title: Encapsulation of Two Potassium Cations in Preyssler-Type Phosphotungstates: Preparation, Structural Characterization, Thermal Stability, Activity as an Acid Catalyst, and HAADF-STEM Images.
abstract: Dipotassium cation (K+)-encapsulated Preyssler-type phosphotungstate, [P5W30O110K2]13-, was prepared by heating monobismuth (Bi3+)-encapsulated Preyssler-type phosphotungstate, [P5W30O110Bi(H2O)]12-, in acetate buffer in the presence of an excess amount of potassium cations. Characterization of the isolated potassium salt, K13[P5W30O110K2] (1a), and its acid form, H13[P5W30O110K2] (1b), by single crystal X-ray structure analysis,31P and183W nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV), high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS), and elemental analysis revealed that two potassium cations are encapsulated in the Preyssler-type phosphotungstate molecule with formal D5hsymmetry, which is the first example of a Preyssler-type compound with two encapsulated cations. Incorporation of two potassium cations enhances the thermal stability of the potassium salt, and the acid form shows catalytic activity for hydration of ethyl acetate. Packing of the Preyssler-type molecules was observed by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).
authors: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
authors: Akio
authors: A
authors: Hayashi
authors: Division of Instrumental Analysis, Department of Instrumental Analysis and Cryogenics, Advanced Science Research Center, Okayama University , 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan.
authors: Hiromi
authors: H
authors: Ota
authors: Departament de Química Física i Inorgànica, Universitat Rovira i Virgili , c/Marcel·lí Domingo 1, 43007 Tarragona, Spain.
authors: Xavier
authors: X
authors: López
authors: Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST) , 4-2-1 Nigatake, Miyagino, Sendai 983-8551, Japan.
authors: Norihito
authors: N
authors: Hiyoshi
authors: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
authors: Nao
authors: N
authors: Tsunoji
authors: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
authors: Tsuneji
authors: T
authors: Sano
authors: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
authors: Masahiro
authors: M
authors: Sadakane