WO2014049139A1

WO2014049139A1 - Method for preparing a hybrid zno/organic material, said material and the uses thereof

Info

Publication number: WO2014049139A1
Application number: PCT/EP2013/070242
Authority: WO
Inventors: Jonathan SKRZYPSKI; Aurélien AUGER
Original assignee: Commissariat à l'énergie atomique et aux énergies alternatives
Priority date: 2012-09-28
Filing date: 2013-09-27
Publication date: 2014-04-03
Also published as: FR2996226A1

Abstract

The present invention concerns a method for preparing a zinc oxide particle comprising at least one phthalocyanine derivative, said method comprising a step consisting of condensing a silicon or titanium phthalocyanine derivative with a zinc oxide particle, in the presence of an organic solvent. The present invention also concerns the zinc oxide particle functionalised at the surface and covalently by a phthalocyanine derivative prepared in this way, and the uses of same.

Description

PROCESS FOR PREPARING ZNO / ORGANIC HYBRID MATERIAL, LEDIT

MATERIAL AND USES

DESCRIPTION TECHNICAL FIELD

The present invention belongs to the technical field of zinc oxide (ZnO) particles and in particular ZnO nanoparticles comprising phthalocyanine dyes.

Indeed, the present invention relates to a process for preparing ZnO particles and, more particularly, ZnO nanoparticles functionalized, surface and covalently, with phthalocyanine dyes.

The present invention also relates to the ZnO particles and, more particularly, the functionalized ZnO nanoparticles obtained by this method and their various uses.

STATE OF THE PRIOR ART

Recently, there has been increasing interest in organic ZnO + hydride molecular films to incorporate them into low-cost electronic and photonic technologies such as solar cells, light-emitting diodes (LEDs), or LEDs. still the sensors.

These materials combine the important conjugated (or electronic) system of the small organic molecule with the structure and chemical stability of the inorganic compound (ZnO). Moreover, the combination of these two materials in successive nanometric layers has proved the drastic improvement of the charge transport phenomenon and the electronic properties.

The interface of the heterogeneous structures composed of these two materials in thin films plays a major role in the efficiency of the system in order to ensure the transport of electrons through the structure of the layer system, also called the photo-induced electron transfer mechanism.

It is important to note that the photovoltaic response of these systems such as solar cells is due to the formation of an interconnected network between the donor (p-type organic molecule) and the acceptor (n-type ZnO).

Several techniques are commonly used to achieve these layers and successive deposits, among which include electrostatic adsorption and electrodeposition. These techniques can be implemented with dyes such as phthalocyanine or porphyrin derivatives, as organic molecules.

Karan and Mallik describe the preparation of copper phthalocyanine films

(CuPc) on ZnO nanoparticle films deposited on glass coated with ITO (for "Iron Tin Oxide") [1]. The process used to deposit the CuPc layer on the ZnO layer is called the thermal evaporation process. Such a process requires special conditions such as a low pressure (10 ^-6 torr) .The morphology of the CuPc layer shows that the latter is in the form of nanoparticles, aggregates and / or nanobaglets, depending on the annealing temperature to which it has been subjected.

Alternatively, Cruickshank et al. describe the electroplating of ZnO nanoparticles on CuPc molecular films [2]. The electrodeposition using an aqueous solution, saturated with oxygen and comprising 5 mM Zn (NO ₃ ) ₂ and 0.1 M KCl is carried out at 80 ° C.

The synthesis of CuPc: ZnO aggregates is described by Sharma et al., 2006 [3]. ZnO and CuPc are mixed, in a ratio 1/10 expressed by mass, using methanol as solvent and this, for 12 h at 75 ° C. In the aggregates thus obtained, CuPc is adsorbed on the surface of ZnO by weak affinity electrostatic bonds.

(PcCu => OZn).

On the contrary, Hiromitsu et al. describes a process for obtaining hybrid materials in which the organic molecules are covalently bound to ZnO [4]. However, the method described by Hiromitsu et al. involves a step of functionalization of ZnO nanoparticles by L-cysteine. Thanks to that functionalization, porphyrinic aromatic macrocycles can be anchored on ZnO nanoparticles via L-cysteine bridges. Thus, obtaining a covalent type bond is obtained only by making the preparation process longer and more complex.

In view of the growing interest of ZnO / organic molecules, the inventors have set themselves the goal of proposing a simple, practical and industrially applicable method for preparing such materials which do not have the disadvantages of the processes listed below. above.

STATEMENT OF THE INVENTION

The present invention overcomes the disadvantages and technical problems listed above. Indeed, the latter proposes a process for preparing particulate materials based on zinc oxide and comprising phthalocyanine derivatives, said process not requiring heavy processes or steps and using easily accessible products, not dangerous and not very toxic. In fact, the method according to the invention is not only a low-cost process, but has also an adjustable process on a large scale or pilot scale and therefore industrially applicable. The method according to the present invention also has the advantage of being able to be implemented at ambient temperature and pressure.

The work of the inventors has demonstrated that the use of silicon phthalocyanine derivatives or tita does not overcome the multilayer systems by directly functionalizing ZnO particles with a phthalocyanine-derived organic molecule.

Indeed, the use of phthalocyanine derivatives of silicon or tita makes it possible to obtain ZnO particles and in particular ZnO nanoparticles functionalised on the surface and covalently by surface condensation of the organic macrocycle. The implementation of covalent bonds ensures the transport of electrons and a good interface between the organic and inorganic system. In the present invention, by its nature ie electronic, the electronic bond resulting from the condensation of the organic molecule on the surface of the ZnO validates the electron transfer.

The present invention describes the synthesis of surface-functionalized ZnO particles (electronic covalent bonds) with a phthalocyanine derivative of silica or titanium by condensation of the latter in organic solution.

Indeed, phthalocyanine has a central cavity allowing the incorporation of a large number of atoms, including silicon or titanium. The silicon (or titanium) atom being tetravalent, and requiring two bonds for its incorporation into the cavity and the plane of the phthalocyanine aromatic macrocycle, two bonds remain available. These two bonds are axial to the plane defined by the silicon atom and phthalocyanine, and are generally terminated by functions such as hydroxyl functions, carboxyl, chlorides or fluorides. These functions being reactive, they participate as reagents in the sol-gel synthesis of surface-doped ZnO particles.

Thus, the present invention relates to a method for preparing a zinc oxide particle comprising at least one phthalocyanine derivative, said process comprising a step of condensing a phthalocyanine derivative of silicon or titanium of formula (I):

(I) in which :

M represents a silicon atom or a titanium atom,

R 1, R ₂ , R 3 and R ₄ , which may be identical or different, represent an optionally substituted arylene group and

R ₅ and R ₆ , which are identical or different, are chosen from the group consisting of -Cl, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms, and especially from 1 to 6 carbon atoms, optionally substituted or a group -Si (R ") ₃ where each R" independently represents a linear or branched alkyl of 1 to 12 carbon atoms and especially 1 to 6 carbon atoms, optionally substituted,

with a zinc oxide particle, in the presence of an organic solvent.

By "substituted alkyl" is meant, in the context of the compounds of formula (I), an alkyl substituted by a halogen, an amino group, a diamine group, an amide group, an acyl group, a vinyl group or a hydroxyl group. , an epoxy group, a phosphonate group, a sulfonic acid group, an isocyanate group, a carboxyl group, a thiol (or mercapto) group, a glycidoxy group or an acryloxy group and in particular a methacryloxy group. Advantageously, R 'represents a methyl or an ethyl.

For the purposes of the present invention, the term "arylene group" means an aromatic or heteroaromatic carbon structure, optionally mono- or polysubstituted, consisting of one or more aromatic or heteroaromatic rings each comprising from 3 to 8 atoms, the (or ) heteroatom (s) which can be N, O, P or S.

"Substituted arylene" means an arylene group which may be mono- or polysubstituted by a group selected from the group consisting of a carboxylate; an aldehyde; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol. Advantageously, the groups R 1, R ₂ , R 3 and R ₄ are identical or different, each representing a phenylene, a naphthylene or an anthracene. More particularly, the groups R 1, R ₂ , R 3 and R ₄ are identical and represent a phenylene, a naphthylene or an anthracene.

In particular, the phthalocyanine derivative of silicon or titanium used in the context of the present invention is a compound of formula (II):

(Π)

in which :

the groups R ₇ to R ₂₂ , which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

M and the groups R ₅ and R ₆ are as previously defined. As a variant, the phthalocyanine derivative of silicon or titanium used in the context of the present invention is a compound of formula (III) of the naphthalocyanine type:

(III)

in which :

the groups R ₂ 3 to R ₄₆ , which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol,

M and the groups R ₅ and R ₆ are as previously defined. A compound of formula (I II) that is preferred in the context of the present invention is the compound in which the groups R ₂₃ to R ₄₆ represent a hydrogen and the groups R ₅ and R ₆ are as previously defined.

In the formulas (I), (I I) and (I I I), the dotted bonds represent coordination bonds or dative bonds.

In a 1 ^st embodiment, when M represents a silicon atom, the groups R ₅ and R ₆ in the compounds of formula (I), (II) or (III) are identical and are selected from the group consisting of - C1, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted or a group - Si (R " ) ₃ wherein each R "independently represents an alkyl, linear or branched, of 1 to 12 carbon atoms and especially from 1 to 6 carbon atoms, optionally substituted. Advantageously, the groups R ", identical or different, are chosen from methyl, ethyl, propyl, cyclopropyl, butyl, cyclobutyl, heptyl, cycloheptyl, hexyl and cyclohexyl. The groups R ₅ and R ₆ are especially selected from the group consisting of -Cl, -F, -OH, -OCH ₃ , -OC ₂ H ₅ , -O-Si (CH ₃ ) ₃ , -O-Si (C ₂ H ₅ ) ₃ , -O-Si (C ₃ H ₇ ) ₃ , -O-Si (C ₄ H ₉ ) ₃ , -O-Si (C ₅ Hn) ₃ and -O-Si (C ₆ H ₃ ) ₃ . ", identical or different, are selected from methyl, ethyl, propyl, cyclopropyl, butyl, cyclobutyl, heptyl, cycloheptyl, hexyl and cyclohexyl. Preferably, the groups R ₅ and R ₆ are identical.

In a 2 ^nd embodiment, when M represents a titanium atom, the groups R ₅ and R ₆ in the compounds of formula (I), (II) or (III) are identical and are chosen from the group consisting of: C1, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms and especially 1 to 6 carbon atoms, optionally substituted and in particular chosen from the group consisting of by -Cl, -F, -OH, -OCH ₃ and -OC ₂ H ₅ . More particularly, the groups R ₅ and R ₆ in the compounds of formula (I), (II) or (I II) are identical and represent -Cl. The compounds of formula (II) or (III) that can be used particularly in the context of the present invention are:

the compound of formula (IV) which is unsubstituted titanium phthalocyanine chloride corresponding to a compound of formula (II) in which, M represents a titanium atom, the groups R ₇ to R ₂₂ all represent a hydrogen and the groups R ₅ and R ₆ are -Cl:

the compound of formula (V) which is the peripherally substituted titanium phthalocyanine chloride corresponding to a compound of formula (II) in which M represents a titanium atom, the groups R ₅ and R ₆ are -Cl, the groups R _7, Rio, Rn, Ri4, Ris, Ris, R19 and R ₂₂ are all hydrogen and the groups R _8, Rg, R _2, R13, Ri6, R17, R ₂ o and R _2i are identical and chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol:

the compound of formula (VI) which is non-peripherally substituted titanium phthalocyanine corresponding to a compound of formula (II) in which M represents a titanium atom, the groups R ₅ and R ₆ are -Cl, the groups R _8, Rg, R12, R13, Ri6, R17, R20 and R _2i are all hydrogen and the R ₇ groups, Rio, Ru, Ri _4, R15, Ris, R19 and R ₂₂ are identical and selected from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol:

the compound of formula (VII) corresponding to a compound of formula (II) in which M represents a silicon atom, the groups R ₂₃ to R ₄₆ all represent a hydrogen and the groups R ₅ and R ₆ are identical and represent a grouping

-O-Si [CH ₂ (CH ₂ ) ₄ CH ₃ ] ₃ ;

a phthalocyaninatodichlorosilane complex corresponding to a compound of formula (II) in which M represents a silicon atom, the groups R ₇ to R ₂₂ all represent a hydrogen and the groups R ₅ and R ₆ are -Cl, a phthalocyanine-hydroxysilane complex corresponding to a compound of formula (II) in which M represents a silicon atom, the groups R ₇ to R ₂₂ all represent a hydrogen and the groups R ₅ and R ₆ are -OH, a phthalocyaninadifluoroxysilane complex corresponding to a compound of formula (II) in which M represents a silicon atom, the groups R ₇ to R ₂₂ all represent a hydrogen and the groups R ₅ and R ₆ are -F, a naphthalocyaninatodichlorosilane complex corresponding to a compound of formula (III) in which M represents an atom of silicon, the groups R ₂₃ to R ₄₆ are all hydrogen and the groups R ₅ and R ₆ are -Cl, a naphthalocyaninatodihydroxysilane complex corresponding to a compound of formula (III) in which M represents a silicon atom, the groups R ₂₃ to R ₄₆ are all hydrogen and the groups R ₅ and R ₆ are -OH and a naphthalocyaninatodifluoroxysilane complex corresponding to a compound of formula (III) wherein M represents a silicon atom, the R ₂₃ to R _{46 groups} all represent a hydrogen and the groups R ₅ and R ₆ are -F. These complexes can be represented with R representing -OH, -Cl or -F as follows:

By "condensation" is meant, in the context of the present invention, the chemical reaction for combining the ZnO particle with a phthalocyanine derivative of silicon or titanium as previously defined so as to obtain, on the one hand, a ZnO particle comprising at least one phthalocyanine derivative and, secondly, a single molecule. This condensation reaction can be schematized as follows:

Pc-R ₆ + NP-ZnOH -> NP-Zn-O-Pc + R ₆ H

In this schematization, Pc-R ₆ corresponds to the phthalocyanine derivative of silicon or titanium as defined above with R ₆ representing the substituent group for the silicon or titanium atom as previously defined. In addition, NP-ZnOH corresponds to the particle and in particular to the zinc oxide nanoparticle which carries on its surface at least one ZnOH group. Thus, NP-Zn-O-Pc represents the particulate material based on zinc oxide comprising at least one phthalocyanine derivative obtained by carrying out the process of the invention. More particularly, NP-Zn-O-Pc represents a particle and in particular a zinc oxide nanoparticle with a phthalocyanine derivative grafted covalently at the surface of said (nano) particle, as represented in FIG. method according to the invention comprises, more particularly, the following successive steps:

a) optionally preparing a zinc oxide particle,

b) contacting the zinc oxide particle optionally prepared in step (a) with a phthalocyanine derivative of silicon or titanium as defined above in the presence of an organic solvent, whereby said phthalocyanine derivative of silicon or titanium condenses with said zinc oxide particle and a zinc oxide particle comprising at least one phthalocyanine derivative is obtained, and

c) recovering the zinc oxide particle comprising at least one phthalocyanine derivative obtained in step (b).

Step (a) of the process is optional. Indeed, the method according to the present invention can be implemented from previously prepared or commercial ZnO particles. The ZnO particles used in the context of the present invention may have various forms, such as spheroidal, ellipsoid, hexagonal, rod or star shapes. The average particle size distribution of the ZnO particles used is between 10 nm and 1 μιη and in particular between 20 and 900 μιη. We can therefore speak of nanoparticles of zinc oxide.

When, in the process according to the invention, step (a) is not optional, any technique known to those skilled in the art to prepare ZnO particles may be used. The experimental section below and the publication [4] present examples of such techniques.

Advantageously, prior to the implementation of step (b) of the process according to the invention, the ZnO particles are in the form of a dispersion or suspension in an organic solvent. Any organic solvent is usable for this dispersion or suspension. Advantageously, the organic solvent used is an aprotic or polar aprotic organic solvent. In particular, the organic solvent in which the ZnO particles are dispersed is selected from the group consisting of dichloromethane, chloroform, pentane, cyclopentane, hexane, cyclohexane, benzene, 1,2-dichlorobenzene, toluene, dimethylformamide (DMF), acetone, ethyl acetate, propylene carbonate, tetrahydrofuran (THF), 1,4-dioxane, diethyl ether, acetonitrile, dimethyl sulfoxide (DMSO) or a mixture thereof. More particularly, the organic solvent in which the ZnO particles are dispersed is 1,2-dichlorobenzene.

The ZnO particles are present in the suspension in an amount of between 0.5 and 10 mg / ml of organic solvent and in particular between 1 and 5 mg / ml of organic solvent.

The contacting between the ZnO particles and the phthalocyanine derivatives of silicon or titanium during step (b) of the process consists in adding, to the dispersion or suspension of ZnO particles as defined above, at least one phthalocyanine derivative of silicon or titanium as previously defined and then mixing the solution (S) thus obtained.

The phthalocyanine derivative (s) of silicon or titanium can be added in solid form, in liquid form or in solution. When several different silicon or titanium phthalocyanine derivatives are used, they may be mixed at once or added one after the other or in groups. Advantageously, the phthalocyanine derivative (s) of silicon or titanium is (are) in the form of one (or more) solution (s) containing one or more silicon phthalocyanine derivative (s). or titanium.

In the solution containing a phthalocyanine derivative of silicon or titanium, the solvent is an organic solvent. Advantageously, the organic solvent used for the solution containing a phthalocyanine derivative of silicon or titanium is an aprotic polar or aprotic polar solvent. In particular, the organic solvent containing a phthalocyanine derivative of silicon or titanium is chosen from the group consisting of dichloromethane, chloroform, pentane, cyclopentane, hexane, cyclohexane, benzene, 1,2-dichlorobenzene, toluene, dimethylformamide (DMF), acetone, ethyl acetate propylene carbonate, tetrahydrofuran (THF), 1,4-dioxane, diethyl ether, acetonitrile and dimethyl sulfoxide (DMSO) or a mixture thereof. More particularly, the organic solvent containing a phthalocyanine derivative of silicon or titanium is tetrahydrofuran (THF).

The phthalocyanine derivative of silicon or titanium is present in the solution in an amount of between 0.5 and 10 mM and especially between 1 and 5 mM.

The organic solvent of the suspension of ZnO particles and that of the solution containing a phthalocyanine derivative of silicon or titanium may be the same or different. When these two organic solvents are identical, the organic solvent referred to in step (b) of the process according to the invention corresponds to this organic solvent.

In contrast, when the organic solvent of the suspension of ZnO particles is different from that of the solution containing a phthalocyanine derivative of silicon or titanium, the organic solvent referred to in step (b) of the process according to the invention corresponds to the mixture of these two solvents. A particular example of such a mixture is a mixture of THF and 1,2-dichlorobenzene. In this mixture, the volume ratio between the organic solvent of the suspension of ZnO particles and that of the solution containing a phthalocyanine derivative of silicon or titanium is between 1/10 and 10/1, in particular between 1/5 and 5/1 and in particular between 1/3 and 3/1.

During step (b) of the process, the addition of the solution containing a phthalocyanine derivative of silicon or titanium to the suspension of ZnO particles is advantageously carried out by means of a dropper.

The mixture during step (b) of the process is carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer, and may be used at a temperature of between 10 ° C. and 40 ° C. C, advantageously between 15 ° C. and 30 ° C. and, more particularly, at room temperature ambient (ie 23 ° C ± 5 ° C) for a period of between 6 and 48 h, in particular between 12 and 36 h and, in particular, for 24 h.

In a particular embodiment, the solution (S) implemented during step (b) of the process may contain not only particles of ZnO and one (or more) derivative (s) of silicon phthalocyanine or titanium but also one (or more) compound (s) based on silane. This (or these) last (s) typically allows to encapsulate the surface of ZnO. In addition, if the (or a) silane-based compound is moreover functionalized or functionalizable, such functionalization may make it possible to confer particular properties on the particles, for example, hydrophilic or hydrophobic properties which may be of importance. for the implementation of the particles later.

When a silane compound or several silane compounds, identical or different, are present, they are incorporated into the mixture obtained during step b. ), in the suspension containing the ZnO nanoparticles and / or in the solution containing one or more different derivatives of silicon phthalocyanine or titanium. The silane-based compound (s) can be introduced in solid form, in liquid form or in solution in an organic solvent. When several different silane compounds are used, they may be mixed at one time or added one after the other or in groups.

When the silane-based compound (s) is (are) used in solution in an organic solvent, the latter may be identical to or different from the organic solvent of the solution or suspension in which the solution of silane compound (s) is added.

Advantageously, the compound (s) based on silane is (are) introduced into the solution obtained in step (b) in liquid form. In this solution, the silane-based compound (s) is (are) present in a proportion of between 0.1 and 40%, in particular between 1 and 30% and, in particular, between and 25% by volume relative to the total volume of said solution. In this solution, the (or) silane-based compound (s) present (s) a molarity of between 100 μΜ and 400 mM, in particular between 500 μΜ and 300 mM and, in particular, between 1 mM and 200 mM.

Advantageously, said silane-based compound (s) is (are) of general formula SiR _a R _b R _c R _d in which R _a , R _b , R _c and R _d are, independently of one another selected from the group consisting of hydrogen; a halogen; an amino group; a diamine group; an amide group; an acyl group; a vinyl group; a hydroxyl group; an epoxy group; a phosphonate group; a sulfonic acid group; an isocyanate group; a carboxyl group; a thiol group (or mercapto); a glycidoxy group; an acryloxy group such as a methacryloxy group; an alkyl group, linear or branched, optionally substituted, of 1 to 12 carbon atoms, especially 1 to 6 carbon atoms; an aryl group, linear or branched, optionally substituted, of 4 to 15 carbon atoms, in particular of 4 to 10 carbon atoms; an alkoxyl group of formula -OR _e with R _e representing an alkyl group as defined above and their salts.

By "optionally substituted" is meant, in the context of alkyl and aryl groups, silane compounds substituted with halogen, amino group, diamine group, amide group, acyl group, vinyl group, hydroxyl group, an epoxy group, a phosphonate group, a sulfonic acid group, an isocyanate group, a carboxyl group, a thiol (or mercapto) group, a glycidoxy group or an acryloxy group and in particular a methacryloxy group.

In particular, said silane-based compound (s) is (are) alkyl (or) alkylsilane (s) and / or (or) alkoxysilane (s). Also, the silane compound is more particularly selected from the group consisting of dimethylsilane (DMSi), phenyltriethoxysilane (PTES), tetraethoxysilane (TEOS), tetramethoxysilane (TEMOS), n-octyltriethoxysilane, octadecyltriethoxysilane, dimethyldimethoxysilane

(DMDMOS), (3-mercaptopropyl) trimethoxysilane, (3-mercaptopropyl) triethoxysilane, (mercapto) -triethoxysilane, (3-aminopropyl) triethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, 3- [bis (2-hydroxyethyl) amino] propyltriethoxysilane, hexadecyltrimethoxysilane, phenyltrimethoxysilane, N- [3- (trimethoxysilyl) propyl] -1,2-ethanediamine and acetoxyethyltriethoxysilane, 2-hydroxy-4- (3-triethoxysilylpropoxy) diphenyl ketone, methyltriethoxysilane, vinyltrimethoxysilane, (3-glycidoxypropyl) trimethoxysilane, (benzoyloxypropyl) trimethoxysilane, sodium 3-trihydroxysilylpropylmethylphosphonate, (3-Trihydroxysilyl) -1-propanesulphonic acid, (diethylphosphonatoethyl) triethoxysilane, and mixtures thereof. More particularly, the silane compound is tetraethoxysilane (TEOS, Si (OC ₂ H ₅ ) ₄ ).

In another particular embodiment of step (b) of the process according to the invention, one (or more) compound (s) promoting the condensation reaction may optionally be added to the solution ( S) containing ZnO particles, one (or more) different derivative (s) of silicon phthalocyanine or titanium as previously defined and optionally one (or more) compound (s) based on silane as previously defined.

In this embodiment, the solution containing ZnO particles, one (or more) derivative (s) of phthalocyanine silicon or titanium and optionally one (or more) compound (s) containing silane with a solution (S ') obtained by dissolving at least one compound promoting the condensation reaction in an organic solvent as defined above.

The solution (S ') can be prepared before or simultaneously with step (b) of the process according to the present invention.

The organic solvent used in the solution (S ') may be identical to the organic solvent of the solution (S) or to one of the organic solvents of the solution (S) or be different from this (or these) solvent (s).

It should be noted that "compound favoring the condensation reaction" means a compound, of base type, allowing not only the condensation, with the ZnO particles, of a silane-based compound such as previously defined but also the condensation of a phthalocyanine derivative of silicon or titanium as previously defined.

The compound that promotes the condensation reaction is advantageously chosen from the group consisting of urea, thiourea, ammonia, an amine such as trimethylamine or triethylamine and mixtures thereof. The compound promoting the condensation reaction used in the context of the present invention is, more particularly, urea or ammonia.

The compound promoting the condensation reaction has a molarity of between 100 μΜ and 400 mM, in particular between 500 μΜ and 300 mM and, in particular, between 1 mM and 200 mM in the solution (S ').

Any technique making it possible to recover the surface-functionally and covalently functionalized zinc oxide particles by phthalocyanine derivatives and optionally by silane derivatives obtained during step (b) may be implemented during the step (c) of the process according to the invention.

Advantageously, this step (c) implements one or more steps, identical or different, chosen from the centrifugation, sedimentation and washing steps. The washing step (s) is (are) carried out in a polar solvent. By "polar solvent" is meant in the context of the present invention a solvent selected from the group consisting of water, deionized water, distilled water, acidified or basic, hydroxylated solvents such as methanol and ethanol, low molecular weight liquid glycols such as ethylene glycol, dimethyl sulfoxide (DMSO), acetonitrile, acetone, tetrahydrofuran (THF) and mixtures thereof.

When the recovery step uses several washes, the same polar solvent is used for several or even all washes or several different polar solvents are used at each wash. Regarding one (or more) centrifugation stage (s), it (s) can be implemented by centrifuging the functionalized ZnO particles in particular in a wash solvent at room temperature, at a speed of between 4000 and 8000 rpm and, in particular, of the order of 6000 rpm (ie 6000 ± 500 rpm) and this, for a period of between 5 min and 2 h, in particular between 10 min and 1 h and, in particular, for 15 minutes. The method according to the present invention may comprise, following step (c), an additional step of purifying the functionalized ZnO particles obtained hereinafter referred to as "step (d)".

Advantageously, this step (d) consists in putting the functionalized ZnO particles recovered after step (c) of the process according to the invention in contact with a very large volume of water. By "very large volume" is meant a volume greater by a factor of 50, in particular by a factor of 500 and, in particular, by a factor of 1000 to the volume of particles of titanium oxide, recovered after the step ( c) the process according to the invention. Step (d) may be a dialysis step, the functionalized ZnO particles being separated from the volume by a cellulose membrane, of the Spectra / Por ^® - MWCO3500 (Proud) type. Alternatively, an ultrafiltration step can be provided in place of the dialysis step, via a polyethersulfone membrane.

Step (d) may, in addition, be carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer, at a temperature between 0 ° C. and 30 ° C., advantageously between 2 ° C. ° C and 20 ° C and, more particularly, cold (ie 6 ° C ± 2 ° C) and this, for a period of between 30 hours and 15 days, especially between 3 and 10 days and, in particular, during 1 week.

The present invention further relates to a zinc oxide particle comprising at least one phthalocyanine derivative capable of being prepared by the process of the present invention.

The particle according to the present invention is distinguished from the prior art ZnO particles by the presence of the phthalocyanine derivative at the single surface of the ZnO particle and the nature of the covalent bond linking the phthalocyanine derivative. to the ZnO particle without the need for an organic cysteine bridge.

More particularly, the phthalocyanine derivatives and optionally the silane derivatives form, on the surface of the ZnO particles, a SAM-type monolayer (for "self-assembled monolayers") or a very thin layer whose thickness is less than 10 nm and especially less than 5 nm. The functionalized ZnO particles, surface and covalently, by phthalocyanine derivatives according to the invention are in the form of nanoparticles since advantageously obtained from nanoparticles of ZnO. Thus, ZnO particles functionalised, surface and covalently, with phthalocyanine derivatives can have various forms, such as spheroidal, ellipsoid, hexagonal, rod or star shapes. The mean particle size distribution of the ZnO particles functionalized, surface and covalently, by phthalocyanine derivatives is between 10 nm and 1.2 μιη and in particular between 20 nm and 1 μιη.

It should be noted that the functionalized ZnO particles, surface and covalently, by phthalocyanine derivatives have remarkable properties. Indeed, in these particles, the ZnO is colored in blue or green, remains crystalline and therefore very stable.

Also, ZnO particles functionalised, surface and covalently, by phthalocyanine derivatives are a material with a very good stability at high temperature because of the melting temperature of phthalocyanine derivatives greater than 300 ° C. In addition, this material can be in the form of a stable colloidal system in water. Finally, depending on the substituents of the phthalocyanine derivatives grafted covalently on the surface of the ZnO particles, the particles thus obtained may have properties comparable to those of liquid crystals.

The properties of ZnO particles functionalised, surface and covalently, by phthalocyanine derivatives in particular as listed above but also presented in point IV of the experimental part below make it good candidates as photocatalysts and dyes.

Therefore, the present invention relates to the use of a znO particle surface-covalently functionalized with phthalocyanine derivatives according to the present invention or prepared according to the process of the present invention in the paper industry. the textile industry, the pharmaceutical industry, the plastics industry and the photovoltaic industry and, more particularly, in the fields chosen in the group consisting of coloring agents (inks, paints, paper and textiles); photocatalysis and photodegradation; UV protection agents; solar light-keeping agents; anti-light and anti-UV protection agents; electronic, optical, sensor, energy conversion and storage devices and organic semiconductors.

Other features and advantages of the present invention will become apparent to those skilled in the art on reading the examples given below by way of illustration and not limitation, and with reference to the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of a nanoparticle of zinc oxide functionalized, surface and covalently, with a phthalocyanine derivative and prepared by the method according to the invention.

Figure 2 shows a view obtained from transmission electron microscopy (M ET) of zinc oxide nanoparticles.

Figure 3 presents the energy dispersive analysis (EDS) of zinc oxide nanoparticles.

FIG. 4 shows a view obtained by M ET of surface-functionalised zinc oxide nanoparticles with a phthalocyanine derivative and prepared, by the process according to the invention, from a silicone phthalocyanine derivative.

FIG. 5 shows the energy dispersive analysis (EDS) of surface-functionalised zinc oxide nanoparticles with a phthalocyanine derivative and prepared, by the method according to the invention, from a silicone phthalocyanine derivative.

FIG. 6 shows a view obtained by M ET of surface-functionalised zinc oxide nanoparticles with a phthalocyanine derivative and prepared, by the process according to the invention, from a titanium phthalocyanine derivative.

FIG. 7 shows the energy dispersive analysis (EDS) of surface-functionalised zinc oxide nanoparticles with a phthalocyanine derivative and prepared, by the process according to the invention, from a titanium phthalocyanine derivative. FIG. 8 shows the electron absorption spectra, in water and at different concentrations, of nanoparticles of ZnO / N Pc according to the invention.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS I. Synthesis and Analysis of ZnO Nanoparticles.

The synthesis of the pure ZnO nanoparticles was carried out by co-precipitation with, as initial reactants, hydrated zinc nitrate and sodium carbonate.

To prepare 10 g of a sample of pure ZnO, a 0.2 mol / L solution of Zn (NO ₃ ) 2.6H ₂ O is prepared, i.e. 36.5 g of ns 615 mL. distilled water. A 0.5 mol / l solution of sodium carbonate was made by dissolving 13.78 g in 246 ml of distilled water.

The zinc nitrate solution is added dropwise to the sodium carbonate solution with vigorous mechanical stirring. The solution is then stirred for 2 hours at room temperature. The precipitate is filtered on a Buchner funnel.

The powder thus recovered is dried overnight in an oven at

100 ° C. The solid is then calcined under air (100 L / h) at 400 ° C for 4 h.

The nanoparticles obtained are 20 to 30 nm in diameter and are crystallized (FIG. 2). Elemental analysis reveals the presence of zinc in the sample (Figure 3). II. Synthesis and analysis of ZnO-NPc nanoparticles.

A suspension of ZnO nanoparticles previously prepared at 2 mg / ml in 20 ml of dichlorobenzene is stirred at room temperature.

A tetrahydrofuran solution (10 mL) containing the naphthalocyanine (silicon naphthalocyanine dihydroxide, CAS No: 92396-90-2) at a concentration of 2 x 10 ^"3 M is added dropwise with vigorous stirring The reaction mixture is stirred. at room temperature for 24 h.

The reaction mixture is then centrifuged and the nanoparticles obtained are washed three times with ethanol and once with water, each washing being followed by sedimentation in the centrifuge (15 min at 6000 rpm). After the washing step, the purification of the obtained nanoparticles is completed by dialysis (nominal MCWO 3500 Daltons) in water (1 L) with magnetic stirring for one week.

The nano-objects dispersed in water (40 mL) are then characterized by transmission electron microscopy (TEM) analysis. According to the TEM images, the functionalized ZnO nanoparticles NPc have the shape of beads with a diameter of between 25 and 30 nm (FIG. 4). These nanoparticles are green and elemental analysis reveals the presence of zinc (Figure 5).

III. Synthesis and analysis of ZnO-TiPc nanoparticles.

A suspension of ZnO nanoparticles previously prepared for

2 mg / mL in 20 mL of dichlorobenzene is stirred at room temperature.

A tetrahydrofuran solution (10 mL) containing 25.2 mg of titanyl phthalocyanine dichloride IV or English "titanium IV phthalocyanine dichloride" (CAS: 16903-42-7) at a concentration of 1.3 x 10 ^{" 3} M is added dropwise with vigorous stirring.

The reaction mixture is stirred at room temperature for 24 hours. The reaction mixture is then centrifuged and the nanoparticles obtained are washed three times with ethanol and once with water, each washing being followed by sedimentation in the centrifuge (15 min at 6000 rpm). After the washing step, the purification of the nanoparticles obtained is completed by dialysis (nominal MCWO 3500 Daltons) in water (1 L) with magnetic stirring for one week.

The nano-objects dispersed in water (40 mL) are then characterized by TEM analysis. According to the TEM images, the functionalized ZnO nanoparticles NPc have the shape of beads with a diameter of between 25 and 30 nm (FIG. 6). These nanoparticles are blue and the elemental analysis reveals the presence of zinc (Figure 7).

IV. Adsorption spectra of the ZnO: NPc nanoparticles according to the invention.

The absorption spectra of the naphthalocyanine derivatives generally show two typical absorptions called "-band" (740-760 nm) and "B". band "or" Soret band "(420-460 nm), which generally show greater absorption and bathochromic absorption than their phthalocyanine analogues.

These absorptions are sensitive to the molecular substitutions of the phthalocyanine ring both at peripheral and non-peripheral sites, as well as to the electronic environment in which said phthalocyanine resides.

In the case of the invention, the traditional peak resulting from the absorption of ZnO is observed at 375 nm and coalesce with that of the NPc Soret band at 440 nm. The peak of the Q-band is observed at 760 nm for various concentrations obtained by successive dilutions (Figure 8). The observation of all the electronic transitions makes it possible to affirm the good transfer of electrons in the system and makes this material a potential candidate for photovoltaic applications.

REFERENCES

Karan and Mallik, 2008, "Nanostructured organic-inorganic photodiodes with high rectification ratio," Nanotechnology, vol. 19: 495202 (10 pp)

Cruickshank et al., 2011, "Electrodeposition of ZnO Nanostructures on Molecular Thin Films", Chem. mater., vol. 23, pp. 3863-3870.

Sharma et al., 2006, "Charge Generation and Photovoltaic Properties of Hybrid Solar Cells Based on ZnO and Copper Phthalocyanines (CuPc)", Solar Energy Materials & Solar Cells, Vol. 90, pages 933-943.

[4] Hiromitsu et al., 2009, "Photoinduced energy transfer in ZnO-tetraphenylporphyrin Systems," Chemical Physics Letters, vol. 474, pages 315-319.

Claims

1) Process for preparing a zinc oxide particle comprising at least one phthalocyanine derivative, said process comprising a step of condensing a phthalocyanine derivative of silicon or titanium of formula (I):

(I)

in which

M represents a silicon atom or a titanium atom,

R 1, R ₂ , R ₃ and R ₄ , which are identical or different, represent an optionally substituted arylene group and

R ₅ and R ₆ , which are identical or different, are chosen from the group consisting of -Cl, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms, and especially of 1 to 6 carbon atoms, optionally substituted or a group -Si (R ") ₃ where each R" independently represents a linear or branched alkyl of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted

with a zinc oxide particle, in the presence of an organic solvent. 2) Process according to claim 1, characterized in that said phthalocyanine derivative of silicon or titanium is a compound of formula (II):

(Π)

in which :

M and the groups R ₅ and R ₆ are as defined in claim 1.

3) Process according to claim 1, characterized in that said phthalocyanine derivative of silicon or titanium is a compound of formula (III) of the naphthalocyanine type:

(III)

in which :

M and the groups R ₅ and R ₆ are as previously defined in claim 1.

4) Method according to any one of claims 1 to 3, characterized in that said method comprises the following successive steps:

a) optionally preparing a zinc oxide particle,

b) contacting the zinc oxide particle optionally prepared in step (a) with a phthalocyanine derivative of silicon or titanium in the presence of a organic solvent, whereby said silicon or titanium phthalocyanine derivative condenses with said zinc oxide particle and a zinc oxide particle comprising at least one phthalocyanine derivative is obtained, and

5) Process according to claim 4, characterized in that, prior to the implementation of said step (b), the ZnO particle is in the form of a dispersion or suspension in an organic solvent.

6) Process according to claim 4 or 5, characterized in that said placing in contact during said step (b) comprises adding to the dispersion or suspension as defined in claim 5, at least one silicon phthalocyanine derivative or titanium and then mix the solution (S) thus obtained.

7) Process according to claim 5, characterized in that said organic solvent is selected from the group consisting of dichloromethane, chloroform, pentane, cyclopentane, hexane, cyclohexane, benzene, 1,2-dichlorobenzene toluene, dimethylformamide (DMF), acetone, ethyl acetate, propylene carbonate, tetrahydrofuran (THF), 1,4-dioxane, diethyl ether, acetonitrile and dimethyl sulfoxide (DMSO) or a mixture thereof.

8) Process according to claim 6, characterized in that said solution (S) contains one (or more) compound (s) based on silane.

9) Process according to claim 8, characterized in that said (or said) compound (s) based on silane is (are) of general formula:

SiR _a RbRcRd

wherein R _a , Rb, R _c and R _d are, independently of one another, selected from the group consisting of hydrogen; a halogen; an amino group; a group diamine; an amide group; an acyl group; a vinyl group; a hydroxyl group; an epoxy group; a phosphonate group; a sulfonic acid group; an isocyanate group; a carboxyl group; a thiol group (or mercapto); a glycidoxy group; an acryloxy group such as a methacryloxy group; an alkyl group, linear or branched, optionally substituted, of 1 to 12 carbon atoms, especially 1 to 6 carbon atoms; an aryl group, linear or branched, optionally substituted, of 4 to 15 carbon atoms, in particular of 4 to 10 carbon atoms; an alkoxyl group of the formula -OR _e with R _e representing an alkyl group and their salts. 10) Process according to claim 8 or 9, characterized in that said (or said) compound (s) based on silane is (are) chosen from the group consisting of dimethylsilane (DMSi), phenyltriethoxysilane (PTES ), tetraethoxysilane (TEOS), tetramethoxysilane (TEMOS), n-octyltriethoxysilane, n-octadecyltriethoxysilane, dimethyldimethoxysilane (DMDMOS), (3-mercaptopropyl) trimethoxysilane, (3-mercaptopropyl) triethoxysilane, (mercapto) triethyloxysilane, (3-aminopropyl) triethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, 3- [bis (2-hydroxyethyl) amino] propyltriethoxysilane, hexadecyltrimethoxysilane, phenyltrimethoxysilane, N- [3- (trimethoxysilyl) propyl] -1,2-ethanediamine and acetoxyethyltriethoxysilane, 2-hydroxy-4- (3-triethoxysilylpropoxy) diphenyl ketone, methyltriethoxysilane, vinyltrimethoxysilane, (3-glycidoxypropyl) trimethoxysilane, (benzoyloxypropyl) trimethoxysilane, the Sodium 3-trihydroxysilylpropylmethyl phosphonate, (3-trihydroxysilyl) -1-propanesulphonic acid, (diethylphosphonatoethyl) triethoxysilane, and mixtures thereof. 11) Process according to any one of claims 6 to 10, characterized in that said solution (S) contains one (or more) compound (s) promoting the condensation reaction.

12) Process according to claim 11, characterized in that said (or said) compound (s) promoting the condensation reaction is (are) chosen (s) in the group consisting of urea, thiourea, ammonia, an amine such as trimethylamine or triethylamine and mixtures thereof.

13) Method according to any one of claims 4 to 12, caacticized in that said step (c) implements one or more steps, identical or different, selected from the centrifugation, sedimentation and washing steps.

14) Zinc oxide particle comprising at least one phthalocyanine derivative capable of being prepared by a process as defined in any one of Claims 1 to 13, characterized in that it is in the form of a ZnO nanoparticle functionalized, surface and covalently, by phthalocyanine derivatives.