Investigation of Photophysical Properties on Carbazole and Pyrazine Based Conjugated Polymer: Excellent Fluorescence Sensing Towards to Cadmium Ion

Abstract

Developing fluorescent sensor is most advantages in recent years to detect metal ions from biological and environmental systems. Hence, three new donor (carbazole)–acceptor (pyrazine) conjugated polymers (P1–P3) were synthesized by Wittig route. The polymers was structurally confirmed using FTIR, NMR spectroscopy and expressed excellent emission behavior (480–520 nm) towards various polarity of the solvents. Luminescent quantum yield of the polymers P1–P3 were 0.64, 0.69, and 0.72 in chloroform with optical band gap of 2.13, 2.10, and 2.06 eV respectively. Excellent thermal stability with an onset decomposition temperature of P1–P3 was 320, 340, and 200°C under nitrogen atmosphere. Cyclic voltammetry results depicted that the LUMO and HOMO was 3.41 to 3.45 eV and–5.72 to–5.65 eV respectively. Spherical and rod shaped surface morphology of the polymer thin film has been observed from AFM technique. The fluorescence sensitivity of the polymers has been detected towards to Cd2+ ion and its ability of the limit of detection (LOD) was found to be (0.8–1.3) × 10–5 M. This kind of cadmium ion sensing fluorescent polymer probe is highly useful for biomedical applications.