The Aggregations and Strong Emissions of d<sup>8</sup> and d<sup>10</sup> Metal−8-Hydroxyquinaldine Complexes

Five new d<sup>8</sup> and d<sup>10</sup> metal complexes, Pd(8-hq)<sub>2</sub> (<b>1</b>), [Ag(8-Hhq)<sub>2</sub>]NO<sub>3</sub> (<b>2</b>), Ag(8-hq)(8-Hhq) (<b>3</b>), [(8-H<sub>2</sub>hq)<sub>2</sub>PdCl<sub>4</sub>]·2H<sub>2</sub>O (<b>4</b>), and Pt(8-hq)(tht)Cl (<b>5</b>) (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 <b>1</b>−<b>3</b> and <b>5</b> in solid states with orange, cyan, and green luminescences originating from metal···<sup></sup>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 <b>1</b> are in good agreement with the experiments. Thermogravimetric analyses and UV/vis spectra with composition of certain simulated results are also reported.