Synthesis and chemosensory properties of terpyridine-containing diblock polycarbazole through RAFT polymerization

This paper describes the synthesis of a terpyridine-containing diblock copolymer, poly(N-vinylcarbazole)-block-poly[4'-( (4-vinylphenyl) phenyl)-2,2':6',2- terpyridine] (poly(VK15-b-TPY4)), using the macro-chain transfer agent VK macro-CTA, and employing two-step reverse addition-fragmentation transfer (RAFT) polymerization. We examined the effect of terpyridine units on sensory characteristics of fluorescent chemosensors. VK macro-CTA and diblock copolymer poly(VK15-b-TPY4) both exhibited moderate thermal stability, with thermal decomposition temperatures of 5% weight losses at approximately 307 degrees C and 378 degrees C, respectively, suggesting that the enhancement of thermal stability was attributed to the incorporation of terpyridine segments into the block copolymer. Poly(VK15-b-TPY4) exhibited higher sensitivities to Ni2+ and Mn2+ ions, with Stern-Volmer constants (K-sv) of 2.58 x 10(5) M-1 and 2.57 x 10(5) M-1, respectively. Adding a Zn2+ ion not only caused partial fluorescence enhancement (3.2-fold quantum efficiency) but also induced a bathochromic shift of emission peak by approximately 56 nm (from 429 nm to 485 nm), indicating that the Zn2+ -terpyridine complex reduced the twist and vibration of the C-C polymer backbone and enhanced the charge transfer from donors to acceptors because of the more planar and rigid structure. Our results suggest that poly(VK15-b-TPY4) is a promising material for chemosensory applications. (C) 2015 Elsevier B.V. All rights reserved.