Morphology, Crystal Structure, and Thermal and Spectral Studies of Semiorganic Nonlinear Optical Crystal LAHClBr

Solubility and specific heat properties of the semiorganic nonlinear optical crystal, l -arginine hydrocholorobromide (LAHClBr), have been measured as a function of temperature. The compound crystallizes in a rectangular bipyramidal shape with well-developed {100} and {001} pinacoids. X-ray diffraction analysis shows that it belongs to the space group P 2 1 with two independent molecules in asymmetric units and lattice parameters a = 11.158(2) Å, b = 8.579(3) Å, c = 11.235(3) Å, β = 91.55°(4). The arginine molecules occur as zwitterions, with the amino groups and the guanidyl groups each accepting a proton from the acid groups present in the molecule. The molecules are held together by a three-dimensional network of hydrogen bonds.