Modulation of aluminum sensing properties of a sulphone group containing chemosensor and its biological applications.

A chemosensor with two binding pockets facilitates binding of one metal ion in either of the pockets providing a better chance for the interaction and hence recognition of the cation. We report here a chemosensor, namely 2,2'-(1E)-(5,5'-sulfonylbis(2-hydroxy-5,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)dinaphthalen-1-ol (HL-naph), for selective sensing of Al in DMF- HEPES buffer (1:4, v/v, pH 7.4). It shows almost 100-fold fluorescence enhancement at 532 nm (λ = 482 nm) in the presence of Al. Its quantum yield and excited state lifetime enhances significantly with the cations. HL-naph forms a 1:2 complex with Al with an association constant value of 2.18 × 10 M. Fluorescence enhancement may be attributed to CHEFF mechanism and restriction of >CN isomerization. Effect of the presence of naphthyl rings instead phenyl ring of a previously reported probe has resulted shifting of excitation/emission peak towards longer wavelength. The probe has been applied to image Al in L6 cells with no significant cytotoxicity.