Compound of general formula: where - R 1 represents a hydrogen atom, a halogen atom or an alkoxy radical of 1 to 3 carbon atoms; - R 2 is a phenyl ring, optionally substituted by: a phenyl radical, a halogen atom, a -SO 2 -phenyl group, a -S-X or -O-X group, X being an alkyl radical of 1 to 4 carbon atoms, an alkoxy of 1 to 4 carbon atoms, a PEG of formula -(CH 2 -CH 2 -O) n -R with n being 1 to 10 and R is a hydrogen atom or a methyl radical, or a -CO-Y or -CO-O-Y group, Y being chosen from a hydrogen atom, an alkyl radical of 1 to 4 carbon atoms, a phenyl ring or an allyl group (-CH 2 -CH=CH 2); - R 3 represents a thiophene ring substituted by: * an alkyl radical of 1 to 3 carbon atoms; * a halogen atom; * a phenyl radical optionally substituted by an alkoxy radical of 1 to 3 carbon atoms, a -CN group, a -NO 2 group or a -COX or -COOX group with X an alkyl radical of 1 to 4 carbon atoms or a combination of these substituents; * a -SY group, Y being an alkyl radical of 1 to 4 carbon atoms or a phenyl radical; * a-CN group; * a -CH 2 -N 3 group; * an aromatic heterocycle of 5 or 6 atoms which can be chosen from a furane, thiophene, pyrrole, pyrroline, pyrrolidine, dioxolane, oxazole, thiazole, imidazole, imidazoline, imidazolidine, pyrazole, isoxazole, isothiazole, pyran, pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, pyrazine ring; optionally substituted by at least one alkyl radical of 1 to 3 carbon atoms and/or a -CH 2 -N 3 group; - R 4 represents a methyl radical. - R 1 represents a hydrogen atom, a halogen atom or an alkoxy radical of 1 to 3 carbon atoms; - R 2 is a phenyl ring, optionally substituted by: a phenyl radical, a halogen atom, a -SO 2 -phenyl group, a -S-X or -O-X group, X being an alkyl radical of 1 to 4 carbon atoms, an alkoxy of 1 to 4 carbon atoms, a PEG of formula -(CH 2 -CH 2 -O) n -R with n being 1 to 10 and R is a hydrogen atom or a methyl radical, or a -CO-Y or -CO-O-Y group, Y being chosen from a hydrogen atom, an alkyl radical of 1 to 4 carbon atoms, a phenyl ring or an allyl group (-CH 2 -CH=CH 2); - R 3 represents a thiophene ring substituted by: * an alkyl radical of 1 to 3 carbon atoms; * a halogen atom; * a phenyl radical optionally substituted by an alkoxy radical of 1 to 3 carbon atoms, a -CN group, a -NO 2 group or a -COX or -COOX group with X an alkyl radical of 1 to 4 carbon atoms or a combination of these substituents; * a -SY group, Y being an alkyl radical of 1 to 4 carbon atoms or a phenyl radical; * a-CN group; * a -CH 2 -N 3 group; * an aromatic heterocycle of 5 or 6 atoms which can be chosen from a furane, thiophene, pyrrole, pyrroline, pyrrolidine, dioxolane, oxazole, thiazole, imidazole, imidazoline, imidazolidine, pyrazole, isoxazole, isothiazole, pyran, pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, pyrazine ring; optionally substituted by at least one alkyl radical of 1 to 3 carbon atoms and/or a -CH 2 -N 3 group; * an alkyl radical of 1 to 3 carbon atoms; * a halogen atom; * a phenyl radical optionally substituted by an alkoxy radical of 1 to 3 carbon atoms, a -CN group, a -NO 2 group or a -COX or -COOX group with X an alkyl radical of 1 to 4 carbon atoms or a combination of these substituents; * a -SY group, Y being an alkyl radical of 1 to 4 carbon atoms or a phenyl radical; * a-CN group; * a -CH 2 -N 3 group; * an aromatic heterocycle of 5 or 6 atoms which can be chosen from a furane, thiophene, pyrrole, pyrroline, pyrrolidine, dioxolane, oxazole, thiazole, imidazole, imidazoline, imidazolidine, pyrazole, isoxazole, isothiazole, pyran, pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, pyrazine ring; optionally substituted by at least one alkyl radical of 1 to 3 carbon atoms and/or a -CH 2 -N 3 group; - R 4 represents a methyl radical.