Syntheses, structures, properties and DFT calculations of coordination polymers constructed by 2,6-bis(benzimidazolyl)pyridine

Five new compounds constructed with bzimpy, namely [Zn(bzimpy)(H2O)2(NO3)]·NO3 (1), [Co(bzimpy)(bipy)(H2O)]·CH3OH·ClO4·NO3 (2), [Ni(bzimpy)(bipy)Cl]·ClO4 (3), [Ce(bzimpy)2 (NO3)2]·bipy·CH3OH·ClO4 (4) and [Pr(bzimpy)2(NO3)2]·bipy·CH3OH·ClO4 (5) (bzimpy = 2,6-bis (benzimidazolyl)pyridine, bipy = 2,2′-dipyridine), have been synthesized and characterized by elemental analysis, IR and fluorescence spectra, electrochemical analysis and single crystal X-ray diffraction. For 1, DFT and TD-DFT calculations have been performed to obtain its UV–Vis absorption spectrum, and a satisfactory theoretical–experimental agreement was achieved. These compounds are all ionic complexes and are stabilized in the solid state by complicated networks of hydrogen bonds between the crystallized cationic complexes and anionic fragments, as well as solvent molecules. Moreover, hydrogen bonds, π–π and C–H⋯π stacking interactions seem to be effective in stabilizing the crystal structures. Electrochemical investigations indicate metal centered reduction couples. The fluorescence properties were studied in solvents with different dipole moments. The different shifts between different solvents provide information for the application as luminescent materials in further studies.

Graphical abstractFive new compounds constructed with 2,6-bis(benzimidazolyl)pyridine have been synthesized and characterized by elemental analysis, IR and fluorescence spectra, electrochemical analysis and single crystal X-ray diffraction. DFT and TD-DFT calculations for 1 have been performed to obtain its UV–Vis absorption spectrum, and satisfactory theoretical-experimental agreement was achieved. The electrochemical and luminescence properties of these compounds have been investigated as well.Figure optionsDownload full-size imageDownload as PowerPoint slide