title: Guest-induced modification of a magnetically active ultramicroporous, gismondine-like, copper(II) coordination network.
abstract: A novel ultramicroporous coordination polymer, namely [Cu(F-pymo)2(H2O)1.25]n (1, F-pymo = 5-fluoropyrimidin-2-olate), has been prepared and structurally characterized. 1 displays a zeolitic gismondine (GIS) topology, with ca. 2.9 A wide helical channels which, in the thermally activated counterpart (1'), account for a 13% void volume and are responsible for the observed selective solid-gas adsorption properties toward H2, N2, and CO2. At 77 K 1' behaves as a molecular sieve, selectively adsorbing H2 over N2, possibly due to size-exclusion reasons. At variance, although CO2 molecules are slightly larger than the pore size, they are readily incorporated by 1' at temperatures as high as 433 K. Variable-temperature X-ray powder diffraction (TXRPD) studies, in the temperature range 303-473 K, show that dehydration is reversible and has almost negligible effects on the network. At variance, the uptake of CO2 occurs through a transient phase and channels expansion. While the gas storage capacity of 1' is not very high-H2, 0.56 wt % and 0.010 kg H2/L at 90 K and 900 Torr, and CO2, 7.6 wt % at 273 K and 900 Torr-the guest molecules achieve very high densities, comparable to that of the liquid for H2 (0.023 vs 0.021 molecules A-3) and to that of the solid for CO2 (0.014 vs 0.022 molecules A-3). In addition, we have also studied the effect of the perturbation exerted by the guest molecules on its magnetic properties. The results show that while dehydration of 1 has negligible effect on its spin-canted antiferromagnetic behavior, CO2 incorporation in the pores is responsible for an increment of the transition temperature at which the weak ferromagnetic ordering takes place from 22 to 29 K.
authors.affiliation: Departamento de Química InorgAnica, Universidad de Granada, Av. Fuentenueva S/N, 18071 Granada, Spain. jarn@ugr.es
authors.forename: Jorge A R
authors.initials: JA
authors.lastname: Navarro
authors.forename: Elisa
authors.initials: E
authors.lastname: Barea
authors.forename: Antonio
authors.initials: A
authors.lastname: Rodríguez-Diéguez
authors.forename: Juan M
authors.initials: JM
authors.lastname: Salas
authors.forename: Conchi O
authors.initials: CO
authors.lastname: Ania
authors.forename: José B
authors.initials: JB
authors.lastname: Parra
authors.forename: Norberto
authors.initials: N
authors.lastname: Masciocchi
authors.forename: Simona
authors.initials: S
authors.lastname: Galli
authors.forename: Angelo
authors.initials: A
authors.lastname: Sironi
mesh_terms: D000327:Adsorption; D002245:Carbon Dioxide / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D008280:Magnetics; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D016062:Porosity; D033362:Powder Diffraction; D011743:Pyrimidines / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: C528825:5-fluoropyrimidin-2-olate; D009942:Organometallic Compounds; D011743:Pyrimidines; D002245:Carbon Dioxide; D003300:Copper; D006859:Hydrogen; D009584:Nitrogen