| Description |
The fundamental interactions between two biologically and environmentally relevant metals, Zn2+ and Cd2+, complexed with water, crown ethers, and histidine are examined using a variety of experimental methods and quantum chemical calculations. Chapters 3 and 6 detail the first experimentally determined hydration energies for n = 6 - 10 for Zn2+(H2O)n and n = 3 - 11 for Cd2+(H2O)n measured using threshold collision-induced dissociation in a guided ion beam mass spectrometer. Kinetic energy dependent cross sections are obtained for each reactant and analyzed to yield 0 K threshold measurements for loss of one, two, and three water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. The threshold measurements are converted from 0 K to 298 K values to give the hydration enthalpies and free energies for sequentially losing one water from each complex. Theoretical geometry optimizations and single point energy calculations are performed on reactant and product complexes using several levels of theory and basis sets to obtain thermochemistry for comparison to experiment. The charge separation process, M2+(H2O)n - MOH+(H2O)m + H+(H2O)n-m-1, is also observed, analyzed, and discussed in detail in both Chapters 4 and 6 for M = Zn and Cd. In Chapter 5, complexes of Zn2+(H2O)n, where n = 6 - 12, are also examined using infrared multiple photon dissociation (IRMPD) spectroscopy, blackbody infrared radiative dissociation (BIRD), and theory for experimental determination of the coordination behavior of Zn2+. IRMPD spectroscopy experiments and theoretical calculations are also used in Chapter 7 to gain conformational insight into host-guest systems, namely Zn2+ and Cd2+ complexed with crown ethers (12-crown-4, 15-crown-5, and 18-crown-6). Finally, Chapter 8 examines the gas-phase structures of singly and doubly-charged complexes involving Zn and Cd with the amino acid histidine (His) as well as de-protonated His (His-H) using IRMPD spectroscopy. |
