Syntheses,Crystal Structures,and Photophysical Properties of Heteronuclear Zinc(II)/Cadmium(II)‐Lanthanide(III) Coordination Complexes based on Benzoic Acid

The heteronuclear d‐f coordination complexes [Er₂Zn₂(C₆H₅COO)₁₀(phen)₂] (1), [Ho₂Zn₂(C₆H₅COO)₁₀(phen)₂] ( 2 ), [Pr₃Zn₆(C₆H₅COO)₂₁(phen)₃] ( 3 ), [ErCd(C₆H₅COO)₅(phen)·H₂O] ( 4 ), [Ho₂Cd₃(C₆H₅COO)₁₂(phen)₂] ( 5 ), [EuCd₂(C₆H₅COO)₇(phen)₂] ( 6 ) (C₆H₅COOH = benzoic acid;phen = 1,10‐phenanthroline) were synthesized by hydrothermal methods, and their structures were studied by single‐crystal X‐ray diffraction. Complexes 1 , 2 , 4 , and 5 crystallize in the triclinic space group P$bar{1}$ and complexes 3 and 6 in the monoclinic space group C2/c. The room temperature IR, UV/Vis/NIR absorption, and emission spectra of the six complexes were determined and assigned. In the visible and NIR regions, the emission spectra of complexes show characteristic bands of corresponding Ln^III ions, which are attributed to the sensitization from the d block (Zn/Cd‐ligand section) and ligands. In comparison with isolated Ln^III ions, the NIR emission bands of complexes 1 – 5 exhibit shifting, broadening and splitting, which are also present in their UV/Vis/NIR absorption spectra. Thus, the two spectra of complexes can evidence each other.