Diverse Structures and Ferro-/Ferri-/Antiferromagnetic Interactions of Pyridyltetrazole Coordination Polymers with Polycarboxylate Auxiliary Ligands

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• 作者：Ming-Xing Li ; Yan-Fei Zhang ; Xiang He ; Xue-Min Shi ; Ya-Ping Wang ; Min Shao ; Zhao-Xi Wang
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：May 4, 2016
• 年：2016
• 卷：16
• 期：5
• 页码：2912-2922
• 全文大小：759K
• 年卷期：0
• ISSN：1528-7505

文摘

Metal salts and 3/4-pyridyltetrazoles (3/4-Hptz) react with oxalic acid (H₂ox), 1,2,4,5-benzenetetracarboxylic acid (H₄btec), isophthalic acid (H₂ip), and 1,2,3,4-butanetetracarboxylic acid (H₄btca) to afford six coordination polymers, namely, [Cu(4-ptz)(ox)_0.5]_n (1), [Cu(4-Hptz)(btec)_0.5]_n (2), [Co₂(3-ptz)(ip)(OH)(H₂O)]_n (3), {[Co_1.5(3-ptz)(btca)_0.5(H₂O)]·H₂O}_n (4), {[Co₃(4-ptz)₂(btca)(H₂O)₃]·2H₂O}_n (5), and {[Cd₂(4-ptz)₂(btca)_0.5(H₂O)₃]·DMF·4H₂O}_n (6). Their structures were characterized by EA, IR, PXRD, TGA, and single-crystal XRD. 3/4-Pyridyltetrazoles display μ₂-, μ₃-, and μ₅-coordination modes in them. Complex 1 is a 3D MOF constructed from a 2D (4,4) [Cu(4-ptz)]_n grid pillared by an oxalate spacer. Complex 2 displays a 2D network containing a square planar Cu1 and elongated octahedral Cu2 centers. Complex 3 shows a 2D network containing μ₅-ptz, μ₃-ip, and μ₃-OH. Complex 4 exhibits a 3D MOF assembled by a 2D [Co_1.5(btca)_0.5]_n network pillared by a 3-ptz spacer. Complex 5 displays a 3D porous MOF with nanosized rectangular tunnels. Complex 6 features a 3D porous MOF built by 2D [Cd₂(4-ptz)(btca)_0.5]_n network pillared by a 4-ptz spacer. Variable-temperature magnetic susceptibility and magneto-structural correlation studies indicate that five Cu^II/Co^II complexes present remarkable magnetic coupling diversity from ferro-, to ferri-, to antiferromagnetic interactions. Complex 1 shows strong antiferromagnetic behavior originating from the oxalate-bridging Cu^II dimer (J_ox = −94.7 cm^–1) and the tetrazole-bridging Cu^II dimer (J_ptz = −61.0 cm^–1). Complex 2 presents a weak ferromagnetic interaction (J = 0.82 cm^–1) originating from the magnetic orbital orthogonality between square planar Cu^II and octahedral Cu^II centers. Complex 3 displays ferrimagnetic coupling in the Co₃(μ₃-OH) triangle. Two btca Co^II complexes show antiferromagnetic interactions originating from carboxyl-bridging trinuclear Co^II clusters with the θ values of −17.08 K for 4 and −8.6 K for 5. The thermal behaviors of these nitrogen-rich tetrazole complexes are investigated. Anhydrous complexes 1–3 containing rigid polycarboxylates are thermally stable to 250–300 °C and then decompose explosively, whereas complexes 4–6 with flexible butanetetracarboxylate decompose smoothly.