Chiral recognition and behavior of [1,1′-binaphthalene]-2,2′-diol in aqueous solution by fluorescence spectroscopy

The photophysical properties of [1,1′-binaphthalene]-2,2′-diol (BINOL) have been examined with particular emphasis to the effects of chirality and chiral recognition. Few studies have specifically examined the photophysical properties of BINOL. This study was prompted by preliminary observations in our laboratory that revealed anomalously high fluorescence anisotropy values for BINOL. The analyte (BINOL) was examined in various solvents and in aqueous solutions of various pH values in order to perturb the effects of proton transfer, which was observed as a red-shift in the fluorescence emission. The anomalously high anisotropy value could not, however, be attributed to proton transfer phenomena. The anisotropy was found to be concentration dependent and was attributed to the formation of dimers or other higher order aggregates. The chiral recognition of BINOL was also examined by fluorescence anisotropy measurements and compared to that of other binaphthyl analogs.