ja039914m_si_004.pdf (248.69 kB)
A Contrivance for a Dynamic Porous Framework: Cooperative Guest Adsorption Based on Square Grids Connected by Amide−Amide Hydrogen Bonds
journal contribution
posted on 2004-03-31, 00:00 authored by Kazuhiro Uemura, Susumu Kitagawa, Kôichi Fukui, Kazuya SaitoFlexible 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(NO3)2(3-pna)2]n (1), [Co(Br)2(3-pna)2]n (2), and {[Co(NCS)2(4-peia)2]·4Me2CO}n (3 ⊃ 4Me2CO) (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 ⊃ 4Me2CO, 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 ⊃ 4Me2CO
shows amorphous (nonporous)-to-crystal (porous) structural rearrangement in the Me2CO adsorption and
desorption process, where the framework of the 2-D motif is maintained. The adsorption isotherm has
threshold pressure (Pth), a sort of gate pressure. The heat of Me2CO adsorption (ΔHad = −25 kJ/mol) is
obtained from the temperature dependence of threshold pressure (Pth), which is close to acetone vaporization
enthalpy (ΔHvap = 30.99 kJ/mol).
