title: A contrivance for a dynamic porous framework: cooperative guest adsorption based on square grids connected by amide-amide hydrogen bonds.
abstract: Flexible porous coordination polymers containing amide groups as a function origin have been synthesized and categorized as "Coordination Polymer with Amide Groups". Bispyridyl ligands with a spacer of amide group afford two-dimensional (2-D) motifs with a deformed square grid, resulting in three-dimensional (3-D) frameworks of [Co(NO(3))(2)(3-pna)(2)](n)(1), [Co(Br)(2)(3-pna)(2)](n)(2), and [[Co(NCS)(2)(4-peia)(2)].4Me(2)CO](n)(3 subset 4Me(2)CO) (3-pna = N-3-pyridylnicotinamide, 4-peia = N-(2-pyridin-4-yl-ethyl)-isonicotinamide), where the 2-D motifs are bound by complementary hydrogen bond between the amide groups. In the case of the 3 subset 4Me(2)CO, the amide groups form a contrivance for a dynamic porous framework because of their relevant position and orientation in the mutual nearest neighboring motifs. Consequently, 3 subset 4Me(2)CO shows amorphous (nonporous)-to-crystal (porous) structural rearrangement in the Me(2)CO adsorption and desorption process, where the framework of the 2-D motif is maintained. The adsorption isotherm has threshold pressure (P(th)), a sort of gate pressure. The heat of Me(2)CO adsorption (DeltaH(ad) = -25 kJ/mol) is obtained from the temperature dependence of threshold pressure (P(th)), which is close to acetone vaporization enthalpy (DeltaH(vap) = 30.99 kJ/mol).
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Uemura
authors.forename: Susumu
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Kôichi
authors.initials: K
authors.lastname: Fukui
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito