Crystal structure and characterization of L-arginine chlorate and L-arginine bromate*

The salts L-arginine.HClO3 and L-arginine.HBrO3, were synthesized. The crystals obtained were characterized by IR and NQR spectroscopy, thermal analysis, Nd:YAG laser radiation second harmonic generation, dielectric, piezoelectric and pyroelectric measurements and their crystal structures were determined. L-arginine.HClO3 and L-arginine.HBrO3 are crystallized in orthorhombic (space group P212121) and triclinic (space group P1) systems, respectively. Their structures consist of the protonated arginine cation [C(H2N)2CNH(CH2)3- CH(NH3 C)COOK] and respective ClO3 K or BrO3 K anions. Hydrogen bonds (stronger in the bromate) connect anions with cations and the latter with each other. However, these salts have essential distinctions in crystal packing. q 2005 Elsevier B.V. All rights reserved