Orientational disorder and geometrical isomeric effect on nonlinear optical properties of poly bis(glycine)cadmium chloride

Poly bis(glycine)cadmium chloride (BGCC) crystals of both undoped and doped with thiourea (Tu) were grown from saturated solutions by a slow evaporation technique. The geometrical isomerism of the octahedral BGCC molecule is investigated using single crystal XRD, powder XRD and FT-IR. The significant difference between the two isomers namely facial (fac) and meridional (mer), is explained in terms of the different point group symmetries of C3 and C1, respectively. The loss of point group symmetry from C3 to C1 is attributed for the observed powder second-harmonic generation (SHG). Semi-empirical calculations from the optimized geometrical parameters also supported non-linear optical properties of the material.