The role of two coordination compounds as novel transparent nonlinear optical crystals

This paper reports the synthesis, structure and properties of two coordination compounds which are transparent in the visible region and show a relatively strong nonlinear optical (NLO) effect. The first crystal, Zn(2-NH 2 py) 2 CI 2 (2-aminopyridine zinc dichloride, DAZC), shows a SHG (second harmonic generation) effect 8 times as strong as that of KDP. X-ray single crystal structure analysis reveals that the molecule possesses a tetrahedron configuration around the zinc atom, and all the molecules are aligned in an almost fully parallel direction.The second compound, Zn(acac) 2 (PhTU) (phenylthiourea zinc diacetylacetate, PZDA), shows a powder SHG effect as strong as 10 times that of KDP. X-ray single crystal structure analysis shows that the molecule possesses a square pyramidal configuration around the zinc ion, and the molecules are aligned almost in a parallel arrangement in the lattice. These two crystals may represent a novel strategy for designing new transparent NLO materials.