That’s Dr. Charlie To You

“Is there a doctor on board?”

This is it. My time to shine. My opportunity to rise to the occasion. What if I get it wrong? What should I do? The imposter syndrome creeps in. Seconds creep by wasted as I hesitate. I have to do this. This is what I’ve been training for. I raise my hand. “I’m a doctor.”

“Please come this way.”

I follow the attendant to the back of the plane. The passengers we walk by are becoming increasingly distraught. Children are crying. Adults are trembling in their seats. No one is willing to look at the poor soul in the last row who is suffering so visibly.

“Can you help them?”

“I’ll do what I can,” I say solemnly as I approach the passenger. They are hunched over and clearly in pain. I kneel beside them. “What seems to be the problem?”

“I…” they pause, the plane has hit a bit of turbulence. I grab the armrest of their seat to steady myself and it’s then that I notice they have a worn-out composition notebook in their lap and the last few inches of a number two pencil held tightly in their sweaty palm. They speak again. “I don’t remember how to calculate a dilution.”

“Oh,” I say relieved. “Just use the formula M1V1 = M2V2.”

All at once they stop trembling. They look up at me, smiling, tears of joy running down their face. “Yes! Yes! That’s it! Thank you!”

The passengers around us look on in awe as the attendant escorts me back to my seat. The plane erupts into applause. I sit back down and smile as the attendant hands me a complimentary beverage. Finally, all those years of school have paid off.

I graduated this past weekend! After four years of undergrad and six years of grad school, I finally have my doctorate!

I’ve earned my wizard robes at last!

To be precise, I now have a PhD in Chemistry. I defended my dissertation and passed back in March. Once you pass your defense, people like to start calling you “Dr” already but in my experience, it doesn’t feel real until graduation. I’m not sure what will come next, but it feels good to have reached this milestone.

My dissertation was on redox-coupled spin crossover in cobalt coordination complexes. Like most interesting things about transition metals, this process primarily concerns the d-orbitals. Seeing the shape of these orbitals helps us understand much of their behavior.

Shapes of the d-orbitals. Note that the high energy eg orbitals are aligned with the axes along which ligands coordinate to the metal center. D-orbital-splitting.png

The names of these orbitals come from their positions relative to the XYZ axes in three-dimensional space. Unlike s- and p-orbitals, the d-orbitals do not play a direct role in sigma bonding but can form pi bonds with suitable ligands. In a lone metal ion, these d-orbitals all have the same energy. Once a ligand, which can be any Lewis base, coordinates to the metal it interacts with the d-orbitals through electrostatic interactions that change their energies relative to each other. These energy differences determine the electronic configurations in these orbitals. In certain first-row transition metals this can lead to either high-spin or low-spin configurations. Spin is a property of electrons and some subatomic particles denoted by upwards and downwards pointing arrows.

d-orbital diagrams for an octahedral d5 complex showing low-spin (left) and high-spin (right) configurations. Paulin eta Hunden printzipioak.png

This is a fundamental aspect of inorganic chemistry that seems simple on the surface. But like much of science, these seemingly simple concepts conceal much depth. Because d-orbital electrons determine many of the properties of a transition metal complex including magnetic susceptibility and what spectroscopic transitions are possible, the arrangement of electrons into low- and high-spin configurations is something that a great many researchers are interested in, giving rise to the field of spin crossover.

Spin crossover was first discovered in the 1930s and occurs in first-row transition metal complexes with ligands that induce an intermediate splitting between orbitals so that an appropriate stimulus (i.e. heat, light, pressure) can induce a drastic electronic rearrangement in the complex. This can result in changes in color, magnetic properties, and molecular geometry. A lot of the interest in spin-crossover comes from a desire to create molecular sensors and switches, as well as novel display technologies. My research concerned redox-coupled spin crossover, a lesser-studied variant in which adding or removing an electron causes a subsequent rearrangement of the d-orbitals.

That’s not all I did, though. I also got to be a teaching assistant for multiple classes covering topics like epoxy resins, fractional distillation, chromatography, and organic synthesis. I presented my research at a Gordon Conference and had the honor of being invited to speak at the ENY ACS Future Leader’s seminar. I met a lot of talented scientists and made some great friends. I performed with multiple ensembles as part of the Rensselaer Music Association. I got into tabletop gaming first as a player and then as a game master. And the whole time I’ve been serving as an alumni coordinator for my fraternity in Upstate New York.

I’m looking forward to whatever my next adventure will be. In the meantime, I’ll be catching up on my TBR pile, writing more, and shoveling yet more hours into the furnace that is my crippling addiction to real-time strategy games. Feel free to get in touch if you or someone you know is looking to hire a new PhD chemist.

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