Synthesis and Photophysical Properties of Substituted 2,2:6,2-Terpyridine Derivatives and Analogous Compounds with a Central Thiophene Ring

New 2,2:6,2-terpyridine derivatives were prepared by Suzuki-Miyaura coupling of the corresponding 4,4-bis(nonaflate) with the appropriate boronic acid derivatives. The corresponding 4,4-diazido terpyridine derivative allowed a copper(I)-promoted click reaction with phenyl acetylene to provide the bis(triazolyl)-substituted terpyridine in excellent yield. For comparison, analogs or terpyridines with a central thiophene ring were synthesized by applying the well proven cyclocondensation reaction of the bis(-ketoenamide) derived from 2,5-thiophenedicarboxylic acid. The UV/Vis spectra as well as the fluorescence spectra of these new compounds were recorded and compared with related heterocycles.