. " identical or different, selected from the nitrogen, oxygen or sulphur atoms, such as thiophene, thiazole, furan, pyrrole, imidazole, isoxazole or pyrazole, optionally substituted by at least one substituent, which are identical or different, selected from the halogen atoms including fluorine and chlorine and the alkyl, containing 1 to 4 carbon atoms, aryl, containing 6 to 10 carbon atoms, alkoxy," . . . . .