Microwave assisted facile one pot synthesis of novel pyrazole derivative for multi-analyte detection (Fe3+ and Zn2+) and its solvatochromic studies

Abstract

A novel heterocyclic pyrazole-based probe Ph-DB was synthesised by microwave assisted concatenation of phenyl hydrazine and 2,5-dibromo-3-thiophenecarboxylaldehyde. The veracity of synthesized pyrazole derivative was established using 1H NMR,13C NMR, HRMS and FT-IR. ICT studies were conducted in different organic solvents of varying polarity to comprehend the solvatochromic nature of compound. DFT studies were performed to elucidate the intricacies of the Ph-DB’s electronic structure. The electrochemical band gap and optical band gap were calculated using cyclic voltammetry and Tauc's plot respectively. SEM analysis was carried out to explore the surface morphology of Ph-DB which was found to show small microwires like structures which supports optoelectrical properties of Ph-DB. The photophysical studies were carried out to check the chromogenic and fluorogenic response of Ph-DB towards different metal ions. It was observed that Ph-DB shows noticeable fluorescence enhancement with Zn2+ ions with the detection limit of 6.1 µM and chromogenic change with Fe3+ with a detection limit of 6.6 µM. Additionally quantum yield, binding constant and recovery experiment of Ph-DB probe were performed. Ph-DB probe was utilised for precise monitoring of Zn2+ and Fe3+ ions in water samples.