A compound having formula selected in the group consisting of formula and formula: wherein: R 2', R 1 and R 2, independently of each other, are selected in the group consisting of phenyl group and substituted phenyl groups; Ar', Ar", independently of each other, are moieties selected in the group consisting of monocyclic aryl groups, substituted monocyclic aryl groups, polycyclic aryl groups, substituted polycyclic aryl groups, monocyclic heteroaryl groups, substituted monocyclic heteroaryl groups, polycyclic heteroaryl groups, substituted polycyclic heteroaryl groups and combinations thereof as dimers, trimers and tetramers; R 15 is selected in the group consisting of hydrogen, halogen, C 1 -C 20 linear or branched alkyl groups, C 1 -C 20 linear or branched heteroalkyl groups, C 1 -C 20 linear or branched heteroalkoxyalkyl groups, C 1 -C 20 linear or branched halogenoalkyl groups, C 3 -C 20 linear or branched cycloalkyl groups, C 1 -C 20 linear or branched hydroxyalkyl groups, C 1 -C 20 linear or branched alkoxyl groups and C 1 -C 20 linear or branched nitrile groups; n, r, independently of each other, are integers between 1 and 50; p is an integer between 0 and 5; and T is a terminal unit of the compound and is selected among hydrogen, C 1 -C 40 linear or branched alkyl groups, C 1 -C 40 linear or branched haloalkyl groups, C 1 -C 40 linear or branched heteroalkyl groups, C 3 -C 40 linear or branched cycloalkyl groups, C 1 -C 40 linear or branched hydroxyalkyl groups, C 1 -C 40 linear or branched alkoxyl groups, C 1 -C 40 linear or branched heteroalkoxyalkyl groups, C 1 -C 40 linear or branched alkylcarboxylic groups, C 1 -C 40 linear or branched alkylcarboxyamide groups, C 1 -C 40 linear or branched alkylsulphonic groups, and C 1 -C 40 linear or branched nitrile groups, monocyclic aryl groups, substituted monocyclic aryl groups, polycyclic aryl groups, substituted polycyclic aryl groups, monocyclic heteroaryl groups, substituted monocyclic heteroaryl groups, polycyclic heteroaryl groups, substituted polycyclic heteroaryl groups, benzyl groups and substituted benzyl groups and combinations thereof as dimers, trimers and tetramers; with the exception of compounds of formula A: wherein R 13 is selected in the group consisting of phenyl, 4-chlorophenyl, 3-trifluoromethylphenyl; R 14 is selected in the group consisting of phenyl, 2-fluorphenyl, 3-fluorphenyl, 4-fluorphenyl, 2-chlorphenyl, 3-chlorphenyl, 4-chlorphenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2-trifluoromethylphenyl, 3-trifluormethylphenyl, 4-trifluormethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2,4-dichlorphenyl, 2,4,6-trimethylphenyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; and R 20 is selected in the group consisting of H, Cl, F, methyl, methoxy. R 2', R 1 and R 2, independently of each other, are selected in the group consisting of phenyl group and substituted phenyl groups; Ar', Ar", independently of each other, are moieties selected in the group consisting of monocyclic aryl groups, substituted monocyclic aryl groups, polycyclic aryl groups, substituted polycyclic aryl groups, monocyclic heteroaryl groups, substituted monocyclic heteroaryl groups, polycyclic heteroaryl groups, substituted polycyclic heteroaryl groups and combinations thereof as dimers, trimers and tetramers; R 15 is selected in the group consisting of hydrogen, halogen, C 1 -C 20 linear or branched alkyl groups, C 1 -C 20 linear or branched heteroalkyl groups, C 1 -C 20 linear or branched heteroalkoxyalkyl groups, C 1 -C 20 linear or branched halogenoalkyl groups, C 3 -C 20 linear or branched cycloalkyl groups, C 1 -C 20 linear or branched hydroxyalkyl groups, C 1 -C 20 linear or branched alkoxyl groups and C 1 -C 20 linear or branched nitrile groups; n, r, independently of each other, are integers between 1 and 50; p is an integer between 0 and 5; and T is a terminal unit of the compound and is selected among hydrogen, C 1 -C 40 linear or branched alkyl groups, C 1 -C 40 linear or branched haloalkyl groups, C 1 -C 40 linear or branched heteroalkyl groups, C 3 -C 40 linear or branched cycloalkyl groups, C 1 -C 40 linear or branched hydroxyalkyl groups, C 1 -C 40 linear or branched alkoxyl groups, C 1 -C 40 linear or branched heteroalkoxyalkyl groups, C 1 -C 40 linear or branched alkylcarboxylic groups, C 1 -C 40 linear or branched alkylcarboxyamide groups, C 1 -C 40 linear or branched alkylsulphonic groups, and C 1 -C 40 linear or branched nitrile groups, monocyclic aryl groups, substituted monocyclic aryl groups, polycyclic aryl groups, substituted polycyclic aryl groups, monocyclic heteroaryl groups, substituted monocyclic heteroaryl groups, polycyclic heteroaryl groups, substituted polycyclic heteroaryl groups, benzyl groups and substituted benzyl groups and combinations thereof as dimers, trimers and tetramers;