A Highly Fluorinated Chiral Aldehyde for Enantioselective Fluorescent Recognition in a Biphasic System

A 1,1'-bi-2-naphthol (BINOL)-based aldehyde containing four perfluoroalkyl groups has been designed and synthesized. It shows enantioselective fluorescence enhancement at 420 nm when treated with the enantiomers of trans-1,2-diaminocyclohexane in an organic/fluorous biphasic system. The enantiomeric excess of the diamine in methanol can be linearly correlated with the emission intensity of of the aldehyde in perfluorohexane (FC-72). This is the first example to determine the enantiomeric composition of a chiral molecule by using a fluorescent sensor in a fluorous/organic biphasic system. The mechanism of the reaction was investigated by NMR spectroscopy and mass spectrometry.