Henry Nkabyo

Biography

I am an Assistant Professor of Inorganic Chemistry at Louisiana State University in Shreveport. I received BSc degree in Chemistry from the University of Buea (Cameroon) with a minor in materials science and technology. I also received a BSc honors (Chemistry), a MSc (Chemistry), and a PhD (Chemistry) degree in Inorganic Chemistry from Stellenbosch University in South Africa. Before joining LSUS, I held a postdoctoral research associate position at Texas A&M University, an Alexander von Humboldt postdoctoral research fellowship at the Julius Maximilians-Universität in Würzburg Germany, a German Exchange Service (DAAD) research fellowship at the University of Regensburg in Germany, and a National research Foundation (NRF) scarce-skills postdoctoral fellowship at Stellenbosch University in South Africa.

Degrees

Research Interests

Photocytotoxic transition metal complexes:
The cis and trans complexes of platinum(II) and palladium(II) thiourea complexes show promising anticancer activity towards certain cancer cells, with the trans isomers more cytotoxic than to their cis counterparts. Understanding the factors resulting from the difference in cytotoxicity activity for these complexes is of interest. Research in our lab aims at investigating if photoexcitation of the representative cis complexes will result in increased cytotoxicity activity in cells. Such a study would be relevant for cancer photochemotherapy applications, and thus significantly contribute to knowledge and research on platinum based anticancer drug development. This project involves organic synthesis of several new substituted thiourea derivatives and their platinum and palladium complexes. Spectroscopic tools such as 1H, 195Pt NMR, UV-Vis and ESI-MS, and X-ray crystallography enable structure elucidation, monitoring the formation of photoproducts, and deciphering associated reaction kinetics.

Luminescent Transition Metal Complexes:
Luminescent organometallic compounds are attractive building blocks for biolabeling applications partly due to the plausible tuning of their photophysical properties. Less attention has been paid to conjugation reactions directly in the inner coordination sphere of a metal center. It would be advantageous to replace the currently used chelators with cyclometallating ligands harboring relatively stronger electron-donating capability. Complexes derived from these ligands are not only known for their strong luminescent characteristics, but also for applications in anticancer chemotherapy. One of our research goals is to design and synthesize potentially luminescent transition metal complexes of platinum, palladium, ruthenium, iridium, and gold complexes from cyclometallating ligands. The photophysical properties, DFT, and excited state dynamics of the resulting complexes are also studied with collaborating partners.

Photophysically active Metallo-Supramolecular complexes for Separation and Storage:
Transition metal complexes featuring substituted acylthioureas as coordinating ligands are known to display a higher coordination versatility. Results from our work have shown that the thiourea-based complexes form mixed-ligand and supramolecular structures under varying reaction conditions. The formation of multi-metallic supramolecular structures opens potential new routes to complex materials for applications in sensor technology and other guest-host, and storage applications. Students involved in this project develop a range of skills in ligand synthesis, organometallic, and supramolecular chemistry.

Separation and Identification of Metal Complexes During Solvent Extraction:
Substituted thiourea derivatives are widely used as anticancer, antibacterial, and antifungal agents. They also serve as effective chelating agents for anion recognition and solvent extraction of metals. Our research focuses on the synthesis and application of acylthiourea derivatives to the pre-concentration and quantification of metal ions, particularly during the separation of platinum(II), palladium(II), rhodium(III), ruthenium(III), cobalt(III), and gold(I) in solution. These platinum-group metals (PGMs) are active catalysts in chemical reactions, including those in the automotive industry, and in fine chemicals and pharmaceuticals production. The mining and refining of these metals can have significant environmental consequences. Efficient separation processes are therefore essential to reduce waste, minimize the release of harmful substances, and enable the recycling of metals from spent catalysts, electronic waste, and other sources. We use High-performance liquid chromatography under reverse-phased conditions for identifying the thiourea derivatives and their metal complexes in solution following solvent-extraction. A combination FTIR, NMR, and microanalysis is also utilized for the unequivocal characterization of intermediate species formed during secondary processes.

Selected Publications

Teaching Assignments

CHEM 124, CHEM 124L, CHEM 470

Office Hours