l-Homoproline-Directed Synthesis of Organic-Inorganic Metal Iodides for Second Harmonic Generation.

Three organic-inorganic metal iodides, namely, (NH 4 )(l-hp)ZnI 3 ( 1 ), [Cd(l-hp) 4 ]Cd 3 I 8 ( 2 ), and (l-Hhp)(l-hp)PbI 3 ( 3 ), have been synthesized using l-homoproline (l-hp) as the structure-directing agent. These compounds feature different noncentrosymmetric structures and optical properties. In particular, compound 3 shows a large second-harmonic-generation response of 3.4 times that of KH 2 PO 4 . Density functional theory calculations were performed to gain insight into its structure-property relationship.