Highly fluorescent complexes with gold, palladium or platinum linked to perylene through a tetrafluorophenyl group

Abstract

Treatment of 3-(1-hexynyl)perylene with Co₂(CO)₈ resulted in the formation of the dinuclear cobalt complex [Co₂(CO)₆(μ–η²-C₄H₉CC-Per)] (Per = 3-perylenyl) (1). The perylene derivatives 3-(2,3,5,6-tetrafluorophenyl)perylene (PerC₆F₄H) and 3-(2,3,5,6-tetrafluorophenyl)-9(10)hexylperylene (C₆-PerC₆F₄H) were prepared and used to synthesize [AuR(CN^tBu)] (R = PerC₆F₄2a), [AuR(CN(C₆H₂)-3,4,5-(OC₁₂H₂₅)₃)] (R = PerC₆F₄ (3a), R = C₆-PerC₆F₄ (3b)), trans-[PdR(PR′₃)₂X] (R = PerC₆F₄, R′ = Ph, X = I (4a)); (R = C₆-PerC₆F₄, R′ = Ph, X = I (4b)); (R = PerC₆F₄, R′ = Et, X = I (5a)); (R = C₆-PerC₆F₄, R′ = Et, X = I (5b)); (R = PerC₆F₄, R′ = Ph, X = NCS (6a)), and trans-[Pd(PerC₆F₄)(PEt₃)₂X] (X = Br (7a); X = I (8a)). The molecular structure of complexes 1, 2a, and 6a has been determined by X-ray diffraction analysis. The perylenyl fragments of complexes 2a or 6a are essentially planar and make dihedral angles to the tetrafluorophenyl plane of 57.49° (2a) and 77.75° (6a). No π–π stacking of perylenyl rings is observed in any of the three molecules, but 2a shows association of two monomers (arranged almost antiparallel), with an Au⋯Au distance of 3.114 Å. DFT calculations were performed on the absorption spectra of representative PerC₆F₄Y (Y = H, F, Au(CNMe), PtBr(PMe₃)₂ and PdBr(PMe₃)₂). All complexes exhibit fluorescence associated with the perylene fragment with emission quantum yields, in solution at room temperature, in the range 0.20–0.90 and emission lifetimes ∼4 ns, and no significant differences in the emission maxima, due to an efficient electronic decoupling of the metal fragment from the HOMO and LUMO of the perylene chromophore. The latter is confirmed by DFT calculations.