Host-Guest Symmetry and Charge Matching in Glycine-Templated Metal Sulfate-Oxalates Obtained by a Solvent-Free Method.

Two metal sulfate-oxalates, (Hgly) 2 ·Zn(SO 4 )(C 2 O 4 ) ( 1 ) and Hgly·In(SO 4 )(C 2 O 4 )(gly) ( 2 ), were prepared under solvent-free conditions, where gly = glycine. They have similar layered structures despite the fact that aliovalent metal ions are used as structural nodes. Notably, glycine molecules play dual roles as a protonated cation and a zwitterionic ligand in compound 2 . The two compounds display moderate second-harmonic-generation (SHG) responses, confirming their noncentrosymmetric structures. Theoretical calculations were performed to reveal the origin of their SHG responses.