Multistep N2 breathing in the metal-organic framework co(1,4-benzenedipyrazolate).
A variety of spectroscopic techniques combined with in situ pressure-controlled X-ray diffraction and molecular simulations have been utilized to characterize the five-step phase transition observed upon N(2) adsorption within the high-surface area metal-organic framework Co(BDP) (BDP(2-) = 1,4-benzenedipyrozolate). The computationally assisted structure determinations reveal structural changes involving the orientation of the benzene rings relative to the pyrazolate rings, the dihedral angles for the pyrazolate rings bound at the metal centers, and a change in the metal coordination geometry from square planar to tetrahedral. Variable-temperature magnetic susceptibility measurements and in situ infrared and UV-vis-NIR spectroscopic measurements provide strong corroborating evidence for the observed changes in structure. In addition, the results from in situ microcalorimetry measurements show that an additional heat of 2 kJ/mol is required for each of the first four transitions, while 7 kJ/mol is necessary for the last step involving the transformation of Co(II) from square planar to tetrahedral. Based on the enthalpy, a weak N(2) interaction with the open Co(II) coordination sites is proposed for the first four phases, which is supported by Monte Carlo simulations.
Salles
Fabrice
F
Institut Charles Gerhardt Montpellier, UMR CNRS 5253, Université Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 05, France.
Maurin
Guillaume
G
Serre
Christian
C
Llewellyn
Philip L
PL
Knöfel
Christina
C
Choi
Hye Jin
HJ
Filinchuk
Yaroslav
Y
Oliviero
Laetitia
L
Vimont
Alexandre
A
Long
Jeffrey R
JR
Férey
Gérard
G
D000327:Adsorption; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009010:Monte Carlo Method; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D033362:Powder Diffraction; D013499:Surface Properties
D009942:Organometallic Compounds; C555114:cobalt(II) (1,4-benzenedipyrazolate); D009584:Nitrogen