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.