Dual role of cyclic Diselenide containing coumarin based scaffold supported with DFT/TD-DFT studies: Superoxide...

Cyclic diselenide-based coumarin compound 4-methyl-7-((naphtho [1,8-cd][1,2]diselenol-3-ylmethylene)amino)-2H-chromen-2-one (probe) was successfully synthesized and characterized using ¹H, ¹³C NMR, HRMS, and FT-IR spectroscopy. The probe endured systematic evaluation against a broad panel of reactive oxygen species (ROS) and biothiols, revealing exceptional selectivity and sensitivity for superoxide relative to other tested analytes. The probe has a lower detection limit of 32 nM for superoxide, as determined through the fluorescence titration method, with a high stock shift of 74 nm. Comparative study revealed that the probe possessed a quantum yield of 1.22%, which increased to 27.3% following reaction with superoxide, indicating a 22-fold increment in fluorescence intensity once oxidised by superoxide. The Density Functional Theory (DFT) studies have predicted that the probe is present in cis conformation with the SeN (imine) bonding. The mechanism of the conversion of the cis-trans isomers of the probe has been investigated, and the interconversion between predicted possible oxidation products is confirmed via combined spectroscopic monitoring (UV-Vis and fluorescence time-course studies), supported by theoretical analysis experimentally. In vitro cell viability assays confirmed that the probe is biocompatible with normal MDCK cells while revealing potent anti-cancer effects against cancerous cells (HeLa and MCF7).