N-H•••N hydrogen bonds in trimethoprim salicylate methanol solvate [trimethoprim is 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine]

In the title compound, trimethoprim salicylate methanol solvate [3,4,5-trimethoxybenzyl)pyrimidin-1-ium salicylate methanol solvate], C14H19N4O3+.C7H5O3-.CH4O, the trimethoprim molecule is protonated at N1. The carboxylate group of the salicylate ion interacts with the protonated pyrimidine moiety of trimethoprim through a pair of nearly parallel N-H...O hydrogen bonds. This is reminiscent of the carboxylate-trimethoprim interaction observed in dihydrofolate reductase-trimethoprim complexes. The pyrimidine moieties of the trimethoprim cations are centrosymmetrically paired through a pair of N-H...o hydrogen bonds involving the 4-amino group and the unsubstituted pyrimidine N atom. The pyrimidine plane makes a dihedral angle of 89.5 (4)degrees with the phenyl ring in the trimethoprim cation.