Research Check-In Part 3

It has been confirmed by spectroscopy techniques that my desired ligand has been synthesized, although in small quantity. The next step is to attach the ligand to a metal in order to form a catalytic compound. The chemical reaction which combines the ligand and the metal was performed and the resulting substance was allowed to sit undisturbed in an attempt to crystallize. In this method of crystallization, the substance is dissolved in a liquid solvent #1, which is placed either below or on top of a liquid solvent #2 in a vial. The substance cannot be dissolved in solvent #2. As solvents #1 and #2 begin to mix, the substance slowly travels from #1 to #2 and precipitates out into solid crystals. Once the crystals have precipitated, they can be electrochemically tested for hydrogen oxidation. I will soon be synthesizing more of the initial ligand so that more metal compound syntheses can be attempted.

Next Step: Titanium Dioxide

During my last week of research, I started a new phase of my project. After completing the study of the electron transfer dynamics of the dye Rhodamine 560 on glass, I moved on to studying the behavior of this dye on titanium dioxide. While we can learn a lot from the studies of R560 on glass especially when we compare it to other rhodamine dyes on glass, that entire phase of experimentation was just a control for comparison with the results on titanium dioxide. In actual dye-sensitized solar cells, the application of this research, titanium dioxide or some other semiconductor is necessary for the generation of electricity.

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Single Molecule Blinking Traces

At the end of my last post, I mentioned that I had taken a break from trying to measure the fluorescence lifetime of individual molecules of the organic dye Rhodamine 560, since I was unable to get a lifetime curve with a high enough signal to noise ratio at single molecule concentrations. Instead, I returned to a technique called single molecule blinking, which allows us to observe changes in emission intensity while an individual molecule is under continuous excitation.

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Research Check-In Part 2

The current goal for my project is to synthesize a functional catalyst for the hydrogen oxidation reaction (HOR) of significant yield. Several mechanistic reaction pathways have been proposed, including methods used by lab members in past years, as well as methods from published literature. For each attempt to correctly synthesize the ligand (where the “ligand’ is a compound that will later be attached to a metal to make up the catalyst), I must perform the reaction, and then test it to see whether or not the reaction worked and whether or not I have truly synthetized what I’m looking for. The difficulty stems not from the reaction itself, but from the post-reaction purification step, which involves lengthy separation of the compound from any impurities.  From the set-up of the initial reaction, to testing the purity of the molecule post-separation, the entire process of synthesizing a ligand can take from a few days to a week. With every attempt, there always variables that can be tweaked to improve the conditions of the procedure and thus increase yield of the product.

Measuring Single Molecule Lifetimes


During the first few weeks of summer research, I’ve been working toward my main goal of studying the behavior of an inexpensive organic dye at the molecular level by integrating two techniques: single molecule spectroscopy (SMS) and time-correlated single photon counting (TCSPC). SMS lets us look at the electron transfer processes happening in individual molecules, which is important because in dye-sensitized solar cells (the eventual application of this research) the environment is heterogeneous, meaning that each molecule undergoes different processes at very different speeds. TCSPC measures fluorescence lifetime decays of individual molecules, and can detect processes that happen in picoseconds, while SMS alone can detect electron transfer events down to only the millisecond timescale.

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