Molecular recognition in solid‐state crystallization: Colored chiral adduct formations of 1,1′‐Bi‐2‐naphthol derivatives and benzoquinone with a third component

Molecular recognition in solid-state crystallization involving derivatives of 1,1'-bi-2-naphthol and benzoquinone was studied. No adduct crystal was formed when crystals of biphenyl were further added as a third component to a grinding mixture of crystals of chiral 1,1'-bi-2-naphthol and benzoquinone, which by itself did not form an adduct. This contrasts with the case in which further addition of naphthalene crystals to the same mixture produced a new red crystal. Adduct formations using chiral 6,6'-dibromo-1,1'-bi-2-naphthol in place of 1,1'-bi-2-naphthol were also studied. In this case, adducts were produced either with or without biphenyl as a third compound, but the colors of the adducts differed significantly in the two cases: red and bluish-black. The same three-component adduct crystals were produced from solid-grinding and solution crystallization and the structure was determined by X-ray diffractometry. Based on the crystal structures, theoretical calculations were carried out to compare the mechanism of colorations in the binary and the ternary complexes.