Hydrothermal synthesis, structural characterization, magnetic and photoelectric properties of two cobalt(II) coordination polymers

Two cobalt(II) coordination polymers, {[Co(mu-4,4'-bipy)(4,4'-bipy)(2)(H2O)(2)]center dot(OH)(3)center dot(Me4N)center dot 4,4'-bipy center dot 4H(2)O}(n) (1) and {[Co(mu-4,4'-bipy)(H2O)(4)] center dot suc center dot 4H(2)O}(n) (2) (4,4'-bipy = 4,4'-bipyri-dine, 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(mu-4,4'-bipy)(4,4'-bipy)(2)(H2O)(2)](n) (1) and [Co(mu-4,4'-bipy)(H2O)(4)](n) (2), respectively In 1, the chains are further linked by the hydrogenbond and pi-pi stacking interaction, producing extended layer structure. The 4,4'-bipy molecules in I 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 similar to 300 K) magnetic susceptibility of I indicates a tendency of spin-transition in the temperature range of I 10 K to 22 K, which attributes to the transition of high-spin to low-spin from Co2+ (d(7)) ion. Also, the result of surface photovoltage spectroscopy (SPS) reveals that the polymer I has significant photoelectric conversion property in the region of 300-800 nm.