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)

The crystal structures of two hydrogen-bonded compounds, namely 4-methoxybenzoic acid-1,3-bis(pyridin-4-yl)propane (2/1), C₁₃H_14.59N₂·C₈H_7.67O₃·C₈H_7.74O₃, (I), and biphenyl-4,4′-dicarboxylic acid-4-methoxypyridine (1/2), C₁₄H_9.43O₄·C₆H_7.32NO·C₆H_7.25NO, (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.