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 C 2 ‐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)