Synthesis and characterization of 1,2,3-triazole appended polythiophene based reusable fluorescent probe for the efficient detection of trace nitroaromatics

Emissive pi-conjugated poly(3-benzyl-1,2,3-triazole thiophene) (P1) and poly(3-benzylthiophene) (P2) have been synthesized via Ni(II)-mediated Grignard metathesis (GRIM) polymerization from the corresponding monomers, 2-bromo-5-iodo-3-benzyl-1,2,3-triazole thiophene (M2) and 2,5-dibromo-3-benzyl thiophene (M3) respectively. The well-defined and soluble pi-conjugated polymers have been characterized by multinuclear NMR spectra as well as by tetradetector GPC studies showing molecular weight (M-n) of 19.3 and 17.6 kDa with the polydispersity indices of 1.35 and 1.24 respectively. The synthesized pi-conjugated polymers have been explored as fluorescent chemosensor for nitroaromatics (NACs). P1 polymeric probe having 1,2,3-triazole appendage shows the superiority over P2 towards the detection of picric acid vapor as manifested by the fluorescent quenching profile (89% and 41% respectively) due to the facile supramolecular interaction between p-type polymer and electron deficient NACs assisted by the polar 1,2,3-triazolyl unit. To understand the 'turn-off' sensing mechanism though photo-induced electron transfer (PET), the detailed photophysical studies have been carried out Furthermore, test paper kits have also been fabricated, showing remarkable trace detection towards picric acid in nano-molar range by naked eye, making it a useful tool for a quick, easy and inexpensive way of detecting NAC explosives. (C) 2017 Elsevier Ltd. All rights reserved.