Series of Novel 3D Heterometallic Frameworks Based on the Co(II) Coordination Chains and Ln(III) Coordination Layers

A family of novel Co­(II)–Ln­(III) heterometallic
coordination
polymers [Ln2Co­(tia)4(H2O)4]∞ (tia2– = 5-(1H-1,2,3-triazol-1-yl) isophthalate, Ln = La 1, Ce 2, Pr 3, Nd 4, Sm 5, Eu 6, Gd 7, Tb 8, Dy 9) have been synthesized through in situ ligand
transformation reactions, in which 5-(4-carboxy-1H-1,2,3-triazol-1-yl) isophthalic acid (H3ctia) undergoes
decarboxylation and double deprotonation to tia2–. X-ray structural analysis reveals that compounds 1–9 are isomorphous. The heterometallic Ln3+ and Co2+ ions are connected by the dianionic
linker (tia2–) to form unique 3D heterometallic
frameworks. Moreover, we have systematically investigated the magnetic
behaviors and fluorescent properties of these compounds. The out-of-phase
ac signals observed for 9 suggest slow magnetization
relaxation, which is unusual in 3D coordination polymers, especially
in 3D heterometallic frameworks. In NIR regions, complexes 3, 4, 5, and 9 show the characteristic
luminescence of the corresponding Ln­(III ions.

一类新型的Co(II)-Ln(III)异金属配位聚合物[Ln2Co(tia)4(H2O)4]∞（其中tia2–代表5-(1H-1,2,3-三唑-1-基)异苯二甲酸根，Ln代表La1, Ce2, Pr3, Nd4, Sm5, Eu6, Gd7, Tb8, Dy9）]已通过原位配体转化反应合成。在此反应中，5-(4-羧基-1H-1,2,3-三唑-1-基)异苯二甲酸（H3ctia）经历脱羧和双去质子化过程生成tia2–。X射线结构分析显示，化合物1至9具有同质构性。异金属的Ln3+和Co2+离子通过二阴离子桥联剂（tia2–）相连，形成独特的三维异金属框架。此外，我们对这些化合物的磁性行为和荧光性质进行了系统研究。对于化合物9观察到的反相交流信号表明，其磁化弛豫速度缓慢，这在三维配位聚合物中尤为罕见，尤其是在三维异金属框架中。在近红外区域，复合物3、4、5和9展现出对应Ln(III)离子的特征荧光。