Connecting BINOL and terpyridine: the electronic effects of the linkage

1,1′-Bi-2-naphthol and terpyridine are covalently connected either directly or through different linkers. It is found that in contrast to the directly connected one, when the saturated methyleneoxy linker is used, there is inefficient electronic communication between the BINOL and terpyridine units and the fluorescence of the BINOL unit cannot be completely quenched by the coordination of terpyridine unit with a Cu2+ ion. However, a phenylene linker allows an efficient electronic communication between the BINOL and terpyridine units and the fluorescence of the BINOL is almost completely quenched upon Cu2+ coordination. The interaction of these compounds with valinol is studied and large fluorescence enhancements are observed for those with efficient electronic communication between the BINOL and terpyridine units.