Crystal structures of 8-arylethynyl substituted guanosine derivatives: are hydrogen-bonded ribbons a surprise?

Abstract

Crystal structures of two 8-arylethynyl substituted guanosines reveal twisted hydrogen-bonded ribbon superstructures, contrasting a previous report of guanine quartet formation from 8-aryl derivatives. The structural switch is attributed to the stabilization of the ribbon through intermolecular [π⋯π] stacking between the optimally positioned electron-poor arylethynyl substituents and electron-rich guanine nuclei.