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

This paper reports the synthesis, structure and properties of two coordinat ion compounds which are transparent in the visible region and show a relati vely strong nonlinear optical (NLO) effect. The first crystal, Zn(2-NH(2)py )(2)Cl-2 (2-aminopyridine zinc dichloride, DAZC), shows a SHG (second harmo nic generation) effect 8 times as strong as that of KDP. X-ray single cryst al structure analysis reveals that the molecule possesses a tetrahedron con figuration around the zinc atom, and ail the molecules are aligned in an al most fully parallel direction. The second compound, Zn(acac)(2)(PhTU) (phen ylthiourea zinc diacetylacetate, PZDA), shows a powder SHG effect as strong as 10 times that of KDP. X-ray single crystal structure analysis shows tha t the molecule possesses a square pyramidal configuration around the zinc i on, and the molecules are aligned almost in a parallel arrangement in the l attice. These two crystals may represent a novel strategy for designing new transparent NLO materials.