Synthesis, photophysical and DFT studies of a new p-phenylenevinylene material based on triazole for fluorescent sensing application

Abstract

This paper covers the elaboration of a new semi-conducting material (PPVTRI) for sensing application.This new material containing highly emissive chromophore type p-phenylenevinylene (PPV) and chelating triazole moieties, is soluble in common organic solvents. The molecular structure of PPVTRI was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies. Thermal characterization shows that the material has a good thermal stability up to 220 °C. The intrinsic optical properties of this π-conjugated material were investigated by UV–vis absorption and photoluminescence spectroscopies. The UV–vis absorption shows the presence of the phenomen of intramolecular charge transfert in dilute solution between donor (conjugated system) and acceptor (spacer unit) groups. The organic material PPVTRI exhibits a yellowish-green emission in dilute solution. The HOMO and LUMO levels were estimated using cyclic voltammetry analysis. The computational analyses on the synthesized chemical structure were performed using Density Functional Theory (DFT) and time-dependent (TD-DFT) employing the B3LYP functional with the 6–31g(d) basis set to get insight into the conformation, electronic and optical properties. Based on theory study, the configuration of the elaborated semi-conducting material PPVTRI is composed majority of Z-E isomer. The Molecular electrostatic (MEP) results show that there are electronegative groups that can be trapping sites for metal cations. Then, the PPVTRI was investigated as a fluorescent sensor by analyzing the photoluminescence quenching of its dilute solution in the presence of different metals, showing remarkable responses towards Cu2+ and Fe2+ cations. The value of limit of detection (LOD) of the Cu2+ and Fe2+ provide that PPVTRI material could be suitable for the detection of those cations in drinking water samples.