A compound having formula selected in the group consisting of formula, formula, formula and formula: wherein: R 1, R 2, R 2' independently of each other, are selected in the group consisting of hydrogen, C 1 -C 40 linear or branched alkyl 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 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; Ar is selected in the group consisting of monocyclic aryl groups, polycyclic aryl groups, monocyclic heteroaryl groups and polycyclic heteroaryl groups; Ar', Ar", independently of each other, are selected in the group consisting of monocyclic aryl groups, polycyclic aryl groups, monocyclic heteroaryl groups and polycyclic heteroaryl groups; n, r, independently of each other, are integers between 1 and 50; and p is an integer between 0 and 5; with the exception of compounds of formula A: wherein R 4 is selected in the group consisting of C 1 -C 4 alkyls; and R 5 is selected in the group consisting of monocyclic aryl groups and substituted monocyclic aryl groups; with the exception of the compound of formula 132: and with the exception of compounds of formula B: wherein R 6 is selected in the group consisting of isopropyl, cyclopropyl and terbutyl groups and R 7 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. R 1, R 2, R 2' independently of each other, are selected in the group consisting of hydrogen, C 1 -C 40 linear or branched alkyl 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 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; Ar is selected in the group consisting of monocyclic aryl groups, polycyclic aryl groups, monocyclic heteroaryl groups and polycyclic heteroaryl groups; Ar', Ar", independently of each other, are selected in the group consisting of monocyclic aryl groups, polycyclic aryl groups, monocyclic heteroaryl groups and polycyclic heteroaryl groups; n, r, independently of each other, are integers between 1 and 50; and p is an integer between 0 and 5; with the exception of compounds of formula A: wherein R 4 is selected in the group consisting of C 1 -C 4 alkyls; and R 5 is selected in the group consisting of monocyclic aryl groups and substituted monocyclic aryl groups; with the exception of the compound of formula 132: and with the exception of compounds of formula B: wherein R 6 is selected in the group consisting of isopropyl, cyclopropyl and terbutyl groups and R 7 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.