Synthesis of novel coumarin containing conjugated fluorescent polymers by Suzuki cross-coupling reactions and their chemosensing studies for iron and mercury ions

Abstract

Conjugated fluorescent polymers are very useful materials for chemical and biochemical sensors. Herein we report the synthesis of four novel conjugated coumarin-containing fluorescent co-polymers (P1–P4) by palladium catalyzed Suzuki-Miyaura cross-coupling reaction. 4-Methyl/phenyl coumarin ditriflates and diboronic acids such as benzene-1,4-diboronic acid and 9,9-dioctylfluorene-2,7-diboronic acid were used as coupling partners. All the polymers were well-characterized using NMR and gel permeation chromatography. TGA studies revealed that these polymers are stable over 300 °C. The photophysical properties of these novel polymers were studied by UV–Vis and fluorescence spectroscopy. Among these four polymers, polymer P3 having 4-methylcoumarin and dioctylfluorene as alternating monomers showed intense fluorescence with 0.73 quantum yield in the DMF medium. Polymer P3 was also found as selective fluorescence “turned-off” chemosensor for the detection of Hg(II) and Fe(II)/Fe(III) ions over the other metal ions dissolved in water.