Three-Dimensional Supramolecular Architectures with CoII Ions Assembled from Hydrogen Bonding and π···π Stacking Interactions: Crystal Structures and Antiferromagnetic Properties
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Five CoII complexes based on H3L1 and H3L2, namely, [Co3(L1)2(4,4′-bipy)(H2O)3]n (1), [Co3(L1)2(4,4′-bipy)3(H2O)4]n (2), {[Co2(L1)(4,4′-bibp)(μ3-OH)(H2O)]·H2O}n (3), {[Co3(L2)2(dib)3]·2H2O}n (4), and [Co3(L2)2(4,4′-bibp)3]n (5) [(H3L1 = 4-[(3-carboxynaphthalen-2-yl)oxy]phthalic acid, H3L2 = 3-[(3-carboxynaphthalen-2-yl)oxy]phthalic acid, 4,4′-bipy = 4,4′-bipyridine, dib = 1,4-di(1H-imidazol-1-yl) benzene, and 4,4′-bibp = 4,4′-bis(imidazol)-biphenyl] have been synthesized by solvothermal reactions. Complex 1 displays a (4,4,6)-connected topology with a Schläfli symbol of (4.104.12)(411.64)(45.6)2, and the two-dimensional (2D) structure was assembled to form a three-dimensional (3D) framework by C–H···π interactions of internaphthalene rings, showing the dominant antiferromagnetic exchanges in a triangular {Co3} cluster. Complex 2 presents a 2D (3,4,4)-connected network with a Schläfli symbol of (5.62)2(52.63.7)2(54.82) and weakly antiferromagnetic behavior. Complex 3 features a novel (4,4,8)-connected topology with a Schläfli symbol of (32.4.52.6)2(32.42.52)2(34.46.58.67.72.8). In addition, complex 3 based on a parallelogram-shaped [Co4(μ3-OH)2]6+ secondary building unit provides antiferromagnetic interactions mediated by μ3-OH and syn-syn-COO– groups. The driving forces in 3D supramolecular frameworks are C–H···O, C–H···π, and π···π stacking interactions for 2–3. Complexes 4–5 have an identical (4,4,5)-connected 2D network with a Schläfli symbol of (4.64.8)(42.67.8)2(44.62)2. Additionally, the C–H···O hydrogen bonds between naphthalene rings and uncoordinated carboxy oxygen atoms extend 2D networks into 3D supramolecular frameworks. Magnetic investigations reveal that 4 and 5 exhibit antiferromagnetic interactions in the linear {Co3} unit.
本研究通过溶剂热反应合成了5种基于配体H₃L¹和H₃L²的钴(II)配合物，分别为[Co₃(L¹)₂(4,4′-联吡啶(4,4′-bipy))(H₂O)₃]ₙ（1）、[Co₃(L¹)₂(4,4′-联吡啶(4,4′-bipy))₃(H₂O)₄]ₙ（2）、{[Co₂(L¹)(4,4′-二(咪唑基)联苯(4,4′-bibp))(μ₃-羟基(μ₃-OH))(H₂O)]·H₂O}ₙ（3）、{[Co₃(L²)₂(1,4-二(1H-咪唑-1-基)苯(dib))₃]·2H₂O}ₙ（4）以及[Co₃(L²)₂(4,4′-二(咪唑基)联苯(4,4′-bibp))₃]ₙ（5）；其中H₃L¹为4-[(3-羧基萘-2-基)氧基]邻苯二甲酸，H₃L²为3-[(3-羧基萘-2-基)氧基]邻苯二甲酸，4,4′-联吡啶(4,4′-bipy)，1,4-二(1H-咪唑-1-基)苯(dib)，4,4′-二(咪唑基)联苯(4,4′-bibp)。配合物1呈现(4,4,6)连接拓扑，其施莱夫利符号(Schläfli symbol)为(4·10⁴·12)(4¹¹·6⁴)(4⁵·6)₂；该二维(2D)结构通过萘环间的C–H···π相互作用组装为三维(3D)骨架，在三角形{Co₃}簇中表现出主导性的反铁磁交换作用。配合物2具有二维(2D) (3,4,4)连接网络，其施莱夫利符号为(5·6²)₂(5²·6³·7)₂(5⁴·8²)，并表现出弱反铁磁行为。配合物3展现出新颖的(4,4,8)连接拓扑，其施莱夫利符号为(3²·4·5²·6)₂(3²·4²·5²)₂(3⁴·4⁶·5⁸·6⁷·7²·8)；此外，以平行四边形结构的[Co₄(μ₃-OH)₂]⁶⁺次级结构单元(secondary building unit)为基础的配合物3，存在由μ₃-羟基桥基和顺顺-羧酸根介导的反铁磁相互作用。对于配合物2和3，其三维超分子骨架的构筑驱动力为C–H···O氢键、C–H···π相互作用以及π···π堆积相互作用。配合物4和5具有相同的(4,4,5)连接二维(2D)网络，其施莱夫利符号为(4·6⁴·8)(4²·6⁷·8)₂(4⁴·6²)₂；此外，萘环与未配位羧基氧原子之间的C–H···O氢键将二维网络拓展为三维超分子骨架。磁性研究表明，配合物4和5在线性{Co₃}单元中存在反铁磁相互作用。
