1D Cobalt‐Cytidine Monophosphate Coordination Polymer Exhibiting Efficient Ultraviolet Second‐Harmonic Generation

ABSTRACT In pursuit of new ultraviolet (UV) nonlinear optical (NLO) materials, a novel cobalt‐based hydrogen‐bonded coordination complex, [complex ( 1 )], is synthesized via a slow evaporation method. Complex ( 1 ) crystallizes in the noncentrosymmetric (NCS) space group P2 1 and features a distorted octahedral Co(II) coordination environment that extends into a 3D framework. Remarkably, complex ( 1 ) exhibits a strong second‐harmonic generation (SHG) response, approximately 7.4 times greater than that of KH 2 PO 4 (KDP). The pronounced activity arises from robust hydrogen‐bonding interactions that suppress antiparallel packing, as well as from the highly distorted, polarizable Co(II) coordination geometry. In addition, complex ( 1 ) exhibits an optical bandgap (3.41 eV), indicating UV transparency. These findings make a complex ( 1 ) Co(II)‐based framework that can be used in UV NLO applications and emphasize it as an effective synthetic approach to the design of polar metal‐organic systems with improved optical properties.