Ferro- or antiferromagnetic interactions controlled by ditopic or chelating auxiliary ligands in 3D metal-organic frameworks.
Three 3D Co(ii) metal-organic frameworks of the general formula [Co(DNNDC)(NN)]nwere reported, where DNNDC = 1,5-dinitronaphthalene-3,7-dicarboxylate and NN = bridging or chelating dipyridyl ligands. The MOFs exhibit similar 3D [Co(DNNDC)]nframeworks in which double-carboxylate-bridged [Co(OCO)2]nchains are cross-linked by naphthalene backbones. The bridging dipyridyl ligands [4,4'-bipyridine (bpy) and 1,2-bis(4-pyridyl)ethane (bpe)] serve as additional linkers between the chains to generate a reinforced framework with new net topology, while the chelating ligand 1,10-phenanthroline (phen) reinforces the frameworks through π-π stacking and C-HO interactions. Remarkably, varying the auxiliary ligand leads to a change in the sign of the magnetic exchange through the double carboxylate bridge: the MOFs with the ditopic bpy and bpe ligands show ferromagnetic interactions, while the one with the chelating phen ligand shows antiferromagnetic exchange. The difference in magnetic exchange is attributable to the subtle change in the coordination conformation of the carboxylate bridge.
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China. eqgao@chem.ecnu.edu.cn and School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China.
Hua
H
Tian
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China. eqgao@chem.ecnu.edu.cn.
Ai-Ling
AL
Cheng
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China. eqgao@chem.ecnu.edu.cn.
En-Qing
EQ
Gao