Remarkable Alteration of Photophysical Properties of Cyclic Trinuclear Complexes of Monovalent Coinage Metals upon Interactions with Small Organic Molecules

Abstract Interaction of cyclic trinuclear complexes of Au(I), Ag(I), and Cu(I) with vapor, liquid, or solid forms of small organic molecules leads to remarkable photophysical changes from those of the parent complex. The luminescence changes are generally attributed to alteration of the intertrimer metal-metal interactions that become perturbed by the organic molecule. In some instances, as manifest by interaction of {[3,5-(CF3)2Pz]Ag}3 with benzene and its alkylated derivatives, the luminescence signal was turned on due to exciplex formation as the non-luminescent trimer becomes brightly phosphorescent when the organic vapor is introduced or when crystals are grown from solutions in the aromatic solvent. A second instance was manifest by luminescence color change from blue for [Au(μ-C2,N3-bzim)]3 (bzim = 1-benzylimidazolate) or green for [Au(μ-C(OEt) = N(ρ-C6H4CH3)]3 to yellow phosphorescence upon their interaction with octafluoronaphthalene due to the latter's triplet state that becomes sensitized by a strong gold heavy atom effect. Likewise, various Cu(I) complexes {[3,5-(R,R′)Pz]Cu}3 alter the metal-centered phosphorescence characteristic of each solid to remarkable emission colors that can be tuned across the entire visible region in glassy matrices of various organic solvents. Finally, the phosphorescent emissions of the same aforementioned trimers [Au(μ-C(OEt) = N(ρ-C6H4CH3)]3 and [Au(μ-C2,N3-bzim)]3 undergo complete quenching upon interaction with vapors of the Lewis acidic C6F6 molecule and the strong organic acceptor TCNQ due to disruption of the intertrimer aurophilic interaction and electron transfer, respectively. Keywords: acid-based interactionphosphorescence sensitizationtrinuclear coinage metal complexes ACKNOWLEDGMENTS The author is indebted to her former mentors (Prof. John P. Fackler, Jr./Texas A&M University and Prof. Howard H. Patterson/University of Maine), collaborators (Prof. H. V. Rasika Dias/University of Texas, Arlington and Prof. Mohammad A. Omary/University of North Texas), and research group members (Dr. Maher D. Rashdan and the late Dr. Oussama Elbjerami), with whom she has had the pleasure of working on the various projects described in this article. Financial support is gratefully acknowledged for projects at Texas Woman's University that have been funded by a DARPA Young Investigator Award (W71B7J-7078-B368), ACS-PRF (# 49511-UNI3), and a departmental Welch Foundation grant.