Fluorescent sensor based on BINOL for recognition of cysteine, homocysteine, and glutathione.

A new and simple fluorescent sensor based on unmodified BINOL was developed. The fluorescence of BINOL could be turned off with high selectivity toward Cu(II) among 27 metal ions. Meanwhile, it was found that BINOL was oxidized to dibenzo[a,kl]xanthen-1-ol (A) by Cu(NO3)(2). A new peak appeared at similar to 482 nm upon addition of thiol-containing cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). Thus, a cascade recognition of Cu(II) and Cys, Hcy, and GSH are well presented.