title: Syntheses, structure solutions, and catalytic performance of two novel layered silicates.
abstract: Two novel layered silicates, PKU-13 and PKU-13a, were hydrothermally synthesized by using trimethylpropylammonium hydroxide as the structure directing agent (SDA). Their structures were solved by using powder X-ray diffraction data in combination with electron diffraction technique and NMR spectroscopy. These two silicates are built from the same r52 layer in different stacking modes: the adjacent r52 layers in PKU-13a have a 0.5b + 0.68c shift compared with those in PKU-13. The difference is due to the SDA cations located between the layers. The SDA cations exist as a monolayer in the structure of PKU-13, and link the adjacent layers by Coulomb actions in combination with strong hydrogen bonds. In PKU-13a, the SDA cations present in the bi-layer expend the distance between layers and destroy the inter-layer hydrogen bonds. PKU-13a can transform to PKU-13 after treatment with acetic acid solution. The co-existence of intra-layer hydrogen bonds in PKU-13 interfere in its condensation to an ordered crystalline microporous framework. Both PKU-13 and PKU-13a exhibit good catalytic activities as base catalysts in the Knoevenagel condensation reaction.
authors.affiliation: College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China. yxwang@pku.edu.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: Liang
authors.forename: Jie
authors.initials: J
authors.lastname: Su
authors.forename: Yanping
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhaofei
authors.initials: Z
authors.lastname: Li
authors.forename: Kuo
authors.initials: K
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zou
authors.forename: Fuhui
authors.initials: F
authors.lastname: Liao
authors.forename: Yingxia
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianhua
authors.initials: J
authors.lastname: Lin