GILDED ORGANOMETALLICS

Abstract

The (phosphine)- and (N-heterocyclic carbene)gold(I) fragments are isolobal with the proton; they can attach terminally to fluorescent organic molecules in place of hydrogen. A new synthetic protocol, base-promoted transmetallation, has been developed that binds gold(I) to the peripheries of aromatic molecules through direct C–Au σ-bonds. Photophysical investigations indicate that a single gold center induces triplet excited-state behavior. Gold-induced perturbations of an azadipyrromethene chromophore are also discussed; here gold binds through nitrogen. In all instances considered, gold(I) acts as a relativistic functional group that perturbs its ligands' excited state manifolds through spin-orbit coupling.

Keywords:

• emission spectroscopy
• gold
• photophysics
• transmetallation

Abbreviations:

• 2-MeTHF, 2-methyltetrahydrofuran
• bpy, 2,2′-bipyridyl
• Cy, cyclohexyl
• DFT, density-functional theory
• HOMO, highest occupied Kohn-Sham orbital
• i-Pr, iso-propyl
• LUMO, lowest unoccupied Kohn-Sham orbital
• Me, methyl; NMR, nuclear magnetic resonance
• OTf, triflate
• PCM, polarizable continuum model
• Ph, phenyl
• TDDFT, time-dependent density-functional theory
• THF, tetrahydrofuran

ACKNOWLEDGMENTS

I thank my students and co-workers: Dr. D. V. Partyka, M. A. Peay, J. B. Updegraff III, T. J. Robilotto, L. Gao, K. Grigas, T. S. Teets, J. M. Vergotz, and J. Winkler. I thank Dr. M. Zeller and Prof. A. D. Hunter, Youngstown State University, for X-ray diffraction crystallography, Dr. A. Esswein, MIT, for emission lifetime measurements, and Prof. D. G. Nocera, MIT, for access to instrumentation. Acknowledgment is made to Case Western Reserve University and the donors of the Petroleum Research Fund, administered by the American Chemical Society (Grant 42312-G3 to T. G. G.) for support. The diffractometer at CWRU was funded by NSF grant CHE0541766; that at YSU by NSF grant 0087210, by the Ohio Board of Regents grant CAP-491, and by Youngstown State University.