title: 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.
abstract: Selective synthetic routes to coordination polymers [Cu(bpy)(2)(OTf)(2)](n) (bpy = 4,4'-bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent-solution 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 N(2), CO(2), and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH(4) 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.
authors.affiliation: Collaborative Innovation Center for Nanotech FIBER (nanoFIC), Shinshu University, 3-15-1 Tokida, Ueda 386-8567, Japan. kondoa@cc.tuat.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kondo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kajiro
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Noguchi
authors.forename: Lucia
authors.initials: L
authors.lastname: Carlucci
authors.forename: Davide M
authors.initials: DM
authors.lastname: Proserpio
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Ciani
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kato
authors.forename: Masaki
authors.initials: M
authors.lastname: Takata
authors.forename: Hiroko
authors.initials: H
authors.lastname: Seki
authors.forename: Masami
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hattori
authors.forename: Fujio
authors.initials: F
authors.lastname: Okino
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Maeda
authors.forename: Tomonori
authors.initials: T
authors.lastname: Ohba
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kaneko
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kanoh