Extending the bounds of modern chemistry
Esselman’s research reveals molecules’ chemical structures.Image By: Jordan Gaal
Chemistry is everywhere. It makes up everything. The universe is buzzing with an imperceptible world of lively, vivacious molecules. It is the driving force the keeps everything together. Chemists are approaching new frontiers in a world that is mind-bendingly smaller than imaginable.
Brian Esselman is an avid chemist and an assistant organic lab director at UW-Madison. He collaborates with chemistry professors Claude Woods and Bob McMahon and together, their research is out of this world. Literally. The chemistry that sparks his interest is extraterrestrial space dust. Esselman becomes visibly excited when talking about Pyridazine, which sounds like the complex name of a prescription drug advertised on late-night TV. Pyridazine is actually a peculiar chemical, and better yet, most likely found in space.
Esselman wants to know Pyridazine’s precise structure. Once he knows everything there is to know about it, it will be that much easier to find in dense celestial gas clouds. Pyridazine contains a certain atom called nitrogen.
If nitrogen sounds familiar, it should—it makes up 78 percent of the Earth’s atmosphere. And according to Esselman’s calculations, it could be quite abundant outside of Earth too.
The world is made of atoms such as carbon and nitrogen. Atoms are small: if every atom in a grapefruit was enlarged to the size of a blueberry, the grapefruit would be the size of the Earth.
Together, atoms attach to each other by bonding, which allows groups of atoms to create molecules. Just like Legos connect to create more complicated structures, atoms attach and form structures as well. They are the building blocks of life.
It’s as simple as that.
“Chemistry is about structure, all of the reactivity we see is based on structure. So of course it’s important,” said Esselman.
These structures of atoms can tell scientists about other chemicals. “All of the physical properties of chemicals are based on their structure,” said Esselman. “More precisely we understand the structure of the molecules the more we understand their reactivity, the better we know their physical properties.” However, this is not an easy task.
“Structure determinations take months to years, it’s not a trivial thing where you just walk up, put the substance in there and go ‘oh look, there’s the structure.’” Esselman and other chemists use a complicated method called “rotational spectroscopy.” There is one recognizable word in that piece of jargon: rotational. In order to measure the size of an atom it must spin around in the gaseous state. Unlike atoms in solid or liquid states, gas atoms have the freedom to move.
The rotation of every molecule and every atom is unique. It can be used to determine the mass, or size, of the atom. When chemists understand how big or small the atoms are, they can determine how far apart they are. This gives them the length of the bond. All of this comes together when the structure of the molecule is discovered.
“All of the things you can measure that are real about molecules come from some form of spectroscopy. We make measurements of molecules using spectroscopy,” said Esselman as he gazed at his one-of-a-kind rotational spectroscopy machine.
The apparatus is something straight out of Dr. Frankenstein’s very own laboratory. It occupies the space of an entire room, tucked away in the fifth floor of the Chemistry Department.
This massive mammoth of an instrument can only be described as organized chaos. To the left sits a 5-foot metal box with flashing lights and numerous knobs with wires leading to a maze of glass tubes. The room is filled with an ever-so-slight buzz.
A large pipe sits in the middle of the jumble and quickly draws the eye. An uninformed individual stumbling upon this lab would most likely mistake it for a Doc Brown experiment gone haywire.
All of this to determine the structure of an atom.
The atom, as a gas, snakes its way through a series of glass tubes, piping and other complicated systems. The results are displayed on an unassuming computer on the desk in the front of the room. This is after it has been analyzed by the many other information systems.
After all is said and done and after intricate mathematical equations are utilized, Esselman has a precise chemical structure. This data is extremely useful for other chemists. “This helps computational chemists benchmark what they are doing. We provide the real data to compare it to,” said Esselman.
This precise chemical structure determination is used to aid in determining the structure of the molecules in space through powerful telescopes. After determining Pyridazine, the data will be used to search for it in the skies.
Uncovering space molecules might not be a pressing matter to everyone. “In terms of ‘Can you put it in a bottle and sell it to somebody?’ Not really, it doesn’t have an important industrial or practical application,” Esselman said.
He gave his own reason, which might elicit a chuckle from the average organic chemistry student: “Who wouldn’t want to know more about a molecule?”
Esselman’s research tests the bounds of human discovery. It delves into a world unknown for centuries. “It’s pushing the frontier of knowledge, which is pretty important.”Subscribe to The Daily Cardinal Newsletter