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Interplay between the Structural and Magnetic Probes in Elucidation of the Structure of Novel 2D Layered V4O4(OH)2(O2CC6H4CO2)4·DMF

The title compound has been synthesized under solvothermal conditions by reacting vanadium(V) oxytriisopropoxide with terephthalic acid in N, N-dimethylformamide. A combination of synchrotron powder diffraction, infrared spectroscopy, scanning and transmission electron microscopy, thermal and chemical analysis elucidated the chemical, structural and microstructural features of new 2D layered inorganic-organic 10 framework. Due to the low-crystallinity of the final material, its crystal structure has been solved from synchrotron X-ray powder diffraction data using a direct space global optimization technique and subsequent constraint Rietveld refinement. [V4O4(OH)2(O2CC6H4CO2)4·DMF] crystallizes in the monoclinic system (space group P2/m (No. 10)) ; cell parameters: a = 20.923(4), b = 5.963(4), c = 20.425(1) Å,  = 123.70(6) º, V = 2120.1(9) Å3, Z = 2. The overall structure can be described as an array of parallel 2D layers running along [-101] direction, consisting of two types of vanadium oxidation states and coordination polyhedra: face-shared trigonal prisms (V4+) and distorted corner-shared square pyramids 15 (V5+). Both configurations form independent parallel chains oriented along the 2-fold symmetry crystallographic b-axis mutually interlinked with terephthalate ligands in a monodentate mode perpendicular to it. The morphology of the compound exhibits long nanofibers, with the growth direction along the layered [-101] axis. The magnetic susceptibility measurements show that the magnetic properties of V4O4(OH)2(O2CC6H4CO2)4·DMF can be described by a linear antiferromagnetic chain model, with the isotropic exchange interaction of J = −75 K between the nearest V4+ neighbours of S = 1/2.

inorganic-organic hybrid; structural characterization; magnetic properties

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