Mechanisms of Chiral Features of Atomically Precise Metal Clusters and Resonant Transition Metal Complexes: Insights from Vibrational Optical Activity
Creators: Alshalalfeh, Mutasem M
Publisher: name: University of Alberta Library
Year: 2024

<p>My PhD thesis primarily focuses on exploring chiroptical events and to elucidate the mechanisms responsible for chiroptical signatures in various compounds. These compounds encompass several atomically precise silver and copper clusters, a europium complex, and two highly flexible monosaccharide derivatives, which will serve as prototypes for future europium sensing studies, as well as several transition metal complexes. In pursuit of these objectives, a multifaceted approach was adopted, leveraging a combination of chiroptical spectroscopic techniques, and complemented by theoretical calculations. The employed chiroptical methodologies encompass Raman optical activity (ROA), vibrational circular dichroism (VCD), and electronic circular dichroism (ECD).<br>
More specifically, Chapter 3 describes the vibrational optical activity properties of atomically precise hexanuclear silver and copper clusters that have rarely been explored in the literature.<br>
These clusters are separately decorated with two different ligands. One main goal is to examine the effects of different metal cores on the VCD features of the ligands and the reverse chirality<br>
transfer from the metal core to chiral ligands, to complement the commonly reported transfer from the ligands to the metal cores. The second goal is to examine the deficiencies of simplified models in predicting VCD spectra of these clusters, which have been commonly applied in previous pioneering research reports, by using the experimental data and the full metal models. We highlight the critical importance of a complete model for extracting rich information hidden in the<br>
experimental VCD features, including bidirectional chirality transfer between ligands and metal cores, as well as the VCD enhancement mechanism. Another focal point of my thesis research involves examine mechanisms of the observed IR – IL<br>
features of some lanthanide species, often subject to (near) resonance conditions with the excitation laser source utilized in ROA. The chemical coordination mechanism in this system was<br>
effectively eliminated through the use of a double-cell experimental ROA setup, ensuring no chemical contact between the chiral Ni molecule, the racemic europium complex, and an achiral europium salt. We unraveled the key mechanism responsible for the observed IR – IL signals in the<br>
Eu species and coined this innovative form of chirality transfer as the “backscattering luminescence mechanism”.<br>
 In Chapter 5, we conducted a thorough chiroptical analysis of two highly flexible monosaccharide derivatives, phenyl-D-glucopyranoside and 4- (hydroxymethyl)phenyl-D-glucopyranoside. This examination involved the utilization of VCD and ROA spectroscopies, complemented by advanced theoretical modeling. In our forthcoming research, we plan to explore the application of the europium complex as a sensing tool for elucidating the chirality of these biomolecules. <br>
Chapter 6 describes the significant VCD enhancement of an open-shell Co(II) transition metal complex with low-lying electronic states. Considerable theoretical modelling, coupled with symmetry consideration in vibronic coupling, was carried out to extract structural information and gain further insights into the enhancement mechanisms.</p>