title: Synthesis, crystal structure and characterization of novel open framework CHA-type aluminophosphate involving a chiral diamine.
abstract: A highly crystalline new precursor of CHA-type zeolite AlPO4-34 was obtained by using an aluminophosphate gel with a chiral diamine [(S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine; C9H18N2] as an organic structure directing agent under hydrothermal synthesis conditions. This precursor (called GAM-1) was changed into the zeolite AlPO4-34 which had a high porosity (the Brunauer-Emmett-Teller (BET) surface area is approximately 700 m3g-1) using calcination. The GAM-1 obtained was characterized by various measurements, e.g., powder X-ray diffraction, scanning electron microscopy, and solid-state nuclear magnetic resonance spectroscopy, and so on. Structure determination from powder diffraction data revealed that the new precursor GAM-1 has triclinic symmetry [space group P1[combining macron], a = 9.16535(11) Å, b = 9.23042(11) Å, c = 9.29228(11) Å, α = 79.8243(7)°, β = 87.4593(7)°, γ = 86.5365(7)°] and the chemical formula was estimated to be: |Al6P6O24H2F2|(C9H18N2)·2.5(H2O). It also revealed that a two edge sharing AlO4F2octahedron with an [triple bond, length as m-dash]Al-F-Al[triple bond, length as m-dash] bridge was included in the framework. GAM-1 was transformed into AlPO4-34 with rhombohedral symmetry (R3[combining macron]) by elevating temperature to over 400 °C. At high temperatures, AlO4F2octahedron connectivity was changed into an AlO4tetrahedron. The crystal structure of the dehydrated AlPO4-34 changed back to a triclinic symmetry (P1) model again after rehydration in the atmosphere.
authors.affiliation: Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Komura
authors.affiliation: Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Horibe
authors.affiliation: Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yajima
authors.affiliation: Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology, Nigatake 4-2-1, Sendai, 983-8551, Japan. takuji-ikeda@aist.go.jp.
authors.forename: Norihito
authors.initials: N
authors.lastname: Hiyoshi
authors.affiliation: Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology, Nigatake 4-2-1, Sendai, 983-8551, Japan. takuji-ikeda@aist.go.jp.
authors.forename: Takuji
authors.initials: T
authors.lastname: Ikeda