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Bifunctional pyrazolate–carboxylate ligands for isoreticular cobalt and zinc MOF-5 analogs with magnetic analysis of the {Co4(μ4-O)} node.
- Source :
- CrystEngComm; 2013, Vol. 15 Issue 45, p9757-9768, 12p
- Publication Year :
- 2013
-
Abstract
- The ditopic ligands 3,5-dimethyl-pyrazolate-4-carboxylate, <superscript>–</superscript>Me<subscript>2</subscript>pzCO<subscript>2</subscript><superscript>–</superscript>, and 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, <superscript>–</superscript>Me<subscript>2</subscript>pzC<subscript>6</subscript>H<subscript>4</subscript>CO<subscript>2</subscript><superscript>–</superscript>, combine a pyrazolate and carboxylate functionality in axial orientation and lead to porous cobalt or zinc azolate–carboxylate frameworks that have the same cubic pcu-a topology and {M<subscript>4</subscript>(μ<subscript>4</subscript>-O)} nodes (M = Co, Zn) as MOF-5 and other IRMOFs. The microporous networks [M<subscript>4</subscript>(μ<subscript>4</subscript>-O)(Me<subscript>2</subscript>pzCO<subscript>2</subscript>)<subscript>3</subscript>] (M = Co, Zn) with the short linker exhibit a solvent-induced gate effect, evidenced by gas desorption hysteresis due to small pore apertures of 2.8 Å diameter together with small amounts of high-boiling solvent remaining in the activated samples. For [Co<subscript>4</subscript>(μ<subscript>4</subscript>-O)(Me<subscript>2</subscript>pzCO<subscript>2</subscript>)<subscript>3</subscript>], the low-pressure H<subscript>2</subscript> storage capacity (1.7 wt%, 1 bar , 77 K) is higher than for MOF-5, and the CO<subscript>2</subscript> uptake of 20.8 wt% puts it among the top MOFs for low-pressure CO<subscript>2</subscript> sorption even though the BET surface is less than 1000 m<superscript>2</superscript> g<superscript>−1</superscript>. The analysis of the magnetic properties of [Co<subscript>4</subscript>(μ<subscript>4</subscript>-O)(Me<subscript>2</subscript>pzCO<subscript>2</subscript>)<subscript>3</subscript>] takes into account the distribution of tetrahedra resulting from the disorder of the pyrazolate–carboxylate linker. An antiferromagnetic coupling observed for [Co<subscript>4</subscript>(μ<subscript>4</subscript>-O)(Me<subscript>2</subscript>pzCO<subscript>2</subscript>)<subscript>3</subscript>] arises from the interactions of the cobalt(ii) ions through the combined μ<subscript>4</subscript>-O + syn–syn carboxylate and μ<subscript>4</subscript>-O + pyrazolate bridges. [ABSTRACT FROM AUTHOR]
- Subjects :
- PYRAZOLATES
CARBOXYLATES
COBALT
ZINC
SOLVENTS
SORPTION
Subjects
Details
- Language :
- English
- ISSN :
- 14668033
- Volume :
- 15
- Issue :
- 45
- Database :
- Complementary Index
- Journal :
- CrystEngComm
- Publication Type :
- Academic Journal
- Accession number :
- 100892440
- Full Text :
- https://doi.org/10.1039/c3ce41426d