A rare diarboxylate and N-oxide/H2O bridged metal-organic framework with nickel(II)-oxide octahedral chains: synthesis, crystal structure, and magnetic properties with theoretical investigations on the exchange mechanism

• One 3D ferromagnetic material constructed from infrequent μ-O nickel chains has been synthesized.
• The polymer has been characterized by IR, XRPD, TG and elemental analysis.
• X-ray single-crystal structure analysis and discussion for the polymer.
• Magnetic property analysis indicates an intrachain alternating antiferromagnetic/ferromagnetic coupling with long-range order.

One 3D metal-organic framework {[Ni2(1,4-NDC)2(4,4′-dpdo)(H2O)]·3 H2O}n1 (1,4-H2NDC=1,4-naphthalenedicarboxylate acid and 4,4′-dpdo=4,4′-Dipyridyl-N,N′-dioxide) has been hydrothermally synthesized and well-characterized. Polymer 1 arranges in the I1O1 fashion. The hexacoordinated Ni(II) centers are triply bridged by two 1,4-NDC2− carboxylate group plus μ-4,4-dpdo or μ–H2O to form an alternating chain. Each metal chain is cross-connected to four other chains to shape a 3D network. Magnetic studies show that 1 exhibits dominant ferromagnetic interactions with intrachain alternating antiferromagnetic/ferromagnetic interactions.

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