Katie Guye

Mentor: Jonas Goldsmith

Synthesis and fluorescence studies of organo-bimetallic catalysts for hydrogen production 

Transition metal complexes have the unique ability to exist stably at various oxidation states, allowing for many applications including photocatalytic reduction of water to produce hydrogen gas. Such generation of hydrogen gas has been the subject of intense study in the search for clean, renewable energy. The Goldsmith lab looks to synthesize and characterize a series of potential organometallic photocatalysts and the derivatives of each respective catalyst, as well as perform fluorescence experiments to better understand the electronic properties of the macromolecules.

Successful catalysts are marked by high yield and a large turnover number, able to return to their original state for another catalytic cycle, without being destroyed in the reaction. Many labs have investigated molecules with a single metal redox center. The Goldsmith group, along with others however, are investigating photocatalysts with two metal centers to increase the efficiency of photocatalysts for hydrogen production through water reduction.

The Goldsmith lab has already begun such synthesis, tethering two bis-bipyridal-metal centers by an organic ligand. Catalysts with Ru/Ru, Ir/Ir, Rh/Rh, and doublet combinations of the three (e.g. Ru/Ir) as metal centers with a six-carbon ligand have been synthesized and investigated using electrochemical techniques. Derivative molecules include, but are not limited to, the removal of a metal center, the metal center, and the metal center with a fractionated ligand.

The goal of this project is to synthesize similar catalysts and derivatives with a carbon ligand of differing lengths. Two 2,2'-bipyridine-5-carboxyllic acid molecule will be tethered by ligands of 3- and 6-carbon lengths. Each of the bipyridine ends of this new ligand will attach to a bis-bipyridine metal center

With these syntheses, it is hoped to maximize yield and purity. All products will be characterized by 1H and 13C nuclear magnetic spectroscopy and electrospray-ionization mass spectroscopy. Electronic properties of these catalysts will be explored by fluorescence spectroscopy using Co(bpy)3 and triethanolamine (TEOA) as quenchers.