l-Argininium(+) maleate(−) dihydrate.

The title complex, C6H15N4O2+·C4H3O4−·2H2O, contains a planar ring formed by sharing one H atom between the O atoms in the carboxyl groups of the maleate anion. This hydrogen bond is slightly asymmetric. In thel-argininium(+) cation, both the α-amino and the guanidyl groups are protonated. The nonlinear optical response of the compound is derived from the intrinsic hyperpolarizabilities of thel-argininium cations, maleate anions and intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]