Super Flexibility of a 2D Cu-Based Porous Coordination Framework on Gas Adsorption in Comparison with a 3D Framework of Identical Composition: Framework Dimensionality-Dependent Gas Adsorptivities
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- 作者：Atsushi Kondo ; Hiroshi Kajiro ; Hiroshi Noguchi ; Lucia Carlucci ; Davide M. Proserpio ; Gianfranco Ciani ; Kenichi Kato ; Masaki Takata ; Hiroko Seki ; Masami Sakamoto ; Yoshiyuki Hattori ; Fujio Okino ; Kazuyuki Maeda ; Tomonori Ohba ; Katsumi Kaneko ; Hirofumi Kanoh
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：July 13, 2011
- 年：2011
- 卷：133
- 期：27
- 页码：10512-10522
- 全文大小：1116K
- 年卷期：v.133,no.27(July 13, 2011)
- ISSN：1520-5126
文摘
Selective synthetic routes to coordination polymers [Cu(bpy)2(OTf)2]n (bpy = 4,4鈥?bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent鈥搒olution system. They show a quite similar local coordination environment around the Cu(II) centers, but these assemble in a different way leading to the 2D and 3D building-up structures. Although the two kinds of porous coordination polymers (PCPs) both have flexible frameworks, the 2D shows more marked flexibility than the 3D, giving rise to different flexibility-associated gas adsorption behaviors. All adsorption isotherms for N2, CO2, and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH4 and water, in addition to these gases. The 3D structure, having hydrophilic and hydrophobic pores, shows the size-selective and quadrupole-surface electrical field interaction dependent adsorption. Remarkably, the 2D structure can accommodate greater amounts of gas molecules than that corresponding to the inherent crystallographic void volume through framework structural changes. In alcohol adsorption isotherms, however, the 2D PCP changes its framework structure through the guest accommodation, leading to no stepwise adsorption isotherms. The structural diversity of the 2D PCP stems from the breathing phenomenon and expansion/shrinkage modulation.