In situ Cu(II)-containing chiral polymer complex sensor for enantioselective recognition of phenylglycinol

A chiral polymer P1 was synthesized by the polymerization of 2,5-dibutoxy-1,4-di(benzaldehyde)-1,4-diethynylbenzene (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via Schiffʹs base formation, and the chiral polymer P2 could be obtained by the reduction reaction of P1 with NaBH4. P2 can serve as a “turn-off” fluorescent sensor toward Cu2+ and Ni2+. The in situ generated Cu(II)-containing polymer complex of P2 (Cu(II)-P2) can exhibit remarkable “turn-on” fluorescence enhancement response and considerable enantioselectivity toward unmodified phenylglycinol via a ligand displacement mechanism. More importantly, (R,R)-Cu(II)-P2 solution can turn on bright blue fluorescence color change again upon addition of l-phenylglycinol under a commercially available UV lamp, which can be clearly observed by the naked eyes for direct visual discrimination at low concentration. The simple, rapid and sensitive benign process makes this protocol promising for recognition of phenylglycinol enantiomers.