Synthesis and optical characterization of two new gold(Ⅰ)complexes bearing chromophoric N-heterocyclic carbene(NHC)ligands are described.Ligands with electron-releasing(diphenylamino)and electron-withdrawing(benzothi...Synthesis and optical characterization of two new gold(Ⅰ)complexes bearing chromophoric N-heterocyclic carbene(NHC)ligands are described.Ligands with electron-releasing(diphenylamino)and electron-withdrawing(benzothiazolyl)substituents are described,and metalation with gold(Ⅰ)bromide is demonstrated.Crystallographic characterization reveals both complexes to have linear,twocoordinate gold and an absence of aurophilic interactions in the solid state.The absorption spectra of both gold(Ⅰ)complexes are similar to the free ligand absorption spectra indicating ligand localized π-π^(*) absorption.The new gold complexes show moderate fluorescence and observable phosphorescence;binding of a single gold atom suffices to populate triplet excited states.The fluorescence of the benzothiazolyl derivative is π-π^(*) in nature,while the fluorescence of the diphenylamino derivative is chargetransfer in nature.The phosphorescence of both complexes is vibronically structured,indicative of metalperturbed π-π^(*) character.Phosphorescence at 298 K persists for hundreds of microseconds.Intersystem crossing is the dominant excited state kinetic pathway with quantum yields of intersystem crossing greater than 50% for both gold complexes.Density-functional theory calculations indicate that the lowest excited singlet and triplet states are dominated by the carbene-fluorenyl-substituent conjugate.We believe the incorporation of gold as a heavy atom through a strongly σ-donating and moderately π-accepting NHC-linker provides a general strategy for achieving NHC complexes with phosphorescence.展开更多
基金supported by the Air Force Office of Scientific Research,contract FA9550-22-1-0436 to T.G.GAll AFRL affiliated authors recognize the Air Force Office of Scientific Research under AFOSR Award 9550-19-1-18RX056+2 种基金the Air Force Research Laboratory/RXAP contract FA8650-16-D-5402-0001All USAFA affiliated authors recognize support provided by the Air Force Office of Scientific Research Small Grants programNSF is acknowledged through the Major Research Instrumentation Program under Grant No.CHE 1625543 to M.Z.(funding for the single crystal X-ray diffractometer).
文摘Synthesis and optical characterization of two new gold(Ⅰ)complexes bearing chromophoric N-heterocyclic carbene(NHC)ligands are described.Ligands with electron-releasing(diphenylamino)and electron-withdrawing(benzothiazolyl)substituents are described,and metalation with gold(Ⅰ)bromide is demonstrated.Crystallographic characterization reveals both complexes to have linear,twocoordinate gold and an absence of aurophilic interactions in the solid state.The absorption spectra of both gold(Ⅰ)complexes are similar to the free ligand absorption spectra indicating ligand localized π-π^(*) absorption.The new gold complexes show moderate fluorescence and observable phosphorescence;binding of a single gold atom suffices to populate triplet excited states.The fluorescence of the benzothiazolyl derivative is π-π^(*) in nature,while the fluorescence of the diphenylamino derivative is chargetransfer in nature.The phosphorescence of both complexes is vibronically structured,indicative of metalperturbed π-π^(*) character.Phosphorescence at 298 K persists for hundreds of microseconds.Intersystem crossing is the dominant excited state kinetic pathway with quantum yields of intersystem crossing greater than 50% for both gold complexes.Density-functional theory calculations indicate that the lowest excited singlet and triplet states are dominated by the carbene-fluorenyl-substituent conjugate.We believe the incorporation of gold as a heavy atom through a strongly σ-donating and moderately π-accepting NHC-linker provides a general strategy for achieving NHC complexes with phosphorescence.
