ABSTRACT
The crystal structure of the title compound, [NaV(C3H2O4)(NH2O)2O(H2O)2], is built up of NaO6 and VO5N2 polyhedra connected through malonate bridges. The NaO6 octahedra are linked by edge sharing in the equatorial plane to form one-dimensional infinite chains. These chains are linked together by the malonate bridges to form two-dimensional layers. The distorted VO5N2 pentagonal bipyramid is grafted on to the layer by a malonate carboxylate O atom. Adjacent layers are connected through O-H...O and N-H...O hydrogen bonds to build up a three-dimensional supramolecular structure.
Subject(s)
Macromolecular Substances/chemistry , Organometallic Compounds/chemistry , Vanadium/chemistry , Crystallography, X-Ray , Hydrogen Bonding , Models, MolecularABSTRACT
A novel technique was developed to prepare highly pure heteropoly acid (HPA) nanocrystals inside mesoporous SBA-15 by the imprisoned reaction of HPA etherate and water, which was utilized as a main driving force for the transportation of building-blocks. The transmission electron microscopy, X-ray diffraction, FT-IR spectrum and NMR characterizations unambiguously demonstrate that this method allows the highly pure heteropoly acid nanocrystals with intact Keggin-type structure controlled directionally self-assembly within mesopores of silica SBA-15. Such method may open up a new entry to the highly pure multicomponent nanocrystalline particles inside the cavity of the porous materials.
ABSTRACT
The title compound, (C(10)H(10)N(2))(2)[Fe(C(2)O(4))(2)(H(2)O)(2)](C(2)HO(4))(2), appears to be a modular associate consisting of a complex anion containing bivalent Fe as the central atom, a bridging hydrogen oxalate anion and a diprotonated 4,4-bipyridine acting as the counter-cation. The Fe(II) ion in the complex anion occupies a position on a centre of inversion. Its coordination environment is formed by six O atoms from two bidentate oxalate ligands, forming a basal plane, and two water molecules approximately perpendicular to the plane, representing a distorted octahedral geometry. These three kinds of ions are connected by strong hydrogen bonds, with donor-acceptor distances (N...O and O...O) lying in the range 2.54-2.98 A, and pi-pi stacking interactions between the 4,4'-bipyridinium cations, thus forming a three-dimensional supramolecular structure.
ABSTRACT
Keggin-type 12-tungstophosphoric acid (TPA) nanocrystals have been assembled inside the pores of mesoporous silica through a vacuum impregnation method by using large-pore SBA-15 as a nanoreactor. The product was characterized by Brunauer-Emmet-Teller particle size distribution (BET-PSD), NMR and FT-IR spectroscopy, X-ray diffraction (XRD), tranmsission electron microscopy (TEM), differential thermal analysis (DTA) and FT-IR of adsorbed pyridine. The experimental results illustrate that the TPA nanocrystals are excellent Brønsted acid catalytic materials at room temperature.
