Hyperbranched Copolymer Containing Triphenylamine and Divinyl Bipyridyl Units for Fluorescent Chemosensors

A fluorescent hyperbranched copolymer (HTP) and a linear copolymer (PTP) as a reference sample to HTP both containing triphenylamine and divinyl bipyridyl units were synthesized via Heck coupling reaction from 5,5'-Divinyl-2,2'-bipyridyl with tris(4-bromophenyl)amine and with 4,4'-dibromotriphenylamie, respectively. The chemical structure of HTP was confirmed by FTIR, H-1 NMR, and C-13 NMR. The polymer HTP had a number-average molecular weight of 1895 and a weight-average molecular weight of 2315, and good solubility in conventional organic solvents, such as THF, DMF, and chloroform, and exhibited good thermal stability. The UV-vis absorption and photoluminescence (PL) spectra exhibited absorption maximum at 428 nm and emissive maximum at 531 nm for the HTP solution. The spectroscopic results of HTP and PTP indicated that hyperbranched conjugated structure increases the effective conjugation length, as compared with corresponding linear conjugated structure. The fluorescence of the polymer in solution can be quenched by various transition metal ions. The effect of backbone structure of the conjugated polymer-based chemosensors on the sensitivity and selectivity in metal ions sensing have been investigated, and the quenching effect of HTP is more sensitive toward transition metal than linear copolymer PTR. (c) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 222-230, 2009