Compounds of formula (Ia) and/or formula (Ib), are disclosed wherein R1 and R3 are independently selected from the group consisting of H, halogen, alkyl, fluorinated or partly fluorinated alkyl, and heteroaryl, R2 is selected from the group consisting of halogen, fluorinated and partly fluorinated alkyl, R4 and R5 are independently selected from the group consisting of halogen, alkyl, fluorinated or partly fluorinated alkyl, alkenyl, alkinyl, alkoxy, aryl, and heteroaryl, Z is independently selected from the group consisting of CH2, CHR6 or CR7R8, with R6, R7 and R8 independently selected from the group consisting of H, halogen, alkyl, alkoxy, aryl, and heteroaryl, wherein n is independently 1, 2 or 3, U, V and W of formula (Ia) independently form an aryl ring or a heteroaryl ring, and T, U, V and W of formula (Ib) form an aryl ring or a heteroaryl ring.