Methane sorption and structural characterization of the sorption sites in Zn2(bdc)2(dabco) by single crystal X-ray crystallography.
Sorption isotherms of methane in Zn(2)(bdc)(2)(dabco) are measured up to a pressure of 35 bar in the temperature range between 198-296 K. The methane sorption measurements at 296 K showed an uptake of 137 cm(3) cm(-3) at 35 bar. The enthalpy of methane adsorption for Zn(2)(bdc)(2)(dabco) estimated by the virial equation is 13.6 kJ mol(-1) at zero coverage. X-ray structure analysis of methane-adsorbed Zn(2)(bdc)(2)(dabco) by synchrotron radiation at 90 K revealed that methane molecules occupy three independent sorption sites (A, B, and C) with a stoichiometry of Zn(2)(bdc)(2)(dabco) x 6.69 CH(4), which is consistent with the results of the gas sorption measurements at 198 K. In a cavity, eight symmetry-related methane sorption sites A are located near the {Zn(2)(CO(2))(4)} paddle-wheel units, while four symmetry-related methane sorption sites B are near the center of the small windows along the a and b axes. Both A and B sites are half-occupied. Methane molecules occupying sites A are not only in van der Waals contact with the paddle-wheel units, but also interact with the phenyl rings of bdc ligands through partial pi-HC interactions. Methane molecules in B sites interact with the side of the phenyl rings through van der Waals interaction. The site C, located at the center of the cavity, is a secondary sorption site; methane molecules occupying sites C are in van der Waals contact with those in sites A and B.
Kim
Hyunuk
H
National Creative Research Initiative Center for Smart Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea), Fax: (+82) 54-279-8129.
Samsonenko
Denis G
DG
National Creative Research Initiative Center for Smart Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea), Fax: (+82) 54-279-8129.|Current address: Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Avenue, Novosibirsk 630090 (Russia).
Das
Sunirban
S
National Creative Research Initiative Center for Smart Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea), Fax: (+82) 54-279-8129.
Kim
Ghyung-Hwa
GH
Beamline Division, Pohang Accelerator Laboratory, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea).
Lee
Heung-Soo
HS
Beamline Division, Pohang Accelerator Laboratory, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea).
Dybtsev
Danil N
DN
Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Avenue, Novosibirsk 630090 (Russia).|Current address: Graduate Institute of Advanced Materials Science, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea).
Berdonosova
Elena A
EA
Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russia).
Kim
Kimoon
K
National Creative Research Initiative Center for Smart Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784 (Republic of Korea), Fax: (+82) 54-279-8129.