanocomposite material according to claim 1, wherein the polymer or copolymer is selected from the group consisting of PEO, crosslinked PEO-ureasil, crosslinked PEO-urethanesil, polymethylmethacrylate-poly(ethylene oxide) methacrylate (PMMA-PEOMA), polydimethylsiloxane-PEO (PDMS-PEO), polyvinylpyrrolidone-PEO (PVP-PEO), polyurethane-PEO (PU-PEO), polystyrene-PEO (PS-PEO), polyethylene-PEO (PE-PEO) polyester-PEO (PES-PEO), polyamide-PEO, polycaprolactone-PEO and mixtures thereof.

7. A photonic device comprising a nanocomposite material according to claim 1.

8. The photonic device according to claim 7, wherein it is a light-emitting diode (LED) coated with a film of the nanocomposite material.

9. A method for crop growth comprising lighting a crop with the photonic device according to claim 7.

10. A method for emitting phosphorescence comprising irradiating the nanocomposite material according to claim 1 with a light having a wavelength in the range comprised between 340 nm and 480 nm.

11. A method for generating singlet oxygen comprising reacting the nanocomposite material according to claim 1 with triplet oxygen.

12. A process for preparing a nanocomposite material according to claim 1, comprising a step: of dipping the polymer-matrix in a solution containing the dissolved alkali metal, hydronium or ammonium salts of the polyanionic metal clusters, or of polymerizing the monomer units of the polymer or copolymer as defined in claim 1 in a reaction medium containing the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters, or of crosslinking a polymer or copolymer precursor in order to obtained a crosslinked polymer or copolymer as defined in claim 1 in a reaction medium containing the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters.

13. A solid nanocomposite material consisting of a polymer-matrix in which are dispersed alkali metal, hydronium or ammonium salts of polyanionic metal clusters, wherein the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters are salts or a mixture of salts of the general formula A.sub.nM.sub.6X.sup.i.sub.8L.sup.a.sub.6, wherein: A represents Cs, Na, K, a hydronium or NR.sub.1R.sub.2R.sub.3R.sub.4, wherein R.sub.1 to R.sub.4 represent, independently of each other, a hydrogen atom or a C.sub.1-C.sub.6 alkyl group; n ranges from 2 to 5; M represents Mo, W or a mixture thereof; X.sup.i is an inner ligand and represents a halogen or a chalcogen atom or a mixture thereof; and L.sup.a is an apical ligand and represents a halogen atom, an organic ligand or a mixture thereof, wherein the polymer-matrix comprises at least a linear or branched polymer or copolymer containing one or several poly(ethylene oxide) (PEO) chains, said polymer or copolymer being optionally crosslinked and each PEO chain having at least 4 ethylene oxide monomer units, and wherein the salts of polyanionic metal clusters interact with the polymer-matrix solely by means of weak interactions in between the alkali metal, hydronium or ammonium cation and the PEO chains of polymer or copolymer.

14. The nanocomposite material according to claim 13, wherein: X.sup.i represents Cl, Br, I or a mixture thereof; and L.sup.a represents Cl, Br, I, CN, SCN, a carboxylate or a mixture thereof.

15. The nanocomposite material according to claim 13, wherein the polymer or copolymer is: at least a linear PEO polymer, at least a branched copolymer containing PEO chains grafted as side-chains onto the backbone chain of the copolymer, or at least a linear or branched copolymer containing one or several PEO chains that are part of the backbone chain of the copolymer.

16. The nanocomposite material according to claim 13, wherein the polymer-matrix comprises at least a linear PEO polymer, optionally with one or two identical or different light-emitting moieties grafted on its extremities.

17. The nanocomposite material according to claim 13, wherein said polymer or copolymer is selected from the group consisting of PEO, crosslinked PEO-ureasil, crosslinked PEO-urethanesil, polymethylmethacrylate-poly(ethylene oxide) methacrylate (PMMA-PEOMA), polydimethylsiloxane-PEO (PDMS-PEO), polyvinylpyrrolidone-PEO (PVP-PEO), polyurethane-PEO (PU-PEO), polystyrene-PEO (PS-PEO), polyethylene-PEO (PE-PEO) polyester-PEO (PES-PEO), polyamide-PEO, polycaprolactone-PEO and mixtures thereof.

18. A process for preparing a nanocomposite material according to claim 13, comprising a step: of dipping the polymer-matrix in a solution containing the dissolved alkali metal, hydronium or ammonium salts of the polyanionic metal clusters, or of polymerizing monomer units of the polymer or copolymer as defined in claim 13 in a reaction medium containing the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters, or of crosslinking a polymer or copolymer precursor in order to obtain a crosslinked polymer or copolymer as defined in claim 13 in a reaction medium containing the alkali metal, hydronium or ammonium salts of the polyanionic metal clusters.

19. A photonic device comprising a nanocomposite material according to claim 13.

20. The photonic device according to claim 19, wherein it is a light-emitting diode (LED) coated with a film of the nanocomposite material.

21. A method for crop growth comprising lighting a crop with the photonic device according to claim 19.

22. A method for emitting phosphorescence comprising irradiating the nanocomposite material according to claim 13 with a light having a wavelength in the range comprised between 340 nm and 480 nm.

23. A method for generating singlet oxygen comprising reacting the nanocomposite material according to claim 13 with triplet oxygen.

Description

FIGURES

(1) FIG. 1 represents a picture of the nanocomposite E1 obtained by μ X-ray fluorescence spectrometry for Mo element.

(2) FIG. 2 represents the emission spectra of PEO1900 (black plain line), E2 (black dot-dashed line) and E4 (black dotted line) under 380-400 nm excitation. The photosynthesis active spectrum (absorption spectrum) is also represented in dashed grey line.

(3) FIG. 3 represents the Commission Internationale d'Eclairage (CIE) 1931 Chromaticity diagram for PEO1900 (reference, square) and nanocomposite materials E1 (circle), E2 (triangle), E3 (inverted triangle) and E4 (diamond) according to the invention as a function of the excitation wavelength (from 365 nm up to 450 nm, every 5 nm).

(4) FIG. 4 displays the emission spectra of PEO1900 samples doped at 10 wt % with Cs.sub.2W.sub.6I.sub.14 (plain line), Cs.sub.2Mo.sub.6I.sub.14 (dashed line), Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6 (dotted line), Cs.sub.2Mo.sub.6Cl.sub.14 (dashed-dotted line), Cs.sub.2Mo.sub.6Br.sub.14 (dashed-dotted-dotted line) Cs.sub.2Mo.sub.6Br.sub.8I.sub.6 (short-dashed line) or Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 (short-dotted line).

(5) FIG. 5 represents adsorption kinetic studies of Cs.sub.2Mo.sub.6Cl.sub.14 (starting concentration 10 mg.Math.mL.sup.−1) by PEO1900 matrix.

(6) FIG. 6a corresponds to a schematic representation of a ternary cluster salt of general formula A.sub.2[M.sub.6X.sup.i.sub.8X.sup.a.sub.6].

(7) FIG. 6b corresponds to a schematic representation of the integration of the cluster ternary salt Cs.sub.2[M.sub.6X.sup.i.sub.8X.sup.a.sub.6] in the polymer-matrix.

(8) FIG. 7 represents .sup.133Cs MAS NMR spectra of a) crystalline Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6, b) P.sub.1C, c) P.sub.2C, d) P.sub.5C and e) mixture of Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 with pure PMMA.

(9) FIG. 8 represents absorption spectra of CH.sub.3CN solutions containing Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 (black plain line), doped P.sub.1C (black dashed line), doped P.sub.2C (black dotted line), doped P.sub.5C (black dash-dotted line), pure P.sub.1 (grey dotted line), pure P2 (grey dashed line) and pure P5 (grey plain line).

(10) FIG. 9 represents normalized emission spectra at λ.sub.exc=370 nm of Cs.sub.2Mo.sub.6I.sub.8(C.sub.2F.sub.5OCO).sub.6 (plain line), doped P.sub.1C (dashed line), doped P.sub.2C (dotted line) and P.sub.5C (dash-dotted line).

(11) FIGS. 10a and 10b represent InkJet printed P.sub.1C patterns under UV light excitation and corresponding colorimetric profiles for a) thin films and b) drops.

(12) FIG. 11a represents emission spectra recorded for 395 nm commercial blue LED (d) and P.sub.1C covered blue LED recorded at 0° (c), 30° (b) and 60° (a).

(13) FIG. 11b represents NIR emission spectrum obtained with the P.sub.1C covered blue LED with corrected spectrum in inset.

(14) FIG. 12 represents pieces of P2 (PEOMA-PMMA) copolymer doped with a) Cs.sub.2Mo.sub.6Cl.sub.14 b) Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 c) Cs.sub.2Mo.sub.6Br.sub.14 d) Cs.sub.2Mo.sub.6Br.sub.6I.sub.6 e) Cs.sub.2Mo.sub.6I.sub.14 f) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6, g) Cs.sub.2W.sub.6I.sub.14 metal cluster salts under white light (top) and UV light (bottom).

(15) FIG. 13 displays the emission spectra of P2 samples doped at 5 wt % with Cs.sub.2Mo.sub.6I.sub.14 (plain line), Cs.sub.2Mo.sub.6Cl.sub.14 (dashed line), Cs.sub.2Mo.sub.6Br.sub.8I.sub.6 (dotted line), Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 (dashed-dotted line), Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6 (dashed-dotted-dotted line) or Cs.sub.2W.sub.6I.sub.14 (short-dashed line).

(16) FIG. 14 represents SEM pictures of P2 samples doped with 5 wt % of Cs.sub.2Mo.sub.6Br.sub.14, Cs.sub.2W.sub.6I.sub.14, Cs.sub.2Mo.sub.6Cl.sub.14 and Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6.

(17) FIG. 15 represents a polyanionic metal nanocluster of general formula [M.sub.6X.sup.i.sub.8L.sup.a.sub.6].sup.n−.

(18) FIG. 16 represents DSC thermograms of PMMA1 on heating (straight) and cooling (dot) and PMMA2 on heating (dash) and cooling (dash-dot) at 10 K.Math.min.sup.−1.

(19) FIG. 17 represents DSC thermograms of PS on heating (straight) and cooling (dash) cycles at 10 K.Math.min.sup.−1.

(20) FIG. 18 represents DSC thermograms of PU1 on heating (straight) and cooling (dash) and PU2 on heating (dot) and cooling (dash-dot) at 10 K.Math.min.sup.−1.

(21) The examples that follow illustrate the invention without limiting its scope in any way.

EXAMPLES

Abbreviations

(22) AIBN: azobisisobutyronitrile

(23) AQY: absolute quantum yield

(24) BD: butandiol

(25) CIE: Commission Internationale d'Eclairage

(26) DBTDL: dibutyltin dilaureate

(27) DSC: differential scanning calorimetry

(28) exc: excitation

(29) FRET: Forster-type resonance energy transfer

(30) FWHM: full width at half maximum

(31) HDI: hexamethylenediisocianate
LED light-emitting diode
MAS: magic angle spinning
MMA: methylmethacrylate
NIR: near infrared
NMR: nuclear magnetic resonance
PEO: poly(ethylene oxide)
PEOMA: poly(ethylene oxide) methacrylate
PMMA: polymethylmethacrylate
PS: polystyrene
PU: polyurethane
SEC: size exclusion chromatography
STYPEO: styrene-poly(ethylene oxide)
TEA: triethanolamine
THF: tetrahydrofuran
UV: ultraviolet
wt weight

I—Example 1

(32) This first example relates to nanocomposite materials consisting of a polymer-matrix containing polyethyleneglycol grafted with ureasil moieties which are then crosslinked, in which is dispersed the cluster ternary salt Cs.sub.2Mo.sub.6Br.sub.14.

I-1. Synthesis of the Nanocomposite Materials

(33) O,O′-bis(2-aminopropyl)-poly(ethylene oxide) with a molecular weight of 1900 g.Math.mol.sup.−1 (Jeffamine® ED-2000), 3-isocyanatopropyltriethoxysilane (ICPTES), ethanol (ETOH) and tetrahydrofuran (THF), were purchased from Sigma-Aldrich. All these chemicals were used as received.

(34) A ureasil-PEO polymer-matrix (PEO1900) was synthesized according to J. Sol-Gel Sci. Technol., 2014, 70:317, by crosslinking of the following polymer in order to form cross-linking ureasil nodes:

(35) ##STR00001##

(36) Firstly, the ureasil cross-linking agent was covalently bound to both ends of the macromer polyether by reacting the terminal aminopropyl groups of the end-functionalized PEO. O,O′-bis(2-aminopropyl)-poly(ethylene oxide) (average molecular weight (Mw) 1900 g.Math.mol.sup.−1) with 3-(isocyanatopropyl)-triethoxysilane in a molar ratio of 1:2 were stirred together in THF under reflux for 24 h at 70° C. The THF solvent was eliminated by evaporation at 60° C., resulting in a hybrid precursor solution. This precursor solution obtained was stored at room temperature in a desiccator to prevent any further hydrolysis reaction. Secondly, silanol moieties were generated and condensation reactions followed to afford cross-linking ureasil nodes. The hydrolysis of —(SiOCH.sub.2CH.sub.3).sub.3 was initiated by adding 0.035 mL of an aqueous HCl/ETOH solution (2 mol L.sup.−1) to 1.5 g of precursor which is followed by condensation.

(37) Finally, cylindrical monolithic xerogels of approximately 20 mm diameter and 3 mm height were obtained after drying under vacuum at 70° C. for 24 h.

(38) The ternary salt Cs.sub.2Mo.sub.6Br.sub.14 was prepared according to Z. Anorg. Ag. Chem., 2005, 631, 411.

(39) The nanocomposite materials were prepared according to one of the following procedures.

(40) Procedure 1:

(41) The ternary salt Cs.sub.2Mo.sub.6Br.sub.14 was added at different concentrations, namely 0.1, 0.5, 1.0 and 3.0 wt %, to the reaction medium used to perform the hydrolysis step during the preparation of PEO1900. The obtained nanocomposite materials are named E1, E2, E3 and E4 respectively.
Procedure 2:
The ternary salt Cs.sub.2Mo.sub.6Br.sub.4 was solubilized in a H.sub.2O/EtOH (1:1 v/v) solution at 200 mg.Math..sup.−1. The PEO1900 xerogel (0.25 g) obtained as disclosed previously was let to stand in the solution during 24 hours. The cluster adsorption was followed by UV-visible spectrometry (conducted on an Agilent Technologies Cary 60) by monitoring the decrease of the cluster adsorption bands within the mother liquor. The obtained nanocomposite material is named PEO1900CA.

I-2. μX-Ray Fluorescence Spectrometry

(42) The homogeneity of the repartition of the cluster in the polymer-matrix was assessed by μx-ray fluorescence spectrometry for Si, Cs, Mo and Br elements.

(43) FIG. 1 reports results obtained for E1, which assess about the excellent distribution of clusters within the polymer-matrix. Indeed, the homogeneity of colors is an excellent indication of the good repartition of clusters.

I-3. Emission Properties

(44) Material and Methods:

(45) Luminescence spectra were recorded with an ocean optic QE65000 photodetector mounted via an optical fiber on an optical microscope Nikon 80i equipped with a Nikon Intensilight irradiation source. In order to take into account the nonlinear sensitivity of the set up, it was calibrated with an Ocean Optics HL-2000-CAL Calibrated Tungsten Halogen Light Source. Optical filters were used to select the excitation wavelength with a bandwidth of 350-380 nm. Absolute quantum yield measurements were calculated with a Hamamatsu H9920-03G set up.

(46) Results:

(47) The obtained emission spectra are presented in FIG. 2.

(48) Exciting samples at 350-380 nm induces a two bands emission. The higher energetic band with a maximum located around 450 nm corresponds to the emission of the ureasil matrix, while the broad signal with a maximum around 680 nm is related to the cluster red-NIR emission.

(49) The proportional decrease of PEO1900 luminescence with the increase of Cs.sub.2Mo.sub.6Br.sub.14 concentration shows that there is some kind of transfer between both luminophores.

(50) The nanocomposite materials show some gas permeability as the absolute quantum yield (AQY) of cluster emission increases under N.sub.2 atmosphere, as demonstrated by values shown in Table 1 below for E4 and PEO1900CA, obtained with λ.sub.exc=380 nm.

(51) TABLE-US-00001 TABLE 1 sample Air N.sub.2 E4 0.063 0.172 PEO1900CA 0.076 0.171

(52) FIG. 3 plots the CIE 1931 xy chromaticity diagrams for all samples as a function of the excitation wavelength. The CIE chromaticity diagram is a color space designed to represent all the colors perceived by a human eye [Evans, Douglas, Anal. Chem., 2006, 78, 5645; Hunt, Measuring Colour, Ellis Horwood, Chichester 1991]. Color-matching functions, related to the response of the cones in a human eye, are used to represent the profile of a given emission spectrum as a set of (x, y) color coordinates on the CIE chromaticity diagram. It seems straightforward that for E2 sample white luminescence is achieved for excitation wavelength varying from 365 up to 385 nm.

(53) Moreover, it shows that by varying the doping concentration and the excitation wavelength, the emission can be tuned across the entire visible spectrum.

I-4. Synthesis of Other Nanocomposite Materials

(54) Using procedure 2 of example 1, several metal cluster salts, namely Cs.sub.2Mo.sub.6Cl.sub.14, Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6, Cs.sub.2Mo.sub.6Br.sub.8I.sub.6, Cs.sub.2Mo.sub.6I.sub.14, Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6, Cs.sub.2W.sub.6I.sub.14, (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6, K.sub.2Mo.sub.6Cl.sub.14, (H.sub.3O).sub.2Mo.sub.6Cl.sub.14 and (H.sub.3O).sub.2W.sub.6Cl.sub.14 were introduced in the PEO xerogel.

(55) The ternary salts Cs.sub.2Mo.sub.6Cl.sub.14, Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6, Cs.sub.2Mo.sub.6Br.sub.8I.sub.6, Cs.sub.2Mo.sub.6I.sub.14 were prepared according to Prévôt et al. J. Mater. Chem. C 2015, 3, 5152.

(56) The ternary salt Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6 was prepared according to Prévôt et al. Adv. Funct. Mater. 2015, 25, 4966-4975.

(57) The ternary salt Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 was prepared according to the procedure described in (Dalton Trans., 2016, 45, 237).

(58) The ternary salt Cs.sub.2W.sub.6I.sub.14 was prepared according to Hummel et al. Eur. J. Inorg. Chem. 2016, 5063-5067.

(59) The ternary salt (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6 was prepared by solubilizing Cs.sub.2Mo.sub.6Br.sub.14 in a water/ethanol (1/1) solution containing an excess of NH.sub.4SCN. After stirring at 25° C. for 17 h. the compound was extracted with chloroform and obtained after solvent evaporation.

(60) The ternary salt K.sub.2Mo.sub.6Cl.sub.14 was prepared according to Lindler et al., Z. Anorg. Allg. Chem., 1923, 130, 209-228

(61) The ternary salt (H.sub.3O).sub.2Mo.sub.6Cl.sub.14 was prepared according to Sheldon et al., J. Chem. Soc., 1960, 1007-1014

(62) The ternary salt (H.sub.3O).sub.2W.sub.6Cl.sub.14 was prepared according to Schafer et al., Monatsh. Chem. 1971, 102, 1293-1304

(63) FIG. 4 shows the emission spectra of several corresponding hybrids.

(64) Table 2 below gathers the absolute quantum yield emission values obtained for doped PEO xerogel under air or N.sub.2 atmosphere.

(65) TABLE-US-00002 TABLE 2 Xerogel AQY.sub.air AQY N.sub.2 Cs.sub.2Mo.sub.6Cl.sub.14 15.2 17.5 Cs.sub.2Mo.sub.6Br.sub.14 10.6 17.1 Cs.sub.2Mo.sub.6I.sub.14 10.8 9.7 Cs.sub.2Mo.sub.6Br.sub.8I.sub.6 4.3 6.9 Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 12.8 20.6 Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 3.3 22.1 Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6 2.9 17.8 (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6 6.0 31.6 K.sub.2Mo.sub.6Cl.sub.14 5.6 17.2 (H.sub.3O).sub.2Mo.sub.6Cl.sub.14 2.9 5.9 (H.sub.3O).sub.2W.sub.6Cl.sub.14 0.7 1.2 Cs.sub.2W.sub.6I.sub.14 26.1 23.8

II—Example 2

(66) PEO1900 sample is allowed to stand in a solution of acetone containing Cs.sub.2Mo.sub.6C.sub.14 at 10 mg.Math.ml.sup.−1 concentration. The solution is left under stirring and little amount of the solution are taken from time to time to control the cluster concentration by UV-Vis spectroscopy. As depicted by FIG. 5, up to 80 wt % of Cs.sub.2Mo.sub.6Cl.sub.14 can be adsorbed within the PEO1900 matrix.

III—Example 3

(67) This second example relates to nanocomposite materials consisting of a polymer-matrix containing a PMMA-PEOMA copolymer, in which is dispersed the cluster ternary salt Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 (FIG. 6b).

III-1. Synthesis of the Nanocomposites

(68) PEOMA (Poly(ethylene glycol) methyl methacrylate, M=950 g.Math.mol.sup.−1, 20 OC.sub.2H.sub.4 units) and MMA monomers were purchased from Alfa Aesar. MMA was distilled before use. PEOMA initiator agent was remove prior to use. AIBN was purified by recrystallization in diethyl ether prior to use. Toluene (98%) solvent was used as received.

(69) Several PMMA-PEOMA copolymers containing 0, 1, 2 or 5 mol % of PEOMA (respectively referenced as P0 (reference), P1, P2 and P5) were prepared according to the following procedure: PEOMA (0, 178, 357, 905 mg (0, 1, 2 and 5 mol %)) and freshly distilled MMA (1.88 g, 2 ml) were dissolved in 20 ml of toluene. The solution was then degassed with argon during 15 min. After addition of 0.2 wt % of AIBN compared to MMA, the solution was heated at 80° C. under argon atmosphere during 24 hours. Purification of the product was achieved by performing at least two precipitations in toluene/methanol solvents. The obtained precipitate was filtered, washed with methanol and dried using a rotavapor. The samples were obtained as white powder after drying under vacuum for 17 h.

(70) The nanocomposite materials, named respectively P.sub.1C, P.sub.2C and P.sub.5C, were prepared according to the following procedure:

(71) a solution of Pi in acetone was mixed with a solution of acetone containing 10 wt % (compared to the polymer) of Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6. P.sub.iC samples were obtained after evaporation of the resulting solution.

(72) The .sup.1H NMR spectra obtained for P.sub.0 and the P.sub.iC samples are detailed below:

(73) .sup.1H NMR (400 MHz, CDCl.sub.3, δ):

(74) P.sub.0: 3.62 (s, 3H, COO—CH3), 2.38 (s, toluene), 2.04-1.73 (m, 2H, CH.sub.2), 1.56 (s, HDO), 0.96 (d, J=68.7 Hz, 3H, C—CH3)

(75) P.sub.1C: 3.67 (s, 1H, C.sub.2H.sub.4O—CH.sub.3), 3.62 (s, 3H, COO—CH.sub.3), 2.38 (s, toluene), 2.04-1.73 (m, 2H, CH.sub.2), 1.57 (s, HDO), 0.96 (d, J=68.7 Hz, 3H, C—CH.sub.3)

(76) P.sub.2C: 3.67 (s, 2H, C.sub.2H.sub.4O—CH.sub.3), 3.62 (s, 3H, COO—CH.sub.3), 2.04-1.73 (m, 2H, CH.sub.2), 0.96 (d, J=68.7 Hz, 3H, C—CH.sub.3)

(77) P.sub.5C: 3.67 (s, 3H, C.sub.2H.sub.4—O—CH.sub.3), 3.62 (s, 3H, COO—CH.sub.3), 2.04-1.73 (m, 2H, CH.sub.2), 1.59 (s, HDO), 0.96 (d, J=68.7 Hz, 3H, C—CH.sub.3)

III-2. Organic-Inorganic Interactions

(78) MAS solid state .sup.133Cs was realized to observe the organic-inorganic moieties interactions (see respectively FIG. 7).

(79) .sup.133Cs MAS NMR spectra of crystalline Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 contains 2 signals located at −4.97 ppm and −106.52 ppm corresponding to the two crystallographic positions of Cs.sup.+ within the Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 crystal structure. When Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 is mixed with pure PMMA, these two signals remain exactly in the same position showing that the metal cluster salt crystalizes within the polymer and does not interact with the polymer matrix.

(80) For P1C, P2C and P5C, only one signal appears at −30.69 ppm, −36.56 ppm, −37.92 ppm, respectively.

(81) The significate shift of Cs.sup.+ signal in MAS .sup.133Cs NMR experiments observed when the ternary salt is integrated in the copolymer matrix assesses the strong interactions existing between the alkali cluster counter cations with the PEO lateral chains.

III-3. Absorption and Emission Properties

(82) Absorption measurements were realized in acetonitrile solution for all samples and show that pure copolymers have a very low absorption after 320 nm (FIG. 8). Thus, doped copolymers absorption spectra contain mainly the cluster absorption bands between 350 and 450 nm, the most suitable UV-blue area to irradiate the ternary salt and observe its strong red-NIR emission.

(83) Doped copolymers were deposited on quartz substrates and irradiated at 370 nm to observe the cluster broad phosphorescence emission band centered around 680 nm (FIG. 9).

(84) Absolute quantum yield (AQY) measurements were realized alternatively in air or N.sub.2 atmosphere and show a perfectly reversible enhancement of the AQY from 8% up to around 50% (Table 3). Such change in the emission efficiency is due to the quenching of the cluster excited state by triplet oxygen [a) Jackson et al., J. Phys. Chem., 1990, 94, 4500-4507; b) Jackson et al., Chem. Mater., 1996, 8, 558-564; c) Ghosh et al., Appl. Phys. Lett., 1999, 75, 2885-2887]. This phenomenon being a physical phenomenon, it is perfectly reversible as it does not imply any degradation of the material.

(85) Lifetime of the emissive species were determined using a nanosecond YAG Laser exciting the samples at 355 nm. Obtained results are summarized in the table below. In all cases, the emission decay profile could be fitted with a long component and a short component as previously observed when the same inorganic anion was integrated via ionic assembling in a polyurethane matrix [Amela-Cortes et al., Chem. Commun., 2015, 51, 8177-8180]. Measurements under a N.sub.2 flow induce an increase of the longer component from 80 μs to around 200 μs that correlates well with the behavior of phosphorescent dyes dynamically quenched by molecular oxygen [Lu, Chen, Chemical Society Reviews, 2012, 41, 3594-3623]. Indeed, a 200 μs phosphorescence lifetime fits well to the usual emission lifetime of the ternary salt observed in fully degassed solution [Maverick et al., J. Am. Chem. Soc., 1983, 105, 1878-1882]. Hence, these experiments show that the developed integration method does not affect the abilities of clusters to strongly emit.

(86) TABLE-US-00003 TABLE 3 τ PEOMA Φ [μs] Sample [Mol %] N.sub.2 air Air N.sub.2 P.sub.0 — P.sub.1C 1.2 50 8 30 (0.53) 30 (0.20) 80 (0.47) 200 (0.80) P.sub.2C 2 51.7 12 30 (0.59) 30 (0.24) 90 (0.41) 190 (0.76) P.sub.5C 5 50 8 20 (0.05) 50 (0.10) 70 (0.95) 210 (0.90) N.B.: Φ: calculated absolute quantum values under air and N.sub.2 atmosphere (accuracy 10%); τ: calculated phosphorescence lifetime decay (contribution in parenthesis) for clusters doped copolymers.

(87) Following the procedure described in Robin et al., ACS Appl. Mater. Interfaces, 2015, 7, 21975-21984 for inkjet printing of a blend of Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster precursor (5 wt %) and an epoxy based ink (SU8 2000.5), P.sub.1C copolymer has been inkjet printed on glass substrates. FIGS. 10a and 10b shows inkjet printed thin film and drops under UV light excitation (λ.sub.exc=370 nm).

(88) Contrary to previously printed SU8 thin film that contained half amount of clusters, P.sub.1C printed film shows no phase segregation leading to a good local homogeneity.

(89) This observation highlights the important contribution of the PEO chains in the design and stability of the hybrid.

(90) Thus, high AQY combined with high doping level with no phase segregation makes this copolymer an excellent candidate for optical applications.

III-4. Coated LED

(91) The red emitting doped copolymers have been combined with a UV-blue commercial LED to demonstrate their potentialities in display or lighting applications.

(92) To do so, a thin film of P.sub.1C was deposited by drop casting on top of a commercially available 395 nm UV-blue LED.

(93) The emission spectra were recorded for the LED with and without copolymer coating and with different viewing angles (FIG. 11a). The native UV-blue LED emission spectrum possesses two components, the most intense centered at 395 nm and its corresponding second harmonic at 790 nm.

(94) Once coated with P.sub.1C, the emission spectra depend significantly on the orientation of the optical fiber used to record the signal compared to the normal of the LED plan. At 0°, the radiative energy transfer from blue to red is only partial because the copolymer layer is not thick enough to absorb all the UV light. As a result, the blue component of the emission is stronger than the red one. When the angle increases, the red emission becomes stronger compared to the blue LED emission. This phenomenon is mainly due i) to the fact that increasing the angle of detection implies that the UV light passes through an increased polymer thickness and thus more clusters are excited, and ii) to the ability of polymers to guide the emitted light.

(95) This example shows the high potential of this red phosphorescent copolymer as external conversion layer for optical applications.

(96) Moreover, as demonstrated above with AQY measurements under air or inert atmosphere, the cluster triplet excited state reacts efficiently with triplet oxygen to generate the emissive singlet oxygen and, compared to pure doped PMMA [Amela-Cortes et al. Dalton Trans., 2016, 45, 237-245], the introduction of PEO chains strongly affects the hybrids gas permeability.

(97) We therefore investigated whether it was possible to detect directly singlet oxygen emission when the hybrid polymer was deposited as a thin film either on a quartz substrate or irradiated by the blue LED. As shown in FIG. 11b, irradiating the nanocomposite at 375 nm leads to the appearance of a weak emission band centered around 1270 nm related to singlet oxygen emission.

(98) Therefore, a simple device made of a UV-LED covered with our copolymer could act as a local .sup.1O generator, of particular interest for photodynamic therapy like in dermatology for e.g. melanoma treatments [Hong-Tao, Yoshio, Science and Technology of Advanced Materials, 2014, 15, 014205], or bactericidal photodynamic applications [Beltran et al., J. Mater. Chem. B, 2016, 4, 5975-5979.].

IV—Example 4

(99) Previous P2 (PEOMA-PMMA) copolymer (200 mg) was dissolved in acetone. 10 mg of metal cluster salt (5 wt % compared to P2 amount) were dissolved in acetone. Metal cluster salt used were: Cs.sub.2Mo.sub.6Cl.sub.14, Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6, Cs.sub.2Mo.sub.6Br.sub.14, Cs.sub.2Mo.sub.6Br.sub.8I.sub.6, Cs.sub.2Mo.sub.6I.sub.14, Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6, Cs.sub.2W.sub.6I.sub.14, Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6, (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6 and K.sub.2Mo.sub.6Cl.sub.14. Both solutions were mixed and stirred for 10 minutes. Homogeneous films of doped polymers were obtained by slow evaporation. FIG. 12 represents pieces of polymers under white light and UV light containing different metal cluster salts a) Cs.sub.2Mo.sub.6Cl.sub.14 b) Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 c) Cs.sub.2Mo.sub.6Br.sub.14 d) Cs.sub.2Mo.sub.6Br.sub.8I.sub.6 e) Cs.sub.2Mo.sub.6I.sub.14 f) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6, g) CS.sub.2W.sub.6I.sub.14. The doped copolymers emission spectra are presented in FIG. 13. The homogeneity of films was further confirmed by SEM-EDAX analysis as depicted by FIG. 14 for different samples highlighting that no phase segregation is observed (no spots corresponding to a high metal concentration observed).

(100) Table 4 below gathers the absolute quantum yield emission values obtained for doped copolymers under air or N.sub.2 atmosphere.

(101) TABLE-US-00004 TABLE 4 P2 AQY.sub.air AQY N.sub.2 Cs.sub.2Mo.sub.6Cl.sub.14 12.1 13.7 Cs.sub.2Mo.sub.6Br.sub.14 11.3 13.5 Cs.sub.2Mo.sub.6I.sub.14 8.9 11.4 Cs.sub.2Mo.sub.6Br.sub.8I.sub.6 4.2 4.5 Cs.sub.2Mo.sub.6Br.sub.8Cl.sub.6 14.1 16.4 Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 8 51.7 Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.3F.sub.7).sub.6 14 26.6 (NH.sub.4).sub.2Mo.sub.6Br.sub.8SCN.sub.6 13.5 26.9 K.sub.2Mo.sub.6Cl.sub.14 8.9 15.9 Cs.sub.2W.sub.6I.sub.14 22.2 26.5

V—Example 5

(102) This example relates to nanocomposite materials consisting of a polymer-matrix containing either a PMMA-PEO, a PS-PEO or a PU-PEO copolymer, in which is dispersed the cluster ternary salt Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6. In the PMMA-PEO and the PU-PEO copolymers, the PEO chains are located on the main chain of the copolymer, while in the PS-PEO copolymer, the PEO chains are grafted onto the backbone PS chain as side-chains.

V-1. Synthesis of the Nanocomposite Materials

(103) Reagents:

(104) MMA monomer was purchased from Alfa Aesar. MMA was distilled before use. AIBN was purified by recrystallization in diethyl ether prior to use. PEO-bisamine (CAS 24991-53-5), PEO-diacrylate (CAS 26570-48-9), and PS-PEO (see formula below) were purchased from Specific Polymers and used without further purification. Butandiol, hexamethylenediisocianate, dibutyltin dilaureate, triethanolamine were purchased from Sigma Aldrich and used without further purification.

(105) ##STR00002##

Synthesis of the Nanocomposite Materials Comprising a PMMA-PEO Matrix

(106) Procedure 1:

(107) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster compound was dissolved in 4 mL of dry THF and mixed to PEO-diacrylate (at 1 wt %). The mixture was heated at 50° C. under stirring to homogenized and the solvent was evaporated. The mixture PEO-diacrylate/Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 was added to distilled MMA (at 20 wt %). The mixture was homogenized in an ultrasounds bath for 5 min. Radical initiator AIBN (0.2 wt %) was added and the mixture was subjected to ultrasounds for 5 min. The solution was kept for 72 h in an oven at 70° C. A transparent light-yellow solid nanocomposite material was obtained, which is named PMMA1.

(108) Procedure 2:

(109) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster compound was mixed with PEO-diacrylate (at 10 wt %) and to that, distilled MMA was added (20 wt % PEO-diacrylate/Mo to MMA). The mixture was homogenized in an ultrasounds bath for 5 min. Radical initiator AIBN (0.2 wt %) was added and the mixture was homogenized in an ultrasounds bath for 5 min. The mixture was then kept at 70° C. in an oven for 72 h. A dark orange solid nanocomposite material was obtained, which is named PMMA2.

(110) Table 5 below shows glass transition temperatures (Tg) measured by differential scanning calorimetry 10K/min of two samples (2.sup.nd cooling cycle) (see also FIG. 16).

(111) TABLE-US-00005 TABLE 5 Cluster in Cluster PEO total MMA PEO Cluster T.sub.g Sample (wt %) (wt %) (mg) (mg) (mg) (° C.) PMMA1 1 0.2 800 200 2 81.3 PMMA2 10 2 800 200 20 61.3

Synthesis of the Nanocomposite Material Comprising a PS-PEO Matrix

(112) PS-PEO was dissolved in 4 mL of dry THF and to that Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster compound was added (1 wt % of total mass). The mixture was homogenized by stirring at 50° C. and the solvent evaporated. A transparent orange solid nanocomposite material was obtained, which is named PS.

(113) Table 6 below shows glass transition temperature (Tg) measured by differential scanning calorimetry 10K/min of the samples (2.sup.nd cooling cycle) (see also FIG. 17).

(114) TABLE-US-00006 TABLE 6 Cluster total PS-PEO STYPEO Cluster T.sub.g Sample (wt %) (mg) (wt %) (mg) (° C.) PS 1 990 5-10 10 11.5

Synthesis of the Nanocomposite Materials Comprising a PU-PEO Matrix

(115) Procedure 1:

(116) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster compound was dissolved in 4 mL of dry THF and mixed to PEO-bisamine matrix (at 1 wt %). The mixture was heated at 50° C. under stirring to homogenized and the solvent was evaporated. The mixture PEO-bisamine/Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 (23 wt % total mass) and butandiol (BD, 11.5 wt %) was heated to 80° C. to melt to afford a homogeneous mixture. To that, hexamethylenediisocianate (HDI, 60 wt %), the catalyst dibutyltin dilaureate (DBTDL, 1 mL) and the crosslinker triethanolamine (TEA, 2.9 wt %) were added. The mixture was kept for 72 h at 70° C. to afford a light orange segmented elastomer. The obtained nanocomposite material is named PU1.

(117) Procedure 2:

(118) Cs.sub.2Mo.sub.6I.sub.8(OCOC.sub.2F.sub.5).sub.6 cluster compound) was mixed to PEO-bisamine matrix (at 10 wt %) by heating to 80° C. for 5 min (23% wt of PEO-bisamine to total mass). Once the mixture wax homogeneous butandiol (BD, 11.5 wt %) was added. To that, hexamethylenediisocianate (HDI, 60 wt %), the catalyst dibutyltin laureate (DBTL, 1 mL) and the crosslinker triethanolamine (TEA, 2.9 wt %) were added. The mixture was kept for 72 h at 70° C. to afford a dark orange segmented elastomer. The obtained nanocomposite material is named PU2.

(119) Table 7 below shows the composition of two materials as well as the T.sub.g and the melting temperatures (Tm), determined by DSC at a rate of 10 K/min of two samples (2.sup.nd cooling cycle) (see also FIG. 1).

(120) TABLE-US-00007 TABLE 7 Cluster in Cluster total BD HDI PEO TEA T.sub.g T.sub.m1 T.sub.m2 Sample PEO (wt %) (wt %) (mg) (mg) (mg) (mg) (° C.) (° C.) (° C.) PU1 1 0.23 100 525 200 25 −61.9 −36.9 −8.5 PU2 10 2.3 360 672 200 25 −62 −38 21

V-2. Optical Properties

(121) The following table 8 gathers the optical data of the previous nanocomposite materials.

(122) TABLE-US-00008 TABLE 8 AQY AQY excitation after 3 min FWHM 365 nm under N2 Sample I.sub.max (cm.sup.−1) under air flow PMMA1 700 2313 2.0 3.1 PS 700 2452 1.1 2.5 PU1 700 2449 2.8 3.4 PU2 690 2366 10.7 19.0 PMMA2 678 2492 3.0 5.0