Date on Master's Thesis/Doctoral Dissertation

8-2021

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemistry

Degree Program

Chemistry, PhD

Committee Chair

Grapperhaus, Craig

Committee Co-Chair (if applicable)

Buchanan, Robert

Committee Member

Buchanan, Robert

Committee Member

Handa, Sachin

Committee Member

Spurgeon, Joshua

Author's Keywords

Transamination; hydrogen; amines; electrocatalysis; point-charge; coordination

Abstract

Bis-(thiosemicarbazones) are a class of ligands that have found a wide range of uses from electrocatalysts to medicinal and diagnostic reagents. These ligands contain a diimine backbone, N2S2 chelating core, and pendent amines. In order to further explore this class of ligands, the previously underreported transamination reaction, which exchanges one pendent amine group for another, was utilized to create several derivatives using aliphatic and aromatic amines. The transamination reaction is appealing alternative to making the desired thiosemicarbazide. Further appeals come from the fact that it is a one-pot reaction that gives highly pure products in good yields. Product yields were improved as varying reaction conditions and solvents. One of these newly transaminated species that contained hindered amine bases were then treated with nickel(II) and copper(II) salts resulting in the corresponding metal complexes. These complexes were then alkylated to create charged pendent frameworks. Subsequently, both the charged and free base metal complexes were tested for homogeneous HER activity. It was observed that the free base complexes were the most active due to a proposed proton relay mechanism involving the pendent amine groups. The charged species did display an anodic shift in the onset potentials, however they were found to be less active as HER catalysts. Heterogeneous studies were conducted with NiATSM on p-Si electrode surfaces. Initial films were form by drop casting an acetonitrile solution of NiATSM followed by evaporation. The films were found to peel off after a short period of time during HER studies in 0.5 M H2SO4 as the acid source. To stabilize the film, a Nafion solution (5% w/v) was drop casted over the NIATSM film and evaporated in an oven for 15 minutes prior to use in HER studies. With this, there was no drop off in activity of the catalytic film. The photo indued HER studies for NiATSM indicated that it was a viable material with low onset potential needed.

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