Highly fluorescent 3-perylenyldiphenylphosphane compounds: An experimental and theoretical study

Abstract

The perylene derivative, 3-perylenyldiphenylphosphane (PPh₂Per, 1), was prepared and used to synthesize the oxidized P(V) compounds A = PPh₂Per (A = O (2); A = S (3)). Substitution reactions led to mononuclear gold(I) complexes [AuX(PPh₂Per)] (X = Cl (4); X = C₆F₅ (5)), [AuX(S=PPh₂Per)] (X = Cl (6); X = C₆F₅ (7)) and palladium(II) complexes trans-[Pd(C₆F₅)₂(PPh₂Per)₂] (8). X-ray single crystal studies of compounds 5 and 7 confirmed the expected structures. The UV–Vis absorption spectra display intense peaks in the visible region with maxima from 454 to 461 nm. A DFT study was performed for the absorption spectra of ligands and complexes, showing that the lowest most intense transition is a HOMO → LUMO transition in the perylene core, although affected by functional group and metallic fragment. The ligands and their complexes are fluorescent in solution, due to the perylene fragment, showing an emission in the range 450–550 nm, with maxima from 467 to 472 nm. Quantum yield starts at 13 % for the phosphane and increases dramatically to the range of 63–87 % after oxidation or coordination to a metal fragment. This work illustrates how the PET effect can be used to recover the initial extremely intense emission of free unfunctionalized perylene ring system.