3-(4-Carb-oxy-5-carboxyl-ato-1H-imidazol-2-yl)pyridin-1-ium monohydrate.

In the zwitterionic mol-ecule of the title compound, C(10)H(7)N(3)O(4)·H(2)O, one carboxyl group is deprotonated and the pyridine N atom is protonated. The pyridinium and imidazole rings form a dihedral angle of 5.23 (1)°. An intramolecular O-H⋯O hydrogen bond occurs. In the crystal, inter-molecular N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds link the zwitterions and water mol-ecules into sheets parallel to (102).

[N'-(3-Meth-oxy-2-oxidobenzyl-idene)nicotinohydrazidato]dimethyl-tin(IV).

In the title complex, [Sn(CH(3))(2)(C(14)H(11)N(3)O(3))], the Sn atom is in a distorted trigonal-bipyramidal coordination, with Sn-O distances of 2.138 (2) and 2.176 (2) Å. The dihedral angles between the two chelated benzene rings and the O-Sn-N group are 71.73 (9) and 83.30 (9)°.