Syntheses, Structure And Photo-physical Properties Of Series Of Zn(Cd)/Ln Coordination Complexes

A series of coordination complexes have been synthesized by hydrothermal method. Inwhich, aromatic carboxylic acids were selected as the main ligands, the d10ions andlanthanide ions were chosen as the central metal ions. The structures of the elevencoordination complexes were determined by single-crystal X-ray diffraction, the molecularformulas are as follows:Complex（1）:[EuCd₂（C₆H₅COO）₇（phen）₂] Complex（2）:[Ho₂Cd₃（C₆H₅COO）₁₂（phen）₂]Complex（3）:[ErCd（C₆H₅COO）₅（phen）·H₂O] Complex（4）:[Pr₃Zn₆（C₆H₅COO）₂₁（phen）₃]Complex（5）:[Ho₂Zn₂（C₆H₅COO）₁₀（phen）₂] Complex（6）:[Er₂Zn₂（C₆H₅COO）₁₀（phen）₂]Complex（7）:[Pr₂（C₈H₄O₄）₂（C₆H₈O₄）·4H₂O]nComplex（8）:[Nd₂（C₈H₄O₄）₂（C₆H₈O₄）·4H₂O]_nComplex（9）:{[Pr（2,6-pdc）（2,6-Hpdc）（H₂O）₄]·（H₂O）₄}_nComplex（10）:[Cd（phen）Cl₂]_nComplex（11）:[Cd（NA）₂·2H₂O]_nAt room temperature, UV-Vis-NIR, the IR, excitation and emission spectra in the visiblearea of the eleven complexes were characterized and analyzed. Absorption bands of Ln（Ⅲ）ions in the UV-Vis-NIR spectra of complex （3）～（6） present shift, split and broad, except forthe effect of crystal field, this may be attributed to the construction of d-f complexes, theintrinsic f-orbital of Ln（Ⅲ） ions may be adjusted owing to the small separation of d…Ln（Ⅲ）.The emission bands of complexes （2）～（9） should be very obvious in near-infrared region.However, NIR spectra of these complexes have not been determined due to the limit ofinstrument.The emission spectra in the visible region of the eleven complexes, were analysed andassignmented compared with the fluorescence emission spectra of raw materials. As can beseen, the aromatic carboxylate ligands in the Cd-Ln, Zn-Ln complexes, act as excellentenergy donors to sensitize the luminescence of Ln（Ⅲ） ions, and the emission bands werechanged.The emission spectrum of complex （1） exhibites characteristic emission of Eu（Ⅲ） ion.One reason is that the level of triplet state of ligands matched with the excited state level ofEu（Ⅲ） ion; another reason is introducing Cd（Ⅱ） ion, it could sensitize luminescence ofEu（Ⅲ） preferably. And the energy absorbed by the ligands will be transfered through theform of jumping of within the system to the excited level of Eu（Ⅲ） ion effectively. Therefore,the emission spectra of complex （1） exhibit strong characteristic emission in the visible area.