Hydrothermal Synthesis, Structural Characterization, Magnetic and Photoelectric Properties of Two Cobalt(II) Coordination Polymers

Abstract

AbstractTwo cobalt(II) coordination polymers, {[Co(μ‐4,4′‐bipy)(4,4′‐bipy)2(H2O)2]·(OH)3·(Me4N)·4,4′‐bipy·4H2O}n (1) and {[Co(μ‐4,4′‐bipy)(H2O)4]·suc·4H2O}n (2) (4,4′‐bipy = 4,4′‐bipyridine, suc = succinate dianions), were hydrothermally synthesized and structurally characterized by X‐ray diffraction analysis, UV‐Vis‐NIR, and ICP. The main structure feature common to the both polymers is presence of the infinite linear chains, [Co(μ‐4,4′‐bipy)(4,4′‐bipy)2(H2O)2]n (1) and [Co(μ‐4,4′‐bipy)(H2O)4]n (2), respectively. In 1, the chains are further linked by the hydrogen‐bond and π‐π stacking interaction, producing extended layer structure. The 4,4′‐bipy molecules in 1 play three different roles. In 2, the chains are linked into three‐dimensional network structure via complicated hydrogen bonding system. The variable temperature (2.0∼300 K) magnetic susceptibility of 1 indicates a tendency of spin‐transition in the temperature range of 110 K to 22 K, which attributes to the transition of high‐spin to low‐spin from Co2+(d7) ion. Also, the result of surface photovoltage spectroscopy (SPS) reveals that the polymer 1 has significant photoelectric conversion property in the region of 300‐800 nm.