One novel three-dimensional framework constructed from infrequent μ-O metal chains with alternating antiferromagnetic/ferromagnetic interactions

摘要

One novel metal-organic framework of formula {[Co_2(1,4-NDC)_2(4,4'-dpdo)(H_2O)]·3H_2O}_n 1 (1,4-H_2NDC=1,4-naphthalenedicarboxyiate acid and 4,4'-dpdo=4,4'-dipyridyl-N,N'-dioxide) has been synthesized, and structurally and magnetically characterized. X-ray single crystal structure shows that polymer 1 exhibits a 3D metal-organic framework containing alternating metal chains with two kinds of triple bridge (two carboxylate plus μ-4,4-dpdo or μ-H_2O). the metal centers exhibit somewhat distorted octahedral surroundings with two opposite vertexes shared with the adjacent in the chain. Each alternating chain segment is cross-linked to four other different chains through four 1,4-NDC~(2-) ligands to form the 3D structure. The variable-temperature magnetic susceptibility of 1 was investigated in the temperature range of 1.8-300 K. The magnetic coupling behavior between metal atoms can be estimated with the model developed by Fisher for an alternating chain of classical spins. The result indicates that it could be considered as an alternating chain with-AF-FM-AF-FM-interaction.