Stereoselective Sensing by Substrate‐Controlled syn/anti Interconversion of a Stereodynamic Fluorosensor

A stereoselective sensing method that is based on the unique stereodynamic and photochemical properties of 1,8‐diquinolylnaphthalenes has been developed. The ability to undergo substrate‐induced syn/anti interconversion and the striking difference in the fluorescence intensity of the syn and anti isomers of 1,8‐bis(2‐isopropyl‐4‐quinolyl)naphthalene (1) have been utilized for stereoselective sensing of the isomers of 1,2‐diaminocyclohexane (5). The conformational stability of 1 at room temperature greatly facilitated spectroscopic and crystallographic studies of this new prototype of stereodynamic fluorosensors. Fluorescence measurements of the anti and syn isomer of 1 revealed a quantum yield of 11.6% and 2%, respectively. NMR spectroscopy experiments confirmed that trans‐5 stabilizes the C2‐symmetric anti isomers of 1, whereas cis‐5 favors formation of the less fluorescent meso syn‐1 isomer, which results in a reduced fluorescence response. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)