Effects of Terminal Halide Ions on Structures and Photoluminescence Properties of three Mercury Coordination Polymers

Abstract— The halide anions have shown crucial influence on the structures of the Hg(II) halide coordination polymers (CPs) and these interesting phenomena have been widely explored, while it still remains elusive to predict which halide anions give similar or different structures. The present three novel CPs [Hg(Hbpt)X₂]_n (X = Cl (1), Br (2), I (3), Hbpt is 4,4'-bis(4-pyridyl)-1,2,4-triazoles) give a special example to verify the effect of halide ions on the structures and photoluminescence properties. Single crystal X-ray diffraction analyses indicated the terminal coordinated halide ions play important roles in the structural diversity since the 1D chains in the three CPs display various configurations, symmetries and packing modes although they are all formed by Hbpt ligand connecting Hg(II) cations. The photoluminescence experiments and DFT calculations results suggest that both the halide anions and conjugated Hbpt ligands show significant roles in the emission process, while halide anions have a limited effect on tuning the photoluminescence properties.