fac-Re(CO)3 complexes of 2,6-bis(4-substituted-1,2,3-triazol-1-ylmethyl)pyridine “click” ligands: synthesis, characterisation and photophysical properties
作者:Christopher B. Anderson、Anastasia B. S. Elliott、James E. M. Lewis、C. John McAdam、Keith C. Gordon、James D. Crowley
DOI:10.1039/c2dt31569f
日期:——
The syntheses of the 4-n-propyl and 4-phenyl substituted fac-Re(CO)3 complexes of the tridentate âclickâ ligand (2,6-bis(4-substituted-1,2,3-triazol-1-ylmethyl)pyridine) are described. The complexes were obtained by refluxing methanol solutions of [Re(CO)5Cl], AgPF6 and either the 4-propyl or 4-phenyl substituted ligand for 16 h. The ligands and the two rhenium(I) complexes were characterised by elemental analysis, HR-ESMS, ATR-IR, 1H and 13C NMR spectroscopy and the molecular structures of both complexes were confirmed by X-ray crystallography. The electronic structure of the fac-Re(CO)3 âclickâ complexes was probed using UV-Vis, Raman and emission spectroscopy, cyclic voltammetry and DFT calculations. Altering the electronic nature of the ligandâs substituent, from aromatic to alkyl, had little effect on the absorption/emission maxima and electrochemical properties of the complexes indicating that the 1,2,3-triazole unit may insulate the metal centre from the electronic modification at the ligandsâ periphery. Both Re(I) complexes were found to be weakly emitting with short excited state lifetimes. The electrochemistry of the complexes is defined by quasi-reversible Re oxidation and irreversible triazole-based ligand reduction processes.
本文介绍了三叉 "click "配体(2,6-双(4-取代的-1,2,3-三唑-1-基甲基)吡啶)的 4-正丙基和 4-苯基取代面-Re(CO)3 复合物的合成。通过元素分析、HR-ESMS、ATR-IR、1H 和 13C NMR 光谱对配体和两种铼(I)配合物进行了表征,并通过 X 射线晶体学确认了两种配合物的分子结构。通过紫外-可见光谱、拉曼光谱、发射光谱、循环伏安法和 DFT 计算,研究了 Fac-Re(CO)3âclickâ复合物的电子结构。改变配体取代基(从芳基到烷基)的电子性质对配合物的吸收/发射最大值和电化学性质影响甚微,这表明 1,2,3-三唑单元可能使金属中心免受配体外围电子修饰的影响。两种 Re(I)络合物都具有弱发射性,激发态寿命短。这些配合物的电化学性质由准可逆的 Re 氧化和不可逆的基于三唑的配体还原过程决定。