WO2012013719A1

WO2012013719A1 - New cyclometalated complexes for solar cells

Info

Publication number: WO2012013719A1
Application number: PCT/EP2011/062936
Authority: WO
Inventors: Alessandro Abbotto; Norberto Manfredi; Carmine Coluccini; Dominique Roberto; Renato Ugo; Claudia Dragonetti; Adriana Valore; Alessia Colombo
Original assignee: Universita' Degli Studi Di Milano Bicocca; Universita' Degli Studi Di Milano; Fondazione Cassa Di Risparmio Delle Provincie Lombarde
Priority date: 2010-07-28
Filing date: 2011-07-27
Publication date: 2012-02-02
Also published as: ITMI20101400A1

Abstract

The present invention relates to a cyclometalated complex of formula (I) [M L₁ L₂ L₃]^+q wherein M is a divalent metal selected from Fe, Ru, Os, or a trivalent metal selected from Co, Rh, Ir; and L₁, L₂, L₃ are ligands, such cyclometalated complexes being useful as photosensitizers in dye solar cells and as emitters in photo and electroluminescent devices for a photoelectric conversion of energy.

Description

NEW CYCLOMETALATED COMPLEXES FOR SOLAR CELLS

FIELD OF THE INVENTION

The present invention concerns new cyclometalated complexes, useful as photosensitizers in dye solar cells and as emitters in photo- and electroluminescent devices.

STATE OF THE ART

The energy demands of modern society has encouraged the development of new technologies based on renewable alternatives to fossil fuels. Photovoltaic technology is one of the most promising, thanks to the inexhaustible source of energy from the sun (Jacoby, M. Chem. Eng News 2007, 85, 16-22; Kleiner, K. Nature 2009, 459, 740). Dye-sensitized solar cells (DSC) show one of the best potential in terms of power conversion efficiency from solar energy to electricity and lower production costs (Graetzel, M. Acc. Chem. Res 2009, 42, 1788; Elliott, C. M. Nature Chemistry 201 1 , 3, 188; Nazeeruddin, M. K.; Baranoff, E.; Gratzel, M. Solar Energy 201 1 , 85, 1 172; Hagfeldt, A. ; Boschloo, G. ; Sun, L; Kloo, L ; Pettersson, H. Chem. Rev. 2010, 1 10, 6595). Under light irradiation a compound or dye, also referred to as the sensitizer or photosensitizer S, is promoted to its excited state S* from which an electron injection into the conduction band (CB) of TiO2 takes place, leaving the dye in its oxidized state S⁺. The collected electrons at the photoanode are then transferred through the external load to the counter electrode where, via Pt catalysis, reduce triiodide to iodide which, in turn, regenerates the sensitizer (S⁺→ S). A DSC is a very efficient scheme where, formally, one photon is converted to one electron with no chemical change, in principle allowing an unlimited number of cycles. (O'Regan, B.; Graetzel, M. Nature 1991 , 353, 737-740; Graetzel, M. Nature 2001 , 414, 338-344; Hamann TW, Jensen, RA, Martinson, ABF; Ryswyk, HV, Hupp, JT Energy Environ. Sci 2008, 1 , 66-78, Luo, Y., Li, D., Meng, Q. Adv. Mater. 2009, 21 , 4647-4651 ).

The homoleptic Ru(ll) complexes bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(ll) (N3) and its bis(tetrabutylammonium) salt (N719) are the most representative DSC sensitizers, with power conversion efficiencies exceeding 1 1 % (Nazeeruddin, M.K. ; DeAngelis, F. ; Fantacci, S.; Selloni, A. ; Viscardi, G. ; Liska, P. ; Ito, S.; Takeru, B. ; Gratzel, M. J. Am. Chem. Soc. 2005, 127, 16835-1 6847). The 2,2'-bipyridyl-4,4'- dicarboxylate (dcbpy) ligand has the function of anchoring, through the carboxylic functionality, the complex to the Ti02 nanoparticle surface in order to promote an efficient electron injection from the sensitizer to the n-type conductor oxide.

A main drawback of these families of Ru(l l) complexes is the presence of the thiocyanate SCN ligand. Thiocyanate coordinates through only one atom, and is therefore easier to be replaced by other competing ligands yielding less efficient species, and its coordination to metal ions requires purification steps in order to separate the active N- from the inactive S-coordinated isomer (Nazeeruddin, M. K. ; Baranoff, E. ; Gratzel, M. Solar Energy 201 1 , 85, 1 172-1 178; Asghar, M.I. ; Miettunen, K. ; Halme, J. ; Vahermaa, P. ; Toivola, M. ; Aitola, K.; Lund, P. Energy Environ. Sci. 2010, 3, 418-426). Unfortunately, previous efforts to replace SCN by other ligands such as halides or cyanide always yielded much lower energy conversion efficiencies (Wadman, S. H.; Kroon, J. M. ; Bakker, K. ; Lutz, M.; Spek, A. L ; van Klink, G. P. M. ; van Koten, G. Chem. Commun. 2007, 1 907-1909). Recently, some researchers have described a cyclometalated ruthenium complex where the thiocyanate ligands have been replaced by the deprotonated form of 2-(2,4-difluorophenyl)pyridine (Bessho, T. ; Yoneda, E.; Yum, J.-H. ; Guglielmi, M.; Tavernelli, I.; Imai, H. ; Rothlisberger, U. ; Nazeeruddin, M.K. ; Graetzel, M. J. Am. Chem. Soc. 2009, 131, 5930-5934). This sensitizer is the first reported thiocyanate-free Ru(l l) complex showing power conversion efficiencies of approximately 1 0%.

Despite this cyclometalated complex shows good power conversion efficiencies, the presence of a simple ligand such as the cyclometalated 2-(2,4-difluorophenyl)pyrdine, in which the pyridine ring does not have any substituent on its ring, does not allow a tuning of the photophyswical, electronic, and photovoltaic properties of the photosensitizer, thus limiting the possibility of greatly improving the power conversion efficiencies.

In addition, it is known that, in iridium or platinum based systems containing cyclometallated phenylpyridines, the presence of substituents on the aryl or pyridyl ring allows to modulate the energy levels HOMO and LUMO, and therefore the photophyscial and electronic properties (for example, the absorption energy) of the complex (Brooks, J.; Babayan, Y.; Lamansky, S.; Djurovich, P. I.; Tsyba, I.; Bau, R.; Thompson, M.E. Inorg. Chem. 2002, 41, 3055; Yin, B.; Niemeyer, F; Williams, J.A.G., Jaing, J.; Boucekkine, A.; Toupet, L; Le Bozec, H.; Guerchais, V. Inorg. Chem. 2006, 45, 8584). In particular, it was reported that the effect of substituents on the pyridyl ring is much stronger than on the aryl ring. (Brooks, J.; Babayan, Y.; Lamansky, S.; Djurovich, P. I.; Tsyba, I.; Bau, R.; Thompson, M.E. Inorg. Chem. 2002, 41, 3055). Recently, some complexes of Ru(ll) with two 2,2'-bipyridyl-4,4'-dicarboxylate ligands and one phenylpyridine variously substituted on the aryl ring were described (Bomben, P.G.; Koivisto, B.D.; Berlinguette, CP. Inorg. Chem. 2010, 49, 4960) but no derivatives with aromatic/heteroaromatic substituents on the pyridyl ring have been reported.

SUMMARY OF THE INVENTION

In accordance with the present invention, new compounds useful as photosensitizers in power conversion photovoltaic devices are provided having the following formula (I): [M Ι__! L₂ L₃p

(I) wherein M is a divalent metal selected from Fe, Ru, Os, or trivalent selected from Co, Rh, Ir, and l_i , l_₂, L₃ is a ligand defined as follows;

the net charge q is equal to 0 or 1 , and when q=1 , a counterion is present selected among the anions alkylsulfonate, arylsulfonate, polyarensulfonate, triflate, halide, sulfate, methosulfate, phosphate, polyphosphate; and wherein at least one of the ligands U, l__2, L₃, being the same or different, is a negatively charged bidentate ligand being cyclometalated, that is formally obtained by removing a proton H⁺ from an aromatic or heteroaromatic cycle of formula (II): Het Ri

(II) wherein Heti is selected from the following heteroaromatic groups

and wherein is an aromatic or heteroaromatic substituent selected from the group

wherein substituents R₃, being one or more per aromatic/heteroaromatic ring, are selected from the group consisting of H, alkyl groups having from 1 to 18 carbon atoms, halide, alkoxy, aminoalkyi, alkylhalide, hydroxyalkyi, alkyl groups containing hydroxy and amino functions, alkoxyalkyl, aryl, formyl.

In He^ the group R₂ is a monovalent organic substituent having at least one aromatic or heteroaromatic ring and is selected from the group of

wherein X is selected among O, S, NZ and Se, wherein Z = H, alkyl, aryl;

wherein substituents R₄, being the same or different, are selected from the group consisting of H, alkyl groups having from 1 to 18 carbon atoms, alkoxy, aminoalkyi, alkylhalide, hydroxyalkyl, alkyl groups containing hydroxy and amino functions, alkoxyalkyl, alkylsulfide, alkylthiol, alkylazide, alkylcarboxylic, alkylsulfonic, alkyyiisocyanate, alkylisothiocyanate, alkylalkene, alkylalkyne, aryl, formyl, groups containing the carbonyl -C(O)- or carboxylic -C(0)0- function, cyano, nitro, groups containing the -S(O)- or -P(O)- function, groups containing an electron-poor 6- membered or 5-membered aromatic or heteroaromatic ring, groups containing the function wherein R = H, alkyl, electron-withdrawing aliphatic, aromatic, or heteroaromatic group, or being part of an electron-wihdrawing aromatic or heteroaromatic ring;

and wherein n is 0,1 ,2;

and wherein Y is optionally present and selected among

wherein m is 0,1 ,2;

and wherein at least one of the ligands l_i , l_₂, L₃, if different from HetrRi of formula (II), is a bidentate, tridentate, or tetradentate ligand of formula (III):

wherein R₅ is an anchoring substituent selected among the group of -COOH, -P0₃H₂, -P0₄H₂, B(OH)₂, S0₃H₂ or any corresponding deprotonated form thereof including organic and/or inorganic counterions,

and wherein any of substituents R₅ may be bonded to any pyridine ring of formula (II), and wherein p is 0,1 ,2. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED

EMBODIMENTS

Preferred ligands according to the said formula (II) are the compounds 2a - 8a and 2b - 8b (Scheme 1 ). The unsubstituted compounds 1 a and 1 b are reference systems from the prior art. The synthesis of the compounds 2a - 8a and 2b - 8b is shown in Scheme 2. SCHEME 1

1a 1 b — H

2a 2b exyl

SCHEME

Substituents R as in Scheme 1 . i) Pd(PPh₃)₄, Na₂C0_3! THF/H₂0, reflux, boronate ester for 3c, 4c, and 6c or boronic acid for 7c; ii) 2-phenylboronic acid, Pd(PPh₃)₄, Na₂C0_3! THF/H₂0, microwave max. 150 W at 70 °C; iii) 2,4-difluorophenylboronic acid, Pd(PPh₃)₄, Na₂C0₃, THF/H₂0, reflux or microwave max. 150 W at 70 °C.

7a/b 8a/b

i

i) Piperidine cat., CH₃CN or EtOH.

In the following table the yields of the two sequential Suzuky cross-coupling reactions for the synthesis of 2-bromopyridine intermediates c and 2-arylpyridines a and b are reported. Values were always higher than 40%, in a few cases above 90% yield, suggesting a wide applicability of the synthetic route to rapidly and conveniently prepare 4-substituted-2-arylpyridines.

Table. Yields (%) of Suzuky cross-coupling reactions to 2-bromopyridines 2c - 8c, 2- phenylpyridines 2a - 7a, and 2-(2,4-difluorophenyl)pyridines 2b - 7b.

R c a b

2 [aj 74 66

3 91 44 78

4 94 44 74

5 [a] 82 99

6 58 82 90

7 60 65 87

[a] Previously reported (J. -J. Kim, H. Choi, C. Kim, M.-S. Kang, H. S. Kang, J. Ko, Chem. Mater. 2009, 21, 5719-5726). BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become readily apparent by reference to the following detailed description in conjunction with the accompanying drawings, in which:

Figures 1 and 2 show the absorption spectra of 2-phenylpyridines 2a - 8a and 2-(2,4- difluorophenyl)pyridines 2b - 8b according to the general formula (II), along with those of the corresponding reference systems 1 a and 1 b (methylene chloride solution);

Figure 3 shows the large variety and tenability of molecular orbital (HOMO and LUMO) and bangap energies of the compounds 2a - 8a and 2b - 8b according to the general formula (II), along with those of the corresponding reference systems 1 a and 1 b.

Figure 4 shows the absorption spectra of complexes 9, 10, 12, 13 according to the general formula (I).

Figure 5 shows a scheme of a photovoltaic cell containg a compound as photosensitizer according to the invention.

Figure 6 shows the current density - voltage characteristics with irradiation with a solar simulator under standard reporting conditions (AM 1.5G, 1000 W/m², 25 °C) of a DSC cell containing compound [Ru(dcbpy)₂(7b)]PF₆ according to formula (I) of the invention as a photosensitizer, wherein dcbpy=2,2'-bipyridine-4,4'-dicarboxylic acid. A detailed description of the invention is provided with reference to certain compounds belonging to the general formula (II) with examples which are not limiting the present invention. Preparation of synthetic of precursors of the compounds 2a - 8a and 2b - 8b according to the general formula (II) (number of precursors are as in Scheme 2). 2-Bromo-4-(3-n-hexylthien-2-yl)pyridine (3c): A mixture of 2-bromo-4-iodopyridine (500 mg, 1 .76 mmol), 3-hexylthiophene-2-boronic acid pinacol ester (518 mg, 1.76 mmol) (Sigma Aldrich), Na₂CO₃ (299 mg, 2.82 mmol), Pd(PPh₃)₄ (102 mg, 0.088 mmol) in THF (38 mL) and H₂0 (23 mL) was refluxed for 9 h. After cooling down to room temperature the mixture was extracted with CH₂CI₂ (3 χ 100 mL). The organic layer were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (petroleum ether/CH₂Cl₂, 1 :1 ) affording the pure product as a yellow viscous oil (518 mg, 1 .6 mmol, 91 %). ¹ H NMR (500 MHz, CDCI₃): 6 - 8.38 (d, J - 5.1 Hz, 1 H), 7.60 (broad s, 1 H), 7.38-7.14 (m, 2 H), 7.02 (d, J - 4.3 Hz, 1 H), 2.70 (t, J - 8.2 Hz, 2 H), 1 .62 (m, 2 H), 1 .28 (m, 6 H), 0.88 (m, 3 H). HRMS- ESI: m/z calcd. for Ci₅H₁₉ ⁷⁹BrNS [M + H]⁺ 324.0416, found 324.0420; calcd. for Ci₅Hi₉ ⁸¹ BrNS [M + H]⁺ 326.0396, found 326.0399..

2-Bromo-4-[5-(5-n-hexylthien-2-yl)thien-2-yl]pyridine (4c): A mixture of 2-bromo-4- iodopyridine (670 mg, 2.36 mmol), 5'-hexyl-2,2'-bithiophene-5-boronic acid pinacol ester (888 mg, 2.36 mmol) (Sigma Aldrich), Na₂C0₃ (375 mg, 3.53 mmol), and Pd(PPh₃)₄ (272 mg, 0.23 mmol) in THF (50 mL) and H₂0 (30 mL) was stirred at reflux for 9 h. After cooling down to room temperature, the mixture was extracted with CH₂CI₂ (3 x 50 mL). The combined and dried organic layers left, after evaporation of the solvent under vacuum, a residue which was purified by flash chromatography (hexane/CH₂Cl2, 1 :1 ). The pure product 3c was obtained as a red solid (900 mg, 2.22 mmol, 94%). M.p. 69 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.31 (d, J - 5.2 Hz, 1 H), 7.63 (s, 1 H), 7.40 (d, J = 3.8 Hz, 1 H), 7.37 (d, J = 5.2 Hz, 1 H), 7.10 (d, J = 3.8 Hz, 1 H), 7.07 (d, J = 3.5 Hz, 1 H), 6.72 (d, J- 3.4 Hz, 1 H), 2.81 (t, J = 7.5 Hz, 2 H), 1 .69 (quintet, J = 7.3 Hz, 2 H), 1.45 - 1 .30 (m, 6 H), 0.89 (t, J = 7.5 Hz, 3 H). HRMS-ESI: m/z calcd. for Ci₉H₂i⁷⁹BrNS₂ [M + H]⁺ 406.0299, found 406.0293; calcd. for Ci₉H₂i⁸¹ BrNS₂ [M + H]⁺ 408.0278, found 408.0275.

2-Bromo-4-(3,4-ethylenedioxy-5-n-octylthien-2-yl)pyridine (6c):

A) 3,4-Ethylenedioxy-5-n-octylthiophene. A solution of 3,4-ethylenedioxythiophene (2.0 g, 14.1 mmol) in anhydrous THF (15 mL) was cooled at -78 °C and n-butyllithium (2.5 M in n-hexane, 4.5 mL, 1 1.3 mmol) was added dropwise under a nitrogen atmosphere. The mixture was stirred 20 min at 0 °C and cooled at -78 °C. n- Bromooctane (2.4 mL, 14 mmol) was then added dropwise. The mixture was stirred for 15 h at room temperature and finally quenched with H₂0 (100 mL). The mixture was extracted with Et₂0 (3 x 200 mL). The combined organic layers were treated with aqueous NaHC0₃ and, after removed the solvent, left a residue which was submitted to flash chromatography (petroleum ether/ethyl acetate, 95:5) affording the pure product as a yellow viscous oil (1 .5 g, 5.9 mmol, 42%). ¹ H NMR (500 MHz, CDCI3): δ = 6.1 1 (s, 1 H), 4.17 (m, 4 H), 2.62 (t, J - 7.6 Hz, 2 H), 1 .59 (quintet, J = 7.8 Hz, 2 H), 1 .36 - 1 .26 (m, 10 H), 0.88 (t, J = 7.0 Hz, 3 H).

B) 5'-Octyl-3,4-ethylenedioxy-thiophene-5-boronic acid pinacol ester. A solution of 3,4-ethylenedioxy-5-/7-octylthiophene (430 mg, 1 .7 mmol) in anhydrous THF (15 mL) was cooled at -78 and n-butyllithium (1 .6 M in n-hexane, 2.1 mL, 3.4 mmol) was added dropwise under a nitrogen atmosphere. The mixture was stirred 20 min at 0 °C and cooled at -78 °C. 2-lsopropoxy-4,4,5,5,-tetramethyl-1 ,3,2-dioxaborolane (1 .4 mL, 6.8 mmol) was then added dropwise. After stirring for 17 h at room temperature, the reaction mixture was quenched by aqueous NH₄CI (50 mL) and extracted with Et₂0 (3 x 100 mL). The dried combined layers were evaporated to dryness under reduced pressure affording the pure product as an oil (482 mg, 1 .3 mmol, 75%). ¹ H NMR (500 MHz, CDCI3): δ = 4.27 (m, 2 H), 4.16 (m, 2 H), 2.64 (t, J = 7.7 Hz, 2 H), 1 .60 (quintet, J - 7.2 Hz, 2 H), 1 .36 - 1 .20 (m, 22 H), 0.88 (t, J - 7.0 Hz, 3 H).

C) 2-Bromo-4-(3,4-ethylenedioxy-5-n-octylthien-2-yl)pyridine. A mixture of 2-bromo-4- iodopyridine (361 mg, 1 .27 mmol), 5'-octyl-3,4-ethylenedioxy-thiophene-5-boronic acid pinacol ester (482 mg, 1 .27 mmol), Na₂C0₃ (202 mg, 1 .91 mmol), and Pd(PPh₃)₄ (73 mg, 0.063 mmol) in THF (25 mL) and H₂0 (15 mL) was stirred at reflux for 20 h. After cooling down to room temperature, the mixture was extracted with CH₂CI₂ (3 x 50 mL). The combined and dried organic layers left, after evaporation of the solvent under vacuum, a residue which was purified by flash chromatography (CH₂CI₂). The pure product 6c was obtained as a red oil (300 mg, 0.73 mmol, 58%). ¹ H NMR (500 MHz, CDCI3): δ = 8.21 (d, J - 5.4 Hz, 1 H), 7.76 (d, J = 1 .4 Hz, 1 H), 7.43 (dd, J - 5.3, 1 .5 Hz, 1 H), 4.35 (m, 2 H), 4.24 (m, 2 H), 2.66 (t, J = 7.5 Hz, 2 H), 1 .61 (quintet, J = 7.3 Hz, 2 H), 1 .34 - 1 .27 (m, 10 H), 0.88 (t, J - 7.1 Hz, 3 H). MS-ESI : m/z calcd. for Ci₉H₂5⁷⁹BrN0₂S [M + H]⁺ 410, found 410; calcd. for Ci₉H₂5⁸¹ BrN0₂S [M + H]⁺ 412.0769, found 412.0890.

2-Bromo-4-(5-formylthien-2-yl)pyridine (7c): A mixture of 2-bromo-4-iodopyridine (213 mg, 0.75 mmol), 5-formyl-2-thienyl-boronic acid (1 17 mg, 0.75 mmol) (Sigma- Aldrich), Na₂C0₃ (1 19 mg, 1 .12 mmol), Pd(PPh₃)₄ (26 mg, 0.02 mmol) in THF (16 mL) and H₂0 (9 mL) was refluxed for 20 h. After cooling down to room temperature the mixture was extracted with CH₂CI₂ (3 x 50 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (ethyl acetate/CH₂CI₂, 1 :9) affording the pure product (120 mg, 0.45 mmol, 60%) as a yellow solid. M.p. 164 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 9.95 (s, 1 H), 8.43 (d, J = 5.4 Hz, 1 H), 7.80 (d, J = 4.0 Hz, 1 H), 7.74 (s, J = 1 .2 Hz, 1 H), 7.58 (d, J - 4.0 Hz, 1 H), 7.49 (dd, J - 5.2, 1 .6 Hz, 1 H). HRMS-ESI: m/z calcd. for Ci₀H₇ ⁷⁹BrNOS [M + H]⁺ 267.9432, found 267.9452; calcd. for Ci₀H₇ ⁸¹ BrNOS [M + H]⁺ 269.941 1 , found 269.9430

Preparation of the compounds 2a - 8a and 2b - 8b according to the general formula (II).

EXAMPLE 1

2-Phenyl-4-(5-n-hexylthien-2-yl)pyridine (2a): A mixture of 2c (J. -J. Kim, H. Choi, C. Kim, M.-S. Kang, H. S. Kang, J. Ko, Chem. Mater. 2009, 21, 5719-5726) (230 mg, 0.71 mmol), phenylboronic acid (88 mg, 0.71 mmol), Na₂C0₃ (1 13 mg, 1 .1 mmol), Pd(PPh₃)₄ (50 mg, 0.04 mmol) in THF (15 mL) and H₂0 (10 mL) was stirred in a microwave reactor at 70 "C (max. 150 W) for 20 min. After cooling down to room temperature the mixture was extracted with CH₂CI₂ (3 x 100 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (cyclohexane/CH₂CI₂, 2:8) affording the pure product as a yellow viscous oil (170 mg, 0.53 mmol, 74%). ¹ H NMR (500 MHz, CDCI₃): δ = 8.63 (d, J = 5.2 Hz, 1 H), 8.01 (d, J = 7.1 Hz, 2 H), 7.84 (d, J = 1.6 Hz, 1 H), 7.51 (t, J = 7.2 Hz, 2 H), 7.44 (t, J = 7.1 Hz, 1 H), 7.39 (d, J = 3.6 Hz, 1 H), 7.38 (dd, J = 5.2, 1 .6 Hz, 1 H), 6.82 (d, J = 3.6 Hz, 1 H), 2.85 (t, J = 7.5 Hz, 2 H), 1 .71 (quintet, J = 7.3 Hz, 2 H), 1.45 - 1 .30 (m, 6 H), 0.92 (t, J = 7.5 Hz, 3 H). ¹³C NMR (126 MHz, CDCI₃): δ = 158.1 1 (1 C), 150.02 (1 CH), 148.55 (1 C), 142.60 (1 C), 139.36 (1 C), 138.60 (1 C), 129.03 (1 CH), 128.71 (2 CH), 126.98 (2 CH), 125.53 (1 CH), 125.20 (1 CH), 1 17.98 (1 CH), 1 16.51 (1 CH), 31 .52 (1 C), 31 .50 (1 CH₂), 30.35 (1 CH₂), 28.71 (1 CH₂), 22.52 (1 CH₂), 14.02 (1 CH₃). HRMS-ESI: m/z calcd. for C₂i H₂₄NS [M + H]⁺ 322.16240, found 322.16219; calcd. for C₂i H₂₃NNaS [M + Na]⁺ 344.14434, found 344.14421. EXAMPLE 2

2-Phenyl-4-(3-n-hexylthien-2-yl)pyridine (3a): A mixture of 3c (45 mg, 0.14 mmol), phenylboronic acid (17 mg, 0.14 mmol), Na₂C0₃ (22 mg, 0.21 mmol), Pd(PPh₃)₄ (10 mg, 0.008 mmol) in THF (3 mL) and H₂0 (2 mL) was stirred under microwave irradiation at 70 °C (max. 150 W) for 20 min. After cooling down to room temperature H₂0 was added and the mixture was extracted with CH₂CI₂ (3 x 25 mL). Solvent was removed from the combined and dried extracts to leave a residue which was purified by flash chromatography (cyclohexane/CH₂CI₂, 2:8) affording the pure product as a yellow viscous oil (20 mg, 0.062 mmol, 44%). ¹ H NMR (500 MHz, CDCI₃): δ = 8.71 (d, J = 5.0 Hz, 1 H), 8.02 (d, J = 7.4 Hz, 2 H), 7.79 (d, J = 1.6 Hz, 1 H), 7.50 (t, J = 7.3 Hz, 2 H), 7.44 (t, J = 7.1 Hz, 1 H), 7.34 (d, J = 5.2 Hz, 1 H), 7.31 (dd, J = 5.2, 1 .3 Hz, 1 H), 7.04 (d, J = 5.1 Hz, 1 H), 2.76 (t, J = 7.8 Hz, 2 H), 1 .69-1.63 (m, 2 H), 1.37 - 1 .25 (m, 6 H), 0.86 (t, J - 6.7 Hz, 3 H). ¹³C NMR (126 MHz, CDCI₃): 6 = 157.84 (1 C,), 149.85 (1 CH), 143.39 (1 C), 140.79 (1 C), 139.30 (1 C), 134.92 (1 C), 130.21 (1 CH), 129.10 (CH), 128.79 (2 CH), 127.05 (2 CH), 125.41 (1 CH), 121.95 (1 CH), 120.51 (1 CH), 31 .63 (1 CH₂), 30.95 (1 CH₂), 29.20 (1 CH₂), 28.98 (1 CH₂), 22.59 (1 CH₂), 14.05 (1 CH₃). HRMS-ESI: m/z calcd. for C₂i H₂₄NS [M + H]⁺ 322.16240, found 322.16278; calcd. for C₂i H₂₃NNaS [M + Na]⁺ 344.14434, found 344.14500.

EXAMPLE 3 2-Phenyl-4-[5-(5-n-hexylthien-2-yl)thien-2-yl]pyridine (4a): A mixture of 4c (57 mg, 0.14 mmol), phenylboronic acid (17 mg, 0.14 mmol), Na₂C0₃ (22 mg, 0.21 mmol), Pd(PPh₃)₄ (10 mg, 0.008 mmol) in THF (3 imL) and H₂0 (2 imL) was stirred in a microwave reactor at 70 "C (max. 150 W) for 20 min. After cooling down to room temperature H₂0 was added and the mixture was extracted with CH₂CI₂ (3 x 25 ml_). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (cyclohexane/CH₂CI₂, 3:7) affording the pure product as a yellow viscous oil (25 mg, 0.062 mmol, 44%). M.p. 52 °C. ¹ H NMR (500 MHz, CDCI₃): δ - 8.66 (d, J = 5.2 Hz, 1 H), 8.03 (d, J = 7.1 Hz, 2 H), 7.86 (d, J = 1.7 Hz, 1 H), 7.50 (t, J - 7.3 Hz, 2 H), 7.46 (d, J - 3.7 Hz, 1 H), 7.44 (t, J - 7.1 Hz, 1 H), 7.39 (dd, J = 5.2, 1 .7 Hz, 1 H), 7.13 (d, J - 3.8 Hz, 1 H), 7.07 (d, J = 3.6 Hz, 1 H), 6.72 (d, J = 3.6 Hz, 1 H), 2.81 (t, J = 7.5 Hz, 2 H), 1 .70 (quintet, J = 7.3 Hz, 2 H), 1 .45 - 1 .30 (m, 6H), 0.93 (t, J= 7.3 Hz, 3H). ¹³C NMR (126 MHz, CDCI₃) δ 158.29 (1 C), 150.19 (1 CH), 146.47 (1 C), 141 .95 (1 C), 139.80 (1 C), 139.32 (1 C), 139.10 (1 C), 134.1 1 (1 C), 129.08 (1 CH), 128.72 (2 CH), 126.98 (2 CH), 126.02 (1 CH), 124.97 (1 CH), 124.10 (1 CH), 123.92 (1 CH), 1 17.88 (1 CH), 1 16.39 (1 CH), 31.52 (1 CH₂), 31 .50 (1 CH₂), 30.18 (1 CH₂), 28.72 (1 CH₂), 22.53 (1 CH₂), 14.01 (1 CH₃); HRMS-ESI: m/z calcd. for C₂₅H₂₆NS₂ [M + H]⁺ 404.15012, found 404.14979; calcd. for C₂₅H₂₅NNaS₂ [M + Na]⁺ 426.13206, found 426.13203.

EXAMPLE 4

2-Phenyl-4-(5-hexylthieno[3,2-d]thien-2-yl)pyridine (5a): A mixture of 5c (J. -J. Kim, H. Choi, C. Kim, M.-S. Kang, H. S. Kang, J. Ko, Chem. Mater. 2009, 21, 5719-5726) (45 mg, 0.12 mmol), phenylboronic acid (14 mg, 0.12 mmol), Na₂C0₃ (20 mg, 0.19 mmol), Pd(PPh₃)₄ (7.0 mg, 0.006 mmol) in THF (3 imL) and H₂0 (2 imL) was stirred under microwave irradiation at 70 "C (max. 150 W) for 20 min. After cooling down to room temperature H₂0 (20ml_) was added and the mixture was extracted with CH₂CI₂ (3 x 50 ml_). The extracts were combined, dried, and evaporated under reduced pressure leaving a residue which was purified by flash chromatography (hexane/ethyl acetate, 8:2) affording the pure product as a yellow solid (50 mg, 0.012 mmol, 82%). M.p. 215 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.66 (d, J = 5.2 Hz, 1 H), 8.03 (d, J = 7.3 Hz, 2 H), 7.88 (d, J = 0.5 Hz, 1 H), 7.68 (s, 1 H), 7.51 (t, J = 7.2 Hz, 2 H), 7.45 (t, J= 7.3 Hz, 1 H), 7.42 (dd, J = 5.3 1 .5 Hz, 1 H), 6.98 (s, 1 H), 2.91 (t, J = 7.6 Hz, 2 H), 1 .73 (quintet, J = 7.4 Hz, 2 H), 1 .41 (m, 2 H), 1.35 - 1 .25 (m, 4 H), 0.90 (t, J= 7.0 Hz, 3 H). ¹³C NMR (126 MHz, CDCI₃) δ = 158.03 (1 C), 150.72 (1 C), 149.85 (1 CH), 143.20 (1 C), 140.80 (1 C), 139.78 (1 C), 138.91 (1 C), 138.20 (1 C), 129.28 (1 CH), 128.82 (2 CH), 127.05 (2 CH), 1 18.01 (CH), 1 16.53 (1 CH), 31 .54 (1 CH₂), 31 .43 (1 CH₂), 31 .28 (1 CH₂), 28.74 (1 CH₂), 22.56 (1 CH₂), 14.08(1 CH₂), (1 CH₃); HRMS- ESI: m/z calcd. for C₂₃H₂₄NS₂ [M + H]⁺ 378.13502, found 378.13430; calcd. for C₂₃H₂₃NNaS₂ [M + Na]⁺ 400.1 1696, found 400.1 1650.

EXAMPLE 5

2-Phenyl-4-(3,4-ethylenedioxy-5-octylthien-2-yl)pyridine (6a): A mixture of 6c (60 mg, 0.15 mmol), phenylboronic acid (18 mg, 0.18 mmol), Na₂C0₃ (25 mg, 0.24 mmol), Pd(PPh₃)₄ (10 mg, 0.008 mmol) in THF (3 mL) and H₂0 (2 mL) was stirred in a microwave reactor at 70 °C (max. 150 W) for 20 min. After cooling down to room temperature H₂0 was added and the mixture was extracted with CH₂CI₂ (3 x 25 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (CH₂CI₂) affording the pure product as a yellow viscous oil (50 mg, 0.012 mmol, 82%). ¹ H NMR (500 MHz, CDCI₃): δ = 8.58 (d, J = 5.3 Hz, 1 H), 8.01 (d, J = 7.2, 2H), 7.98 (d, J = 1 .1 Hz, 1 H), 7.50 (dd, J = 5.1 , 1 .7 Hz, 1 H), 7.48 (t, J = 7.8 Hz, 2H), 7.42 (t, J =7.5 Hz, 1 H), 4.35 (m, 2 H), 4.26 (m, 2 H), 2.69 (t, J = 7.7 Hz, 2 H), 1 .65 (quintet, J = 7.4 Hz, 2 H), 1 .40 - 1 .28 (m, 10 H), 0.89 (t, J = 7.1 Hz, 3 H). ¹³C NMR (126 MHz, CDCI₃) δ 157.70 (1 C), 149.74 (1 CH), 141.43 (1 C), 141 .01 (1 C), 139.80 (1 C), 138.18 (1 C), 128.78 (1 CH), 128.63 (2 CH), 126.98 (2 CH), 120.14 (1 CH), 1 17.88 (1 C), 1 16.33 (1 C), 1 10.49 (1 CH), 65.09 (1 CH₂), 64.28 (1 CH₂), 31.85 (1 CH₂), 30.26 (1 CH₂), 29.28 (1 CH₂), 29.21 (1 CH₂), 29.14 (1 CH₂), 25.93 (1 CH₂), 22.65 (1 CH₂), 14.1 1 (1 CH₃); HRMS- ESI: m/z calcd. for C₂5H30NO₂S [M + H]⁺ 408.19972, found 408.19939; calcd. for C₂₅H₂₉NNa0₂S [M + Na]⁺ 430.18167, found 430.18132.

EXAMPLE 6

2-Phenyl-4-(5-formylthien-2-yl)pyridine (7a): A mixture of 7c (154 mg, 0.57 mmol), phenylboronic acid (71 mg, 0.58 mmol), Na₂C0₃ (77 mg, 0.73 mmol), Pd(PPh₃)₄ (33 mg, 0.06 mmol) in THF (15 ml_) and H₂0 (10 ml_) was stirred in a microwave reactor at 70 °C (max. 150 W) for 20 min. After cooling down to room temperature H₂0 (50ml_) was added and the mixture was extracted with CH₂CI₂ (3 x 50 ml_). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (CH₂Cl₂/ethyl acetate, 9:1 ) affording the pure product as a yellow solid (100 mg, 0.37 mmol, 65%). M.p. 121 °C. ¹ H NMR (500 MHz, CDCI3): δ = 9.96 (s, 1 H), 8.77 (d, J = 5.1 Hz, 1 H), 8.04 (d, J = 7.1 Hz, 2 H), 7.95 (d, J- 1 .1 Hz 1 H), 7.81 (d , J - 3.9 Hz, 1 H), 7.64 (d, J = 3.9Hz, 1 H), 7.51 (t, J = 3.9 Hz J = 7.6 Hz , 2 H), 7.48 - 7.46 (m, 2 H). ¹³C NMR (126 MHz, CDCI₃): δ 182.89 (s, CHO), 158.73 (1 C), 150.55 (1 CH), 144.36 (1 C), 141 .22 (1 C), 138.67 (1 C), 137.00 (1 CH), 131.89 (1 C), 129.69 (1 CH), 129.04 (2 CH), 127.16 (2 CH), 126.25 (1 , CH) , 1 18.88 (1 CH), 1 17.46 (1 CH). HRMS-ESI: m/z calcd. for Ci₆Hi₂NOS [M + H]⁺ 266.06396, found 266.06385; calcd. for Ci₆Hn NNaOS [M + Na]⁺ 288.04590, found 288.04550.

EXAMPLE 7

2-Dicyanomethylene-4-{2-[5-(2-phenylpyrid-4-yl)thien-2-yl]ethen-1-yl}-3-cyano- 5,5-trimethyl-2,5-dihydrofuran (8a): A mixture of 7a (1 10 mg, 0.41 mmol), 2-(3- cyano-4,5,5-trimethyl-5 --furan-2-ylidene)-malononitrile (S. Liu, M. A. Haller, H. Ma, L. R. Dalton, S. H. Jang, A. K. Y. Jen, Adv. Mater. 2003, 15, 603 -607) (125 mg, 0.62 mmol) and three drops of piperidine in CH₃CN (10 mL) was stirred at room temperature for 15 h. After removing the solvent at reduced pressure, the residue was dissolved in CH₂CI₂ (5 mL). The precipitate formed after adding cyclohexane (40 mL) was collected and taken up with EtOH (10 mL) to afford the product as a red solid (60 mg, 0.13 mmol, 32%). M.p. > 250 °C. ¹ H NMR (500 MHz, [D₆]DMSO): 6 = 8.75 (d, J - 5.2 Hz, 1 H), 8.30 (s, 1 H), 8.22 (d, J = 7.3 Hz, 2 H), 8.20 - 8.16 (m, 2 H), 7.95 (d, J = 4.0 Hz, 1 H), 7.74 (dd, J - 5.1 , 1 .35 Hz, 1 H), 7.54 (t, J - 7.0 Hz, 2 H), 7.50 (t, J = 7.1 Hz, 1 H), 6.96 (d, J = 16.2 Hz, 1 H), 1 .8 (s, 6 H). ¹³C NMR (126 MHz, [D₆]DMSO): 6 = 177.29 (1 C), 174.79 (1 C), 157.69 (1 C), 151 .07 (1 CH), 147.58 (1 C), 141 .77 (1 C), 140.97 (1 C), 140.09 (1 CH), 138.61 (1 C), 137.29 (1 CH), 129.94 (1 C), 129.38 (1 CH), 129.24 (1 CH), 127.31 (1 CH), 1 19.14 (1 CH), 1 16.63 (1 CH), 1 15.06 (1 CH), 1 13.16 (1 C), 1 12.38 (1 C), 1 1 1 .28 (1 C), 99.89 (1 C), 99.60 (1 C), 25.76 (2 CH₃); HRMS-ESI: m/z calcd. for C₂₇Hi₉N₄OS [M + H]⁺ 447.12796, found 447.12771 ; calcd. for C₂₆Hi₈N₄NaOS [M + Na]⁺ 469.10990, found 469.10964.

EXAMPLE 8

2-(2,4-Difluorophenyl)-4-(5-n-hexylthien-2-yl)pyridine (2b): A solution of 2c (J. -J. Kim, H. Choi, C. Kim, M.-S. Kang, H. S. Kang, J. Ko, Chem. Mater. 2009, 21, 5719- 5726) (329 mg, 1 .02 mmol), 2,4-difluorophenylboronic acid (161 mg, 1 .02 mmol), Na₂CO₃ (256 mg, 2.41 mmol), and Pd(PPh₃)₄ (35 mg, 0.03 mmol) in THF (5 mL) and H₂O (3 mL) was refluxed for 24 h. After cooling down to room temperature the mixture was extracted with CH₂CI₂ (3 x 30 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (hexane/AcOEt, 9:1 ) affording the pure product as a yellow viscous oil (200 mg, 0.56 mmol, 66%). ¹ H NMR (500 MHz, CDCI₃): δ = 8.63 (d, J = 5.2 Hz, 1 H), 8.00 (td, J = 8.8, 6.7 Hz, 1 H), 7.87 (s broad, 1 H), 7.40 - 7.35 (m, 2 H), 7.01 (ddd, J = 9.0, 8.7, 2.5 Hz, 1 H), 6.93 (ddd, J = 1 1.3, 8.8, 2.5 Hz, 1 H), 6.81 (d, J = 2.8 Hz, 1 H), 2.84 (t, J = 7.6 Hz, 2 H), 1 .70 (quintet, J - 7.7 Hz, 2 H), 1 .45 - 1 .35 (m, 2 H), 1.35 - 1 .30 (m, 4 H), 0.90 (t, J - 6.9 Hz, 3 H). ¹³C NMR (126 MHz, CDCI₃) δ 163.22 (dd, J_CF = 251 .1 , 12.1 Hz, 1 CF), 160.57 (dd, J_CF = 251.1 , 1 1 .9 Hz, 1 CF), 153.09 (d, J_CF = 2.2 Hz, 1 C), 150.1 1 (1 CH), 148.74 (1 C), 142.34 (1 C), 138.28 (1 C), 132.15 (d, CH, J_CF = 9.6 Hz), 125.56 (1 CH), 125.39 (1 CH), 123.78 (dd, J_C = 1 1.7, 3.6 Hz, 1 C), 1 19.95 (d, JCF = 9.1 Hz, 1 CH), 1 18.23 (1 CH), 1 1 1.84 (dd, J_CF = 20.9, 3.5 Hz, 1 CH), 104.36 (t, JCF = 26.4 Hz, 1 CH), 31 .52 (1 CH₂), 31.50 (1 CH₂), 30.34 (1 CH₂), 28.73 (1 CH₂), 22.54 (1 CH₂), 14.04 (1 CH₃); HRMS-ESI: m/z calcd. for C₂i H₂₂F₂NS [M + H]⁺ 358.14410, found 358.14322; calcd. for C₂i H₂i F₂NNaS [M + Na]⁺ 380.12605, found 380.12548.

EXAMPLE 9

2-(2,4-Difluorophenyl)-4-(3-n-hexylthien-2-yl)pyridine (3b): A solution of 3c (500 mg, 1 .54mmol), 2,4-difluorophenylboronic acid (244 mg, 1 .54 mmol), Na₂C0₃ (245 mg, 2.31 mmol), Pd(PPh₃)₄ (53 mg, 0.05 mmol) in THF (32 mL) and H₂0 (19 mL) was refluxed for 9h. After cooling down to room temperature the mixture was extracted with CH₂CI₂ (3 x 100 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (petroleum ether/CH₂CI₂, 1 :1 ) affording the pure product as a yellow viscous oil (430 mg, 1 .2 mmol, 78%). ¹ H NMR (500 MHz, CDCI₃): δ = 8.71 (d, J=5.1 Hz, 1 H), 8.04 (td, J= 6.7, 8.9 Hz, 1 H), 7.83 (m, 1 H), 7.34 (d , J = 5.3 Hz, 1 H), 7.32 (dd, J= 5.1 Hz, J - 1 ,7 Hz, 1 H), 7.03-6.99 (m, 2 H), 6.93 (ddd, J= 8.8 Hz, J= 2.5, 1 H), 2.75 (t, J - 7.8 Hz, 2 H), 1 .65 (q, J - 7.3 Hz, 2 H), 1 . 34 (m, 2 H), 1 .37 - 1.26 (m, 4 H), 0.86 (t, J - 7.0 Hz, 3 H). ¹³C NMR (125 MHz, CDCI₃): δ 163.33 (dd, J_CF = 249.6, 1 1.9 Hz, 1 CF), 160.68 (dd, JCF= 251.0, 1 1.5 Hz, 1 CF), 152.77 (1 C), 149.89 (1 CH), 143.17 (1 C), 141.05 (1 C), 134.61 (1 C), 132.20 (dd, J_CF= 4.4, 9.6 Hz), 130.30 (1 CH), 125.52 (1 CH), 123.90 (d, J_CF = 9.4 Hz, 1 C), 123.69 (d, J_CF = 1 1 .2 Hz, 1 CH), 122.21 (1 CH), 1 1 1 .91 (dd, J_CF = 21.0, 3.5 Hz, 1 CH), 104.40 (t, J_CF = 27.5 Hz, 1 CH), 31 .58 (1 CH₂), 30.87 (1 CH₂), 29.10 (1 CH₂), 28.93 (1 CH₂), 22.53 (1 CH₂), 13.99 (1 CH₃). HRMS-ESI: m/z calcd. for C₂i H₂₂F₂NS [M + H]⁺ 358.14410, found 358.14323; calcd. for C₂i H₂₁ F₂NNaS [M + Na]⁺ 380.12605, found 380.12539. EXAMPLE 10

2-(2,4-Difluorophenyl)-4-[5-(5-n-hexylthien-2-yl)thien-2-yl]pyridine (4b): A solution of 4c (300 mg, 0.74 mmol), 2,4-difluorophenylboronic acid (140 mg, 0.89 mmol), Na₂C0₃ (1 18 mg, 1 .1 mmol), and Pd(PPh₃)₄ (26 mg, 0.022 mmol) in THF (5 mL) and H₂0 (3 mL) was stirred at reflux for 1 6 h. After cooling down to room temperature the reaction mixture was extracted with AcOEt (3 x 100 mL). The organic layers were combined, dried, and the solvent evaporated to dryness. The pure product 4b was obtained by silica gel chromatography (petroleum ether/AcOEt, 8:2) as a yellow solid (270 mg, 0.55 mmol, 75%). M.p. 54 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.65 (d, J = 5.4 Hz, 1 H), 8.02 (td, J = 8.8, 6.7 Hz, 1 H), 7.88 (broad s, 1 H), 7.42 (d, J - 3.8 Hz, 1 H), 7.38 (dd, J = 5.2, 1 .7 Hz, 1 H), 7.10 (d, J = 3.8 Hz, 1 H), 7.07 (d, J 3.5 Hz, 1 H), 7.01 (ddd, J = 9.6, 8.6, 2.5 Hz, 1 H), 6.94 (ddd, J = 1 1 .2, 8.8, 2.5 Hz, 1 H), 6.70 (d, J = 3.6 Hz, 1 H), 2.80 (t, J = 7.5 Hz, 2 H), 1 .69 (quintet, J = 7.6 Hz, 2 H), 1 .43 - 1 .37 (m, 2H), 1 .37 - 1 .28 (m, 4 H), 0.90 (t, J - 6.9 Hz, 3 H). ¹³C NMR (126 Hz, CDCI₃) δ 163.30 (dd, J_CF = 251 .1 , 1 2.0 Hz, 1 CF), 160.62 (dd, J_CF = 251 .1 , 1 1 .7, 1 CF), 153.21 (d, JCF = 2.4 Hz, 1 C), 150.19 (1 CH), 146.53 (1 C), 141 .78 (1 C), 140.04 (1 C), 1 38.71 (1 C), 134.05 (1 C), 132.17 (dd, J_CF = 9.6, 4.3 Hz, 1 CH), 126.25 (1 CH), 124.98 (CH), 1 24.16 (1 CH), 1 23.93 (1 CH), 1 23.66 (dd, J_CF = 1 1 .6, 3.6 Hz, 1 C), 1 1 9.87 (d, JCF = 9.2 Hz, 1 CH), 1 18.15 (1 CH), 1 1 1 .86 (dd, J_CF = 20.9, 3.5 Hz, 1 CH), 104.38 (t, J_CF = 26.0 Hz, 1 CH), 31 .53 (1 CH₂), 31 .50 (1 CH₂), 30.1 8 (1 CH₂), 28.73 (1 CH₂), 22.54 (1 CH₂), 14.02 (1 CH₃); HRMS-ESI : m/z calcd. for C₂₅H₂₄F₂NS₂ [M + H]⁺ 440.13182, found 440.13086; calcd. for C₂₅H₂₃F₂NNaS₂ [M + Na]⁺ 462.1 1 377, found 462.1 1 294. EXAMPLE 1 1

2-(2,4-Difluorophenyl)-4-(5-hexylthieno[3,2-d]thien-2-yl)pyridine (5b): A solution of 5c (J. -J. Kim, H. Choi, C. Kim, M.-S. Kang, H. S. Kang, J. Ko, Chem. Mater. 2009, 21, 5719-5726 (45 mg, 0.12 mmol), 2,4-difluorophenylboronic acid (19 mg, 0.12 mmol), Na₂CO₃ (20 mg, 0.19 mmol), and Pd(PPh₃)₄ (7 mg, 0.006 mmol) in THF (3 mL) and H₂0 (2 mL) was stirred in a microwave reactor at 70 °C (max. 150 W) for 20 min. After cooling down to room temperature, THF was evaporated under reduced pressure and H₂0 (20mL) was added. The mixture was extracted with CH₂CI₂ (3 x 50 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (hexane/ethyl acetate, 8:2) affording the pure product as a yellow solid (52 mg, 0.12 mmol, 99%). M.p. 71 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.66 (d, J - 5.2 Hz, 1 H), 8.03 (td, J = 6.7, 8.9 Hz, 1 H), 7.92 (m, 1 H), 7.65 (s, 1 H), 7.41 (dd, J = 5.1 Hz, J - 1 ,7 Hz, 1 H), 7.02 (ddd, J = 10.3, 8.0, 1 .9 Hz, 1 H), 6.97 (s, 1 H), 6.94 (ddd, J - 1 1 .3, 8.8, 2.5 Hz, 1 H), 2.89 (t, J - 7.5 Hz, 2 H), 1 .73 (quintet, J = 7.3 Hz, 2 H), 1 . 39 (m, 2 H), 1 .32 (m, 4 H), 0.90 (t, J = 7.0 Hz, 3 H). ¹³C NMR (125 MHz, CDCI₃): δ 163.28 (dd, J_CF = 249.6, 12.0 Hz, 1 CF), 160.59 (dd, JCF = 251 .0, 1 1 .9 Hz, 1 CF), 153.17 (d, J = 2.1 Hz, 1 C), 150.66 (1 C), 150.20 (1 CH), 142.72 (1 C), 140.64 (1 C), 139.78 (1 C), 138.18 (1 C), 132.17 (dd, JCF= 4.4, 9.6 Hz, 1 CH), 123.62 (dd, J_CF = 1 1 .5, 3.9 Hx, 1 C), 1 19.95 (d, J_CF= 9.4 Hz, 1 C), 1 18.27 (1 CH), 1 18.01 (1 CH), 1 16.48 (1 CH), 1 1 1.92 (dd, J_CF = 20.9, 3.3 Hz, 1 CH), 104.42 (t, JCF = 26.1 Hz, 1 CH), 31 .54 (1 CH₂), 31 .43 (1 CH₂), 31 .26 (1 CH₂), 28.73 (1 CH₂), 22.56 (1 CH₂), 14.07 (1 CH₃). HRMS-ESI: m/z calcd. for C₂₃H₂₂F₂NS₂ [M + H]⁺ 414.1 1617, found 414.1 1570; calcd. for C₂₃H₂₁ F₂NNaS₂ [M + Na]⁺ 436.09812, found 436.09460.

EXAMPLE 12

2-(2,4-Difluorophenyl)-4-(3,4-ethylenedioxy-5-octylthien-2-yl)pyridine (6b): A solution of 6c (82 mg, 0.20 mmol), 2,4-difluorophenylboronic acid (32 mg, 0.20 mmol), Na₂C0₃ (34 mg, 0.32 mmol), and Pd(PPh₃)₄ (1 1 mg, 0.010 mmol) in THF (3 mL) and H₂0 (2 mL) was stirred under microwave irradiation at 70 "C (max. 150 W) for 20 min. After cooling down to room temperature, THF was evaporated under reduced pressure and H₂0 (20 mL) was added. The mixture was extracted with CH₂CI₂ (3 x 50 mL). After evaporating the solvent under reduced pressure from the combined and dried ectracts, the residue was submitted to flash chromatography (CH₂CI₂/ hexane, 8:2) affording the pure product as a white solid (80 mg, 0.18 mmol, 90%). M.p. 49 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.58 (d, J - 5.1 Hz, 1 H), 7.97 (s, 1 H), 7.96 (td, J= 6.7, 8.8 Hz, 1 H), 7.51 (dd, J= 5.1 Hz, J - 1 ,7 Hz, 1 H), 6.99 (ddd, J = 1 1.0, 8.5, 2.0 Hz, 1 H), 6.92 (ddd, J = 1 1 .3, 8.8, 2.5 Hz, 1 H), 4.34 (m, 2 H), 4.25 (m, 2 H), 2.67 (t, J - 7.5 Hz, 2 H), 1 .63 (quintet, J - 7.3 Hz, 2 H), 1. 39 - 1.27 (m, 10 H), 0.88 (t, J - 7.0 Hz, 3 H). ¹³C NMR (125 MHz, CDCI₃): δ 163.06 (dd, J_CF = 249.0, 1 1.7 Hz, 1 CF), 160.52 (dd, J_CF = 251 .0, 1 1 .9 Hz, 1 CF), 152.72 (d, J = 2.1 Hz, 1 C), 149.77 (1 CH), 141 .25 (1 C), 141 .16 (1 C), 138.18 (1 C), 132.12 (dd, J_CF = 4.5, 9.6 Hz, 1 CH), 124.28 (dd, J_CF = 1 1 .5, 4.0 Hx, 1 C), 120.43 (1 , CH), 1 19.79 (d, J_CF= 8.5 Hz, 1 C), 1 18.12 (1 CH), 1 1 1 .70 (dd, J_CF = 20.9, 3.6 Hz, 1 CH), 104.30 (t, J_CF = 26.0 Hz, 1 CH), 65.07 (1 CH₂), 64.26 (1 CH₂), 31.84 (1 CH₂), 30.24 (1 CH₂), 29.27 (1 CH₂), 29.20 (1 CH₂), 29.12 (1 CH₂), 22.64 (1 CH₂), 14.08 (1 CH₃). HRMS-ESI: m/z calcd. for C₂₅H₂₈F₂N0₂S [M + H]⁺ 444.18088, found 444.17995; calcd. for C₂₅H₂₇F₂NNa0₂S [M + Na]⁺ 466.16283, found 466.16243.

EXAMPLE 13

2-(2,4-Difluorophenyl)-4-(5-formylthien-2-yl)pyridine (7b): A solution of 7c (120 mg, 0.45 mmol), 2,4-difluorophenylboronic acid (71 mg, 0.44 mmol), Na₂C0₃ (70 mg, 0.66 mmol), Pd(PPh₃)₄ (16 mg, 0.013 mmol) in THF (9 mL) and H₂0 (6 mL) was refluxed for 9 h. After cooling down to room temperature, H₂0 was added and the mixture was extracted with CH₂CI₂ (2 x 25 mL). The organic layers were combined, dried, and evaporated to dryness leaving a residue which was purified by flash chromatography (ethyl acetate/CH₂CI₂, 1 :9) affording the product (1 15 mg, 0.38 mmol, 87%) as a yellow solid. M.p. 140 °C. ¹ H NMR (500 MHz, CDCI₃): 6 - 10.0 (s, 1 H), 8.75 (d, J = 5.1 Hz, 1 H), 8.05 (td, J= 6.6, 8.8 Hz, 1 H), 7.99 (m, 1 H), 7.79 (d, J = 3.9 Hz, 1 H), 7.61 (d , 1 H, J = 3.9Hz), 7.48 (dd, J = 5.1 , 1.7 Hz, 1 H), 7.03 (ddd, J = 9.5, 8.0, 2.0 Hz 1 H), 6.95 (ddd, J- 1 1 .2 8.8, 2.5, 1 H). ¹³C NMR (126 MHz, CDCI₃): δ 182.69 (CHO), 163.49 (d, J_CF= 250.5, 12.0 Hz, 1 CF), 160.68 (d, J_CF= 251 .4, 12.0 Hz, 1 CF), 153.65 (d, J_CF = 2.1 Hz, 1 C), 150.61 (1 CH) 150.20 (1 C), 144.32 (1 C), 140.72 (1 C), 136.77 (1 CH), 132.20 (dd, J_CF = 4.3, 9.7 Hz, 1 CH), 125.92 (1 CH), 123.12 (d, JCF = 1 1 .4, 3.9 Hz, 1 C), 120.76 (d, J_CF = 9.8 Hz, 1 CH), 1 19.02 (1 CH), 1 12.06 (dd, JCF = 21 .0, 3.4 Hz, 1 CH), 104.49 (t, J_CF = 26.3 Hz, 1 CH). HRMS-ESI: m/z calcd. for Ci₆Hi₀F₂NOS [M + H]⁺ 302.04457, found 302.04436; calcd. for Ci₆H₉F₂NNaOS [M + Na]⁺ 324.02651 , found 324.02646.

EXAMPLE 14

2-Dicyanomethylene-4-(2-{5-[2-(2,4-difluorophenyl)pyrid-4-yl]thien-2-yl}ethen-1- yl)-3-cyano-5,5-trimethyl-2,5-dihydrofuran (8b): A mixture of 7b (280 mg, 0.93 mmol), 2-(3-cyano-4,5,5-trimethyl-5 - -furan-2-ylidene)-malononitrile (S. Liu, M. A. Haller, H. Ma, L. R. Dalton, S. H. Jang, A. K. Y. Jen, Adv. Mater. 2003, 15, 603 -607) (281 mg, 1 .39 mmol) and three drops of piperidine in EtOH (20 mL) was stirred at room temperature for 15 h. After removing the solvent at reduced pressure, the residue was dissolved in CH₂CI₂ (5 mL). The precipitate formed after adding cyclohexane (40 mL) was collected and taken up with EtOH (10 mL) to afford the product as a red solid (220 mg, 0.46 mmol, 49%). M.p. > 250 °C. ¹ H NMR (500 MHz, CDCI₃): δ = 8.78 (d, J = 5.1 Hz, 1 H), 8.07 (td, J = 8.9, 6.7 Hz, 1 H), 7.99 (m, 1 H), 7.83 (d, J = 16.0 Hz, 1 H), 7.62 (d , J = 4.0 Hz, 1 H), 7.52 (d , J = 4.0 Hz, 1 H), 7.47 (dd, J= 5.2, 1 .7 Hz, 1 H), 7.05 (ddd, J= 9.2, 7.9, 1 .8 Hz, 1 H), 6.97 (ddd, J= 1 1 .2, 8.7, 2.5 Hz, 1 H), 6.78 (d, J = 16.0 Hz, 1 H), 1 .79 (s, 6 H). ¹ H NMR (500 MHz, [D₆]DMSO, T = 100 °C): δ = 8.78 (d, J = 5.1 Hz, 1 H), 8.15 - 8.00 (m, 3 H), 7.94 (d, J - 4.0 Hz, 1 H), 7.88 (d, J = 4 Hz, 1 H), 7.73 (dd, J= 5.2, 1.7 Hz, 1 H), 7.30 (ddd, J = 8.2, 6.3, 1.8 Hz, 1 H), 7.22 (ddd, J= 8.7 , 6.2, 2.5 Hz, 1 H), 6.98 (d, J = 16.0 Hz, 1 H), 1 .83 (s, 6 H). ¹³C NMR (125 MHz, [D₆]DMSO, T=100 °C): δ 176.89 (1 CN), 174.94 (2 CN), 163.34 (dd, J_CF = 250.5, 12.0 Hz, 1 CF), 160.69 (J_CF = 251 .4, 12.0 Hz, 1 CF), 153.74 (1 C), 151.15 (d, JCF = 2.1 Hz, 1 C), 147.13 (1 C), 141 .94 (1 C), 140.91 (1 C), 139.58 (1 CH), 136.36 (1 CH), 132.83 (dd, J_CF= 4.3, 9.7 Hz, 1 CH), 129.02 (CH), 120.29 (dd, JCF = 1 1 .4, 3.9 Hz, 1 C), 1 19.43 (1 CH), 1 15.44 (1 CH), 1 12.72 (1 C), 1 12.40 (dd, J_CF = 21 .0, 3.4 Hz, CH), 1 1 1 .98 (1 C), 1 1 1 .04 (1 C), 104.93 (t, J_CF= 26.3 Hz, 1 CH), 99.72 (1 C), 99.42 (1 C), 25.82 (1 CH₃). HRMS-ESI : m/z calcd. for C₂₇Hi₇F₂N₄OS [M + H]⁺ 483.1091 1 , found 483.10982; calcd. for C₂₇Hi₆F₂N₄NaOS [M + Na]⁺ 505.09106, found 505.09004. We describe now other non limitative examples related to compounds of general formula (I).

EXAMPLE 15

[Ru(dcbpy)(2a)]⁺PF₆-

9

Procedure for the synthesis of the precursors of compound 9.

[C₆H₆RuCl₂]₂- This dimer has been prepared by addition of 1 ,3-cyclohexadiene (6 ml) to a solution of RuCI₃.3H₂0 (1 .70 g, 6.5 mmol) in aqueous ethanol (ethanol/water = 90/10 v/v; 100 mL). The resulting solution was heated at 45 ^<€ for 3h and cooled to room temperature. The volume of the solution was reduced up to 30 ml, affording a precipitate that was isolated by filtration under vacuum using fritted glass G4. After washing with EtOH, the red precipitate was dried under vacuum. (Zelonka, R.A. ; Baird, M.C.; Can. J. of Cr/em., 1972, 50, 3063.)

[(2a)Ru(CH₃CN)₄]⁺PF₆ ^". A suspension of [C₆H₆RuCI₂]₂ (0.1000 g, 0.1772 mmol), ligand 2a (0.1 137 g, 0.3543 mmol), NaOH (0.0142 g, 0.3543 mmol), KPF₆ (0.1305 g, 0.7088 mmol) in CH₃CN (5 mL) was stirred at 45 °C for 14 h. The obtained yellow- brown suspension was filtered on AI₂O₃, using a mixture of CH₂CI₂/CH3CN (3%) as eluent. The yellow fraction was dried uder vacuum affording a solid residue which was dissolved in the minimum quantity of CH₂CI₂ and precipitated by addition of diethylether and hexane. (Fernandez, S. ; Pfeffer, M.; Ritleng, V.; Sirlin, C. Organometallics, 1999, 18, 2390);

¹ H NMR (400 MHz, CD₃CN) δ 8.84 (d, J- 6.1 Hz, 1 H), 8.01 (dd, J_{1 =} 4.7 Hz, J₂= 1 1 .8 Hz, 1 H), 7.85 (d, J- 7.7 Hz, 1 H), 7.63 (d, J- 3.7 Hz, 1 H), 7.33 (dd, J_{1 =}2.0 Hz, J₂= 6.1 Hz, 1 H), 7.12 (dt, J_{1 =} 1 .2, J₂= 7.3, J₃= 7.3 Hz, 1 H), 6.99 (m, 1 H), 2.92 (t, J- 7.6 Hz, 2H), 1 .74 (quintet, J- 7.6 Hz, 2H), 1 .44 - 1 .33 (m, 6H), 0.93 (t, J- 6.5 Hz, 3H), 2.18, 2.55 e 2.04 (3s, CH₃CN).

Synthesis of [Ru(dcbpy)(2a)]⁺PF₆ ^" (9). In a two-neck flask containing [(2a)Ru(CH₃CN)₄]⁺PF₆ ^" (0.0324 g, 0.0443 mmol) in degassed methanol, were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0217 g, 0.0887 mmol) and NaOH (0.0079 g, 0.1772 mmol). The mixture was heated under reflux for 24 h. The solvent was removed under vacuum and the resulting solid was purified by column chromatography [Sephadex; MeOH]. The solid was dissolved in water and acidified with HNO₃ 0.2M up to the formation of a dark red precipitate, that was filtered, washed first with water, than with diethylether and finally dried. (Bomben, P.G. ; Koivisto, B.D.; Berlinguette, CP. Inorg. Chem. 2010, 49, 4960).

1 H NMR (400 MHz, CD₃OD/ NaOD) δ 9.04 (s, 1 H), 8.95 (d, J- 0.5Hz, 1 H), 8.89 (dd, Ji = 0.5, J₂= 7.8 Hz, 2H), 8.17 (d, J- 5.90 Hz, 2H) 7.96 (t, J- 6.44 Hz, 2H), 7.91 (d, J= 5.63 Hz, 2H), 7.80 (d, J- 6.5 Hz, 1 H), 7.67 (d, J- 6.5 Hz, 2H), 7.62(d, J- 5.2 Hz, 1 H), 7.57 (d, J- 3.4 Hz, 1 H), 7.47 (d, J- 6.5 Hz, 1 H), 7.16 (d, J- 5.8 Hz, 1 H), 6.94 (dt, J= 7.5 Hz, 1 H), 6.88 (d, J- 3.3 Hz, 1 H), 6.82 (dt, J- 7.5 Hz, 1 H), 6.42 (d, J- 7.5 Hz, 1 H), 2.88 (t, J- 9.4 Hz, 2H), 1 .73 (quintet, J- 7.4 Hz, 2H), 1 .42 - 1 .32 (m, 6H), 0.92 (t, J= 6.9 Hz, 3H). Complex [Ru(dcbpy)(2a)]⁺PF₆ ^" (9) was also obtained by microwave synthesis.

In a vial containing [(2a)Ru(CH₃CN)₄]⁺PF₆ ^" (0.020 g, 0.027 mmol) in methanol (10 ml), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0134 g, 0.055 mmol) and NaOH (0.0044 g, 0.109 mmol). The solution was put in a microwave reactor, modality dynamic, for 25 min at 100°C (Maximum pressure: 2 bar; Maximum power: 280 W). The obtained dark red product was dissolved in distilled water and acidified with HNO₃ 0.2 M, until a precipitate was formed. The dark red precipitate was isolated by filtration under vacuum using fritted glass G4, washed first with some drops of water and then with diethylether.

EXAMPLE 16

[Ru(dcbpy)(4a)]⁺PF₆-

10

Procedure for the synthesis of the precursors of compound 10.

[Ru (p-cymene)(CH₃CN)₂(4a)]PF₆. A mixture of [Ru(p-cymene)CI₂]₂ (0.1 139 g, 0.1861 mmol), ligand 4a (0.1500 g, 0.3722 mmol), NaOH (0.0149 g, 0.3722 mmol) and KPF₆ (0.1 370 mg, 0.7444 mmol) in CH₃CN (2.8 ml_) was heated at 45 °C for 2 days, and then filtered. The filtrate was dried under vacuum to give a crude solid residue that was dissolved in the minimum quantity of a mixture CH₂CI₂/CH₃CN 9/1 and then purified on Al₂0₃ using as eluent the same mixture of solvents. The orange fraction was dried under vacuum and the resulting solid was recrystallized from CH₂Cl₂/Et₂0. (Bomben, P.G.; Koivisto, B.D.; Berlinguette, CP. Inorg. Chem. 2010, 49, 4960);

1 H NMR (400 MHz, CD₃CN) δ 9.12 (d, J- 6.1 Hz, 1 H), 8.18 (dd, 7.5 Hz, 1 H), 8.09 (d, J1 = 1 .95, 1 H), 7.93 (dd,

1 .1 , J₂= 7.7 Hz, 1 H), 3.9 Hz, 1 H), 7.46 (dd, Ji=2.1 , J₂= 6.1 Hz, 1 H), 7.32- 7.23 (m, 2H), 7.22- 7.18 (m, 2H), 6.85 (d, J- 3.6 Hz, 1 H), 5.97 (d, J- 6.5 Hz, 2H), 5.70 (dd,

0.7, J₂= 6.1 Hz, 1 H), 5.46 (dd, J1 = 0.7, J₂= 6.1 Hz, 1 H), 2.87 (t, J- 7.5 Hz, 2H), 1 .72 (quintet, J- 7.4 Hz, 2H), 1 .42 - 1 .34 (m, 6H), 0.98- 0.94 (m, 3H), 2.15 (s, 6H), 2.08 (s, 1 H), 2.03 (s, 3H), 1 .95 (s, 6H). Synthesis of [Ru(dcbpy)(4a)]⁺PF₆ ^" (10). In a two-neck flask containing [(Ligand 4a)Ru(CH₃CN)₄]⁺PF₆ ^" (0.0500 g, 0.0800 mol) in degassed methanol, were added 2,2'- bipyridine-4,4'-dicarboxylic acid (0.0400 g, 0.1600 mmol) and NaOH (0.0130 g, 0.6400 mmol). The mixture was heated under reflux for 30 h, and then the solvent was removed under vacuum. The resulting solid was purified by column chromatography (Sephadex, methanol), and then by precipitation with diethylether from a methanolic solution. The solid was dissolved in water and acidified with HNO₃ 0.2M up to the formation of a precipitate, that was filtered, washed first with water, then with diethylether and finally dried. (Bomben, P.G. ; Koivisto, B.D. ; Berlinguette, CP. Inorg. Chem. 2010, 49, 4960);

¹ H NMR (400 MHz, CD₃OD/NaOD) δ 9.05 (s, 1 H), 8.97 (d, J- 0.6 Hz, 1 H), 8.91 (dd,

0.6, J₂= 9.4 Hz, 2H), 8.20 (s, 1 H), 8.17 (d, J- 6.1 Hz, 1 H), 7.88 (dd, 1 .3, J₂= 5.4 Hz, 2H), 7.85 1 .5, J₂= 5.4 Hz, 1 H), 7.80 (d, J- 5.8 Hz, 1 H), 7.68 (d, J- 3.6 Hz, 1 H) 7.61 (dd,

J₂= 5.8 Hz, 3H),7.54 (d, J- 7.7 Hz, 1 H), 7.49 (d, J- 7.7 Hz, 1 H), 7.1 9 (m, 2H), 7.1 5 (d, J- 3.6 Hz, 1 H), 6.94 (dt,

0.9, J₂= 7.6, J₃= 7.7 Hz, 1 H), 6.85 (dt,

0.9, J₂= 7.6, J₃= 7.7 Hz, 1 H), 6.77 (d, J- 3.6 Hz, 1 H), 6.43 (dd, 0.6, J₂= 7.7 Hz, 1 H), 2.84 (t, J- 7.6 Hz, 2H), 1 .71 (quintet, J- 7.4 Hz, 2H), 1 .43 - 1 .30 (m, 6H), 0.92 (t, J- 6.5 Hz, 3H).

Complex [Ru(dcbpy)(4a)]⁺PF₆ ^" (10) was also obtained by microwave synthesis.

In a vial containing [(4a)Ru(CH₃CN)₄]⁺PF₆ ^" (0.015 g, 0.01 8 mmol) in methanol (10 ml), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0090 g, 0.037 mmol) and NaOH (0.0030 g, 0.074 mmol). The solution was put in a microwave reactor, modality dynamic, for 30 min at 100°C (Maximum pressure: 2 bar; Maximum power: 280 W). The obtained dark red product was dissolved in distilled water and acidified with HNO₃ 0.2 M, until a precipitate was formed. The dark red precipitate was isolated by filtration under vacuum using fritted glass G4, washed first with some drops of water and then with diethylether.

EXAMPLE 17

1 1

Procedure for the synthesis of the precursors of compound 1 1 .

[lr(dpmt)₂CI₂]₂ Iridium trichloride hydrate (0.500 g, 1 .43 mmol) was dissolved under nitrogen in a mixture of 2-methoxyethanol (30 ml) and bidistilled water (10 ml). 4,5- Diphenyl-2-methyl-thiazole (dpmt; 0.848 g, 3.35 mmol) was added and the resulting solution was heated under reflux for 24 h. After cooling to room temperature, the reaction mixture was filtered under nitrogen and the precipitate was washed first with 95% ethanol and then with acetone. Finally the solid residue was dissolved in the minimum quantity of dichloromethane and reprecipitated with pentane in order to give the desired complex (80% yield); ¹ H NMR (300 MHz, DMSO) δ: 7.58 (s, 5H), 6.77 (d, J = 6.55 Hz, 1 H) 6.59 (t, J - 8.57 Hz, 1 H), 6.47 (t, J - 7.64 Hz, 1 H), 6.17 (d, J - 7.69 Hz, 1 H), 3.31 (s, 3H).

Elemental analysis: Calculated for lr₂C6₄H₄8N₄S₄CI₂: C, 52.77%; H, 3.32%; N, 3.85%. Found: C, 52.80%; H, 3.33%; N, 3.80%. (Dragonetti, C; Righetto, S.; Roberto, D. ; Ugo, R. ; Valore, A. ; Demartin, F. ; De Angelis, F. ; Sgamellotti, A. ; Fantacci, S. Inorg. Chim. Acta, 2008, 361, 4070.)

Synthesis of [lr(dpmt)₂(dcbpy)]⁺[PF₆] (1 1 ). A solution of [lr(dpmt)₂CI]₂ (0.100 g, 0.0683 mmol) and dcbpy (0.0335 g, 0.1 373 mmol) in CH₂CI₂: MeOH (60 ml, 2:1 ) was heated under reflux. After 6 h, the red solution was cooled to room temperature and added with an excess of ammonium hexafluorophosphate. The suspension was stirred for about 15 min and then dried. Addition of CH₂CI₂ gave a solution of the cationic complex whereas the insoluble inorganic salts were removed by filtration. The filtrate was dried under vacuum and the crude orange solid residue was crystallizzed from CH₂CI₂-diethylether, cooling at 0°C for one night, affording the desired complex. ¹ H NMR (400 MHz, CD₂CI₂) δ 9.43 (s, 2H), 8.45 (d, J- 4.9 Hz, 2H), 8.18 (d, J- 4.6 Hz, 2H), 7.58 (s, 1 1 H), 7.1 9 (d, J- 7.75 Hz, 2H), 6.96 (t, J- 7.3 Hz, 2H), 6.84 (t, J- 7.6 Hz, 2H), 6.42 (d, J= 7.5 Hz, 2H), 1 .89 (s, 3H). Element Analysis calculated for lrC₄₄H₃₂N₄O₄S₂PF₆: C%= 48.84 N%= 5.18 H%= 2.98 Found: C%= 48.79 N%= 5.15 H%= 2.94. EXAMPLE 18

[Ru(dcbpy)(4b)]⁺PF₆- (12).

Procedure for the synthesis of the precursors of compound 12.

[C₆H₆RuCI₂]₂. This dimer has been prepared by addition of 1 ,3-cyclohexadiene (6 ml) to a solution of RuCI₃.3H₂O (1 .70 g, 6.5 mmol) in acqueous ethanol (ethanol/water = 90/10 v/v; 100 mL). The resulting solution was heated at 45^qC for 3h and cooled to room temperature. The volume of the solution was reduced up to 30 ml, affording a precipitate that was isolated by filtration under vacuum using fritted glass G4. After washing with EtOH, the red precipitate was dried under vacuum. (Zelonka, R.A. ; Baird, M.C.; Can. J. of Chem. ,1972, 50, 3063.)

[(4b)Ru(CH₃CN)₄]⁺PF₆ ^~. A suspension of [C₆H₆RuCI₂]2 (0.0820 g, 0.1452 mmol), ligand 4b (0.1280 g, 0.2904 mmol), NaOH (0.01 16 g, 0.2900 mmol), KPF₆ (0.1069 g, 0.5808 mmol) in CH₃CN (3.7 mL) was stirred at 45 °C for 14 h. The obtained orange- red suspension was filtered on AI₂O₃, using a mixture of CH₂CI₂/CH₃CN (3%) as eluent. The yellow fraction was dried under vacuum affording the pure orange product. (Fernandez, S. ; Pfeffer, M. ; Ritleng, V. ; Sirlin, C. Organometallics, 1999, 18, 2390); ¹H NMR (400 MHz, CD₃CN; Me₄Si; T=300 K) <¾ : 8,93 (1H, d, J= 6,10 Hz), 8,34 (1 H, m), 7,69 (1 H, d, J= 4,11 Hz), 7,56 (1 H, dd, Ji - 2,26 Hz, J₂ = 9,14 Hz), 7,42 (1H, dd, Ji - 2,25 Hz, J₂ = 6,23 Hz), 7,28 (1H, d, J = 4,06 Hz), 7,22 (1H, t, J = 3,62 Hz), 6,84 (1H, d, J = 4,10 Hz), 6,55 (1H, m), 2,87 (2H, t, J = 7,45 Hz), 2,56 (3H, s, CH₃CN equatorial), 2,07 (6H, s, CH₃CN axial), 1,97 (3H, s, CH₃CN equatorial), 1,72 (2H, p, J= 7,32 Hz), 1 ,38 (6H, m), 0,98 (3H, dd, ^ = 5,19 Hz, J₂ = 4,73 Hz)

Synthesis of [Ru(dcbpy)(4b)]⁺PF₆ ^" (12). In a two-neck flask containing [(4b)Ru(CH₃CN)₄]⁺PF₆ ^" (0.0571 g, 0.0673 mmol) in degassed methanol (155 ml_), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0329 g, 0.1346 mmol) and NaOH (0.0108 g, 0.2691 mmol). The mixture was heated under reflux for 26 h. The solvent was removed under vacuum and the resulting solid was purified by column chromatography (Sephadex; MeOH). The solid was dissolved in water and acidified with HNO₃ 0.2M up to the formation of a dark red precipitate, that was filtered, washed first with water, than with diethylether and finally dried. (Bomben, P.G.; Koivisto, B.D.; Berlinguette, CP. Inorg. Chem.2010, 49, 4960).

¹H NMR (400 MHz, CD₃OD/ NaOD 1 drop, Me₄Si; T=300 K) <¾ 9,05 (1H, s), 8,98 (1H, s), 8,93 (2H, d, J = 3,99 Hz), 8,48 (1H, m), 8,12 (1H, d, J = 5,79 Hz), 7,92 (1H, d, J = 5,80 Hz), 7,88 (2H, s), 7,78 (1H, d, J = 5,79 Hz), 7,71 (3H, m), 7,58 (2H, t, J = 4,23 Hz), 7,25 (1H, dd, Ji - 2,12 Hz, J₂ = 3,99 Hz), 7,19 (1H, t, J - 3,69 Hz), 7,15 (1H, d, J - 3,57 Hz), 6,78 (1H, d, J = 3,81 Hz), 6,43 (1H, m), 5,93 (1H, dd, Ji - 2,54 Hz, J₂ = 8,25 Hz), 2,84 (2H, t, J = 7,49 Hz), 1,70 (2H, p, J= 7,61 Hz), 1,36 (6H, m), 0,92 (3H, dd, Ji -5,19 Hz, J₂ = 4,73 Hz)

EXAMPLE 19

[Ru(dcbpy)(2b)]⁺PF₆ ^" (13).

COOH

13

Procedure for the synthesis of the precursors of compound 1 3.

[C₆H₆RuCI₂]₂. This dimer has been prepared by addition of 1 ,3-cyclohexadiene (6 ml) to a solution of RuCI₃.3H₂O (1 .70 g, 6.5 mmol) in acqueous ethanol (ethanol/water = 90/10 v/v; 100 imL). The resulting solution was heated at 45 °C for 3h and cooled to room temperature. The volume of the solution was reduced up to 30 ml, affording a precipitate that was isolated by filtration under vacuum using fritted glass G4. After washing with EtOH, the red precipitate was dried under vacuum. (Zelonka, R.A. ; Baird, M.C.; Can. J. of Chem. ,1972, 50, 3063.)

[(2b)Ru(CH₃CN)₄]⁺PF₆ ^~. A suspension of [C₆H₆RuCI₂]2 (0.0988 g, 0.1751 mmol), ligand 2b (0.1 124 g, 0.3502 mmol), NaOH (0.0140 g, 0.3502 mmol), KPF₆ (0.1289 g, 0.7004 mmol) in CH₃CN (4.4 ml_) was stirred at 45 °C for 14 h. The obtained yellow- green suspension was filtered on AI₂O₃, using a mixture of CH₂CI₂/CH₃CN (3%) as eluent. The yellow fraction was dried under vacuum and the solid residue was recristallized from dichloromethane/pentane. (Fernandez, S.; Pfeffer, M.; Ritleng, V. ; Sirlin, C. Organometallics, 1999, 18, 2390); ¹ H NMR (400 MHz, CD₃CN; Me₄Si; T=300 K) <¾ : 8,89 (1 H, d, J = 6,07 Hz), 8,31 (1 H, dd, Ji - 1 ,77 Hz, J₂ = 3,01 Hz), 7,58 (1 H, dd, Ji - 1 ,36 Hz, J₂ = 3,68 Hz), 7,55 (1 H, ddd, Ji - 2,26 Hz, J₂ = 9, 14 Hz, J₃ - 8,73 Hz), 7,39 (1 H, dt, Ji - 1 ,68 Hz, J₂ = 6, 19 Hz), 6,95 (1 H, dt, Ji - 1 ,06 Hz, J₂ = 3,53 Hz), 6,54 (1 H, m), 2,92 (2H, t, J - 7,45 Hz), 2,55 (3H, s, CH₃CN equatorial), 2,06 (6H, s, CH₃CN axial), 1 ,97 (3H, s, CH₃CN equatorial), 1 ,74 (2H, p, J = 7,36 Hz), 1 ,37 (6H, m), 0,93 (3H, m).

Synthesis of [Ru(dcbpy)(2b)]⁺PF₆ ^" (13). In a two-neck flask containing [(2b)Ru(CH₃CN)₄]⁺PF₆ ^" (0.0300 g, 0.0390 mmol) in degassed methanol (90 ml_), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0191 g, 0.078 mmol) and NaOH (0.0063 g, 0.1575 mmol). The mixture was heated under reflux for 23 h. The solvent was removed under vacuum affording a solid that did not require further purification. The later was dissolved in water and acidified with HNO₃ 0.2M up to the formation of a dark red precipitate, that was filtered, washed first with water, than with diethylether and finally dried. (Bomben, P.G. ; Koivisto, B.D. ; Berlinguette, CP. Inorg. Chem. 2010, 49, 4960).

1 H NMR (400 MHz, CD₃OD/ NaOD 1 drop, Me₄Si; T=300 K) <¾_: 9,05 (1 H, s), 8,97 (1 H, s), 8,92 (2H, d, J = 4,84 Hz), 8,48 (1 H, m), 8,45 (1 H, d, J = 2,79 Hz), 8, 12 (1 H, d, J = 5,80 Hz), 7,88 (3H, m), 7,78 (1 H, d, J = 5,88 Hz), 7,70 (3H, m), 7,53 (1 H, d, J = 6,08 Hz), 7,48 (1 H, d, J = 3,57 Hz), 7,21 (1 H, dd, Ji - 2,05 Hz, J₂ = 5,92 Hz), 6,88 (1 H, m), 6,42 (1 H, m), 5,91 (1 H, dd, Ji - 2,33 Hz, J₂ = 8,08 Hz), 2,88 (2H, t, J = 7,51 Hz), 1 ,72 (2H, p, J = 7,28 Hz), 1 ,36 (6H, m), 0,92 (3H, m)

Complex [Ru(dcbpy)(2b)]⁺PF₆ ^" (13) was also obtained by microwave synthesis.

In a vial containing [(2b)Ru(CH₃CN)₄]⁺PF₆ ^" (0.015 g, 0.020 mmol) in methanol (10 ml), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0096 g, 0.039 mmol) and NaOH (0.0031 g, 0.080 mmol). The red-brown solution was put in a microwave reactor, modality dynamic, for 30 min at 100°C (Maximum pressure: 2 bar; Maximum power: 280 W). The obtained dark red product was dissolved in distilled water and acidified with HNO₃ 0.2 M, until a precipitate was formed. The dark red precipitate was isolated by filtration under vacuum using fritted glass G4, washed first with drops of water and then with diethylether.

EXAMPLE 20

[Ru(dcbpy)(7b)]⁺PF₆- (

14 Procedure for the synthesis of the precursors of compound 14.

[(7b)Ru(CH₃CN)₄]⁺PF₆ ^~. A suspension of [C₆H₆RuCI₂]2 (0.0936 g, 0.1659 mmol), ligand 7b (0.100 g, 0.3319 mmol), NaOH (0.01 33 g, 0.331 9 mmol), KPF₆ (0.1222 g, 0.6638 mmol) in CH₃CN (4.1 ml_) was stirred at 45°C for 14 h. The obtained orange suspension was filtered on AI₂O₃, using a mixture of CH₂CI₂/CH₃CN (3%) as eluent. The yellow fraction was dried under vacuum affording the pure orange-red product. (Fernandez, S.; Pfeffer, M. ; Ritleng, V.; Sirlin, C. Organometallics, 1999, 18, 2390); ¹ H NMR (400 MHz, CD₃CN; Me₄Si; T=300 K) <¾ 9,98 (1 H, a), 9,04 (1 H, d, J = 6,03 Hz), 8,44 (1 H, t, J = 2,50 Hz), 7,98 (1 H, dd, Ji - 1 ,06 Hz, J₂ = 3,98 Hz), 7,86 (1 H, dd, Ji - 1 ,06 Hz, J₂ = 3,98 Hz), 7,57 (1 H, dd, Ji - 2,33 Hz, J₂ = 8,68 Hz), 7,51 (1 H, dd, Ji - 1 ,99 Hz, J₂ = 6, 19 Hz), 6,56 (1 H, m), 2,56 (3H, s, CH₃CN equatorial), 2,06 (6H, s, CH₃CN axial), 1 ,99 (3H, s, CH₃CN equatorial).

Complex [Ru(dcbpy)(7b)]⁺PF₆ ^" (14) was prepared by microwave synthesis.

In a vial containing [(7b)Ru(CH₃CN)₄]⁺PF₆ ^" (0.0084 g, 0.0139 mmol) in methanol (10 ml), were added 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy; 0.0068 g, 0.0277 mmol) and NaOH (0.0022 g, 0.0554 mmol). The vial containing the orange solution was put in a microwave reactor, modality dynamic, for 1 5 min at 100°C (Maximum pressure: 10 bar; Maximum power: 280 W). The crude residue was precipitated from MeOH/diethylether and then purified by chromatography on Sephadex using MeOH as eluent. The obtained dark red product was dissolved in distilled water and acidified with HNO₃ 0.2 M, until a precipitate was formed. The dark red precipitate was isolated by filtration under vacuum using fritted glass G4, washed first with some drops of water and then with diethylether. The pure product is brown.

¹ H NMR (400 MHz, CD₃OD/ NaOD 1 drop, Me₄Si; T=300 K) <¾_: 9,93 (1 H, s), 9,06 (1 H, s), 8,98 (1 H, s), 8,94 (2H, d, Ji - 1 ,73, Hz, J₂ = 6,87 Hz), 8,59 (1 H, t, J = 2,72 Hz ), 8,09 (1 H, d, J = 5,77 Hz), 7,97 (1 H, d, J = 3,79 Hz), 7,89 (3H, m), 7,81 (2H, dd, Ji - 3,44, Hz, J₂ = 4,77 Hz), 7,71 (4H, m), 7,36 (1 H, dd, Ji - 2,02 Hz, J₂ = 6, 10 Hz), 6,45 (1 H, m), 5,95 (1 H, dd, Ji - 2,37 Hz, J₂ = 8,20 Hz). Stability of [Ru(dcbpy)(2b)]⁺PF₆ ^" in the presence of 4-ieri-butyl pyridine.

The stability of complex [Ru(dcbpy)(2b)]⁺PF₆ ^" in acetonitrile solution was tested at relatively high temperature (80°C, 24 h) in the presence of a 100:1 (mol:mol) excess of 4- te/t-butyl pyridine (additive commonly used in DSSCs solar cells) with respect to the Ru complex N71 9. Under these conditions, the complex is stable, as evidenced by ¹ H NMR spectroscopy and mass spectrometry (FAB +). Under the same conditions we found that N71 9 undergoes substitution of SCN ligands by 4-tert- butylpyridine, as confirmed by mass spectrometry, in agreement with previous reports (for example see: Lund, T. et al. Solar Energy Materials and Solar Cells, 2007, 91, 1 934-1 942). The particular stability of the cyclometallated complex can be explained by the presence of a chelating ligand (the substituted phenylpyridine) instead of the monoatom ambidentate SCN ligand.

The cyclometalated compounds according to the invention show photoelectric conversion properties when placed alongside the other components in a photoelectric conversion device, in a solar cell, or in a photovoltaic device.

In this regard, even for purposes of example only, we describe the experimental data related to the evaluation of the photoelectric conversion properties of the compounds according to the invention.

We define the following parameters:

J_sc = maximum current density (short circuit conditions) (imA/cm²);

V_oc = maximum attainable voltage (open circuit conditions) (V);

FF = fill factor, obtained from the ratio between J_mpxV_mp and J_scxV_0C, where J_mp and

V_mp represent the current density and voltage at the maximum power point.;

η = overall power conversion efficiency (sometimes referred to as PCE) obtained from the ratio of maximum output power density (Pout, in W m^"2) and the input light irradiance (Ρ,η, in the same units) (%), measured under standard reporting conditions with the light intensity Ρ,η being 1 000 W m^"2, the sun spectrum AM 1 .5 G, and the sample temperature 25 °C, and may be calculated from the following relationship η = Jsc [mA/cm²] x V_oc [V] x FF / 1₀ [mWcm ²]

where l₀ = 1 00 mW/cm² or 1 000 W/m² under standard reporting conditions. EXAMPLE 21

This example refers to the characterization of the photoelectric conversion properties of the sensitizers when placed in a photoelectric conversion device (DSC cell), whose general scheme is depicted in Figure 5.

This characterization is intended only to demonstrate the photoelectric conversion properties of the new compounds and is not meant to obtain values of photoelectric conversion efficiency optimized and measured under the best conditions to reach. The cell shown schematically in Figure 5 consists of: a) two substrates 1 , containing a conductive layer, including at least one transparent (TCO); b) a semiconductor material 2, for example titanium dioxide, on which a compound according to the present invention with the function of absorbing light is adsorbed; c) a charge transport component 3; d) a counter electrode 4, for example containing platinum. The new complexes have been used as sensitizers in liquid DSCs. DSCs were prepared using a double layer film consisting of a 20-nm-particles transparent 7-μιη layer and a scattering 6-μιη layer. The sensitizer solution contained chenodeoxycholic acid (CDCA) as de-aggregating co-adsorbent agent in 1 :1 proportion. Four different electrolyte solutions were used: a standard electrolyte A6141 (0.6 M A/-butyl-A/-methyl imidazolium iodide, 0.03 M l₂, 0.1 0 M guanidinium thiocyanate, and 0.5 M 4-t- butylpyridine in acetonitrile/valeronitrile 85:15), M1 (0.6 M A/-butyl-/V- methylimidazolium iodide, 0.04 M l₂, 0.025 M Lil, 0.05 M guanidinium thiocyanate, and 0.28 M 4-f-butylpyridine in in acetonitrile/valeronitrile 85:15), A6986 (0.6 M N- butyl-N-methylimidazolium iodide, 0.05 M l₂, 0.1 M Lil, and 0.05 M 4-f-butyl pyridine in acetonitrile/valeronitrile 85:15), and VT (0.6 M N-butyl-N-methylimidazolium iodide, 0.05 M l₂, 0.1 M Li l, and 0.45 M 4-f-butyl pyridine in acetonitrile/valeronitrile 85:15). In order to exclude metal contamination all of containers were in glass or teflon and were treated with EtOH and 10% HCI prior to use. Plastic spatulas and tweezers have been used throughout the procedure. FTO glass plates (Solaronix) were cleaned in a detergent solution for 30 min using an ultrasonic bath, rinsed with pure water and EtOH FTO plates were treated with a freshly prepared 40 mM aqueous solution of TiCI₄ for 30 min at 70 °C and the rinsed with water and EtOH. A first transparent layer was deposited via screen printing using 20-nm transparent TiO₂ paste (Solaronix). The coated films were dried at 125 °C for 6 min and then a titania scattering layer (CCIC) was added. The coated plates were kept in a cabinet for 5 min and then thermally treated under an air flow at 125 °C for 6 min, 325 °C for 10 min, 450 °C for 15 min, and 500 °C for 15 min. The heating ramp rate was 5 - 10 "C/rnin. The sintered layer was treated again with 40 mM aqueous TiCI₄ (70 °C for 30 min), rinsed with water and EtOH and heated at 500 °C for 30 min. After cooling down to 80 °C the TiO₂ coated plate was immersed into a 0.1 mM solution of the dye in EtOH containing 1 :1 chenodeoxycholic acid (Fluka) for 20 h at room temperature in the dark. The thickness of the layers was measured by means of a VEECO Dektak 8 Stylus Profiler.

Counter electrodes were prepared according to the following procedure. A 1 -mm hole was made in a FTO plate using diamond drill bits. The electrodes were then cleaned with a detergent solution for 5 min using an ultrasonic bath, 10% HCI, and finally acetone for 10 min using an ultrasonic bath. After heating at 400 °C for 15 min a drop of a 5 x 10^"3 M solution of H₂PtCI₆ in EtOH was added and the thermal treatment at 400 °C for 15 min repeated. The dye adsorbed TiO₂ electrode and Pt-counter electrode were assembled into a sealed sandwich-type cell by heating with a hot-melt ionomer-class resin (Surlyn 25-30 μιη thickness) as a spacer between the electrodes. A drop of the electrolyte solution was added to the hole and introduced inside the cell by vacuum backfilling. Finally, the hole was sealed with a Bynel. An aluminium foil at the back side of the counter electrode was taped to reflect unabsorbed light back to the photoanode.

Photovoltaic measurements of DSCs (Table) were carried out using a Xenon light source (Oriel Solar Simulator 81 150). The power of the simulated light was calibrated to AM 1 .5 (100 mW cm^"2) using a reference Si photodiode. I-V curves were obtained by applying an external bias to the cell and measuring the generated photocurrent with a Keithley model 2400 digital source meter. Table. Photovoltaic parameters and power conversion efficiencies of DSC devices based on a selection of the compounds according to the invention.

Figure 6 shows the current-voltage characteristics of a DSC cell containing the compound [Ru(dcbpy)₂(7b)]PF₆.

Claims

1 ) Cyclometalated complex of formula (I)

[M Ι_! L₂ L₃] l+q

the net charge q is equal to 0 or 1 , and when q=1 , a counterion is present selected among the anions alkylsulfonate, arylsulfonate, polyarensulfonate, triflate, halide, sulfate, methosulfate, phosphate, polyphosphate;

and wherein at least one of the ligands l_i , l_₂, L₃, being the same or different, is a negatively charged bidentate ligand being cyclometalated, that is formally obtained by removing by removing a proton FT from an aromatic or heteroaromatic cycle of formula (II):

Het R

(II) wherein He^ is selected from the following heteroaromatic groups

and wherein Ri is an aromatic or heteroaromatic substituent selected from the group

In Heti the group R₂ is a monovalent organic substituent having at least one aromatic or heteroaromatic ring and is selected from the group of

wherein X is selected among O, S, NZ and Se, wherein Z = H, alkyl, aryl;

wherein substituents R₄, being the same or different, are selected from the group consisting of H, alkyl groups having from 1 to 18 carbon atoms, alkoxy, aminoalkyi, alkylhalide, hydroxyalkyl, alkyl groups containing hydroxy and amino functions, alkoxyalkyl, alkylsulfide, alkylthiol, alkylazide, alkylcarboxylic, alkylsulfonic, alkyyiisocyanate, alkylisothiocyanate, alkylalkene, alkylalkyne, aryl, formyl, groups containing the carbonyl -C(O)- or carboxylic -C(O)O- function, cyano, nitro, groups containing the -S(O)- or -P(O)- function, groups containing an electron-poor 6- membered or 5-membered aromatic or heteroaromatic ring, groups containing the function wherein R = H, alkyl, electron-withdrawing aliphatic, aromatic, or heteroaromatic group, or being part of an electron-wihdrawing aromatic or heteroaromatic ring;

and wherein n is 0,1 ,2;

and wherein Y is optionally present and selected among

wherein m is 0,1 ,2;

and wherein at least one of the ligands l_i , l_₂, L₃, if different from Het Ri of formula (II), is a bidentate, tridentate, or tetradentate ligand of formula (III):

wherein R₅ is an anchoring substituent selected among the group of -COOH, -PO₃H₂, -PO₄H₂, B(OH)₂, SO₃H₂ or any corresponding deprotonated form thereof including organic and/or inorganic counterions,

and wherein any of substituents R₅ may be bonded to any pyridine ring of formula (II), and wherein p is 0,1 ,2.

2. A cyclometalated complex of formula (I) as defined in claim 1 in which a bond is present between the metal atom M and the ring carbon atom of the aromatic or heteroaromatic groups formally carrying a negative charge, obtained by the formal removal of a proton H⁺ from the structure of formula (II).

3. Compound of formula (II) according to claims 1 and 2, having the following formulas 2a - 7a and 2b - 7b:

4. A cyclometalated complex according to claim 1 , having the formula [Ru(dcbpy)₂(2a)]PF₆, [Ru(dcbpy)₂(4a)]PF_6! [Ru(dcbpy)₂(2b)]PF_6!

[Ru(dcbpy)₂(4b)]PF₆, [Ru(dcbpy)₂(7b)]PF₆, wherein dcbpy=2_!2'-bipyridine-4_!4'- dicarboxylic acid and 2a, 4a,2b, 4b and 7b are defined according to claim 3.

wherein dcbpy=2,2'-bipyridine-4,4' -dicarboxylic acid and dpmt=4,

5-diphenyl-2- methyl-tiazole.

6. Cyclometalated complexes according to claims 1 , 2, 4, 5 for use as components in devices for photoelectric conversion of energy.

7. Compounds of formula (II) according to claims 1 e 2, as such or in a deprotonated form with a formal negative charge, for use as ligands of a cyclometalated complex in a photoelectric energy conversion device.

8. Compounds of formula (II) according to claims from 4 to 6, as such or in a deprotonated form with a formal negative charge, for use as ligands of a cyclometalated complex in a photoelectric energy conversion device.

9. A device for photoelectric conversion of energy or a photovoltaic cell comprising as photosensitizer components one or more cyclometalated complexes of formula

(I).

10. A dye-sensitized solar cell, comprising an anode, a cathode, and an electrolyte, having as photosensitizer components one or more cyclometalated complexes of formula (I).

1 1 . An electrochemical cell comprising as photosensitizer components one or more cyclometalated complexes of formula (I).