Specific complexation of saccharides with dimeric phenylboronic acid that can be detected by circular dichroism

Abstract
For the development of new receptor molecules that can recognize sugar molecules, we synthesized 2,2′-dimethoxydiphenylmethane-5,5′-diboronic acid (1) and diphenyl-3,3′-diboronic acid (2). It was shown that in the presence of 1, some mono- and disaccharides result in a CD band at 275 nm. It was also shown that 2 forms 1:1 complexes with several disaccharides and gives the characteristic exciton coupling in CD spectroscopy owing to immobilization of the two phenyl rings. The results indicate that the CD spectroscopic method using 1 or 2 as receptor molecules serves as a new sensory system for sugar molecules, and the absolute configuration of disaccharides was successfully predicted from the sign of the exciton coupling of the CD spectrum by using 2.