Structural characterization of a nanocrystalline inorganic-organic hybrid with fiberlike morphology and one-dimensional antiferromagnetic properties

Igor Djerdj*, Minhua Cao, Xavier Rocquefelte, Radovan Černý, Zvonko Jagličić, Denis Arčon, Anton Potǒcnik, Fabia Gozzo, Markus Niederberger

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

A new nanocrystalline inorganic-organic hybrid compound, VO(C 6H5COO)2 has been synthesized under solvothermal conditions by reacting vanadium(V) oxytriisopropoxide with benzoic acid in toluene. A detailed investigation of the composition, structure and properties of VO(C6H5COO)2 using chemical and thermal analysis, synchrotron X-ray powder diffraction, electron microscopy techniques including SEM, TEM and SAED, spectroscopy techniques like XPS, EDX and FTIR, SQUID magnetometry and EPR is carefully described. Due to the low-crystallinity of the final material, its crystal structure has been solved from synchrotron X-ray powder diffraction data by combining a direct space global optimization technique and DFT geometry optimization and subsequently refined by the constraint Rietveld method. The compound crystallizes in the monoclinic system with a=20.652(3), b=6.798(1), c=9.954(1)A°, ß=92.145(6)°, space group C2, andZ=4. The inorganic part of the structure can be regarded as staggered V-V-V chains, formed of cornersharing VO6 octahedra, running along the monoclinic b-axis. A strong V-O bond alternation along the chain was evidenced by the DFT geometry optimization. The organic part is based on two crystallographically independent singly ionized benzoate moieties linked to vanadium atoms through a bidentate bridging mode. The morphology of VO(C6H5COO)2 exhibits long nanofibers, which further consist of smaller individual nanofibers aligned in parallel to the growth direction along the b-axis, as expected from the 1D nature of the compound. The magnetic susceptibility and X-band EPR measurements shows that the magnetic properties of VO(C6H5COO) 2 can be described by a S=1/2 linear antiferromagnetic chainmodel with the isotropic interaction between nearest neighbors and an estimated magnetic spin exchange parameter of J=-189K.DFT calculations have also been carried out to simulate the optical response and to estimate the magnetic spin exchange related to VO (C6H5COO)2. Such calculations allowed explaining the yellow-green color of the powder and the one-dimensional character of the magnetic structure.

Original languageEnglish
Pages (from-to)3356-3369
Number of pages14
JournalChemistry of Materials
Volume21
Issue number14
DOIs
Publication statusPublished - 28 Jul 2009

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