title: Intercalation of triethylphosphine oxide bearing a phosphoryl group into Dion-Jacobson-type ion-exchangeable layered perovskites.
abstract: Triethylphosphine oxide [(C2H5)3P[double bond, length as m-dash]O; TEPO] was intercalated into protonated Dion-Jacobson-type ion-exchangeable layered perovskites, HLaNb2O7·xH2O (HLaNb) and HCa2Nb3O10·xH2O (HCaNb), by hydrolysis of their n-decoxy derivatives (C10O-HLaNb or C10O-HCaNb) in the presence of TEPO. The interlayer distances of the products (TEPO/C10O-HLaNb and TEPO/C10O-HCaNb) were smaller than those of the corresponding n-decoxy derivatives, but still larger than those of anhydrous protonated forms of HLaNb and HCaNb. The solid-state (31)P NMR signals of the products observed at 94 ppm (TEPO/C10O-HLaNb) and 93 ppm (TEPO/C10O-HCaNb) exhibited large downfield shifts from that of the physisorbed TEPO. IR spectroscopy also showed decreases in the ν(P[double bond, length as m-dash]O) band wavenumbers upon the reactions. These results clearly indicate that TEPO is intercalated and interacted with Brønsted acid sites, the surface hydroxyl groups generated via hydrolysis of n-decoxy groups. The difference in ν(P[double bond, length as m-dash]O) band wavenumbers as well as that in gallery heights suggests that TEPO exhibited different orientations with respect to the inorganic layers. The chemical shifts of solid-state (31)P NMR signals suggested high Brønsted acidity of HLaNb and HCaNb.
authors.affiliation: Department of Applied Chemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. ys6546@waseda.jp.
authors.forename: Nagisa
authors.initials: N
authors.lastname: Toihara
authors.forename: Yoriyoshi
authors.initials: Y
authors.lastname: Yoneyama
authors.forename: Akira
authors.initials: A
authors.lastname: Shimada
authors.forename: Seiichi
authors.initials: S
authors.lastname: Tahara
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Sugahara