A Switchable fluorescence solid sensor for Hg2+ detection in aqueous media based on a photocrosslinked membrane functionalized with (benzimidazolyl)methyl-piperazine derivative of 1,8-naphthalimide

A Selective fluorescence solid sensor for Hg2+ detection in aqueous solution (M-MBZN) has been developed by grafting N-(2-hydroxyethyl)-4-(4-(1H-benzo[d]imidazol-2-yl)methyl) piperazine-1-yl)-1,8-naphthalimide (MBZN) to a photo-crosslinked M-Cl membrane reaction through the acid chloride groups. The resulting fluorescence sensor undergoes fluorescence enhancement upon binding mercuric ions which provokes a photo induced electron transfer (PET) inhibition process from the piperazine to the naphthalimide moiety. Various photochemical parameters were determined by using pH-dependent absorption and fluorescence spectroscopies as well as the selective detection of Hg2+. The sensing membrane possesses a switchable "turn-on" fluorescence response to Hg2+ in pure water; it is easy to use and reusable and shows high selectivity and sensitivity.