Luminescent heteroleptic copper(I) complexes with phosphine and N-benzoyl thiourea ligands: Synthesis, structure and emission properties

The reactions between [CuX(PPh3)](4) or [CuX(PPh3)(3)], X = Cl or Br, and N-benzoyl-N'-(4-methoxyphenyl)thio-urea (BTU-OMe), N-benzoyl-N'-(4-methylphenyl)thiourea (BTU-Me) in toluene gave new four-coordinated tetrahedral copper(I) complexes of two types: [CuX(BTU)(PPh3)(2)] (1, 2) and [CuX(BTU)(2)(PPh3)] (3,4) [BTU = N-benzoyl-N'-(4-methoxy/methyl phenyl)thiourea derivatives, X = Cl (a) and Br (b)]. These complexes were fully characterized by several analytical and spectroscopic (IR, UV/VIS, H-1, C-13 and P-31 NMR) techniques. The molecular structure of a representative complex, [Cu(BTU-OMe)(PPh3)(2)Cl] (3a), was determined by the single crystal X-ray diffraction method which reveals a distorted tetrahedral geometry where the Cu(I) ion is surrounded by one BTU ligand molecule, two PPh3 groups and one chloride anion. These eight heteroleptic complexes were found to emit in solid state with lifetimes in the 12-99 mu s range and with the highest quantum yield of 4.0% for 3b. The reaction between [CuBr(PPh3)](4) and N-benzoyl-N',N'-(di-n-butyl)thiourea (BTU-Bu-2) ligand gave the simple [CuBr(BTU-Bu-2)(3)] complex (5), when the PPh3 molecules were completely removed by the BTU derivative. The spectroscopic data indicated a distorted tetrahedral geometry produced by three BTU ligand molecules and one bromide anion. Complex 5 has the highest quantum yield (11%) with the lifetime of 29 mu s in solid-state.

Automated summary

The study synthesized two types of four-coordinated tetrahedral copper(I) complexes, which were fully characterized by various analytical and spectroscopic techniques. One of the complexes exhibited high quantum yield and long lifetime in solid state. Additionally, other copper(I) complexes can be easily prepared using BTU derivatives.