Modulation of structural and spectroscopic properties in a series of metal atoms ranging from transition to lanthanide to actinide atoms connected through bridging ligands

Title : Modulation of structural and spectroscopic properties in a series of metal atoms ranging from transition to lanthanide to actinide atoms connected through bridging ligands

Abstract:

The structural features and spectroscopic properties of metal atoms connected through bridging ligands is fascinating. The metal atoms covered in this talk range from transition metals to lanthanides and some of the heaviest actinide metals in the periodic table. Our lab has been attempting for several years to linking more than two metal atoms through bridging ligands. Low dimensional structural motifs are dominant in these complexes. The Metal−Metal interactions between adjacent metal atoms provide highly tunable spectral properties that can be tuned by chemical and physical variations such as choice of counter cation, temperature or, applied pressure. In this presentation correlation between the structural motifs and emission behavior will be discussed for several complexes containing late transition metals and lanthanide and/or actinide metals. Both the structural features and the spectroscopic properties are dominated by the presence of ground and excited state metal-metal interactions as the result of the common low dimensional motifs. The spectroscopic part of this talk will cover some of the unique phenomenon exhibited by these complexes including multiple state emissions, energy transfer, and dual donor emission enhancement. Some unusual luminescence behaviors, such as exciplex and excimer emissions resulting from the unique structural motifs are also discussed on a variety of late transition metal based coordination polymeric compounds.

Biography:

Dr. Assefa obtained his BSc degree from Addis Ababa University and his PhD in 1992 from the University of Maine. He served as a post-doctoral fellow at Texas A&M, and Auburn University focusing in the areas of X-ray crystallography and multi-electron transfer kinetics, respectively. In 1995, Dr. Assefa joined the Oak Ridge National Laboratory and primarily conducted basic research on transuranium elements. He then moved to North Carolina A&T State university to pursue academic career. Dr. Assefa has pursued fundamental research on materials for luminescent sensor application, white light emitting materials, and gold and other Group 11 metal compounds for medicinal applications. Dr. Assefa has published over eighty-five peer-reviewed articles and three book chapters.