Guest-Induced Modification of a Magnetically Active Ultramicroporous, Gismondine-like, Copper(II) Coordination Network
Articolo
Data di Pubblicazione:
2008
Citazione:
Guest-Induced Modification of a Magnetically Active Ultramicroporous, Gismondine-like, Copper(II) Coordination Network / J. A. R. Navarro, E. Barea, A. Rodriguez-Dieguez, J. M. Salas, C. O. Ania, J. B. Parra, N. Masciocchi, S. Galli, A.A.D. Sironi. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - 130:12(2008), pp. 3978-3984. [10.1021/ja078074z]
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 Å 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 highsH2, 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 Torrsthe guest
molecules achieve very high densities, comparable to that of the liquid for H2 (0.023 vs 0.021 molecules
Å-3) and to that of the solid for CO2 (0.014 vs 0.022 molecules Å-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.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
J.A.R. Navarro, E. Barea, A. Rodriguez Dieguez, J.M. Salas, C.O. Ania, J.B. Parra, N. Masciocchi, S. Galli, A.A.D. Sironi
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