title: Synthesis of phase-pure interpenetrated MOF-5 and its gas sorption properties.
abstract: For the first time, phase-pure interpenetrated MOF-5 (1) has been synthesized and its gas sorption properties have been investigated. The phase purity of the material was confirmed by both single-crystal and powder X-ray diffraction studies and TGA analysis. A systematic study revealed that controlling the pH of the reaction medium is critical to the synthesis of phase-pure 1, and the optimum apparent pH (pH*) for the formation of 1 is 4.0-4.5. At higher or lower pH*, [Zn(2)(BDC)(2)(DMF)(2)] (2) or [Zn(5)(OH)(4)(BDC)(3)] (3), respectively, was predominantly formed. The pore size distribution obtained from Ar sorption experiments at 87 K showed only one peak, at ~6.7 Å, which is consistent with the average pore size of 1 revealed by single crystal X-ray crystallography. Compared to MOF-5, 1 exhibited higher stability toward heat and moisture. Although its surface area is much smaller than that of MOF-5 due to interpenetration, 1 showed a significantly higher hydrogen capacity (both gravimetric and volumetric) than MOF-5 at 77 K and 1 atm, presumably because of its higher enthalpy of adsorption, which may correlate with its higher volumetric hydrogen uptake compared to MOF-5 at room temperature, up to 100 bar. However, at high pressures and 77 K, where the saturated H(2) uptake mostly depends on the surface area of a porous material, the total hydrogen uptake of 1 is notably lower than that of MOF-5.
authors.affiliation: National Creative Research Initiative Center for Smart Supramolecules, Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784, Republic of Korea.
authors.forename: Hyunuk
authors.initials: H
authors.lastname: Kim
authors.forename: Sunirban
authors.initials: S
authors.lastname: Das
authors.forename: Min Gyu
authors.initials: MG
authors.lastname: Kim
authors.forename: Danil N
authors.initials: DN
authors.lastname: Dybtsev
authors.forename: Yonghwi
authors.initials: Y
authors.lastname: Kim
authors.forename: Kimoon
authors.initials: K
authors.lastname: Kim
mesh_terms: D000327:Adsorption; D018360:Crystallography, X-Ray; D005740:Gases / Q000737:chemistry; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010795:Phthalic Acids / Q000737:chemistry; D013499:Surface Properties; D015032:Zinc / Q000737:chemistry
chemical_list: C547494:1,4-benzenedicarboxylate; D005740:Gases; D009942:Organometallic Compounds; D010795:Phthalic Acids; D015032:Zinc