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

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 degrees 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) x 10(-5) M. This kind of cadmium ion sensing fluorescent polymer probe is highly useful for biomedical applications.