title: A Convenient Strategy for Designing a Soft Nanospace: An Atomic Exchange in a Ligand with Isostructural Frameworks.
abstract: Direct observation of gas molecules confined in the nanospace of porous materials by single-crystal X-ray diffraction (SXRD) technique is significant because it leads to deep insight into the adsorption mechanism and the actual state of the adsorbents in molecular level. A recent study revealed that flexibility is one of the important factors to achieve periodic guest accommodation in the nanospace enabling direct observation of gas molecules. Here, we report a convenient strategy to tune the framework flexibility by just an atomic exchange in a ligand, which enables us to easily construct a soft nanospace as the best platform to study gas adsorption. Indeed, we succeeded to observe C2H2 and CO2 molecules confined in the pores of a flexible porous coordination polymer (PCP-N) in different configurations using SXRD measurement, whereas gas molecules in a rigid framework (PCP-C) isostructural to PCP-N were not seen crystallographically. The result of the coincident in situ powder X-ray diffraction and adsorption measurement for PCP-N unambiguously showed that the framework could flexibly transform to trap gas molecules with a commensurate fashion. In addition, for PCP-N, we found that the adsorbed gas molecules induced significant structural change involving dimensional change of the pore from one-dimensional to three-dimensional, and subsequently, additional gas molecules formed periodic molecular clusters in the nanospace.
authors.affiliation: School of Chemistry and Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology , Changshu, Jiangsu 215500, People's Republic of China.|Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Yunsheng
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.|Department of Applied Chemistry, Graduate School of Engineering, Nagoya University , Chikusa-ku, Nagoya 464-8603, Japan.|Japan Science and Technology Agency (JST) , PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Matsuda
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University , Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Yuh
authors.initials: Y
authors.lastname: Hijikata
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Liangchun
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Shinpei
authors.initials: S
authors.lastname: Kusaka
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Mawlin
authors.initials: M
authors.lastname: Foo
authors.affiliation: School of Chemistry and Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology , Changshu, Jiangsu 215500, People's Republic of China.
authors.forename: Fengfeng
authors.initials: F
authors.lastname: Xue
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: George
authors.initials: G
authors.lastname: Akiyama
authors.affiliation: School of Chemistry and Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology , Changshu, Jiangsu 215500, People's Republic of China.
authors.forename: Rongxin
authors.initials: R
authors.lastname: Yuan
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.|Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kitagawa