Design and synthesis of fluorescent 6-aryl[1,2-c]quinazolines serving as selective and sensitive 'on-off' chemosensor for Hg2+ in aqueous media

A series of quinazolines (1-3) have been designed, synthesized and characterized by microanalyses, NMR (1H and 13C), HRMS, electronic absorption and emission spectral studies. Consistently 1 and 3 have been structurally authenticated by single crystal X-ray diffraction analyses. Moreover 1-3 exhibit strong fluorescence and selective fluorescence quenching in presence of Hg2+ ions. HRMS, FAB-MS, 1H NMR, Binding constants and Job's plot analysis established 1:1 stoichiometry for Hg2+ with 1 and 2 whereas 1:2 with 3.