The solution-phase metal ion reactivity of ambs and mb-OB3b will be examined by electrospray ionization – IM-MS and density functional theory (DFT). Ultraviolet-visible and fluorescence spectral techniques will be used to check for correlations across gas- and solution-phase analyses to answer the following questions:

1. Which solution-phase behaviors can be examined in the gas phase?
2. How does pH affect the charge states and metal-ion binding?
3. Which sequence residues affect the conformational structure and metal-ion binding?
4. What are the dissociation mechanisms during CID?
5. Can the metal-ion coordination sites be identified using energy-resolved CID and IM-MS?
6. Can metal-ion displacement be monitored by collision cross-section (CCS) changes?
7. Can IM-MS and theoretical CCS identify which type of coordination each metal ion prefers?
8. How do IM-MS, DFT, UV-Vis, and fluorescence findings correlate?

Figure 1. The lowest energy conformers are located using the B3LYP/LanL2DZ method a) [amb5A+H]+ and b) [amb5A+2H]2+. The dashed lines represent the salt-bridges and hydrogen bonds that stabilize the secondary structures and include a tight turn at Pro4 augmented with a hydrogen bond between the backbone carbonyl and amine groups of Gly3 and Tyr5, and a hydrogen bond between the substituent hydroxyl group of Tyr5 and the carbonyl of the N-terminus acetyl group. The 2+ conformer exhibits the most elongated structure, because of the charge repulsion between the two protonated substituent groups of His1 and His6 which are separated by a distance of almost 14 Å. This charge repulsion is mediated in the 1+ conformer, which exhibits a folded secondary structure, due to a salt-bridge between the imidazolium of His1 and the carboxylate of the C-terminus, and a hydrogen bond between the thiol of Cys2 and the C-terminus carboxylate. The theoretical collision-cross sections (Ω) of the 2+ and 1+ conformers are 234 ± 14 Å2 and 203 ± 6 Å2, respectively, which agree with the IM-MS measurements of 220 ± 8 Å2 and 201 ± 8 Å2 (uncertainties 2σ).

Dr. Jang's recent research effort includes two main projects. The first project is focused on the investigation of the catalytic properties of supported metal catalysts for selective hydrogenation, including compounds with a triple bond.  It is our goal to develop and design a more efficient catalyst, with high selectivity and good conversion, for selective hydrogenation of industrial processes, such as the multi-billion dollar polyethylene industry. Non-thermal plasma treatments are applied to noble metal catalysts to obtain novel catalytic materials. Characterizations of catalysts prepared by impregnation, precipitation, ion exchange, and others were routinely carried out by various instrumentation techniques, such as DSC (Differential Scanning Calorimetry), in situ FT-IR (Fourier Transform Infrared spectroscopy), chemisorption, temperature programmed adsorption/desorption, etc.

Although any reaction on catalyst surface is complicated, the selective hydrogenation of acetylene can be shown schematically in the figure below, including adsorption, surface reaction and desorption while catalyst properties could be changed by various procedures, such as reduction, oxidation, plasma, etc.

Another project focuses on bio-oil production from biomass and wastes and the synthesis of carbon based acid catalysts for biodiesel conversion using oleic acid esterification with methanol as the probe reaction. For bio-oil production, biomass or wastes will go through hydrothermal liquefaction processes followed by separation, identification and quantification to characterize the content and composition of the bio-oil. For carbon based acid catalysts, the tasks would be focusing on using starch related materials to prepare catalysts with high density of acid sites via partial carbonization in N2 followed by sulfonation.

The objective of Dr. Bukuo Ni's research project is to develop novel chiral diamine ligands and their application for transition metal catalyzed asymmetric reactions. Due to the high demand and preference for the use of enantiopure compounds in the fields of pharmaceuticals, perfumes, food additives, etc., there has been a great interest in catalytic asymmetric synthesis as a tool for their efficient preparation. However, it has been a big challenge to obtain optically active compounds with good yields and selectivities. In the first phase of these projects, we will build on the knowledge gained from our previous work and design, synthesize and characterize various chiral diamines. In the second phase, the ability of the resulting chiral diamines as ligands for transition metals Ru, Cu, and Ni catalyzed asymmetric reactions will be carried out using selected asymmetric reactions such as Michael reaction, asymmetric transfer hydrogenation, and tandem reactions (Figure 1). Also, the extractive electrospray ionization mass spectrometry (EESI-MS) analysis will be carried out to elucidate the structural information about the reaction intermediates and the coordination chemistry of diamine ligand with transition metal in order to better understand their influence on the asymmetric controls and to assist in optimizing their structures to give more effective chiral diamines. The knowledge gained will provide fundamental insights to better understand the mechanism of asymmetric induction for a wide range of reactions.