Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes

A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (1) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)₂] (X = Cl (2a), I (2b), Phosphole = 1) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (1). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes 2a-b shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds 1, 2a-b exhibited fluorescence between 460 and 583 nm with quantum yields of Φ_f = 0.04 – 0.11. The emission energy of 2b is higher than 2a, suggesting that λ_max is affected by the ligand-field strength of the halogen ions in the complexes (I^- < Cl^- ).