Unveiling Noncentrosymmetric Pyridine Carboxylates from Centrosymmetric Templates through Motif Configuration Modulation in Zero-Dimensional System.

Developing approaches to induce noncentrosymmetric (NCS) frameworks through atomic-scale structural optimizations is crucial due to the growing need for new ultraviolet (UV) nonlinear optical (NLO) materials. Herein, the first two new NCS pyridine carboxylates, ZnBr(CHFNO) () and Cd(CHFNO)(HO) (), were successfully synthesized using centrosymmetric (CS) templates and rational structural reconstructions induced by different ionic radius. Both compounds crystallize in the orthorhombic system and feature metal-centered zero-dimensional (0D) isolated clusters. Substituting the [ZnONO] pyramid in the CS pyridine carboxylate with the [ZnONBr] pyramid in compound breaks the centrality, leading to an NCS framework with a second harmonic generation (SHG) response of 1.7 × KHPO (KDP). Introducing a larger Cd cation results in a -to- transition of the [MON] (M = Zn, Co, and Ni in CS templates, Cd in ) octahedra, forming a wing-shaped asymmetric 0D cluster with an SHG response of 2.1 × KDP. These findings indicate an approach that can effectively induce NCS structures of 0D organic-inorganic hybrid materials.