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Windmill Co 4 {Co 4 (μ 4 ‐O)} with 16 Divergent Branches Forming a Family of Metal–Organic Frameworks: Organic Metrics Control Topology, Gas Sorption, and Magnetism
Author(s) -
Chen Qing,
Xue Wei,
Lin JianBin,
Wei YongSheng,
Yin Zheng,
Zeng MingHua,
Kurmoo Mohamedally,
Chen XiaoMing
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201601826
Subject(s) - sbus , antiferromagnetism , cobalt , metal organic framework , sorption , magnetism , pyridine , crystallography , topology (electrical circuits) , materials science , metal , chemistry , inorganic chemistry , physics , organic chemistry , condensed matter physics , mathematics , adsorption , combinatorics
Abstract A series of highly connected metal–organic frameworks (MOFs), [Co 8 (O)(OH) 4 (H 2 O) 4 (ina) 8 ](NO 3 ) 2 ⋅ 2 C 2 H 5 OH ⋅ 4 H 2 O ( 1 ), [Co 8 (O)(OH) 4 (H 2 O) 4 (pba) 8 ](NO 3 ) 2 ⋅ 8 C 2 H 5 OH ⋅ 28 H 2 O ( 2 ), and [Co 8 (O)(OH) 4 (H 2 O) 4 (pbba) 8 ](NO 3 ) 2 ⋅ guest ( 3 ), in which ina=isonicotinate, pba=4‐pyridylbenzoate, and pbba=4‐(pyridine‐4‐yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co 4 (μ 4 ‐O) central unit having the rare μ 4 ‐O 2− motif, which is decorated by the other four peripheral cobalt atoms through μ 3 ‐OH in a windmill‐like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl‐carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N 2 , CO 2 , CH 4 , and H 2 . In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin‐glass‐like relaxation, with blocking temperatures that are fairly high, 20 K ( 1 ) and 10 K ( 2 ), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties.