Test for Homology: Photoactive Crystalline Assemblies Involving Linear Templates Based on a Homologous Series of Phloroglucinols

摘要

Cocrystallization of frans-1,2-bis(4-pyridyl)ethylene (4,4′-bpe) with eight members of a homologous series of phloroglucinols 1a-h yields molecular solids 2(1a-h)·2(4,4′-bpe) with components held together by four O-H···N hydrogen bonds. In each case, the molecules assemble to form a discrete four-component assembly with olefins preorganized for a [2 + 2] photodimerization. UV irradiation of each member in the series of solids produces rcff-tetrakis(4-pyridyl)cyclobutane (4,4′-tpcb), stereospecifically, in up to 100% yield.