Modulation of charge-transfer complexes assisted by complementary hydrogen bonds of nucleobases: TCNQ complexes of a uracil-substituted EDO-TTF

Abstract

A hydrogen bond functionalized ethylenedioxytetrathiafulvalene (EDO-TTF) derivative having an n-butyluracil moiety was synthesized. In the crystal structure, the Watson–Crick-type complementary hydrogen bonds of the uracil moiety formed a pair of donor molecules, which further aggregated by S⋯S interactions and π-stacks of the TTF moiety to construct a two-dimensional sheet. In the charge-transfer complex formation with tetracyanoquinodimethane, the crystallization conditions modulated the subtle balance between Watson–Crick and reverse Watson–Crick types of complementary hydrogen-bonded pairs, controlling stoichiometry, ionicity and molecular packing of the complexes. A highly conducting mixed valence complex with the Watson–Crick-type hydrogen bonds was yielded by the quick evaporation of reaction solvent, and a low-conducting neutral complex forming reverse Watson–Crick-type hydrogen bonds was obtained by the slow vapor diffusion method.