Synthesis, electrochemical and optical studies of new cyanopyridine based conjugated polymers as potential fluorescent materials

In this communication we describe the design and synthesis of four new conjugated polymers (P1-P4) carrying cyanopyridine in their backbone via Wittig condensation technique. Their structures were well established by FTIR, 1H NMR, elemental analysis and gel permeation chromatographic techniques. They exhibited good thermal stability with the onset decomposition temperature around 300-350 °C in nitrogen atmosphere. Further, their electrochemical, linear and third-order non-linear optical properties have been investigated. The polymers showed low electrochemical band gaps in the range of 1.77-1.99 eV and displayed very good fluorescence emission property in various polar solvents. The fluorescence quantum yields of polymers P1-P4 in tetrahydrofuran (THF) were found to be 35, 42, 38 and 34%, respectively. The effective two-photon absorption coefficients (β) for the polymers were determined by Z-Scan technique and were found to be 1.34 × 10−11, 1.24 × 10−11, 3.04 × 10−11 and 1.85 × 10−11 m/W for polymers P1-P4, respectively.