Crystal structures of 4-methoxybenzoic acid–1,3-bis(pyridin-4-yl)propane (2/1) and biphenyl-4,4′-dicarboxylic acid–4-methoxypyridine (1/2)

Abstract

The crystal structures of two hydrogen-bonded compounds, namely 4-methoxybenzoic acid–1,3-bis(pyridin-4-yl)propane (2/1), C13H14.59N2·C8H7.67O3·C8H7.74O3, (I), and biphenyl-4,4′-dicarboxylic acid–4-methoxypyridine (1/2), C14H9.43O4·C6H7.32NO·C6H7.25NO, (II), have been determined at 93 K. In (I), the asymmetric unit consists of two crystallographically independent 4-methoxybenzoic acid molecules and one 1,3-bis(pyridin-4-yl)propane molecule. The asymmetric unit of (II) comprises one biphenyl-4,4′-dicarboxylic acid molecule and two independent 4-methoxypyridine molecules. In each crystal, the acid and base molecules are linked by short O—H...N/N—H...O hydrogen bonds, in which H atoms are disordered over the acid O-atom and base N-atom sites, forming a linear hydrogen-bonded 2:1 or 1:2 unit of the acid and the base. The 2:1 units of (I) are linked via C—H...π, π–π and C—H...O interactions into a tape structure along [101], while the 1:2 units of (II) form a double-chain structure along [-101] through π–π and C—H...O interactions.