A Novel Organic-Inorganic Hybrid Polyoxoniobate Constructed from {[Cu(en)(H2O)][HNb6O19]}5- Polyoxoanions and Methane-like {K4Na}5+ Cations

A novel organic-inorganic hybrid polyoxoniobate K8Na2{[Cu(en)(H2O)](2) [HNb6O19](2)}center dot 25H(2)O (en = ethylenediamine) 1 has been synthesized by the diffusion method and structurally characterized by elemental analyses, IR, UV-Vis spectra, thermogravimetric (TG) analysis and single crystal X-ray diffraction. The structure analysis indicates that 1 consists of two {[Cu(en)(H2O)][HNb6O19]}(5-) polyoxoanions linked each other by two methane-like {K4Na}(5+) cationic clusters. Surface photovoltage spectroscopy (SPS) and electric field induced surface photovoltage spectroscopy (EFISPS) measurements indicate that 1 is the n-type conduction characteristic. In situ UV and CV studies indicate that 1 can stably exist in the larger pH ranges in aqueous solution.