Organic dye for a dye-sensitized solar cell

Abstract

Organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one -conjugated unit. Said organic dye is particularly useful in a dye-sensitized photoelectric transformation element which, in its turn, can be used in a dye-sensitized solar cell (DSSC).

Claims

1. An organic dye having a formula (I): ##STR00011## wherein: X is a hydrogen atom, or a carboxycyanovinylene group having the formula (II): ##STR00012## wherein R.sub.5 is an hydrogen atom; Z is a carboxycyanovinylene group having the formula (II) or (IV): ##STR00013## wherein R.sub.5 is an hydrogen atom; R.sub.1 and R.sub.2, identical to each other, are a n-hexyl group, a n-octyl group, a n-decyl group, or a n-dodecyl group; R.sub.3 and R.sub.4, identical to or different from each other, are a hydrogen atom or a n-hexyl group, a n-octyl group, a n-decyl group, or a n-dodecyl group; or, R.sub.3 and R.sub.4 are bound to each other to form, together with the other atoms to which they are bound, a saturated cycle containing four carbon atoms and two oxygen atoms; n is 1; p is 0 or 1; and m is 1.

2. A dye-sensitized photoelectric transformation element comprising the organic dye of claim 1, wherein the dye-sensitized photoelectric transformation element is supported on oxide semiconductor particles.

3. A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element of claim 2.

4. The organic dye of claim 1, wherein R.sub.1 and R.sub.2 are an n-octyl group.

5. The organic dye of claim 1, wherein R.sub.3 and R.sub.4, identical or different from each other, are a hydrogen or an n-octyl group.

6. The organic dye of claim 1, wherein R.sub.3 and R.sub.4 are bound to each other to form a 1,4 dioxane.

7. A dye-sensitized photoelectric transformation element comprising the organic dye of claim 4, wherein the dye-sensitized photoelectric transformation element is supported on oxide semiconductor particles.

8. A dye-sensitized photoelectric transformation element comprising the organic dye of claim 5, wherein the dye-sensitized photoelectric transformation element is supported on oxide semiconductor particles.

9. A dye-sensitized photoelectric transformation element comprising the organic dye of claim 6, wherein the dye-sensitized photoelectric transformation element is supported on oxide semiconductor particles.

10. A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element of claim 7.

11. A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element of claim 8.

12. A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element of claim 9.

Description

EXAMPLES

Reagents and Materials

(1) The reagents and materials used in the following examples, as well as their manufacturers, have been below reported: N-bromosuccinimmide (Aldrich): used as such; 2-bromo-3-octyl-thiophene (Aldrich): used as such; dimethylformamide (DMF) (Aldrich): used as such or optionally anhydrified on magnesium (Mg); diethyl ether (Aldrich): used as such; sodium bicarbonate (NaHCO.sub.3) (Aldrich): used as such or in a 1 M aqueous solution; sodium sulfate (Aldrich): used as such; petroleum ether (Aldrich): used as such; dibromoethane (Aldrich): used as such; anhydrous diethyl ether (Aldrich): used as such; magnesium turnings (Aldrich): used as such; 2,5-dibromothiophene (Aldrich): used as such; 1,3-bis(diphenylphosphino)propane]dichloronickel(II) [Ni(dppp)Cl.sub.2]: (Aldrich): used as such; hydrochloric acid (HCl) solution 2 M (Aldrich): used as such or diluted with water; magnesium sulfate (Aldrich): used as such; chloroform (Aldrich): used as such; acetic acid (Aldrich): used as such; dichloromethane (CH.sub.2Cl.sub.2) (Aldrich): used as such; 1,2-dichloroethane (Aldrich): used as such; tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4](Aldrich): used as such; anhydrous toluene (Aldrich): used as such; phosphorous oxychloride (Aldrich): used as such; sodium acetate (C.sub.2H.sub.3NaO.sub.2) (Aldrich): used as such; cyanoacetic acid (Aldrich): used as such; ammonium acetate (Aldrich): used as such; glacial acetic acid (Aldrich): used as such; sodium hydroxide (NaOH) (Aldrich): used as such; ethanol (Carlo Erba): used as such; n-butyl lithium (2.5 M in hexane) (Aldrich): used as such; anhydrous tetrahydrofuran (THF) (Aldrich): used as such; hexane (Carlo Erba): used as such; Celite 545 (Aldrich): used as such; tributyltin chloride (Aldrich): used as such; 2-(3-thienyl)benzoic acid (Aldrich): used as such; bromine (Br.sub.2) (Aldrich): used as such; aluminum trichloride (AlCl.sub.3) (Aldrich): used as such; carbon disulfide (CS.sub.2) (Aldrich): used as such; 3-(3-thienyl)acrylic acid (Aldrich): used as such; palladium on activated charcoal (PdC) (10% by weight of Pd) (Aldrich): used as such; ammonium formate (Aldrich): used as such; iso-propanol (iPrOH) (Carlo Erba): used as such; thionyl chloride (SOCl.sub.2) (Aldrich): used as such; 3,4-ethylenedioxythiophene (Aldrich): used as such; titanium tetrachloride (Aldrich): used as such; N-methyl-N-butylimidazolium iodide (Aldrich): used as such; iodine (Carlo Erba): used as such; lithium iodide (Aldrich): used as such; guanidinium-thiocyanate (Aldrich): used as such; t-butylpyridine (Aldrich): used as such; valeronitrile (Aldrich): used as such; acetonitrile (Carlo Erba): used as such; 2,5-bis(tributylstannyl)thiophene (Aldrich): used as such; 5-bromo-2-thiophenecarbaldheyde (Aldrich): used as such; sodium fluoride (Aldrich) used as such.

(2) In the following examples the characterization methods below reported have been used.

(3) NMR Spectra

(4) The NMR spectra of the obtained compounds have been carried out with a spectrometer NMR Bruker Avance 400.

(5) To this aim, about 10 mg of the sample to be examined have been dissolved in about 0.8 ml of a suitable deuterated solvent directly on the glass pipe used for the measurement. The chemical shifts scale has been calibrated with respect to the tetramethylsilane signal set to 0 ppm.

(6) Mass Spectra

(7) The mass spectra of the compounds obtained have been carried out with a reverse-geometry double-focusing spectrometer AT 95S DCI (Desorption Chemical Ionization) with iso-butane as reagent gas in ions positive mode. The filament emission current has been calibrated at 0.1 mA with an electron beam energy equal to 100 eV and with a ions source temperature kept to 90 C.

Example 1

Synthesis of 5-carboxycyanovinylen-[3,3,3,3-tetraoctyl]-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (Ia)

(8) ##STR00005##

Synthesis of 2-(3-octylthienyl)magnesium bromide having formula (2)

(9) In a 100 ml flask, a solution of 2-bromo-3-octylthiophene having formula (1) (3.0 g, 10.89 mmol) and dibromoethane (0.93 ml, 10.89 mmol) in 10 ml of anhydrous diethyl ether, was added, dropwise to a suspension of magnesium turnings (Mg) (0.53 g) in 50 ml of anhydrous diethyl ether, under argon (Ar) atmosphere, sonicated for 30 minutes, and heated at the reflux temperature of the solvent for another 90 minutes: after the elimination of the excess of magnesium turnings by filtration, a solution containing 2-(3-octylthienyl)magnesium bromide having formula (2) (Grignard reagent) was obtained and was immediately used in the following coupling reaction.

Synthesis of 3,3-dioctyl-2,2:5,2-terthiophene having formula (3)

(10) A solution of 2-(3-octylthienyl) magnesium bromide having formula (2), obtained as described above, was slowly added, at 0 C., in a 100 ml flask containing a solution of 2,5-dibromothiophene (0.4 ml, 3.63 mmol) and 1,3-bis(diphenylphosphino)propane]dichloronickel(II) [Ni(dppp)Cl.sub.2](181 mg, 0.4 mmol) in 50 ml of anhydrous diethyl ether. The obtained reaction mixture was heated at the reflux temperature of the solvent, for 18 hours, subsequently cooled to room temperature (25 C.) and then treated with a mixture of crushed ice and 50 ml of hydrochloric acid (HCl) solution (2 M). Subsequently, the cooled reaction mixture was extracted with diethyl ether (320 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was thoroughly washed with water, 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3), brine, again with water, and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using petroleum ether as eluent obtaining 1.65 g (97% yield) of 3,3-dioctyl-2,2:5,2-terthiophene having formula (3), as a yellow liquid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.18 (d, 2H), 7.05 (s, 2H), 6.94 (d, 2H), 2.77 (t, 4H), 1.65-1.59 (m, 4H), 1.39-1.26 (m, 20H), 0.87 (t, 6H).

Synthesis of 5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (4)

(11) In a 100 ml flask, N-bromosuccinimide (NBS) (0.3 g, 1.75 mmol) was added, in small portions, to a solution of 3,3-dioctyl-2,2:5,2-terthiophene having formula (3) (1.24 g, 2.62 mmol), obtained as described above, in 50 ml of a mixture of chloroform and acetic acid (1:1), at 0 C. The obtained reaction mixture was heated at room temperature (25 C.) and stirred for additional 3 hours. Subsequently, the reaction mixture was poured into water and extracted with dichloromethane (CH.sub.2Cl.sub.2) (320 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was thoroughly washed with water, 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3), brine, again with water, and then was dried over sodium sulfate (Na.sub.2SO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using petroleum ether as eluent obtaining 0.60 g (63% yield) of 5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (4), as a slightly yellow oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.19 (d, 1H), 7.04 (d, 1H), 6.99 (d, 1H), 6.94 (d, 1H), 6.89 (s, 1H), 2.78-2.68 (m, 4H), 1.68-1.58 (m, 4H), 1.35-1.24 (m, 20H), 0.89-0.84 (m, 6H).

Synthesis of 3,3,3,3-tetraoctyl-2,2:5,2:5,2:5,5:2,2: 5-2-heptathiophene having formula (5)

(12) In a 200 ml flask, a mixture of 5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (4) (0.5 g, 0.9 mmol), obtained as described above, 2,5-bis(tributylstannyl)thiophene (0.27 g, 0.41 mmol) and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4](100 mg, 0.085 mmol) in 100 ml of anhydrous toluene, was heated at the reflux temperature of the solvent overnight. Subsequently, the reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 30 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was washed with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), subsequently with water (320 ml), and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (1:3) as eluent obtaining 0.42 g (47% yield) of 3,3,3,3-tetraoctyl-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (5), as a reddish oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.19 (d, 2H), 7.08-7.04 (m, 6H) 7.01 (s, 2H), 6.95 (d, 2H), 2.81-2.74 (m, 8H), 1.73-1.60 (m, 8H), 1.39-1.23 (m, 40), 0.90-0.82 (m, 12H).

Synthesis of 5-formyl-3,3,3,3-tetraoctyl-2,2:5,2:5,2:5,5:-2:2:5,2-heptathiophene having formula (6)

(13) In a 100 ml flask, a Vilsmeier reagent, which was prepared with phosphorous oxychloride (POCl.sub.3) (0.05 ml, 0.49 mmol) in dry dimethylformamide (DMF) (0.04 ml, 0.49 mmol), was added to a cold solution (0 C.) of 3,3,3,3-tetraoctyl-2,2:5,2:5,2:5,5:2,2:-5,2-heptathiophene having formula (5) (0.36 g, 0.35 mmol), obtained as described above, in 20 ml of 1,2-dichloroethane under argon (Ar) atmosphere. After being stirred, at 70 C., for 20 hours, the obtained reaction mixture was cooled to room temperature (25 C.), diluted with dichloromethane (CH.sub.2Cl.sub.2), treated with a solution of sodium acetate (C.sub.2H.sub.3NaO.sub.2), then stirred at room temperature (25 C.), for 2 hours, and subsequently extracted with dichloromethane (CH.sub.2Cl.sub.2) (320 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was washed with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), subsequently with water, and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (1:1) as eluent obtaining 0.12 g (34% yield) of 5-formyl-3,3,3,3-tetraoctyl-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (6), as a reddish solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.59 (s, 1H), 7.25 (d, 1H), 7.19 (d, 1H), 7.12 (d, 1H), 7.08-7.05 (m, 3H), 7.02-7.01 (m, 2H), 6.95 (d, 1H), 2.85-2.74 (m, 8H), 1.70-1.58 (m, 8H), 1.40-1.21 (m, 40), 0.90-0.85 (m, 12H).

(14) Said compound having formula (6) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.4, 141.1, 141.0, 140.3, 140.1, 139.7, 139.0, 138.0, 136.2, 135.5, 135.4, 134.5, 134.4, 130.2, 130.1, 129.7, 128.8, 127.8, 126.6, 126.0, 125.9, 124.4, 124.2, 123.8, 31.8, 30.7, 30.5, 30.4, 30.3, 29.5, 29.4, 29.2, 22.6, 14.1.

(15) Furthermore, said compound having formula (6) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 1052.4258 (0.4 ppm), calculated for C.sub.61H.sub.80OS.sub.7: 1052.4254.

Synthesis 5-carboxycyanovinylen-[3,3,3,3-tetraoctyl]-2,2:5,2:5,2:5,5:-2,2:5,2-heptathiophene having formula (Ia)

(16) In a 100 ml flask, 5-formyl-3,3,3,3-tetraoctyl-2,2:5,2:5,2:-5,5:2,2:5,2-heptathiophene having formula (6) (100 mg, 0.09 mmol), obtained as described above, was mixed with cyanoacetic acid (NCCH.sub.2COOH) (40 mg, 0.19 mmol) and with a solution of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (80 mg, 0.47 mmol) in 40 ml of glacial acetic acid (CH.sub.3COOH): the obtained solution was heated at the reflux temperature of the solvent, for 12 hours. The obtained reaction mixture was slowly cooled to room temperature (25 C.), obtaining a dark precipitate which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 5-carboxycyanovinylen-[3,3,3,3-tetraoctyl]-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (Ia) (70 mg, 66% yield), as a black solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 10.85 (s, 1H), 8.30 (s, 1H) 7.77 (s, 1H), 7.14 (d, 1H), 7.30 (d, 1H), 7.25 (d, 1H), 7.21-7.19 (m, 3H), 7.17 (s, 1H), 7.15 (d, 1H), 7.11 (d, 1H) 6.98 (d, 1H), 2.84-2.74 (m, 8H), 1.7-1.60 (m, 8H), 1.14-1.12 (m, 40), 0.90-0.85 (m, 12H).

(17) Said compound having formula (Ia) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 163.8, 145.9, 141.6, 141.1, 140.8, 140.3, 139.3, 139.2, 139.0, 136.6, 134.6, 134.2, 134.0, 133.2, 130.8, 130.6, 129.7, 129.0, 126.8, 126.6, 126.4, 126.3, 124.7, 116.3, 110.1, 109.5, 99.7, 32.6, 31.4, 31.2, 30.9, 30.3, 30.2, 30.0, 29.8, 23.3, 14.2.

(18) Furthermore, said compound having formula (Ia) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 1119.4323 (1.1 ppm) calculated for C.sub.64H.sub.81NO.sub.2S.sub.7: 1119.4312.

Example 2

Synthesis of 5-carboxycyanovinylen-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (Ib)

(19) ##STR00006##

Synthesis of 5-tributylstannyl-3,3-dioctyl-2,2:5,2-terthiophene (7)

(20) In a 100 ml flask n-butyl lithium (LiBu) (0.51 ml, 2.5 M in hexane, 1.27 mmol) was added dropwise, at 0 C., to a solution containing the compound having formula (3) (0.5 g, 1.06 mmol), obtained as described in Example 1, dissolved in 40 ml of dry tetrahydrofurane (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 30 minutes, at 0 C. Subsequently, tributyltin chloride (SnBu.sub.3Cl) (0.33 ml, 1.16 mmol) was added, dropwise, at 0 C. and the obtained reaction mixture was allowed to warm slowly to room temperature (25 C.). After dilution with diethyl ether (30 ml), a saturated aqueous solution of sodium fluoride (NaF) was added and the obtained reaction mixture was stirred, for 1 hour, at room temperature (25 C.). The obtained precipitate was filtered off by using Celite 545 and the obtained filtrate was washed with a saturated aqueous solution of sodium bicarbonate (NaHCO.sub.3), subsequently with water and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure obtaining 5-tributylstannyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (7) which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.16 (d, 1H), 7.04 (s, 2H), 6.95 (s, 1H), 6.95 (d, 1H), 2.77 (t, 4H), 1.67-1.54 (m, 10H), 1.39-1.26 (m, 26H), 1.13-1.08 (m, 6H), 0.94-0.84 (m, 15H).

Synthesis of 5-formyl-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (8)

(21) In 50 ml flask a mixture of 5-bromo-2-thiophenecarbaldehyde (0.03 ml, 0.26 mmol), 5-tributylstannyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (7) (0.24 g, 0.31 mmol), obtained as described above, and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4](61 mg, 0.052 mmol) in 20 ml of anhydrous toluene was heated at the reflux temperature of the solvent for 20 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 30 ml of dichloromethane (CH.sub.2Cl.sub.2) and the organic phase was washed with a 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), subsequently with water (320 ml) and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane and petroleum ether (1/1) as eluent obtaining 0.25 g (92% yield) of 5-formyl-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (8), as a yellowish solid, which was characterized by .sup.1H NMR (400 MHz, CDCl.sub.3) obtaining the following spectrum: 9.85 (s, 1H), 7.67 (d, 1H), 7.23 (d, 1H), 7.21 (d, 1H), 7.20 (s, 1H), 7.12 (d, 1H), 7.08 (d, 1H), 6.95 (d, 1H), 2.78 (t, 4H), 1.70-1.61 (m, 4H), 1.39-1.26 (m, 20H), 0.87 (t, 6H).

(22) Said compound having formula (8) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.3, 146.8, 141.4, 140.6, 139.9, 137.3, 136.9, 134.8, 133.3, 132.6; 130.1, 130.0, 129.0, 126.4, 126.0, 123.9, 31.8, 30.6, 30.4, 29.5, 29.4, 29.3, 29.2, 22.6, 14.0.

(23) Furthermore, said compound having formula (8) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 582.2 and 582.2133 (2.5 ppm), respectively, calculated for C.sub.33H.sub.42OS.sub.4: 582.2119.

Synthesis of 5-carboxycyanovinylen-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (Ib)

(24) In a 250 ml flask were introduced 0.19 g (2.47 mmol) of 5-formyl-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (8), obtained as described above, and mixed with cyanoacetic acid (NCCH.sub.2COOH) (71 mg, 0.82 mmol), ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.19 g, 2.47 mmol) and 100 ml of glacial acetic acid (CH.sub.3COOH). The solution was heated at the reflux temperature of the solvent, for 12 hours. After slowly cooling the reaction mixture to room temperature (25 C.), a dark precipitate was formed, which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 140 mg (53% yield) of 5-carboxycyanovinylen-4,3-dioctyl-2,2:5,2:5,2-quaterthiophene having formula (Ib), as a black solid, which was characterized by .sup.1H NMR (400 MHz, CDCl.sub.3) obtaining the following spectrum: 8.28 (s, 2H), 7.68 (d, 1H), 7.23 (d, 1H), 7.20 (d, 1H), 7.12 (d, 1H), 7.07 (d, 1H), 6.95 (d, 1H), 2.78 (t, 4H), 1.68-1.60 (m, 4H), 1.40-1.27 (m, 20H), 0.87 (t, 6H).

(25) Said compound having formula (Ib) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 167.9, 148.8, 147.6, 141.0, 140.6, 140.0, 137.2, 134.7, 133.8, 133.7, 132.7, 130.2, 130.0, 126.6, 126.1, 124.2, 124.0, 115.6, 95.6, 31.8, 30.6, 30.4, 29.6, 29.5, 29.4, 29.3, 29.2, 22.6, 14.1.

(26) Furthermore, said compound having formula (8) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 649.3 and 649.2159 (2 ppm), respectively, calculated for C.sub.36H.sub.43NO.sub.2S.sub.4: 649.2177.

Example 3

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-carboxycyanovinylene having formula (Ic)

(27) ##STR00007##

Synthesis of 8H-indeno[2,1-b]thiophen-8-one having formula (11)

(28) In a 50 ml flask, a mixture of 2-(3-thienyl)benzoic acid having formula (9) (2.14 g, 10.49 mmol) and thionyl chloride (SOCl.sub.2) (3.7 ml, 50.35 mmol) was stirred overnight, at 45 C., under argon (Ar) atmosphere. Subsequently, after the evaporation of the excess of thionyl chloride (SOCl.sub.2), the obtained 2-(3-thienyl)benzoyl chloride having formula (10), as a brown oil, was immediately used in the following reaction. Under argon (Ar) atmosphere, a solution of 2-(3-thienyl)benzoyl chloride having formula (10) in carbon disulfide (CS.sub.2) (30 ml) was added dropwise, over a period of 5 minutes, through a dropping funnel, to a 250 ml three-necked round bottom flask containing a suspension of aluminium trichloride (AlCl.sub.3) (3.26 g, 24.13 mmol) in carbon disulfide (CS.sub.2) (40 ml), under stirring. The obtained reaction mixture was heated at the reflux temperature of the solvent, for 6 hours, subsequently cooled to room temperature (25 C.) and then treated with a mixture of crushed ice and 50 ml of hydrochloric acid (HCl) solution (2 M). Subsequently, the cooled reaction mixture was extracted with diethyl ether (240 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was washed with a saturated aqueous solution of sodium chloride (NaCl) (320 ml) and then dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using dichloromethane (CH.sub.2Cl.sub.2) as eluent obtaining 1.47 g (76% yield) of 8H-indeno[2,1-b]thiophen-8-one having formula (11), as yellow solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.74 (d, 1H), 7.47 (d, 1H), 7.33 (m, 1H); 7.17 (d, 1H), 7.16 (m, 1H), 7.12 (d, 1H).

Synthesis of 2-bromo-8H-indeno[2,1-b]thiophen-8-one having formula (13)

(29) In a 100 ml flask, bromine (Br.sub.2) (0.54 ml, 10.54 mmol) was added, dropwise, to a solution of 8H-indeno[2,1-b]thiophen-8-one having formula (11) (1.40 g, 7.53 mmol), obtained as described above, in 30 ml of chloroform, at 0 C. The obtained reaction mixture was heated at room temperature (25 C.) and stirred for additional 7 hours. Subsequently, the reaction mixture was poured into water and extracted with dichloromethane (CH.sub.2Cl.sub.2) (330 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was thoroughly washed with water, aqueous solution of sodium bicarbonate (NaHCO.sub.3), brine, again with water, and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of petroleum ether and dichloromethane (CH.sub.2Cl.sub.2) (1:1) as eluent obtaining 1.78 g (90% yield) of 2-bromo-8H-indeno[2,1-b]thiophen-8-one having formula (13), as a yellow-orange powder, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.47 (ddd, 1H), 7.34 (td, 1H), 7.19 (td, 1H), 7.17 (s, 1H); 7.13 (ddd, 1H).

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-one having formula (14)

(30) In a 100 ml flask, a mixture of 2-bromo-8H-indeno[2, 1-b]thiophen-8-one having formula (13) (0.21 g, 0.78 mmol), obtained as described above, 5-tributylstannyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (7) (0.71 g, 0.94 mmol), obtained as described in Example 2, and tetrakis(triphenylphosphine) palladium(0) [Pd(PPh.sub.3).sub.4](91 mg, 0.077 mmol) in 50 ml of anhydrous toluene, was heated at the reflux temperature of the solvent for 20 hours. Subsequently, the reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 30 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was washed with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), subsequently with water (220 ml), and then was dried over magnesium sulphate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of petroleum ether and dichloromethane (CH.sub.2Cl.sub.2) (1:2) as eluent obtaining 0.30 g (60% yield) 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-one having formula (14), as a dark orange solid, which was characterized by .sup.1H NMR (500 MHz, CDCl.sub.3) obtaining the following spectrum: 7.48 (d, 1H), 7.36 (ddd, 1H), 7.21-7.16 (m, 5H), 7.13 (d, 1H), 7.08 (d, 1H), 6.96 (d, 1H), 2.78 (t, 4H), 1.74-1.61 (m, 4H), 1.40-1.27 (m, 20H), 0.87 (t, 6H).

(31) Said compound having formula (14) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 185.2, 159.1, 151.5, 140.7, 140.0, 139.2, 137.8, 136.9, 134.8, 133.9, 133.6, 133.4, 132.4, 130.1, 130.0, 128.5, 128.4, 126.4, 126.1, 124.0, 123.7, 119.5, 115.8, 31.8, 30.7, 30.5, 29.5, 29.4, 29.3, 29.2, 22.6, 14.0.

(32) Furthermore, said compound having formula (14) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 656.4 and 656.2275 (<1 ppm), respectively, calculated for C.sub.39H.sub.44OS.sub.4: 656.2275

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-carboxycyanovinylene having formula (Ic)

(33) In a 250 ml flask, 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-one having formula (14) (0.27 g, 0.41 mmol), obtained as described above, was mixed with cyanoacetic acid (NCCH.sub.2COOH) (71 mg, 0.82 mmol) and with a solution of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.16 g, 2.46 mmol) in 80 ml glacial acetic acid (CH.sub.3COOH): the obtained solution was heated at the reflux temperature of the solvent, for 72 hours. The obtained reaction mixture was slowly cooled to room temperature (25 C.), obtaining a dark precipitate which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 0.15 g, (50% yield) of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-8H-indeno[2,1-b]thiophen-8-carboxycyanovinylene having formula (Ic), as a black solid, which was characterized by .sup.1H NMR (300 MHz, THF-d.sub.8) obtaining the following spectrum: 8.50 (d, 1H), 7.47-7.41 (m, 3H), 7.36 (ddd, 1H) 7.32 (d, 1H), 7.24 (ddd, 1H), 7.20 (d, 1H), 7.13 (d, 1H), 6.99 (d, 1H), 2.86-2.79 (m, 4H), 1.50-1.62 (m, 4H), 1.39-1.29 (m, 20H), 0.88 (t, 6H).

(34) Said compound having formula (Ic) was also characterized by .sup.13C NMR (75 MHz, THF-d.sub.8) obtaining the following spectrum: 155.1, 152.5, 152.3, 141.5, 140.5, 140.4, 138.7, 137.6, 135.7, 135.3, 134.7, 132.6, 132.5, 130.7, 130.6, 129.1, 128.2, 127.2, 126.9, 126.8, 125.0, 120.7, 117.3, 116.1, 32.7, 31.4, 31.2, 30.3, 30.2, 30.1, 30.0, 29.9, 23.3, 14.2.

(35) Furthermore, said compound having formula (Ic) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 723.8 and 723.2333 (<1 ppm), respectively, calculated for C.sub.42H.sub.45NO.sub.2S.sub.4: 723.2333.

Example 4

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]-thiophen-6(5H)-carboxycyanovinylene having formula (Id)

(36) ##STR00008##

Synthesis of 3-(3-thienyl)propionic acid having formula (16)

(37) In a 100 ml flask, 1.52 g of palladium on activated charcoal (PdC) (10% by weight of Pd) and ammonium formate (3.23 g, 51.22 mmol), were added to a solution of 3-(3-thienyl)acrylic acid having formula (15) (2.6 g, 17 mmol) in 40 ml of iso-propanol (iPrOH): the obtained reaction mixture was heated at the reflux temperature of the solvent, for 6 hours. Subsequently, the reaction mixture was cooled to room temperature (25 C.), filtered through Celite 545 and subsequently evaporated under reduced pressure. The obtained residue was dissolved in 50 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was treated with 20 ml of a hydrochloric acid (HCl) solution (0.1 M). The obtained organic phase was washed with water (310 ml) and subsequently evaporated at reduced pressure obtaining 2.3 g (90% yield) of 3-(3-thienyl)propionic acid having formula (16), as a colorless solid, which was characterized by 1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.28 (dd, 1H), 7.01-6.99 (m, 1H), 6.96 (d, 1H), 2.89 (t, 2H), 2.69 (t, 2H).

Synthesis of 3-(2,5-dibromothiophen-3-yl)propionic acid having formula (17)

(38) In a 100 ml flask, a solution of bromine (Br.sub.2) (1.28 ml, 0.02 mol) in 30 ml of chloroform was added to a solution of 3-(3-thienyl)propionic acid having formula (16) 1.9 g (12.16 mol), obtained as disclosed above, in 30 ml of chloroform, at 0 C. The obtained reaction mixture was heated at room temperature (25 C.), stirred for additional 2 hours and subsequently poured into ice. Subsequently, the cooled reaction mixture was extracted with diethyl ether (240 ml). The overall organic phase (obtained by joining the organic phases obtained as described above, was washed with a saturated aqueous solution of sodium chloride (NaCl) (320 ml) and then dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure obtaining, after crystallization from hexane, 2.41 g (64% yield) of 3-(2,5-dibromothiophen-3-yl)propionic acid having formula (17), as a colorless solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 6.82 (s, 1H), 2.86 (t, 2H), 2.63 (t, 2H).

Synthesis of 2-bromo-4,5-dihydroeyclopenta[b]thiophen-6-one having formula (18)

(39) In a 50 ml flask, 3-(2,5-dibromothiophen-3-yl)propionic acid having formula (17) (0.65 g, 2.07 mmol), obtained as described above, was treated with 0.75 ml of thionyl chloride (SOCl.sub.2) and the obtained reaction mixture was heated at the reflux temperature of the solvent, for 5 minutes. Subsequently, the reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained yellow oil was dissolved in 15 ml of dichloromethane (CH.sub.2Cl.sub.2): subsequently, aluminum trichloride (AlCl.sub.3) (0.82 g, 6.21 mmol) was added and the obtained reaction mixture was heated at the reflux temperature of the solvent, for 10 minutes. Subsequently, the obtained reaction mixture was cooled to room temperature (25 C.) and then treated with a mixture of crushed ice and 20 ml of hydrochloric acid (HCl) solution (0.1 M). Subsequently, the cooled reaction mixture was extracted with chloroform (220 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was washed with a diluted aqueous solution of sodium hydroxide (NaOH), with a hydrochloric acid (HCl) solution (0.1 M) (220 ml), then with water (420 ml) and subsequently dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using dichloromethane (CH.sub.2Cl.sub.2) as eluent obtaining 0.13 g (32% yield) of 2-bromo-4,5-dihydroeyclopenta[b]thiophen-6-one having formula (18), as a colorless powder, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.09 (s, 1H), 3.03-3.00 (m, 2H), 2.91-2.87 (m, 2H).

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]-thiophen-6(5H)-one having formula (19)

(40) In a 100 ml flask, a mixture of 2-bromo-4,5-dihydroeyclopenta[b]thiophen-6-one having formula (18) (0.12 g, 0.53 mmol), obtained as described above, 5-tributylstannyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (7) (0.40 g, 0.53 mmol), obtained as described in Example 2, and tetrakis(triphenylphosphine) palladium(0) [Pd(PPh.sub.3).sub.4](0.062 g, 0.053 mmol) in 30 ml of anhydrous toluene, was heated at the reflux temperature of the solvent, for 20 hours. Subsequently, the obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 40 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was washed with a 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (210 ml), then with water (320 ml) and subsequently dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (2:1) as eluent obtaining 0.20 g (63% yield) of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]thiophen-6(5H)-one having formula (19), as an orange solid, which was characterized by .sup.1H NMR (500 MHz, CDCl.sub.3) obtaining the following spectrum: 7.20 (d, 1H), 7.16 (s, 1H), 7.11 (d, 1H), 7.08 (d, 1H), 6.95 (d, 2H), 3.03-3.00 (m, 2H), 2.96-2.93 (m, 2H), 2.78 (t, 4H), 1.70-1.59 (m, 4H), 1.39-1.26 (m, 20H), 0.87 (t, 6H).

(41) Said compound having formula (19) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 196.7, 169.2, 152.2, 140.7, 140.0, 138.4, 136.9, 134.9, 133.8, 132.5, 130.1, 130.0, 128.7, 126.4, 126.1, 124.0, 119.4, 40.5, 31.8, 30.7, 30.5, 29.5, 29.4, 29.3, 29.2, 24.1, 22.6, 14.0.

(42) Furthermore, said compound having formula (19) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 608.3 and 608.2277 (3.2 ppm), respectively, calculated for C.sub.35H.sub.44OS.sub.4: 608.2275.

Synthesis of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]-thiophen-6(5H)-carboxycyanovinylene having formula (Id)

(43) In a 100 ml flask, 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]thiophen-6(5H)-one having formula (19) (0.18 g, 0.29 mmol), obtained as described above, was mixed with cyanoacetic acid (NCCH.sub.2COOH) (0.051 g, 0.59 mmol) and with a solution of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.14 g, 1.78 mmol) in 80 ml of glacial acetic acid (CH.sub.3COOH): the obtained solution was heated at the reflux temperature of the solvent, for 72 hours. The obtained reaction mixture was slowly cooled to room temperature (25 C.), obtaining a dark precipitate which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 0.035 g (17% yield) of 2-(3,3-dioctyl-[2,2:5,2-terthiophen]-5-yl)-4H-cyclopenta[b]thiophen-6(5H)-carboxy-cyanovinylene having formula (Id), as a black solid, which was characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M-CO.sub.2]: 631.5 and 631.2444 (1 ppm), respectively, calculated for [C.sub.38H.sub.45NO.sub.2S.sub.4CO.sub.2]: 631.2435.

Example 5

Synthesis of 5-carboxycyanovinylen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (Ie)

(44) ##STR00009##

Synthesis of 5-formyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (20)

(45) In a 100 ml flask, a Vilsmeier reagent, which was prepared with phosphorous oxychloride (POCl.sub.3) (0.5 ml, 5.3 mmol) in dry dimethylformamide (DMF) (3 ml), was added to a cold solution (0 C.) of 3,3-dioctyl-2,2:5,2-terthiophene having formula (3) (0.36 g, 0.35 mmol), obtained as described in Example 1, in 50 ml of 1,2-dichloroethane, under argon (Ar) atmosphere. After being stirred, at 70 C., for 24 hours, the obtained reaction mixture was cooled to room temperature (25 C.), diluted with dichloromethane (CH.sub.2Cl.sub.2), treated with a solution of sodium acetate (C.sub.2H.sub.3NaO.sub.2), then stirred at room temperature (25 C.), for 2 hours, and subsequently extracted with dichloromethane (CH.sub.2Cl.sub.2) (320 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was washed with water (220 ml), subsequently with brine (210 ml), and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (1:1) as eluent obtaining 1.58 g (89% yield) of 5-formyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (20) which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.59 (s, 1H), 7.27 (dd, 2H), 7.10 (d, 1H), 6.96 (d, 1H), 2.85-2.75 (m, 4H), 1.17-1.54 (m, 4H), 1.14-1.26 (m, 20H), 0.88-0.85 (m, 6H).

Synthesis of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (21)

(46) In a 250 ml flask, N-bromosuccinimide (NBS) (0.61 g, 3.44 mmol) was added, in small portions, to a solution of 5-formyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (20) (1.57 g, 3.13 mmol), obtained as described above, in 100 ml of a mixture of chloroform and acetic acid (1:1), at 0 C. The reaction mixture was heated at room temperature (25 C.) and stirred for additional 3 hours. Subsequently, the obtained reaction mixture was poured into water and extracted with dichloromethane (CH.sub.2Cl.sub.2) (420 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was thoroughly washed with water, 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3), brine, again with water, and then was dried over sodium sulfate (Na.sub.2SO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using petroleum ether as eluent obtaining 1.6 g (89% yield) 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (21), as a slightly yellow oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.59 (s, 1H), 7.23 (d, 1H), 7.05 (d, 1H), 6.91 (s, 1H), 2.81 (t, 2H), 2.71 (t, 2H), 1.73-1.56 (m, 4H), 1.14-1.26 (m, 20H), 0.89-0.85 (m, 6H).

Synthesis of 2,5-bis(tributylstannyl)-3,4-ethylenedioxythiophene having formula (23)

(47) In a 100 ml flask n-butyl lithium (LiBu) (5.8 ml, 2.5 M in hexane, 14.8 mmol) was added dropwise, at 20 C., to a solution containing 3,4-ethylenedioxythiophene having formula (22) (1 g, 7.04 mmol) dissolved in 30 ml of dry tetrahydrofurane (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 1 hour, at 20 C. Subsequently, tributyltin chloride (SnBu.sub.3Cl) (4.2 ml, 14.8 mmol) was added, dropwise, and the reaction mixture was maintained, under stirring, at 20 C., for 30 minutes: then, the reaction mixture was allowed to warm slowly to room temperature (25 C.). After dilution with diethyl ether (30 ml), a saturated aqueous solution of sodium fluoride (NaF) was added and the reaction mixture was stirred, for 1 hour, at room temperature (25 C.). The obtained precipitate was filtered off by using Celite 545 and the obtained filtrate was washed with a saturated aqueous solution of sodium bicarbonate (NaHCO.sub.3), subsequently with water and then was dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure obtaining 2,5-bis(tributylstannyl)-3,4-ethylenedioxythiophene having formula (23) which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 4.11 (s, 4H), 1.64-1.44 (m, 12H), 1.38-1.26 (m, 12H), 1.12-1.05 (m, 12H), 0.94-0.86 (m, 18H).

Synthesis of 5-formyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (24)

(48) In a 100 ml flask, a mixture of 5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (4) (0.4 g, 0.8 mmol), obtained as described in Example 1, 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (21) (0.5 g, 0.8 mmol), obtained as described above, 2,5-bis(tributylstannyl)-3,4-ethylenedioxythiophene having formula (23) (0.49 g, 0.68 mmol), obtained as described above, and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4](0.10 g, 0.085 mmol) in 50 ml of anhydrous toluene, was heated at the reflux temperature of the solvent, for 12 hours. Subsequently, the obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 50 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was washed with a saturated aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), then with water (310 ml) and subsequently dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using a mixture of dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (1:1) as eluent obtaining 0.19 g (20% yield) of 5-formyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (24), as a reddish solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.59 (s, 1H), 7.24-7.20 (m, 2H), 7.18 (d, 1H), 7.12-7.04 (m, 4H), 6.96-6.93 (m, 1H), 4.42 (s, 4H), 2.86-2.75 (m, 8H), 1.73-1.60 (m, 8H), 1.14-1.12 (m, 40), 0.90-0.85 (m, 12H).

(49) Said compound having formula (24) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.6, 141.2, 140.4, 140.1, 139.7, 139.6, 137.9, 137.6, 135.8, 134.1, 132.9, 132.0, 130.3, 130.0, 129.3, 128.3, 127.8, 126.0, 125.9, 125.7, 123.7, 109.8, 109.2, 65.0, 64.9, 31.8, 30.7, 30.5, 30.3, 29.7, 29.6, 29.5, 29.4, 29.2, 22.6, 14.1.

(50) Furthermore, said compound having formula (24) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 1110.4 and 1110.4408 (0.1 ppm), respectively, calculated for C.sub.63H.sub.82O.sub.3S.sub.7: 1110.4309.

Synthesis of 5-carboxycyanovynilen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (Ie)

(51) In a 100 ml flask, 5-formyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (24) (0.13 g, 0.12 mmol), obtained as described above, was mixed with cyanoacetic acid (NCCH.sub.2COOH) (0.02 g, 0.23 mmol) and with a solution of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.05 g, 0.58 mmol) in 40 ml glacial acetic acid (CH.sub.3COOH): the obtained solution was heated at the reflux temperature of the solvent, for 12 hours. The obtained reaction mixture was slowly cooled to room temperature (25 C.), obtaining a dark precipitate which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 0.10 g (73% yield) of 5-carboxycyanovynilen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (Ie), as a black solid, which was characterized by .sup.1H NMR (300 MHz, THF-d.sub.8) obtaining the following spectrum: 8.22 (s, 1H) 7.62 (s, 1H), 7.33 (d, 1H), 7.18 (d, 2H), 7.14 (d, 1H), 7.08-7.04 (m, 4H), 6.94 (d, 1H), 4.43 (s, 4H), 2.84-2.74 (m, 8H), 1.7-1.60 (m, 8H), 1.14-1.12 (m, 40), 0.90-0.85 (m, 12H).

(52) Said compound having formula (Ie) was also characterized by .sup.13C NMR (75 MHz, THF-d.sub.8) obtaining the following spectrum: 163.8, 145.9, 141.6, 141.1, 140.8, 140.3, 139.3, 139.2, 139.0, 136.6, 134.6, 134.2, 134.0, 133.2, 130.8, 130.6, 129.7, 129.0, 126.8, 126.6, 126.4, 126.3, 124.7, 116.3, 110.1, 109.5, 99.7, 32.6, 31.4, 31.2, 30.9, 30.3, 30.2, 30.0, 29.8, 23.3, 14.2.

(53) Furthermore, said compound having formula (Ie) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 1177.4 and 1177.4358 (0.1 ppm), respectively, calculated for C.sub.66H.sub.83NO.sub.4S.sub.7: 1177.4367.

Example 6

Synthesis of 5,5-dicarboxycyanovinylen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (If)

(54) ##STR00010##

Synthesis of 5,5-diformyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (25)

(55) In a 50 ml flask, a mixture of 2,5-bis(tributylstannyl)-3,4-ethylenedioxythiophene having formula (23) (0.28 g, 0.39 mmol), obtained as described in Example 5, 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (21) (0.50 g, 0.86 mmol), obtained as described in Example 5, and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4](0.10 g, 0.085 mmol) in 20 ml of anhydrous toluene, was heated at the reflux temperature of the solvent for 12 h. Subsequently, the obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The obtained residue was dissolved in 30 ml of dichloromethane (CH.sub.2Cl.sub.2) and the obtained solution was washed with a saturated aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), then with water (410 ml) and subsequently dried over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours. The solvent was subsequently evaporated at reduced pressure and the obtained residue was purified by chromatography on silica gel using dichloromethane (CH.sub.2Cl.sub.2) as eluent obtaining 0.11 g (44% yield) of 5,5-diformyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (25), as a reddish solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 2H), 7.59 (s, 2H), 7.53 (d, 2H), 7.15-7.05 (m, 4H), 4.42 (s, 4H), 2.86-2.75 (m, 8H), 1.73-1.60 (m, 8H), 1.14-1.12 (m, 40), 0.90-0.85 (m, 12H).

(56) Said compound having formula (25) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.5, 141.2, 140.5, 140.2, 140.1, 139.1, 138.4, 137.9, 134.2, 132.8, 128.5, 127.9, 126.0, 125.8, 109.6, 65.0, 31.9, 31.8, 30.5, 30.3, 29.6, 29.5, 29.4, 29.3, 29.2, 22.6, 14.1.

(57) Furthermore, said compound having formula (25) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 1138.3 and 1110.4254 (0.1 ppm), respectively, calculated for C.sub.64H.sub.82O.sub.4S.sub.7: 1138.4258.

Synthesis of 5,5-dicarboxycyanovinylen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (If)

(58) In a 100 ml flask, 5,5-diformyl-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (25) (0.11 g, 0.96 mmol), obtained as described above, was mixed with cyanoacetic acid (NCCH.sub.2COOH) (0.033 g, 0.38 mmol) and with a solution of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.062 g, 0.77 mmol) in 30 ml glacial acetic acid (CH.sub.3COOH): the obtained solution was heated at the reflux temperature of the solvent, for 12 hours. The obtained reaction mixture was slowly cooled to room temperature (25 C.), obtaining a dark precipitate which was recovered by filtration and washed with a diluted aqueous solution of sodium hydroxide and then with water obtaining 0.10 g (82% yield) of 5,5-dicarboxycyanovinylen-[3,3,3,3-tetraoctyl]-3,4-ethylenedioxy-2,2:5,2:5,2:5,5:2,2:5,2-heptathiophene having formula (If), as a black solid, which was characterized by .sup.1H NMR (300 MHz, THF-d.sub.8) obtaining the following spectrum: 8.29 (s, 2H), 7.76 (s, 2H), 7.40 (d, 2H), 7.22 (d, 2H), 7.15 (s, 2H), 4.44 (s, 4H), 2.92-2.81 (m, 8H), 1.72 region (8H are under the THF signal), 1.46-1.30 (m, 40), 0.91-0.86 (m, 12H).

(59) Said compound having formula (If) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 1272.4 and 1272.43998 (2 ppm), respectively, calculated for C.sub.70H.sub.84N.sub.2O.sub.6S.sub.7: 1272.4374.

Example 7

Preparation of Dye-Sensitized Solar Cell (DSSC)

(60) Titanium dioxide (TiO.sub.2) electrodes were prepared by spreading (doctor-blade technique) a colloidal paste containing a 20 nm sized titanium dioxide (TiO.sub.2) particles (TiO.sub.2 Paste DSL 18NR-TDyesol) on a conductive FTO glass (Hartford Glass Co., TEC 8, having a thickness of 2.3 mm and a sheet resistance of 6 /cm.sup.2-9 /cm.sup.2), previously cleaned with water and ethanol, immersed in a freshly prepared aqueous titanium tetrachloride (TiCl.sub.4) solution (4.510.sup.2 M), at 70 C., for 30 minutes, and finally washed with ethanol.

(61) After a first drying at 125 C., for 15 minutes, a reflecting scattering layer containing >100 nm sized titanium dioxide (TiO.sub.2) particles (Ti-Nanoxide R/SPSolaronix) was spread (doctor-blade technique) over the first titanium dioxide (TiO.sub.2) layer and sintered till 500 C., for 30 minutes. The titanium dioxide (TiO.sub.2) film-coated glass was cooled to room temperature (25 C.) and immersed again in a freshly prepared aqueous titanium tetrachloride (TiCl.sub.4) solution (4.510.sup.2 M), at 70 C., for 30 minutes, finally washed with ethanol and sintered at 500 C., for 30 minutes, obtaining a final thickness of the electrode of 12 m.

(62) After sintering, the titanium dioxide (TiO.sub.2) film-coated glass was cooled at about 80 C.-100 C. and immediately immersed into a dichloromethane (CH.sub.2Cl.sub.2) solution (510.sup.4 M] of the compound having formula (Ia), obtained as described in Example 1, at room temperature (25 C.), for 24 h. The dyed titania-glass was washed with ethanol and dried at room temperature (25 C.), under a nitrogen (N.sub.2) flux.

(63) A 50 m thick Surlyn spacer (TPS 065093-50Dyesol) was used to seal the photoanode obtained as described above and the counter electrode constituted of a platinized FTO glass (Hartford Glass Co., TEC 8, having a thickness of 2.3 mm and a sheet resistance of 6 /cm.sup.2-9 /cm.sup.2), subsequently the cell was filled up with the electrolyte solution having the following composition: N-methyl-N-butylimidazolium iodide (0.6 M), iodine (0.04 M), lithium iodide (LiI) (0.025 M), guanidinium-thiocyanate (0.05 M) and t-butylpyridine (0.28 M), in a 15:85 (v/v) mixture of valeronitrile and acetonitrile.

(64) The active area of the cell, calculated by means of a microphotography, was 0.1168 cm.sup.2.

(65) The photovoltaic performance of the cell was measured with a solar simulator (Abet 2000) equipped with a 300 W Xenon light source, the light intensity was adjusted with a standard calibrated Si solar cell (VLSI Standard SRC-1000-RTD-KGS), the current-voltage characteristics were acquired by applying an external voltage to the cell and measuring the generated photocurrent with a Keithley 2602A (3 A DC, 10 A Pulse) digital source meter. The following results were obtained:

(66) Voc (open circuit photovoltage)=685 mV;

(67) FF (fill factor)=65.5%;

(68) Jsc (short-circuit photocurrent density)=21.67 mA/cm.sup.2;

(69) (photoelectric transformation efficiency)=9.72%.

Example 8

Preparation of Dye-Sensitized Solar Cell (DSSC)

(70) With the same procedure described in Example 3, a dye-sensitized solar cell (DSSC) was prepared by using an organic dye of formula (Ib) obtained as described in Example 2, and employing an electrolyte solution having the following composition: N-methyl-N-butylimidazolium iodide (0.6 M), iodine (0.04 M), lithium iodide (LiI) (0.025 M), guanidinium-thiocyanate (0.05 M) and t-butylpyridine (0.28 M), in a 15:85 (v/v) mixture of valeronitrile and acetonitrile. In this case the active area of the cell, calculated by means of a microphotography, was 0.0949 cm.sup.2. The photovoltaic performance of the cell was measured as described in Example 3. The following results were obtained:

(71) Voc (open circuit photovoltage)=663 mV;

(72) FF (fill factor)=68.8%;

(73) Jsc (short-circuit photocurrent density)=16.89 mA/cm.sup.2;

(74) (photoelectric transformation efficiency)=7.71%.