Thiophene anchored coumarin derivative as a turn-on fluorescent probe for Cr ~(3+): Cell imaging and speciation studies

摘要

A thiophene-coumarin hybrid molecule, (6E)-6-((thiophen-2-yl) methyleneamino)-2H-chromen-2-one (TMC) has been prepared and its single crystal X-ray structure is reported. TMC can selectively detect Cr ~(3+) in presence of other common cations. Both TMC and its Cr ~(3+) complex are well characterized by different spectroscopic techniques like ~1H NMR, QTOF-MS ES ~+, FTIR and elemental analysis as well. TMC exhibits fluorescence enhancement upon binding Cr ~(3+) in CH _3CN-HEPES buffer (0.02 M, pH 7.4) (4:6, v/v) medium. Detection limit of the method is 1 × 10 ~(-6) M. Binding constant is estimated with the Benesi-Hildebrand method and the value 8 × 10 ~4 indicates a fairly strong interaction between TMC and Cr ~(3+). Speciation studies have been performed in a fast and environment friendly way using least sample volume, less hazardous chemicals and solvents. Cr ~(3+) assisted restricted rotation around the imine bond and inhibited photo-induced electron transfer from the N,S-donor sites to the coumarin unit are responsible for fluorescence enhancement. TMC is capable to detect intracellular Cr ~(3+) in living cells.