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Lecture

WEB Ligand-Modulated Reactivity and Volatility of Heteroleptic Non-oxo Vanadium(IV) Alkoxides as Versatile Precursors of VO2(B) Nanoplates

Thursday (24.09.2020)
12:05 - 12:20 P: Processing and Synthesis 1
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In this study, a series of chemically tuneable, volatile and stable heteroleptic trans-vanadium(IV) di-tert-butoxy complexes have been synthesized in high yield with a rapid room temperature reaction by deploying fluorinated ß-heteroarylalkenol and enaminone ligands with different denticity. The molecular identity of the compounds were unambiguously established in the solid state by single crystal X-ray diffraction analysis, which revealed an octahedral coordination geometry around the vanadium(IV) centre with trans tert-butoxide ligands, and in solution by EPR spectroscopy, which give insights into the ligand-dependent electronic structure of the d1 systems. The feedback of ligand designs on volatility, reactivity and stability of heteroleptic vanadium(IV) complexes were establish by thermogravimetric investigations, which revealed the selective thermal conversion to VO2(B) by a two step decomposition mechanism modulated by ligand properties. Subsequently, The obtained vanadium (IV) complexes have been utilized as single source molecular precursors to synthesize phase selective crystalline VO2 (B) nanoplates via a simple solvothermal route at 200°C confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The clean ligand strip-off during the first fragmentation facilitates the formation of a uniform thin nano plate-like morphology with thickness of ca. 58 nm verified by transmission electron microscopy (TEM).

Speaker:
David Graf
University of Cologne
Additional Authors:
  • Olusola Ojelere
    University of Cologne
  • Dr. Ashish Lepcha
    University of Cologne
  • Prof. Dr. Sanjay Mathur
    University of Cologne