Chiang Mai Journal of Science

     Two new coordination polymers, [Co(bipy)(HBDC)₂]_n (terephthalic acid = H₂BDC) (1) and {[Co(bix)₃](ClO₄·H₂O)₂}_n (2), were prepared by mixing Co²⁺, 2,5-dihydroxyterephthalic acid and 4,4΄-bipyridine (bipy)/1,4-bis(imidazol-1-ylmethyl)benzene (bix) by a hydrothermal method, respectively. X-ray crystallography reveals there is a one-dimensional chain constructed by tetra-coordinated Co(II) centers, bipy and HBDC⁻ ligands in complex 1, while a 2D network is built by bix ligands in 2. The solid-state photoluminescence properties confirmed that 1 exhibits a strong emission peak at 479 nm which may be due to ligand-to-metal charge transfer (LLCT), and there was no fluorescence in 2. Furthermore, the quantum-chemical calculations of “molecular fragments”extracted from crystal structure 1 were performed using the PBE0/LANL2DZ method at Gaussian 16.