Iclaprim mesylate displaying a hydrogen-bonded mol­ecular tape

The title compound, 2,6-di­amino-5-[(2-cyclo­propyl-7,8-dimeth­oxy-2H-1-benzo­pyran-5-yl)meth­yl]pyrimidin-1-ium methane­sulfonate, C(19)H(23)N(4)O(3) (+)·CH(3)O(3)S(−), is a salt made up from a protonated iclaprim mol­ecule and a mesylate anion. The pyrimidine and chromene units of the iclaprim mol­ecule form an orthogonal arrangement [inter­planar angle of 89.67 (6)°], and the 3-nitro­gen position of the pyrimidine ring is protonated. Four distinct N—H⋯O inter­actions and an additional N—H⋯N hydrogen bond connect iclaprim and mesylate mol­ecules to one another, resulting in an infinite hydrogen-bonded mol­ecular tape structure. The central section of the tape is formed by a sequence of fused hydrogen-bonded rings involving four distinct ring types.