Conformational and Electronic Engineering of Twisted Diphenylacetylenes

Three tethered diphenylacetylene derivatives were prepared by alkyne metathesis. In these cycles, the twist angle between the two benzene rings is variable and determined by the nature of the linker. The engineering of the twist angle leads to a change of the UV−vis spectra of the cycles. The larger the twist angle in the macrocycles, the more blue shifted their λmax (UV−vis), the lower their fluorescence quantum yield, and the lower field shifted their 13C NMR signals of the alkyne carbons are.