Luminescence properties of heterodinuclear Pt–Eu complexes from unusual nonadentate ligands
作者:Pascal Kadjane、Carlos Platas-Iglesias、Raymond Ziessel、Loïc J. Charbonnière
DOI:10.1039/b903522b
日期:——
The synthesis of ligand L1, based on the tetramethyl ester of [4â²-ethynyl-(6,6â³-bis(aminomethyl))-2,2â²:6â²,2â³-terpyridine]tetrakisacetate, and its acidic form L2, are described. Using a Cu-assisted coupling reaction, L1 was connected to the Pt atom of a [(tpy)Pt] precursor (tpy = 2,2â²:6â²,2â³-terpyridine) to afford the [(tpy)PtL1](BF4) metallosynthon, from which a hydrolysis reaction gave Na3[(tpy)PtL2]. The photophysical properties of the metallosynthons were studied by means of absorption and steady state emission spectroscopic techniques in various solvents, which revealed a dramatic impact of the solvent polarity. DFT and TDDFT calculations (B3LYP) were used to investigate the absorption and emission properties of the [(tpy)PtL1]+ system both in vacuo and in different solvents. Spectrophotometric titrations of [(tpy)PtL1]+ with EuCl3·6H2O in acetonitrile revealed the formation of complicated mixtures of complexes with different [(tpyPtL1)xEuy] stoichiometries, all of which display the typical EuIII centred luminescence upon excitation into the Pt centred 1MLCT absorption band. The energy transfer from the Pt subunit of [(tpy)PtL2]3â to EuIII is inefficient in polar solvents, but it is restored in a TFAâCH2Cl2 mixture, together with the observation of a new emission band at 684 nm, likely arising from a charge transfer process involving reduction of EuIII.
本文介绍了以[4â²-乙炔基-(6,6â³-双(氨基甲基))-2,2â²:6â²,2â³-三吡啶]四异乙酸酯的四甲基酯为基础合成的配体 L1 及其酸性形式 L2。通过铜辅助偶联反应,L1 与[(typy)Pt]前体(typy = 2,2â²:6â²,2â³-terpyridine)的铂原子相连,得到了[(typy)PtL1](BF4)金属铂,通过水解反应得到了 Na3[(typy)PtL2]。在各种溶剂中通过吸收和稳态发射光谱技术研究了金属锑的光物理特性,结果表明溶剂的极性对金属锑的光物理特性有显著影响。利用 DFT 和 TDDFT 计算(B3LYP)研究了[(ttpy)PtL1]+ 系统在真空和不同溶剂中的吸收和发射特性。在乙腈中用 EuCl3Â-6H2O 滴定[(ttpy)PtL1]+的分光光度法,发现形成了具有不同[(ttpyPtL1)xEuy]配位系数的复杂混合物,所有这些混合物在激发到以铂为中心的 1MLCT 吸收带时都显示出典型的以 EuIII 为中心的发光。在极性溶剂中,[(ttpy)PtL2]3â 的铂亚基向 EuIII 的能量转移效率很低,但在 TFAâCH2Cl2 混合物中,能量转移得到恢复,同时在 684 纳米波长处观察到一个新的发射带,这可能是由 EuIII 的还原电荷转移过程引起的。