The Aggregations and Strong Emissions of d8 and d10 Metal−8-Hydroxyquinaldine Complexes

Five new d8 and d10 metal complexes, Pd(8-hq)2 (1), [Ag(8-Hhq)2]NO3 (2), Ag(8-hq)(8-Hhq) (3), [(8-H2hq)2PdCl4]·2H2O (4), and Pt(8-hq)(tht)Cl (5) (tht = tetrahydrothiophene), all with a fluorogenic chelating agent, 8-hydroxyquinaldine (8-Hhq), have been synthesized and characterized. The aggregations of their photoactive metal centers through π−π stacking and hydrogen bonding interactions construct the interesting frameworks. The strong emissions of 1−3 and 5 in solid states with orange, cyan, and green luminescences originating from metal···metal and π−π interactions are assigned as metal to ligand charge transfer/metal–metal to ligand charge transfer/intraligand emissions. The solvent effects on their photophysical properties are examined, which exhibit a wide range of strong luminescences in the different organic solvents. In addition, time-dependent density functional theory calculations using the B3LYP functional on 1 are in good agreement with the experiments. Thermogravimetric analyses and UV/vis spectra with composition of certain simulated results are also reported.

本实验成功合成了五种新型d8和d10金属配合物，包括Pd(8-hq)2（1）、[Ag(8-Hhq)2]NO3（2）、Ag(8-hq)(8-Hhq)（3）、[(8-H2hq)2PdCl4]·2H2O（4）以及Pt(8-hq)(tht)Cl（5）（tht代表四氢噻吩），这些配合物均含有荧光性螯合剂8-羟基喹啉（8-Hhq）。通过π-π堆积和氢键相互作用，这些配合物的光活性金属中心形成了引人入胜的框架结构。在固态下，1-3和5表现出强烈的橙、蓝、绿色荧光，其来源归因于金属与金属之间以及π-π相互作用产生的金属到配体电荷转移/金属-金属到配体电荷转移/配体内发射。研究了溶剂对这些配合物光物理性质的影响，结果显示在不同有机溶剂中展现出广泛且强烈的光荧光性质。此外，对1进行的基于B3LYP泛函的时间相关密度泛函理论计算与实验结果吻合良好。同时，还报道了热重分析和紫外-可见光谱，以及某些模拟结果的组成分析。