Cyanopyridine based conjugated polymer-synthesis and characterization

Abstract

Two novel D-A polymers containing pyridine with vinylene spacer, P1 and P2 were synthesised through Heck polymerisation. In both the polymers, pyridine is linked with two donor phenylene at position-4 and -6, and electron withdrawing cyano group at position-3. Additionally, P1 possess methoxy side chain at position-2 of 3-cyanopyridine and P2 is flanked with both methoxy and octyloxy side chain at alternate pyridine. The polymers are well characterised with 1H-NMR, UV–Vis absorption, PL, GPC, TGA, cyclic voltammetry and AFM. TGA data reveal that the polymers P1 and P2 are thermally stable up to 350–400 °C. The UV–Vis absorption spectra for solid thin films envisage efficient molecular stacking with red shifting the absorption maxima to 30 nm when compared to solution. The obtained polymers have a band gap of 1.8–1.93 eV with low laying HOMO and LUMO energy level. The polymers displayed very good blue fluorescence in CHCl3 upon irradiated with UV light (254 nm) and Atomic force microscopy (AFM) applications to polymer P1 and P2 surfaces are providing interesting images of nanometre-scale polymer structures.