Chemical Synthetic Protocol of M-DMAP (M = Ag⁺, Cr³⁺, Cu²⁺, Co²⁺, In³⁺, Ce³⁺) Coordination Compounds and Their Photoelectrochemical Performance

The synthesis and application of coordination compounds are a focal point in coordination chemistry. Pyridine, as a type of nitrogen-containing heterocyclic ligand, exhibits a rich coordination chemistry and plays a significant role in incorporating various metal ions into functional materials. Therefore, enhancing the coordination ability of pyridine N lone pair electrons with metal ions, improving the stability of the coordination compounds, and broadening the research on the synthesis and application of pyridine-based coordination compounds are of great importance. Herein, we report a research strategy based on electronic effects─introducing strong electron-donating groups at the para position of pyridine N to enhance the coordination ability of the lone pair electrons with metal ions, thereby increasing the strength of the coordination bonds and the stability of the coordination compounds. Through precise chemical synthesis, coordination compounds of 4-dimethylaminopyridine (DMAP) with Ag+, Cr3+, Cu2+, Co2+, In3+, and Ce3+ were successfully prepared. Notably, the Ag-DMAP compound exhibits a low HOMO–LUMO energy gap (2.31 eV) and a Tafel slope of −972 mV dec–1. Furthermore, the DMAP-based metal coordination compounds all demonstrate preferable photoelectric applications.