Thiophene derived sky-blue fluorescent probe for the selective recognition of mercuric ion through CHEQ mechanism and application in real time samples

Abstract

A vibrant blue organic luminescent material with enhanced photophysical properties is in great demand for the generation of optoelectronic devices and luminescent sensors. In this context, the thiophene-benzimidazole probe TH-IMI was designed and synthesized by a simple condensation reaction. The synthesized probe has shown excellent photophysical properties like high FL intensity, a high quantum yield of 90% in the solution phase, a low optical bandgap of 2.84 eV, positive solvatochromic effect in emission spectra and Disaggregation Caused Quenching Effect (DCQE). Such a high luminescent probe was employed for the recognition of mercuric ions in the solution phase, solid state detection, and in tracking mercury in green gram sprouts. UV–visible absorption and emission spectra, 1H NMR titration, IR spectroscopic and ESI-MS techniques confirmed that the probe underwent a fluorescence quenching response via the CHEQ effect upon exposure to Hg2+. The stoichiometry was found to be 1:1 through Job’s plot and has a fast response rate and relatively low limit of detection of about 6.13 × 10-11 M in a linear range between 0 and 110 µL.