Highly fluorescent complexes with 3-isocyanoperylene and N-(2,5-di-tert-butylphenyl)-9-isocyano-perylene-3,4-dicarboximide

Abstract

The perylene derivatives 3-isocyanoperylene (Per–NC) (4a) and N-(2,5-di-tert-butylphenyl)-9-isocyano-perylene-3,4-dicarboximide (PMI–NC) (4b) were prepared and used to synthesize gold complexes [AuX(CNR)] (X = C₆F₅ (5a,b), C₆F₄-OⁿBu-p (6b)). The reaction of 5b and 6b with HNEt₂ led to the carbene complexes [AuX{C(NEt₂)(NHR)}] (7b, 8b), respectively. The molecular structure of complexes 7b and 8b have been determined by X-ray diffraction analysis showing intermolecular π-stacking of the perylene groups and C₆F₅ rings and no Au⋯Au interactions. The derivative compounds [M(CO)₅(CNR)] (M = Cr (9a,b), Mo (10a,b) or W (11a,b)) and trans-[Pd(CNR)₂(C₆F₃Cl₂)₂] (12a,b) were also prepared. All complexes exhibit fluorescence associated with the perylene fragment with emission quantum yields, in solution at room temperature, in the range 0.05–0.93 and emission lifetimes ∼ 4 ns. DFT calculations were performed of the absorption spectra of the ligands Per–NC and PMI–NC and representative complexes [Au(C₆F₅)(CNR)], [Cr(CO)₅(CNR)], showing a perylene-dominated intraligand π–π* emissive state, from the HOMO and LUMO orbitals of the perylene chromophore, but with significantly different absorption maxima by the influence of the metal fragment, particularly significant in the Per–NC derivatives.