Intracellular detection of Cu2+ and S2- ions through a quinazoline functionalized benzimidazole-based new fluorogenic differential chemosensor

A new quinazoline functionalized benzimidazole-based fluorogenic chemosensor H3L is synthesized and fully characterized by conventional techniques including single crystal X-ray analysis. It acts as a highly selective colorimetric and fluorescence sensor for Cu2+ ions in DMF/0.02 M HEPES (1 : 1, v/v, pH = 7.4) medium. Reaction of H3L with CuCl2 forms a mononuclear copper(II) [Cu(Cl)(H2L)(H2O)] (H2L-Cu2+) complex which is characterized by conventional techniques and quantum chemical calculations. Electronic absorption and fluorescence titration studies of H3L with different metal cations show a distinctive recognition only towards Cu2+ ions even in the presence of other commonly coexisting ions such as Li+, Na+, K+, Mg2+, Ca2+, Fe2+, Fe3+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+ and Hg2+. Moreover, H2L-Cu2+ acts as a metal based highly selective and sensitive chemosensor for S-2-ions even in the presence of other commonly coexisting anions such as F-, Cl-, Br-, I-, SO42-, SCN-, AcO-, H2PO4-, PO43-, NO3-, ClO4-, NO2-, HSO4-, HSO42-, S2O32-, S2O82-, CN-, CO32- and HCO3- in DMF/0.02 M HEPES (1 : 1, v/v, pH = 7.4) medium. Quantification analysis indicates that these receptors, H3L and H2L-Cu2+, can detect the presence of Cu2+ and S2- ions at very low concentrations of 1.6 x 10(-9) M and 5.2 x 10(-6) M, respectively. The propensity of H3L as a bio-imaging fluorescent probe for detection of Cu2+ ions and sequential detection of S2- ions by H2L-Cu2+ in Dalton lymphoma (DL) cancer cells is also shown.