Structures and light-induced surface electron behavior of some oxo-vanadium complexes

Four oxo-vanadium coordination complexes, {[VIV0.5VV3P4O20(OH)]·2(H2en)·1.5H2O}n (1), {[VIV0.5VV4P4O22(H2O)]·(H2en)}n (2), {[VIV1VV2O5(SO4)2(phen)3(H2O)3]·6H2O} (3) and [VO(o-phta)(phen)(H2O)] (4) (en = 1,2-ethanediamine, o-phta = o-phthalic group, and phen = 1,10-phenanthroline), were synthesized hydrothermally and the structures were determined through single-crystal X-ray diffraction. The surface electron behaviors and photo-electric conversion properties of the complexes were studied emphatically by SPS and UV–Vis absorption spectra. Structural analysis indicates that 1 and 2 are both oxo-vanadium phosphate polymers with V+4/V+5 mixed valence states. Complexes 3 and 4 are vanadyl coordination supramolecules including organic ligands. There are all positive response bands within the range 300–800 nm in the SPS of the four complexes, which indicates that they all possess photo-electric conversion properties. There are three species of O → V LMCT response bands in the SPS and UV–Vis spectra of the complexes, because the coordinated oxygen atoms are from different groups. The similarities and differences of the spectra are compared and discussed.

The surface electron behaviors of four oxo-vanadium complexes were discussed based on their SPS and UV–Vis absorption spectra. There are some species of bands based on LMCT, not only in SPS but also in UV–Vis absorption spectra, which are O(terminal) → V, O(μ-O, H2O, hydroxyl) → V, O(PO43-, SO42-, COO−) → V, N(phen) → V. There are good corresponding relationships between the SPS and UV–Vis absorption spectra.Figure optionsDownload as PowerPoint slideResearch highlights
► Four oxo-vanadium complexes all possess photoelectric conversion properties.
► The O→V band-to-band transitions appear some species in the SPS.
► The order of band-to-band transitions are consistent to the electronegativity order of the ligand.
► The SPS were associated with the UV-Vis spectra.