Probing atomic level structural transformation in O–H⋯N heterosynthon crystal

Abstract

Structural changes of resorcinol (res) and trans-1,2-bis(4-pyridyl)ethylene (bpe) co-crystals during [2 + 2] photodimerization were monitored by means of single crystal X-ray analysis. The crystals lost their integrity with increasing conversion indicating an interesting case of a non-ideal single-crystal-to-single-crystal transformation. The 2(bpe) : 2(res) heterosynthon yielded two different polymorphs upon photodimerization, i.e. the dimer obtained via single-crystal-to-single-crystal transformation (as-dimerized dimer) consists of triclinic P-1 space group which upon re-crystallization adopted a stable conformation with monoclinic P2₁/n space group.