N^N^C platinum (II) complexes based on phenyl-pyridin-2-ylpyrimidine ligands: synthesis, electrochemical and photophysical properties

A series of luminescent chloro- and alkynyl-platinum (II) complexes containing various tridentate cyclometalated ligands derived from phenyl-pyridin-2-ylpyrimidine alkynyl has been successfully synthesized characterized. Their electrochemical, electronic absorption luminescence properties have experimentally investigated supported by (Time-Dependent) Density Functional Theory ((TD)-DFT) calculations. Electrochemical studies show the presence a ligand-centered reduction originating cyclometalating N^N^C ligands, as well major oxidation process (N^N^C or alkynyl) with minor contributions metal. Most exhibits yellow-to-red at room-temperature in diluted solutions, frozen matrices solid state. Electron-withdrawing groups on alkynyl-ligand induce red shift emission band increased quantum yield solution. The is also sensitive to position pyridyl fragment pyrimidine core: electron-poorer 4-pyridin-2-ylpyrimidine exhibit red-shifted decreased compared their 2-pyridin-4yl analogues. In state, chloro-platinum without tBu bulky group excimer emission.