Disubstituted diaryloxybenzoheterodiazole compounds

Abstract

Disubstituted diaryloxybenzoheterodiazole compound of general formula (I): ##STR00001##
in which: Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR.sub.5 group in which R.sub.5 is selected from linear or branched C.sub.1-C.sub.20, or from optionally substituted aryl groups; R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined in the claims. The disubstituted diaryloxybenzoheterodiazole compound of general formula (I) can advantageously be used as a spectrum converter in luminescent solar concentrators (LSCs) which are in turn capable of improving the performance of photovoltaic devices (or solar devices) selected, for example, from photovoltaic cells (or solar cells), photovoltaic modules (or solar modules) on either a rigid substrate or a flexible substrate.

Claims

1. Process for the preparation of a disubstituted diaryloxybenzoheterodiazole compound of general formula (I): ##STR00029## in which Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR.sub.5 group in which R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or from optionally substituted aryl groups; R.sub.1, which are the same as each other, represent a hydrogen atom, R.sub.2 and R.sub.3, which are the same or different, represent a hydrogen atom; or are selected from linear or branched C.sub.1-C.sub.20 alkyl groups; linear or branched C.sub.1-C.sub.20 alkyl groups containing heteroatoms; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted linear or branched C.sub.1-C.sub.20 alkoxyl groups; optionally substituted phenoxyl groups, or —OCOR.sub.6 groups in which R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is a cyano group; or R.sub.2 and R.sub.3 can optionally be linked together so as to form, together with the carbon atoms to which they are linked, a saturated, unsaturated or aromatic cyclic ring or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms; R.sub.4, which are the same or different, are selected from optionally substituted aryl groups, comprising reacting at least one fluorinated disubstituted benzoheterodiazole compound of formula (II): ##STR00030## in which Z has the same meanings as described above, R.sub.2 and R.sub.3, have the same meanings as described above, with at least one aryl alcohol of general formula (III):
R.sub.4—OH  (III) in which R.sub.4 has the same meanings as described above; said fluorinated disubstituted diarylbenzoheterodiazole compound of general formula (II) and said aryl alcohol of general formula (III) being used in molar ratios ranging from 1:2 to 1:10.

2. Process for the preparation of a disubstituted diaryloxybenzoheterodiazole compound of general formula (I) according to claim 1, wherein said process is carried out: in a presence of at least one weak organic base selected from: carboxylates of alkali metals or of alkaline-earth metals, or their mixtures; carbonates of alkali metals or of alkaline-earth metals, or their mixtures; or bicarbonates of alkali metals or of alkaline-earth metals, or their mixtures; said fluorinated disubstituted diarylbenzoheterodiazole compound of general formula (II) and said weak organic base being used in molar ratios ranging from 1:1 to 1:10; and/or in a presence of at least one organic solvent selected from 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran, or their mixtures; toluene, xylene, or their mixtures; or N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide; or their mixtures; said fluorinated disubstituted diarylbenzoheterodiazole compound of general formula (II) being used in said organic solvent in such a quantity as to have a molar concentration in said organic solvent ranging from 0.05 M to 2 M; at a temperature ranging from 60° C. to 150° C., for a time ranging from 1 hour to 24 hours.

3. Process for the preparation of a disubstituted diaryloxybenzoheterodiazole compound of general formula (I): ##STR00031## in which Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR.sub.5 group in which R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or from optionally substituted aryl groups; R.sub.1, R.sub.2 and R.sub.3, which are the same or different, represent a hydrogen atom; or are selected from linear or branched C.sub.1-C.sub.20 alkyl groups; linear or branched C.sub.1-C.sub.20 alkyl groups containing heteroatoms; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted linear or branched C.sub.1-C.sub.20 alkoxyl groups; optionally substituted phenoxyl groups, or —OCOR.sub.6 groups in which R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is a cyano group; wherein said optionally substituted aryl group of R.sub.1 is selected from optionally substituted phenyl, naphthyl, phenyl naphthyl, phenanthrene or anthracene; or R.sub.1 and R.sub.2, can optionally be linked together so as to form, together with the carbon atoms to which they are linked, a saturated, unsaturated or aromatic cyclic ring or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms; or R.sub.2 and R.sub.3 can optionally be linked together so as to form, together with the carbon atoms to which they are linked, a saturated, unsaturated or aromatic cyclic ring or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms; R.sub.4, which are the same or different, are selected from optionally substituted aryl groups; in which at least one of R.sub.1, R.sub.2 and R.sub.3 is/are different from hydrogen, comprising the following steps: (a) reacting at least one disubstituted diaryloxybenzoheterodiazole compound of general formula (Ia1): ##STR00032## in which Z, R.sub.2, R.sub.3 and R.sub.4, have the same meanings as described above, with at least one N-haloimides compound selected from N-bromosuccinimide, N-bromophthalimide, N-iodosuccinimide, or N-iodophthalimide, obtaining a disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV): ##STR00033## in which Z, R.sub.2, R.sub.3 and R.sub.4, have the same meanings as described above and X is a halogen atom selected from bromine or iodine; said disubstituted diaryloxybenzoheterodiazole compound of general formula (Ia1) and said N-haloimides compound being used in molar ratios ranging from 1:2 to 1:3; (b) reacting the disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV) obtained in step (a) with: (i) at least one aryl-boron compound of general formula (V): ##STR00034## in which R.sub.1 has the same meanings as described above, provided that the R.sub.1 substituent does not represent a hydrogen atom, and the R.sub.7 substituents represent a hydrogen atom, or can be selected from linear or branched C.sub.1-C.sub.10 alkyl groups or optionally substituted cycloalkyl groups, or the two R.sub.7 substituents can optionally be linked together so as to form, together with other atoms to which they are linked, a cyclic ring selected from pinacol esters of boronic acid or 1,3-propanodiol esters of boronic acid; or (ii) with at least one aryl-stannylated compound of general formula (VI): ##STR00035## in which R.sub.1 has the same meanings as described above, provided that the R.sub.1 substituent does not represent a hydrogen atom, and the R.sub.8 substituents can be selected from linear or branched C.sub.1-C.sub.8 alkyl groups; said disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV) and said aryl-boron compound of general formula (V), or said aryl-stannylated compound of general formula (VI) being used in molar ratios ranging from 1:2 to 1:5.

4. Process for the preparation of a disubstituted diaryloxybenzoheterodiazole compound of general formula (I) according to claim 3, wherein said step (a) is carried out in a presence of at least one organic solvent selected from: 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran, or their mixtures; chlorinated solvents selected from dichloromethane, chloroform, or their mixtures; or dipolar aprotic solvents selected from N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide; or their mixtures; said disubstituted diaryloxybenzoheterodiazole compound of general formula (Ia1) being used in said organic solvent in such a quantity as to have a molar concentration in said organic solvent ranging from 0.01 M to 5 M at a temperature ranging from 20° C. to 50° C. for a time ranging from 1 hour to 24 hours.

5. Process for the preparation of a disubstituted diaryloxybenzoheterodiazole compound of general formula (I) according to claim 3, wherein said step (b) is carried out: in a presence of palladium catalyst containing at least one compound selected from palladium in oxidation state (0) or (II) selected from palladium-tetrakistriphenylphosphine [Pd(PPh.sub.3).sub.4] or palladium bis-triphenylphosphine dichloride [PdCl.sub.2(PPh.sub.3).sub.2]; said disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV) and said palladium catalyst being used in molar ratios ranging from 1:0.15 to 1:0.01; and/or in a presence of at least one weak organic base selected from: carboxylates of alkali metals or of alkaline-earth metals, or their mixtures; carbonates of alkali metals or of alkaline-earth metals, or their mixtures; or bicarbonates of alkali metals or of alkaline-earth metals, or their mixtures said disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV) and said weak organic base being used in molar ratios ranging from 1:1 to 1:20; and/or in a presence of at least one organic solvent selected from: 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran, or their mixtures; toluene, xylene, or their mixtures; or N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, or their mixtures; or their mixtures;-optionally in admixture with at least one alcohol selected from methanol, ethanol, n-propanol, iso-propanol, or their mixtures; said disubstituted halogenated diaryloxybenzoheterodiazole compound of general formula (IV) being used in said organic solvent in such a quantity as to have a molar concentration in said organic solvent ranging from 0.01 M to 2 M; at a temperature ranging from 50° C. to 140° C. for a time ranging from 2 hours to 36 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a graph for power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from an edge to which a photovoltaic cell of an example or comparative example was attached, expressed in cm (shown in the abscissa).

(2) FIG. 2 shows an obtained value of power (P) generated, expressed in mW (shown in the ordinate) (the number of an example or comparative example is shown in the abscissa).

Example 1

Synthesis of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of Formula (Ia)

(3) ##STR00019##

(4) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, phenol (Aldrich) (742 mg; 7.9 mmoles) and potassium carbonate (Aldrich) (700 mg; 5.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (630 mg; 1.9 mmoles) in N,N-dimethylformamide (Aldrich) (6 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration and washed with distilled water (30 ml), obtaining 865 mg of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) [DTB(OPh).sub.2] (yield=94%).

Example 2

Synthesis of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of Formula (Ib)

(5) ##STR00020##

(6) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 4-t-butylphenol (Aldrich) (1.2 g; 7.9 mmoles) and potassium carbonate (Aldrich) (700 mg; 5.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (630 mg; 1.9 mmoles) in N,N-dimethylformamide (Aldrich) (6 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (30 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 9/1 (v/v)], obtaining 1 g of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ib) [DTB(OPhBu.sup.t).sub.2] (yield=88%).

Example 3

Synthesis of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of Formula (Ic)

(7) ##STR00021##

(8) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2-naphthol (Aldrich) (300 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 10 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 85/15 (v/v)], obtaining 220 mg of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ic) [DTB(O-2-Naph).sub.2] (yield=75%).

Example 4

Synthesis of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of Formula (Id)

(9) ##STR00022##

(10) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 4-phenylphenol (Aldrich) (300 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 10 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 95/5 (v/v)], obtaining 230 mg of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Id) [DTB(OBPh).sub.2] (yield=75%).

Example 5

Synthesis of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of Formula (Ie)

(11) ##STR00023##

(12) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-dimethylphenol (Aldrich) (253 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 85/15 (v/v)], obtaining 230 mg of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ie) [DTB(OPh-2,6-Me.sub.2).sub.2] (yield=81%).

Example 6

Synthesis of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of Formula (a)

(13) ##STR00024##

(14) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, N-bromosuccinimide (Aldrich) (665.3 mg; 3.8 mmoles) was added to a suspension of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) obtained as described in Example 1 (865 mg; 1.8 mmoles) in tetrahydrofuran (Aldrich) (10 ml): the reaction mixture obtained was left in the dark, with stirring, at ambient temperature (25° C.), for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration and washed with distilled water (30 ml), obtaining 1 g of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) (yield=90%).

Example 7

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of Formula (If)

(15) ##STR00025##

(16) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-dimethylphenylboronic acid (Aldrich) (158 mg; 1.05 mmoles) and an aqueous solution of 2.17 M of potassium carbonate (Aldrich) (480 mg in 1.6 ml of water; 3.47 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (270 mg; 0.4 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml), and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (If) [5-(2,6-Me.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=90%).

Example 8

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of Formula (Ig)

(17) ##STR00026##

(18) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,5-dimethylphenylboronic acid (Aldrich) (158 mg; 1.05 mmoles) and an aqueous solution of 2.17 M of potassium carbonate (Aldrich) (480 mg in 1.6 ml of water; 3.47 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (270 mg; 0.4 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml) and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ig) [5-(2,5-Me.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=90%).

Example 9

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of Formula (Ih)

(19) ##STR00027##

(20) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-di-iso-propylphenylboronic acid (Aldrich) (387 mg; 1.8 mmoles) and caesium carbonate (Aldrich) (940 mg; 2.88 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (300 mg; 0.47 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, bis-triphenylphosphine palladium dichloride (Aldrich) (34 mg; 0,048 mmoles) was added obtaining a reaction mixture which was heated to 85° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml), and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 270 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ih) [5-(2,6-Pr.sup.i.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=71%).

Example 10

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of Formula (Ii)

(21) ##STR00028##

(22) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2-naphthylboronic acid (Aldrich) (178 mg; 1.03 mmoles) and an aqueous solution of 2.1 M of potassium carbonate (Aldrich) (419 mg in 1.44 ml of water; 3.04 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (245.8 mg; 0.38 mmoles) in 1,4-dioxane (Aldrich) (15 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) (Aldrich) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml) and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 85/15 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ii) [5-(2-Naph).sub.2DTB(OPh).sub.2] (yield=89%).

Example 11 (Comparative)

(23) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 49.5 mg of 4,7-di-(thien-2′-yl)-2,1,3-benzothiadiazole (DTB), were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of a yellow colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(24) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet

(25) The main surface of the polymer sheet [that coated with the thin film containing the 4,7-di-(thien-2′-yl)-2,1,3-benzothiadiazole (DTB)] was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(26) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge and auto absorption effects.

(27) It will be seen how in the absence of edge effects the mean power generated was 5.69 mW (FIG. 1).

(28) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 12

(29) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 87.1 mg of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) [DTB(OPh).sub.2] obtained as described in Example 1, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of a red colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(30) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(31) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(32) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects.

(33) It will be seen how in the absence of edge effects the mean power generated was 8.49 mW (FIG. 1).

(34) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 13

(35) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 105 mg of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ib) [DTB(OPh-Bu).sub.2] obtained as described in Example 2 were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(36) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(37) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(38) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 5.98 mW (FIG. 1).

(39) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 14

(40) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 105.2 mg of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ic) [DTB(O-2-Naph).sub.2] obtained as described in Example 3, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(41) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(42) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(43) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 7.48 mW (FIG. 1).

(44) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 15

(45) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 82.6 mg of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Id) [DTB(OBPh).sub.2] obtained as described in Example 4, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(46) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(47) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(48) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 7.06 mW (FIG. 1).

(49) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 16

(50) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 97.2 mg of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ie) [DTB(OPh-2,6-Me.sub.2).sub.2] obtained as described in Example 5, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(51) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(52) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(53) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 6.73 mW (FIG. 1).

(54) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 17

(55) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 124.6 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (If) [5-(2,6-Me.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 7, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(56) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(57) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(58) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects.

(59) It will be seen how in the absence of edge effects the mean power generated was 10.58 mW (FIG. 1).

(60) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 18

(61) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 124.6 mg of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ig) [5-(2,5-Me.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 8, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(62) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(63) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(64) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 13.17 mW (FIG. 1).

(65) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 19

(66) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 144.7 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ih) [5-(2,6-Pr.sup.i.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 9, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(67) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(68) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(69) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 5.28 mW (FIG. 1).

(70) FIG. 2 shows the value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 20

(71) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 49.5 mg of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ii) [5-(2-Naph).sub.2DTB(OPh).sub.2] obtained as described in Example 10, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(72) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(73) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(74) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and auto absorption effects. It will be seen how in the absence of edge effects the mean power generated was 9.09 mW (FIG. 1).

(75) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

Example 21 (Comparative) 22-24 (Invention)

(76) 400 ml of methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were heated to 80° C., in 2 hours, under magnetic agitation, in a 1 liter flask.

(77) Subsequently, 40 mg of azo-bis-iso-butyronitrile (AIBN) (Aldrich 98%) dissolved in 40 ml of methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were added: the mixture obtained was heated, under magnetic agitation, to 94° C., in 1 hour, left at said temperature for 2 minutes, and subsequently cooled in an ice bath, obtaining a syrup of pre-polymerized polymethyl-methacrylate (PMMA). 400 ml of the pre-polymerized syrup obtained as described above were loaded into a 1 liter flask, and 25 mg of lauroyl peroxide (Acros 99%) dissolved in methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were added, and a quantity of 4,7-di(thien-2′-il)-2,1,3-benzothiadiazole (DTB) [in Example 21 (comparative)] or of disubstituted diaryloxybenzoheterodiazole compound of general formula (I), obtained as described in the examples reported above [in Examples 22 (invention): compound (Ia) of Example 1; in Example 23 (invention): compound (If) of Example 7; and in Example 24 (invention): compound (Ig) of Example 8], such that the molar percentage of said 4,7-di(thien-2′-il)-2,1,3-benzothiadiazole (DTB) or of said disubstituted diaryloxybenzoheterodiazole compound of general formula (I), with respect to methyl methacrylate (MMA) is equal to 0.3. The mixture obtained was degassed, under magnetic agitation, under a vacuum of 10 mm mercury (Hg), for 45 minutes, at ambient temperature (25° C.), obtaining a solution that was poured into the mold described below.

(78) Said mold was formed by two sheets of glass with dimensions 40×40 cm and thickness 6 mm-10 mm, separated by polyvinylchloride (PVC) gaskets (10 cm diameter). Said sheets of glass were mounted between jaws and pressed together until the space between the two sheets was about 6 mm. After closing the opening through which the aforementioned solution was poured with the gasket, the mold was immersed in a water bath, at 55° C., for 48 hours, and then placed in the stove and heated to 95° C. for 24 hours. Subsequently, the mold was cooled to ambient temperature (25° C.), the jaws and the gasket were removed, the glass sheets of the mold were separated, and the sheet of polymethylmethacrylate (PMMA) obtained was collected. The sheet of polymethyl-methacrylate (PMMA) was then cut into sheets with dimensions 30×7.5 cm in order to carry out the aging tests reported below.

(79) The different sheets obtained as described above were subjected to accelerated aging in an ATLAS XenoTest Beta+, equipped with a Xenon lamp cooled in air and with Xenochrome 300 filter, operating in accordance with standard DIN EN ISO 4892-2-A1 2003-11.

(80) Periodically, the sheets were removed and subjected to UV-visible spectroscopy. The ultraviolet and visible absorption spectra (190 nm-850 nm) were recorded with a double beam UV-Vis-NIR spectrophotometer and double monochromator, with a passband of 2.0 nm and step of 1 nm.

(81) Therefore, through said UV-visible spectroscopy, the quantity of fluorescent compound present on the sheets was determined by measuring the characteristic absorbance of each fluorescent compound, subject to calibration through reference sheets containing known quantities of fluorescent compound dispersed in the polymeric matrix itself.

(82) In the sheets subject to accelerated aging the spectrophotometry of UV-vis absorption allowed the absorbance reduction in the visible region to be monitored by measuring the relative absorbance percentage (A %) defined as (At)/(A0), i.e. the ratio of absorbance at time t (At) to absorbance at time 0 (A0): in particular, the absorbance values (At) and (A0) are the mean of the absorbance values measured on each sheet in various points, at time t and at time zero, respectively.

(83) Table 2 reports the relative absorbance percentage values (A %) [(At)/(A0)] according to the aging time [t (h)].

(84) TABLE-US-00002 TABLE 2 (A%) [(At)/(A0)] Example 21 Example 22 Example 23 Example 24 t (h) (DTB) [compound (Ia)] [compound (If)] [compound (Ig)]   0 100 100 100 100  300  84  93  98  96  500  66  87 100  95  900 —  79  96  91 1000  51 — — — 1500  32  64  93  85 1800  17 —  92  82 2000 — — — —

(85) From the data reported in Table 2 it can be inferred that the fluorescent compounds in accordance with the present invention (Examples 22-24) have a higher relative absorbance percentage (A %) even after a number of hours of aging, with respect to 4,7-di(thien-2′-yl)-2,1,3-benzothiadiazole (DTB) known in the art [Example 21 (comparative)].