Visualization of Molecular Recognition:  A Novel System Based on Charge-Transfer Complexes Composed of 1,1‘-Bi-2-naphthol Derivatives and p-Benzoquinone

Charge-transfer (CT) complexes composed of 1,1‘-bi-2-naphthol derivatives as an electron donor and p-benzoquinone as an acceptor serve as an excellent host system for visual molecular recognition. This is because they form inclusion crystals with guest aromatic compounds which display remarkably different colors depending on the structure of the component molecules and on the method of crystallization (i.e., solution crystallization or solid cogrinding of component crystals).