Organic dye for dye-sensitized solar cell

Abstract

An organic dye for a dye-sensitized solar cell (DSSC) comprising at least one electron-acceptor unit and at least one -conjugated unit is described. 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 formula (I): ##STR00012## wherein: T.sub.1 is a thiophenyl group of formula (II): ##STR00013## wherein R.sub.4 and R.sub.5 equal to or different from each other, represent a hydrogen atom; or are selected from C.sub.1-C.sub.20 alkyl, linear or branched, saturated or unsaturated; T.sub.2 is a 2,2:5,2-terthiophenyl group of formula (IV): ##STR00014## wherein R.sub.11, R.sub.13, R.sub.14 and R.sub.16, equal to or different from each other, represent a hydrogen atom; or are selected from C.sub.1-C.sub.20 alkyl, linear or branched, saturated or unsaturated; R.sub.12 and R.sub.15, equal to or different from each other, are selected from C.sub.1-C.sub.20 alkyl, linear or branched, saturated or unsaturated; R.sub.1 is a hydrogen atom; or is selected from C.sub.1-C.sub.20 alkyl groups, linear or branched, saturated or unsaturated; R.sub.2 and R.sub.3 are bound to each other to form, together with the other atoms to which they are bound, a saturated cycle containing 4 carbon atoms and two heteroatoms; A is a carboxycyanovinylene group having formula (V): ##STR00015## wherein R.sub.17 represents a hydrogen atom; X and Y, equal to or different from each other, represent oxygen or sulphur; n is 1; m is 0 or 1; p is 0 or 1; and m+p is 1 or 2.

2. The organic dye according to claim 1, wherein R.sub.4 and R.sub.5 represent a hydrogen atom.

3. The organic dye according to claim 1, wherein R.sub.11, R.sub.13, R.sub.14, and R.sub.16 represent a hydrogen atom.

4. The organic dye according to claim 1, wherein R.sub.12 and R.sub.15 are a n-hexyl group.

5. The organic dye according to claim 1, wherein R.sub.1 is a hydrogen atom or a n-hexyl group.

6. The organic dye according to claim 1, wherein R.sub.2 and R.sub.3 are bound to each other to form, together with the other atoms to which they are bound, a saturated cycle containing 4 carbon atoms and two heteroatoms, said heteroatoms being oxygen or sulphur.

7. The organic dye according to claim 1, wherein the dye is free of metal.

8. A dye-sensitized photoelectric transformation element comprising at least one organic dye having formula (I) according to claim 1, said dye-sensitized photoelectric transformation element being supported on oxide semiconductor particles.

9. A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element according to claim 8.

10. The dye-sensitized solar cell according to claim 9, wherein a photoelectric transformation efficiency () of the dye-sensitized solar cell is greater than or equal to 7.5%.

Description

EXAMPLES

(1) Reagents and Materials

(2) The reagents and materials used in the following examples, as well as their manufacturers, have been below reported: 2-bromo-3-octyl-thiophene (Aldrich): used as such; dibromoethane (Aldrich): used as such; anydrous diethyl ether (Aldrich): used as such; magnesium turnings (Aldrich): used as such; 2,5-dibromothiophene (Aldrich): used as such; 2-bromothiophene (Aldrich): used as such; 1,3-bis(diphenylphosphino)propane]dichloronickel(II) [Ni(dppp)Cl.sub.2] (Aldrich): used as such; diethyl ether (Aldrich): used as such; magnesium sulfate (MgSO.sub.4) (Aldrich): used as such; hydrochloric acid (HCl) solution 2 M (Aldrich): used as such; petroleum ether (Aldrich): used as such; phosphorous oxychloride (POCl.sub.3) (Aldrich): used as such; dimethylformamide (DMF) (Aldrich): used as such; 1,2-dichloroethane (C.sub.2H.sub.4Cl.sub.2) (Aldrich): used as such; dichloromethane (CH.sub.2Cl.sub.2) (Aldrich): used as such; sodium acetate (C.sub.2H.sub.3NaO.sub.2) (Aldrich): used as such; N-bromosuccinimide (Aldrich): used as such; chloroform (Aldrich): used as such; acetic acid (Aldrich): used as such; sodium sulfate (Na.sub.2SO.sub.4) (Aldrich): used as such; n-butil lithium (Aldrich): used as such; hexane (Carlo Erba): used as such; 3,4-ethylenedioxythiophene (EDOT) (Aldrich): used as such; tetrahydrofuran (THF) (Aldrich): used as such; anhydrous tetrahydrofuran (Aldrich): used as such; 1-bromohexane (Aldrich): used as such; ammonium chloride (NH.sub.4Cl) (Aldrich): used as such; tri-n-butyl tin chloride (Aldrich): used as such; tri-n-butyl tin bromide (Aldrich): used as such; sodium fluoride (NaF) (Aldrich): used as such; sodium bicarbonate (NaHCO.sub.3) (Aldrich): used as such or in aqueous solution 1 M; Celite 545 (Aldrich): used as such; tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4] (Aldrich): used as such; anhydrous toluene (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; 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-(tri-butylstannyl)thiophene (Aldrich): used as such; 3,4-ethylenedithiothiophene (Aldrich): used as such.

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

(4) NMR Spectra

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

(6) 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.

(7) Mass Spectra

(8) 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-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2quaterthiophene having Formula (Ia)

(9) ##STR00007##

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

(10) 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)

(11) A solution containing 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] (0.18 g, 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 2 M hydrochloric acid (HCl) solution. 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, then with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3), then with brine, again with water, and finally 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-formyl-3,3-dioctyl-2,2:5,2-terthiophene having Formula (4)

(12) A Vilsmeier reagent, which was prepared adding 0.5 ml (5.3 mmol) of phosphorous oxychloride (POCl.sub.3) in 3.0 ml of dry dimethylformamide (DMF) was added, in a 100 ml flask, to a cold solution (0 C.) of 3,3-dioctyl-2,2:5,2-terthiophene having formula (3) (1.67 g, 3.53 mmol), obtained as described above, in 1,2-dichloroethane (C.sub.2H.sub.4Cl.sub.2) (50 ml), under argon (Ar) atmosphere. The obtained reaction mixture was stirred at 70 C., for 24 hours, subsequently cooled to room temperature (25 C.) and diluted with 25 ml of dichloromethane (CH.sub.2Cl.sub.2). The obtained reaction mixture was treated with 50 ml of an aqueous solution of sodium acetate (C.sub.2H.sub.3NaO.sub.2) and stirred for 2 hours, at room temperature (25 C.), obtaining an organic phase and an aqueous phase which were separated. The organic phase was washed with water (210 ml), brine (210 ml) and 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, v/v) as eluent obtaining 1.57 g (89% yield) of 5-formyl-3,3-dioctyl-2,2:5,2-terthiophene having formula (4) 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 (5)

(13) In a 100 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 (4) (1.57 g, 3.13 mmol), obtained as described above, in 100 ml of a mixture of chloroform and acetic acid (1:1, v/v), at 0 C. The 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, 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) of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5), 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-n-hexyl-3,4-ethylenedioxythiophene having Formula (7)

(14) In a 100 ml flask, n-butil lithium (n-BuLi) (14.7 ml, 2.5 M in hexane, 36.9 mmol) was added, dropwise, at 0 C., to a solution containing 3,4-ethylenedioxythiophene (EDOT) having formula (6) (5.0 g, 35.2 mmol), dissolved in 40 ml of tetrahydrofuran (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 1 hour, at 78 C. Subsequently, 1-bromohexane (6.5 ml, 45 mmol) was added, dropwise, at 78 C. and the obtained reaction mixture was stirred, for 30 minutes, at 78 C., and then allowed to warm slowly to room temperature (25 C.) and stirred for additional 12 hours. After dilution with diethyl ether (30 ml), a saturated aqueous solution of ammonium chloride (NH.sub.4Cl) was added and the reaction mixture was stirred, for 1 hour, at room temperature (25 C.). After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure and the residue was distillate with a Kugelrhor apparatus, operating at 160 C. and at 10 mbar, obtaining 2.2 g (30% yield) of 2-n-hexyl-3,4-ethylenedioxythiophene having formula (7), which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 6.10 (s, 1H), 4.17 (s, 4H), 2.62 (t, 2H), 1.61-1.55 (m, 2H), 1.40-1.31 (m, 6), 0.88 (t, 3H).

Synthesis of 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedioxythiophene having Formula (8)

(15) In a 100 ml flask, n-butil lithium (n-BuLi) (1.95 ml, 2.5 M in hexane, 4.86 mmol) was added dropwise, at 20 C., to a solution containing 2-n-hexyl-3,4-ethylenedioxythiophene having formula (7) (1.0 g, 4.42 mmol), obtained as described above, in 40 ml of tetrahydrofuran (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 1 hour, at 20 C. Subsequently, tri-n-butyl tin bromide (SnBu.sub.3Br) (1.51 ml, 5.30 mmol) was added, dropwise, at 20 C., and the obtained reaction mixture was stirred, for 30 minutes, at 20 C., and then 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), then with water. After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure obtaining 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedioxythiophene having formula (8), which was used in the following steps without further purifications.

(16) Said compounds having formula (8) was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 4.12 (s, 4H), 2.62 (t, 2H), 1.61-1.55 (m, 8H), 1.45-1.28 (m, 12), 1.05 (t, 6H), 0.91-0.86 (m, 12H).

Synthesis of 5-formyl-3,3-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2-quaterthiophene having Formula (9)

(17) In a 100 ml flask, a mixture of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5) (0.20 g, 0.35 mmol), obtained as described above, 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedioxythiophene having formula (8) (0.21 g, 0.41 mmol), obtained as described above, and tetrakis(triphenylphosphine) palladium(0) [Pd(PPh.sub.3).sub.4] (20 mg, 0.017 mmol), in 50 ml of anhydrous toluene, was heated at the reflux temperature of the solvent overnight. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The residue was dissolved in 30 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) (220 ml), subsequently with water (320 ml) and finally 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, v/v) as eluent obtaining 0.12 g (48% yield) of 5-formyl-3,3-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2-quaterthiophene having formula (9), as a yellowish oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.82 (s, 1H), 7.59 (s, 1H), 7.24 (d, 1H), 7.09 (d, 1H), 6.96 (s, 1H), 4.34-4.32 (m, 2H), 4.24-4.21 (m, 2H), 2.85-2.72 (m, 4H), 2.66-2.61 (m, 2H), 1.71-1.60 (m, 6H), 1.40-1.23 (m, 26), 0.91-0.84 (m, 9H).

(18) Said compound having formula (9) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.8, 141.1, 140.9, 140.7, 140.4, 139.7, 139.0, 138.4, 138.1, 134.2, 128.2, 127.5, 125.8, 125.2, 117.2, 107.6, 65.6, 64.9, 32.2, 31.9, 30.8, 30.7, 30.6, 29.9, 29.8, 29.7, 29.6, 29.1, 26.0, 23.0, 22.9, 14.2.

(19) Furthermore, said compound having formula (9) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 724.3110; calculated for C.sub.41H.sub.56O.sub.3S.sub.4: 724.3112.

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2-quaterthiophene having Formula (Ia)

(20) In a 250 ml flask, were introduced 80 mg (0.11 mmol) of 5-formyl-3,3-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2-quaterthiophene having formula (9), obtained as described above, and mixed with cyanoacetic acid (NCCH.sub.2COOH) (20 mg, 0.22 mmol), ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (53 mg, 0.66 mmol) and 20 ml of glacial acetic acid (CH.sub.3COOH). The obtained reaction mixture was heated at the reflux temperature of the solvent, for 12 hours, and subsequently 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 water obtaining 80 mg (92% yield) of 5-carboxycyanovinylen-3,3-dioctyl-3,4ethylenedioxy-5-hexyl-2,2:5,2:5,2-quaterthiophene having formula (Ia), as a black solid, which was characterized by .sup.1H NMR (300 MHz, THF-d.sup.8) obtaining the following spectrum: 8.21 (s, 1H), 7.68 (s, 1H), 7.31 (d, 1H), 7.11 (d, 1H), 6.94 (s, 1H), 4.25-4.24 (m, 2H), 4.15-4.14 (m, 2H), 2.81 (t, 2H), 2.73 (t, 2H), 2.57 (t, 2H), 1.55-1.52 (m, 2H), 1.37-1.22 (m, 30), 0.91-0.84 (m, 9H).

(21) Said compound having formula (Ia) was also characterized by .sup.13C NMR (75 MHz, THF-d.sup.8) obtaining the following spectrum: 163.8, 146.0, 141.7, 140.9, 140.7, 139.0, 138.8, 135.0, 134.2, 126.9, 126.3, 125.3, 116.7, 116.3, 108.1, 99.6, 66.0, 65.2, 32.6, 32.3, 31.2, 31.1, 30.9, 30.3, 30.2, 30.1, 30.0, 29.8, 29.4, 26.2, 23.4, 23.3, 14.2.

(22) Furthermore, said compound having formula (Ia) was also characterized by mass spectra: FIRMS (ESI) obtaining: [M]: 791.3196; calculated for C.sub.44H.sub.57NO.sub.4S.sub.4: 791.3170.

Example 2

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (Ib)

(23) ##STR00008##

Synthesis of 3,4-ethylenedioxy-5-n-hexyl-2,2-dithiophene having Formula (10)

(24) In a 100 ml flask, a mixture of 2-bromothiophene (0.75 g, 4.5 mmol), 2-tri-n-butyl stannyl-5-n-hexyl-3,4-ethylenedioxythiophene having formula (8) (2.91 g, 5.63 mmol), obtained as described in Example 1, and tetrakis(triphenylphosphine) palladium(0) [Pd(PPh.sub.3).sub.4] (0.26 g, 0.22 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 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 (210 ml), then with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (210 ml), then with brine (210 ml), again with water (210 ml), and finally 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 0.78 g (56% yield) of 3,4-ethylenedioxy-5-n-hexyl-2,2-dithiophene having formula (10), as a yellowish oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.16 (dd, 1H), 7.14 (dd, 1H), 7.00 (dd, 1H), 4.32-4.29 (m, 2H), 4.24-4.20 (m, 2H), 2.63 (t, 2H), 1.65-1.55 (m, 2H), 1.39-1.27 (m, 6), 0.92-0.86 (m, 3H).

(25) Said compound having formula (10) was also characterized by .sup.13C NMR (300 MHz, CDCl.sub.3): 137.4, 137.2, 135.1, 126.9, 122.9, 121.9, 116.1, 107.8, 65.0, 64.5, 31.5, 30.3, 28.7, 25.6, 22.5, 14.1.

(26) Furthermore, said compound having formula (10) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 309.09 and 309.0980, respectively; calculated for C.sub.16H.sub.20O.sub.2S.sub.2: 308.0905.

Synthesis of 3,4-ethylenedioxy-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having Formula (11)

(27) In a 100 ml flask, n-butil lithium (n-BuLi) (1.95 ml, 2.5 M in hexane, 4.86 mmol) was added dropwise, at 78 C., to a solution containing 3,4-ethylenedioxy-5-n-hexyl-2,2-dithiophene having formula (10) (0.41 g, 1.12 mmol), obtained as described above, in 40 ml of tetrahydrofuran (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 1 hour, at 78 C. Subsequently, tri-n-butyl tin bromide (1.51 ml, 5.30 mmol) was added, dropwise, at 40 C. and the obtained reaction mixture was stirred, for 30 minutes, at 40 C., and then 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) then with water. After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure obtaining 3,4-ethylenedioxy-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having formula (11), which was used in the following steps without further purification.

(28) Said compound having formula (11) was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.27 (d, 2H), 7.04 (d, 2H), 4.32-4.29 (m, 2H), 4.24-4.20 (m, 2H), 2.63 (t, 2H), 1.65-1.50 (m, 8H), 1.41-1.24 (m, 12), 1.13-1.06 (m, 6H), 0.94-0.86 (m, 12H).

Synthesis of 5-formyl-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (12)

(29) In a 100 ml flask, a mixture of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5) (0.74 g, 1.34 mmol), obtained as described in Example 1, 3,4-ethylenedioxy-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having formula (11) (0.66 g, 1.12 mmol), obtained as described above, and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4] (77 mg, 0.67 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 extracted with diethyl ether (320 ml). The overall organic phase (obtained by joining the organic phases obtained as described above) was thoroughly washed with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (220 ml), then with water (310 ml), and finally 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 dichloromethane (CH.sub.2Cl.sub.2) as eluent obtaining 0.65 g (72% yield) of 5-formyl-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (12), as a red-orange oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.61 (s, 1H), 7.58 (s, 1H), 7.24 (d, 1H), 7.09 (d, 1H), 7.05-6.99 (m, 3H), 4.33-4.32 (m, 2H), 4.24-4.23 (m, 2H), 2.84-2.72 (m, 4H), 2.64 (t, 2H), 1.69-1.56 (m, 6H), 1.39-1.28 (m, 26), 0.89-0.85 (m, 9H).

(30) Said compound having formula (12) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.4, 141.1, 141.0, 140.1, 140.0, 139.0, 138.2, 137.6, 137.5, 136.0, 134.5, 134.1, 134.0, 128.1, 127.7, 126.0, 125.8, 123.8, 122.3, 116.8, 107.7, 65.1, 64.4, 31.8, 31.5, 30.4, 30.3, 30.2, 29.6, 29.5, 29.4, 29.2, 28.7, 25.7, 22.6, 22.5, 14.1.

(31) Furthermore, said compound having formula (12) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 806.1 and 806.29895, respectively; calculated for C.sub.45H.sub.58O.sub.3S.sub.5: 806.29895.

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (Ib)

(32) In a 250 ml flask, were introduced 0.2 g (0.25 mmol) of 5-formyl-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (12), obtained as described above, and mixed with cyanoacetic acid (NCCH.sub.2COOH) (43 mg, 0.60 mmol), ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (99 mg, 1.24 mmol) and 30 ml of glacial acetic acid (CH.sub.3COOH). The obtained reaction mixture was heated at the reflux temperature of the solvent, for 12 hours, and subsequently 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 water obtaining 150 mg (70% yield) of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedioxy-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (Ib), as black solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 8.20 (s, 1H), 7.60 (s, 1H), 7.30 (d, 1H), 7.10 (d, 1H), 7.04 (d, 1H), 7.01 (d, 1H), 6.97 (s, 1H), 4.34-4.32 (m, 2H), 4.24-4.21 (m, 2H), 2.84-2.73 (m, 4H), 2.64 (t, 2H), 1.72-1.58 (m, 6H), 1.45-1.36 (m, 26), 0.91-0.83 (m, 9H).

(33) Said compound having formula (Ib) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 141.8, 141.2, 140.5, 139.2, 137.9, 137.6, 137.5, 136.2, 134.6, 134.0, 133.6, 132.4, 128.4, 128.1, 126.0, 125.8, 123.9, 122.3, 116.8, 107.8, 65.1, 64.4, 31.9, 31.8, 31.5, 30.3, 30.1, 29.7, 29.6, 29.5, 29.4, 29.2, 28.8, 25.7, 22.6, 22.5, 14.1.

(34) Furthermore, said compound having formula (Ib) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 873.1 and 873.3072, respectively; calculated for C.sub.48H.sub.59NO.sub.4S.sub.5: 873.3048.

Example 3

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4ethylenedioxy-2,2:5,2:5,2quaterthiophene having Formula (Ic)

(35) ##STR00009##

Synthesis of 2-tributylstannyl-3,4-ethylendioxythiophene having Formula (13)

(36) In a 100 ml flask, n-butil lithium (n-BuLi) (3.09 ml, 2.5 M in hexane, 7.73 mmol) was added, dropwise, at 78 C., to a solution of 3,4-ethylendioxythiophene having formula (6) (1.0 g, 7.04 mmol) in 40 ml of dry tetrahydrofuran (THF), under argon (Ar) atmosphere: the reaction mixture was stirred for 1 hour, at 78 C. Tri-n-butyl tin chloride (2.1 ml, 7.4 mmol) was then added, dropwise, at 78 C.: the reaction mixture was stirred, at 78 C., for 30 minutes, and then was allowed to warm slowly to room temperature (25 C.). After dilution with diethyl ether (40 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 using Celite 545 and the obtained filtrate was washed with a saturated solution of sodium bicarbonate (NaHCO.sub.3) (210 ml) then with water (310 ml). After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure obtaining 2-tributylstannyl-3,4-ethylendioxythiophene having formula (13) which was used in the following steps without further purification.

(37) Said compound having formula (13) was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 6.57 (s, 1H), 4.15 (s, 4H), 1.64-1.44 (m, 6H), 1.38-1.26 (m, 6H), 1.12-1.05 (m, 6H), 0.94-0.86 (m, 9H).

Synthesis of 5-formyl-3,3-dioctyl-3,4-ethylendioxy-2,2:5,2:5,2-quaterthiophene having Formula (14)

(38) In a 100 ml flask, a mixture of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5) (0.30 g, 0.52 mmol), obtained as described in Example 1, 2-tributylstannyl-3,4-ethylendioxythiophene having formula (13) (0.24 g, 0.57 mmol), obtained as described above, and tetrakis(triphenylphosphine) palladium(0) [Pd(PPh.sub.3).sub.4] (60 mg, 0.051 mmol), in 50 ml of anhydrous toluene, was heated at reflux temperature of the solvent for 18 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The residue was dissolved in 30 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) (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 (1:1, v/v) as eluent obtaining 0.31 g (94% yield) of 5-formyl-3,3-dioctyl-3,4-ethylendioxy-2,2:5,2:5,2-quaterthiophene having formula (14), as a yellowish oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.82 (s, 1H), 7.59 (s, 1H), 7.24 (d, 1H), 7.11 (d, 1H), 7.05 (s, 1H), 6.24 (s, 1H), 4.37-4.35 (m, 2H), 4.26-4.24 (m, 2H), 2.85-2.74 (m, 4H), 1.72-1.62 (m, 4H), 1.39-1.27 (m, 20), 0.89-0.85 (m, 6H).

(39) Said compound having formula (14) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.5, 141.8, 141.2, 140.3, 140.1, 140.0, 139.1, 138.5, 137.8, 134.0, 133.4, 128.0, 127.8, 125.8, 125.7, 111.8, 97.2, 65.0, 64.5, 31.8, 30.5, 30.2, 29.6, 29.5, 29.4, 29.2, 22.6, 14.1.

(40) Furthermore, said compound having formula (14) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 640.2180 (0.9 ppm); calculated for: C.sub.35H.sub.44O.sub.3S.sub.4: 640.2173.

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylendioxy-2,2:5,2:5,2-quaterthiophene having Formula (Ic)

(41) In a 100 ml flask, were introduced (0.31 g, 0.48 mmol) of 5-formyl-3,3-dioctyl-3,4-ethylendioxy-2,2:5,2:5,2-quaterthiophene having formula (14), obtained as described above, cyanoacetic acid (NCCH.sub.2COOH) (0.083 g, 0.96 mmol), ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) (0.22 g, 0.66 mmol) in 100 ml of glacial acetic acid (CH.sub.3COOH) and the solution was heated at the reflux temperature of the solvent, for 12 hours. After slowly cooling the reaction mixture at room temperature (25 C.), a dark precipitate was formed which was recovered by filtration, washed with 10 ml of a diluted solution of sodium hydroxide and then with water (310 ml) obtaining 0.20 g (61% yield) of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylendioxy-2,2:5,2:5,2-quaterthiophene having formula (Ic), as a black solid, which was characterized by .sup.1H NMR (500 MHz, THF-d.sub.8) obtaining the following spectrum: 8.29 (s, 1H), 7.75 (s, 1H), 7.39 (d, 1H), 7.20 (d, 1H), 7.10 (s, 1H), 6.33 (s, 1H), 4.34-4.33 (m, 2H), 4.23-4.21 (m, 2H), 2.88 (t, 2H), 2.81 (t, 2H), 1.44-1.42 (m, 4H), 1.36-1.29 (m, 20), 0.89-0.86 (m, 6H).

(42) Said compound having formula (Ic) was also characterized by .sup.13C NMR (75 MHz, THF-d.sub.8) obtaining the following spectrum: 163.8, 146.0, 141.7, 140.9, 140.7, 139.0, 138.8, 135.0, 134.2, 126.9, 126.3, 125.3, 116.7, 116.3, 108.1, 99.6, 66.0, 65.2, 32.6, 32.3, 31.2, 31.1, 30.9, 30.3, 30.2, 30.1, 30.0, 29.8, 29.4, 26.2, 23.4, 23.3, 14.2.

(43) Furthermore, said compound having formula (Ic) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 707.2257 (3.6 ppm); calculated for: C.sub.38H.sub.45NO.sub.4S.sub.4: 707.2231.

Example 4

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedioxy-2,2:5,2:5,2:5,2-pentathiophene having Formula (Id)

(44) ##STR00010##

Synthesis of 5-formyl-3,3-di-octyl-2,2:5,2:5,2-quaterthiophene having Formula (16)

(45) In a 100 ml flask, a mixture of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5) (0.50 g, 0.86 mmol), obtained as described in Example 1, 2-(tri-butylstannyl)thiophene having formula (15) (0.34 ml, 1.04 mmol) and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4] (0.05 g, 0.043 mmol), in 50 ml of anhydrous toluene, was heated at the reflux temperature of the solvent, for 18 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The 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) (220 ml), subsequently with water (310 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, v/v) as eluent obtaining 0.41 g (82% yield) of 5-formyl-3,3-di-octyl-2,2:5,2:5,2-quaterthiophene having formula (16), as a yellow oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.60 (s, 1H), 7.26-7.22 (m, 2H) 7.18 (dd, 1H), 7.12 (d, 1H), 7.04-7.01 (m, 2H), 2.85-2.74 (m, 4H), 1.70-1.66 (m, 4H), 1.42-1.27 (m, 20), 0.89-0.85 (m, 6H).

(46) Said compound having formula (16) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.5, 141.0, 140.2, 140.1, 139.1, 138.0, 136.9, 135.7, 134.3, 128.6, 127.9, 127.8, 126.7, 126.0, 124.6, 123.8, 31.8, 30.5, 30.3, 29.5, 29.4, 29.2, 22.6, 14.1.

(47) Furthermore, said compound having formula (16) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 582.2134 (2.5 ppm); calculated for: C.sub.33H.sub.42OS.sub.4: 582.2119.

Synthesis of 5-formyl-3,3-di-octyl-5-bromo-2,2:5,2:5,2-quarter-thiophene having Formula (17)

(48) In a 100 ml flask, N-bromosuccinimide (0.13 g, 0.74 mmol) was added, in small portions, to a solution of 5-formyl-3,3-di-octyl-2,2:5,2:5,2-quaterthiophene having formula (16) (0.39 g, 0.67 mmol), obtained as described above, in 40 ml of a mixture of chloroform and acetic acid (1:1, v/v), at 0 C. The reaction mixture was slowly heated at room temperature (25 C.) and stirred for further 3 hours, then was poured into water (50 ml) 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 (210 ml), then with 1 M aqueous solution of sodium bicarbonate (NaHCO.sub.3) (210 ml), then with brine (210 ml), again with water (310 ml), 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 crystallized from petroleum ether obtaining 0.32 g (73% yield) of 5-formyl-3,3-di-octyl-5-bromo-2,2:5,2: 5,2-quaterthiophene having formula (17), as a slightly yellow solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.83 (s, 1H), 7.60 (s, 1H), 7.25 (d, 1H), 7.11 (d, 1H), 6.98 (d, 1H), 6.95 (d, 1H), 6.92 (d, 1H), 2.85-2.73 (m, 4H), 1.69-1.64 (m, 4H), 1.32-1.24 (m, 20), 0.89-0.85 (m, 6H).

(49) Said compound having formula (17) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 660.1232 (1.3 ppm); calculated for C.sub.33H.sub.41BrOS.sub.4: 660.1224.

Synthesis of 5-formyl-3,3-di-octyl-3,4-ethylendioxy-2,2:5,2:5,2:5,2-pentathiophene having Formula (18)

(50) In a 100 ml flask, a mixture of 5-formyl-3,3-di-octyl-5-bromo-2,2:5,2:5,2-quaterthiophene having formula (17) (0.22 g, 0.33 mmol), obtained as described above, 2-tributylstannyl-3,4-ethylendioxythiophene having formula (13) (0.14 g, 1.04 mmol), obtained as described in Example 3, and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4] (0.050 g, 0.042 mmol), in 50 ml of anhydrous toluene, was heated at reflux temperature of the solvent, for 16 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The residue was dissolved in 30 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) (220 ml), subsequently with water (310 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 dichloromethane (CH.sub.2Cl.sub.2) as eluent obtaining 0.19 g (80% yield) of 5-formyl-3,3-di-octyl-3,4-ethylendioxy-2,2:5,2:5,2:5,2-pentathiophene having formula (18), as an orange solid, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 9.82 (s, 1H), 7.60 (s, 1H), 7.25 (d, 1H), 7.12-7.07 (m, 3H), 7.02 (s, 1H), 6.94 (s, 1H), 4.38-4.35 (m, 2H), 4.27-4.24 (m, 2H), 2.85-2.73 (m, 4H), 1.69-1.65 (m, 4H), 1.43-1.27 (m, 20), 0.89-0.85 (m, 6H).

(51) Said compound having formula (18) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.5, 141.8, 141.0, 140.1, 139.1, 138.1, 137.7, 134.3, 127.8, 126.3, 125.9, 123.8, 123.3, 112.0, 97.2, 65.0, 64.5, 31.8, 30.4, 30.3, 29.6, 29.4, 29.4, 29.2, 22.6, 14.1.

(52) Furthermore, said compound having formula (18) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 722.2045 (0.8 ppm); calculated for C.sub.39H.sub.46O.sub.3S.sub.5: 722.2051.

Synthesis of 5-carboxycyanovinylen-3,3-di-octyl-3,4-ethylendioxy-2,2:5,2:5,2:5,2-pentathiophene having Formula (Id)

(53) In a 100 ml flask were introduced 0.13 g (0.18 mmol) of 5-formyl-3,3-di-octyl-3,4-ethylendioxy-2,2:5,2:5,2:5,2-pentathiophene having formula (18), obtained as described above, 0.031 g, (0.36 mmol) of cyanoacetic acid (NCCH.sub.2COOH), 0.086 g (1.08 mmol) of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) and 50 ml of glacial acetic acid (CH.sub.3COOH) and 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, washed with 10 ml of a diluted solution of sodium hydroxide and then with water (310 ml) obtaining 0.11 g (77% yield) of 5-carboxycyanovinylen-3,3-di-octyl-3,4-ethylendioxy-2,2:5,2:5,2:5,2-pentathiophene having formula (Id), as a black solid, which was characterized by .sup.1H NMR (500 MHz, THF-d.sub.8) obtaining the following spectrum: 10.86 (s, 1H), 8.29 (s, 1H), 7.76 (s, 1H), 7.40 (d, 1H), 7.22 (d, 1H), 7.16-7.12 (m, 3H), 6.33 (s, 1H), 4.35-4.34 (m, 2H), 4.24-4.22 (m, 2H), 2.90-2.87 (t, 2H), 2.84-2.81 (t, 2H), 1.48-1.42 (m, 4H), 1.37-1.29 (m, 20), 0.89-0.87 (m, 6H).

(54) Said compound having formula (Id) was also characterized by .sup.13C NMR (75 MHz, THF-d.sub.8) obtaining the following spectrum: 163.7, 146.0, 143.0, 141.9, 141.7, 140.9, 139.0, 138.8, 136.7, 135.3, 135.1, 134.8, 134.8, 134.3, 129.0, 127.0, 126.9, 124.4, 123.5, 116.3, 112.0, 99.7, 97.7, 65.9, 65.3, 32.6, 31.2, 30.9, 30.3, 30.2, 30.0, 29.8, 23.4, 14.2.

(55) Furthermore, said compound having formula (Ic) was also characterized by mass spectra: HRMS (ESI) obtaining: [M]: 789.2134 (3.16 ppm); calculated for C.sub.42H.sub.47NO.sub.4S.sub.5: 789.2109.

Example 5

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (Ie)

(56) ##STR00011##

Synthesis of 2-n-hexyl-3,4-ethylenedithiothiophene having Formula (20)

(57) In a 100 ml flask, n-butil lithium (n-BuLi) (6.0 ml, 1.6 M in hexane, 9.6 mmol) was added, dropwise, at 78 C., to a solution containing 3,4-ethylenedithiothiophene (EDTT) having formula (19) (1.6 g, 9.19 mmol), dissolved in 40 ml of dry tetrahydrofuran (THF), under argon (Ar) atmosphere. The obtained reaction mixture was stirred for 1 hour, at 78 C. Subsequently, 1-bromohexane (1.72 ml, 12 mmol) was added, dropwise, at 78 C. and the obtained reaction mixture was stirred, for 30 minutes, at 78 C., and then allowed to warm slowly to room temperature (25 C.) and stirred for additional 12 hours. After dilution with diethyl ether (30 ml), the organic phase was washed with 30 ml of a saturated solution of ammonium chloride (NH.sub.4Cl), then with water (320 ml) and finally 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 (1:2, v/v) as eluent obtaining 0.8 g (35% yield) of 2-n-hexyl-3,4-ethylenedithiothiophene having formula (20), as a colorless oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 6.78 (s, 1H), 3.19 (s, 4H), 2.68 (t, 2H), 1.64-1.59 (m, 2H), 1.33-1.29 (m, 6), 0.86 (t, 3H).

(58) Said compound having formula (20) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 137.1, 124.8, 120.6, 114.6, 31.5, 30.2, 28.8, 28.2, 27.8, 27.7, 22.5, 14.0.

(59) Furthermore, said compound having formula (20) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 258.1 and 258.0574 (1.16 ppm), respectively; calculated for C.sub.12H.sub.18S.sub.3: 258.0571.

Synthesis of 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedithiothiophene having Formula (21)

(60) In a 100 ml flask, n-butil lithium (n-BuLi) (1.24 ml, 2.5 M in hexane, 3.11 mmol) was added dropwise at 20 C. to a solution of 0.73 g (2.82 mmol) of 2-n-hexyl-3,4-ethylenedithiothiophene having formula (20), obtained as described above, in 40 ml of dry tetrahydrofuran (THF), under Ar atmosphere. The reaction mixture was stirred for 1 hour, at 20 C., and tri-n-butyl tin chloride (0.97 ml, 3.38 mmol) was added, dropwise, at 20 C. The reaction mixture was stirred at 20 C. for further 30 minutes and then was allowed to warm to room temperature (25 C.). After dilution with diethyl ether (50 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), then with water (320 ml). After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure, obtaining 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedithiothiophene having formula (21), which was used in the following steps without further purification.

(61) Said compound having formula (21) was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 3.19-3.16 (m, 4H), 2.70 (t, 2H), 1.64-1.50 (m, 8H), 1.39-1.26 (m, 12), 1.17-1.12 (m, 6H), 0.94-0.86 (m, 12H).

Synthesis of 3,4-ethylenedithio-5-n-hexyl-2,2-dithiophene having Formula (22)

(62) In a 100 ml flask a mixture of 2-bromothiophene (0.46 g, 2.81 mmol), 2-tri-n-butylstannyl-5-n-hexyl-3,4-ethylenedithiothiophene having formula (21) (1.54 g, 2.81 mmol), obtained as described above, and tetrakis(triphenyl-phosphine) palladium(0) [Pd(PPh.sub.3).sub.4] (0.32 g, 0.27 mmol), in 50 ml of anhydrous toluene, was heated at the reflux temperature of the solvent for 18 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The 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) (220 ml), subsequently with water (310 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, v/v) as eluent obtaining 0.43 g (46% yield) of 3,4-ethylenedithio-5-n-hexyl-2,2-dithiophene having formula (22), as a yellowish oil, which was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.28 (d, 1H), 7.23 (d, 1H), 7.06 (dd, 1H), 3.27-3.19 (m, 4H), 2.70 (t, 2H), 1.69-1.59 (m, 2H), 1.41-1.28 (m, 6), 0.92-0.85 (m, 3H).

(63) Said compound having formula (22) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 135.9, 135.4, 127.3, 125.3, 124.9, 122.1, 121.9, 31.5, 30.2, 28.8, 28.4, 28.2, 27.6, 22.5, 14.0.

(64) Furthermore, said compound having formula (22) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 340.1 and 340.0445 (<1 ppm), respectively; calculated for C.sub.16H.sub.20S.sub.4: 340.0448.

Synthesis of 3,4-ethylenedithio-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having Formula (23)

(65) In a 100 ml flask, n-butil lithium (n-BuLi) (2.5 M in hexane, 1.51 mmol, 0.6 ml) was added, dropwise, at 78 C., to a solution containing 0.43 g (1.26 mmol) of 3,4-ethylenedithio-5-n-hexyl-2,2-dithiophene having formula (22), obtained as described above, in 40 ml of dry tetrahydrofuran (THF), under Ar atmosphere. The reaction mixture is stirred for 1 hour at 78 C. and tributyltin chloride (SnBu.sub.3Cl) (0.43 ml, 1.51 mmol) was added dropwise at the same temperature. The reaction mixture was stirred at 40 C. for further 30 minutes and then allowed to warm to room temperature (25 C.). After dilution with diethyl ether (50 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), then with water (320 ml). After drying over magnesium sulfate (MgSO.sub.4), at room temperature (25 C.), for 3 hours, the solvent was evaporated at reduced pressure, obtaining 3,4-ethylenedithio-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having formula (23), which was used in the following steps without further purification.

(66) Said compound having formula (23) was characterized by .sup.1H NMR (300 MHz, CDCl.sub.3) obtaining the following spectrum: 7.35 (d, 2H), 7.10 (d, 2H), 3.24-3.22 (m, 4H), 2.72 (t, 2H), 1.64-1.51 (m, 8H), 1.41-1.25 (m, 12), 1.37-1.08 (m, 6H), 0.93-0.86 (m, 12H).

Synthesis of 5-formyl-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (24)

(67) In a 100 ml flask, a mixture of 5-formyl-5-bromo-3,3-dioctyl-2,2:5,2-terthiophene having formula (5) (0.21 g, 0.38 mmol), obtained as described in Example 1, 3,4-ethylenedithio-5-n-hexyl-5-tri-n-butylstannyl-2,2-dithiophene having formula (23) (0.3 g, 0.47 mmol), obtained as described above and tetrakis(triphenylphosphine)palladium(0) [Pd(PPh.sub.3).sub.4] (44 mg, 0.038 mmol), in 50 ml of anhydrous toluene, was heated at reflux temperature of the solvent, for 12 hours. The obtained reaction mixture was cooled to room temperature (25 C.) and the solvent was evaporated at reduced pressure. The residue was dissolved in 30 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) (220 ml), subsequently with water (310 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 dichloromethane (CH.sub.2Cl.sub.2) and petroleum ether (1:1, v/v) as eluent obtaining 0.15 g (50% yield) of 5-formyl-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (24), as a red-orange 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), 7.26 (d, 1H), 7.15 (d, 1H), 7.12 (d, 1H), 7.11 (d, 1H), 7.03 (s, 1H), 3.31-3.27 (m, 2H), 3.25-4.21 (m, 2H), 2.85-2.69 (m, 6H), 1.71-1.63 (m, 6H), 1.39-1.28 (m, 26), 0.89-0.85 (m, 9H).

(68) Said compound having formula (24) was also characterized by .sup.13C NMR (75 MHz, CDCl.sub.3) obtaining the following spectrum: 182.4, 141.1, 141.0, 140.2, 140.1, 139.0, 138.1, 136.1, 135.9, 135.5, 134.7, 134.3, 128.7, 127.8, 126.5, 125.9, 125.7, 125.3, 123.9, 122.4, 122.3, 31.8, 31.5, 30.4, 30.2, 29.6, 29.4, 29.3, 29.2, 28.8, 28.5, 28.2, 27.5, 22.6, 22.5, 14.0.

(69) Furthermore, said compound having formula (24) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 838.3 and 838.2510 (2.6 ppm), respectively; calculated for C.sub.45H.sub.58OS.sub.7: 838.2533.

Synthesis of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having Formula (Ie)

(70) In a 100 ml flask, were introduced 0.10 g (0.12 mmol) of 5-formyl-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (24), obtained as described above, 0.020 g, (0.24 mmol) of cyanoacetic acid (NCCH.sub.2COOH), 0.047 g (0.60 mmol) of ammonium acetate (CH.sub.3COO.sup.NH.sub.4.sup.+) and 50 ml of glacial acetic acid (CH.sub.3COOH) and the solution was heated at the reflux temperature of the solvent, for 12 hours. After slowly cooling the reaction mixture at room temperature (25 C.), a dark precipitate was formed which was recovered by filtration, washed with 10 ml of a diluted solution of sodium hydroxide and then with water (310 ml) obtaining 0.075 g (75% yield) of 5-carboxycyanovinylen-3,3-dioctyl-3,4-ethylenedithio-5-hexyl-2,2:5,2:5,2:5,2-pentathiophene having formula (Ie), as a black solid, which was characterized by .sup.1H NMR (500 MHz, THF-d.sub.8) obtaining the following spectrum: 8.28 (s, 1H), 7.74 (s, 1H), 7.38 (d, 1H), 7.22 (d, 1H), 7.17 (m, 3H), 3.26-3.28 (m, 2H), 3.24-3.22 (m, 2H), 2.90-2.82 (m, 4H), 2.72 (t, 2H), 2.02-2.04 (m, 6H), 1.26-1.29 (m, 26), 0.82-0.88 (m, 9H).

(71) Said compound having formula (Ie) was also characterized by .sup.13C NMR (75 MHz, THF-d.sub.8) obtaining the following spectrum: 204.3, 164.0, 145.7, 141.9, 141.5, 140.9, 138.7, 136.4, 136.3, 135.7, 134.9, 134.3, 132.3, 132.2, 129.4, 129.1, 129.0, 128.9, 127.3, 126.9, 126.2, 125.6, 124.6, 123.7, 123.6, 116.4, 100.2, 32.6, 32.3, 31.1, 30.9, 30.4, 30.3, 30.2, 30.1, 29.8, 29.5, 28.9, 28.6, 27.8, 25.6, 23.4, 23.2, 14.2.

(72) Furthermore, said compound having formula (24) was also characterized by mass spectra: MS MALDI and HRMS (ESI) obtaining: [M]: 905.3 and 905.2590 (<1 ppm), respectively; calculated for C.sub.48H.sub.59NO.sub.2S.sub.7: 905.2591.

Example 6

Preparation of Dye-sensitized Solar Cell (DSSC)

(73) 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.

(74) 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.

(75) 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 (Ib), obtained as described in Example 2, at room temperature (25 C.), for 24 hours. The dyed titania-glass was washed with ethanol and dried at room temperature (25 C.), under a nitrogen (N.sub.2) flux.

(76) 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.

(77) The active area of the cell, calculated by means of a microphotography, was 0.1225 cm.sup.2.

(78) 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: Voc (open circuit photovoltage)=655 mV; FF (fill factor)=70.3%; Jsc (short-circuit photocurrent density)=17.99 mA/cm.sup.2; (photoelectric transformation efficiency)=8.28%.

Example 7

Preparation of Dye-sensitized Solar Cell (DSSC)

(79) With the same procedure described in Example 6, a dye-sensitized solar cell (DSSC) was prepared by using an organic dye of formula (Ib) obtained as described in Example 2, and employing a commercial electrolyte solution [EL-HPE (High Performance Electrolyte) from Dyesol]. In this case the active area of the cell, calculated by means of a microphotography, was 0.1211 cm.sup.2. The photovoltaic performance of the cell was measured as described in Example 6. The following results were obtained: Voc (open circuit photovoltage)=638 mV; FF (fill factor)=67.9%; Jsc (short-circuit photocurrent density)=21.09 mA/cm.sup.2; (photoelectric transformation efficiency)=9.14%.

Example 8

Preparation of Dye-sensitized Solar Cell (DSSC)

(80) With the same procedure described in Example 6, a dye-sensitized solar cell (DSSC) was prepared by using an organic dye of formula (Ib) obtained as described in Example 5. In this case the active area of the cell, calculated by means of a microphotography, was 0.1254 cm.sup.2. The photovoltaic performance of the cell was measured as described in Example 6. The following results were obtained: Voc (open circuit photovoltage)=690 mV; FF (fill factor)=69.2%; Jsc (short-circuit photocurrent density)=18.22 mA/cm.sup.2; (photoelectric transformation efficiency)=8.69%.