Coordination Polymers of Lanthanide(III): Toward Encapsulation of Well-Defined Assembly of Guest Molecules

A series of lanthanide(III) coordination polymers [{La(Ben)3(H2O)2}·(4,4′-BPNO)0.5·HBen·DMF]n (1), [{Ce(Ben)3(4,4′-BPNO)(H2O)2}·DMF]n (2), [Tb(Ben)3(4,4′-BPNO)0.5(H2O)]n (3), [{Ln(Ben)3(4,4′-BPNO)(H2O)2}·HBen]n [Ln = La (4), Eu (5), Gd (6), Tb (7)] are synthesized and structurally characterized (where Ben = benzoate; HBen = benzoic acid; 4,4′-BPNO = 4,4′-bipyridyl-N,N′-dioxide; DMF = dimethylformamide). The metal centers in 1 have nine coordinated geometry, while the metal centers in all other coordination polymers are eight coordinated. Polymer 1 comprises one-dimensional chains of lanthanum(III) benzoate that encapsulate hydrogen-bonded assemblies formed by HBen···4,4′-BPNO···HBen interactions in its interstitial space. The polymer 2 and 3 are eight coordinated with square antiprism geometry around the metal node. The other four coordination polymers 4−7 have the same general composition and possess three-dimensional honeycomb like structures that encapsulates benzoic acid molecules in the interstices. The complex 5 (solid) exhibits a strong red luminescence emission characteristic of Eu(III). Magnetic susceptibility of 6 revealed weak antiferromagnetic interactions between the Gd(III) ions.

一系列三价镧系配位聚合物[{La(Ben)₃(H₂O)₂}·(4,4′-BPNO)₀.₅·HBen·DMF]ₙ (1)、[{Ce(Ben)₃(4,4′-BPNO)(H₂O)₂}·DMF]ₙ (2)、[Tb(Ben)₃(4,4′-BPNO)₀.₅(H₂O)]ₙ (3)、[{Ln(Ben)₃(4,4′-BPNO)(H₂O)₂}·HBen]ₙ [Ln = La (4), Eu (5), Gd (6), Tb (7)] 已被成功合成并完成结构表征（其中Ben = 苯甲酸根（benzoate）；HBen = 苯甲酸（benzoic acid）；4,4′-BPNO = 4,4′-联吡啶-N,N′-二氧化物（4,4′-bipyridyl-N,N′-dioxide）；DMF = 二甲基甲酰胺（dimethylformamide））。配合物1中的金属中心为九配位几何构型，其余所有配位聚合物的金属中心均为八配位几何构型。配合物1由苯甲酸镧(III)的一维链构成，其空隙中封装了由HBen···4,4′-BPNO···HBen氢键相互作用形成的超分子组装体。配合物2与3的金属节点为八配位，几何构型为四方反棱柱体。其余四种配位聚合物4~7具有相同的通式组成，且均呈现三维类蜂窝状结构，其空隙中封装了苯甲酸分子。固态配合物5展现出Eu(III)特征的强红色发光性能。对配合物6的磁化率测试结果表明，Gd(III)离子间存在弱的反铁磁相互作用。