Chemist Rick Geier finds efficient ways to make a powerhouse family of colorful, nature-inspired molecules so other scientists can test them in next-generation drugs and devices.

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Blood red and forest green are more than just colors. The names evoke natural pigments that carry out life-sustaining jobs. In the human body, the red protein hemoglobin shuttles vital oxygen to cells. In plants, groups of green proteins known as photosystems capture energy from sunlight in order to make food. But the proteins aren’t really doing the work, nor are they the source of the colors. That task falls to small molecules within the proteins — heme and chlorophyll, respectively, which belong to a family of chemical structures known as the porphyrins.

“The color of porphyrins has led them to be referred to as the colors of life,” says Rick Geier, the Warren ’43 and Lillian Anderson Chair in chemistry at Colgate. Geier has made a career of studying porphyrins and porphyrin-like compounds, in particular finding straightforward ways to make them in a lab.

A porphyrin is like a minuscule chassis. While the chassis in a car holds a metal engine that drives motion, a porphyrin holds a metal atom that drives chemistry. Making changes to the proverbial chassis, or to the metal, changes what a given porphyrin might be able to do. Over eons of evolution, nature has had a field day with that flexibility. One porphyrin is an essential vitamin. Others help break down the body’s waste in the liver so it can be excreted. And the list goes on. “The reason why this family is able to do such an incredibly diverse set of tasks is the combination of different ways in which the structure of the porphyrin itself can be altered,” Geier explains.

Still, nature hasn’t bothered to assemble most of the possible arrangements of atoms that could theoretically go into a porphyrin’s chemical structure. If the relatively limited set of porphyrins that exists in biology can carry out such a spectacular range of tasks, what might other porphyrin relatives be capable of accomplishing?

Scientists have a few ideas. Inspired by natural porphyrins’ light-harvesting role in plants, they are studying lab-made porphyrins’ potential in solar cell materials that convert light to electricity. They are testing porphyrins in molecular memory devices for next-generation computers, because porphyrins are much smaller than the features of conventional memory chips and so they might provide more memory in a smaller space. And they are developing porphyrin drugs. For instance, the Food and Drug Administration–approved drug Photofrin is a porphyrin that homes in on certain cancer cells and then transfers energy from laser light to create cell-destroying, high-energy oxygen molecules.

Porphyrins that aren’t available from nature have to come from somewhere, though. “You can’t study what you don’t have,” as Geier puts it. That’s where his research comes in. “We want to develop efficient, convenient ways to make molecules that feed other studies,” he says.

The scientists who are testing possible porphyrin applications don’t necessarily have molecule-making expertise. So Geier sets out to streamline that for them. He combs scholarly publications, looking for porphyrins that could have promising properties but have yet to be made. He also hunts for porphyrins that other scientists have produced, but that require convoluted tactics nonexperts would avoid.

Once Geier has a molecule in mind, he and his students work to make it in the lab. He prefers what’s called a one-flask route for its relative simplicity. To describe a one-flask route, Geier offers the analogy of automobile production. The classic assembly-line approach to cars is a step-by-step process, which perhaps starts with a frame, and then adds the brakes, the engine, the leather seats, and so on. Much of chemistry is done in this stepwise fashion. In a one-flask method, Geier says, “we would instead throw all of the parts together in a pile, and then shake, shake, shake and hope a car pops out in the end.”

Instead of a car, Geier’s students make a mixture of many porphyrins and related chemical compounds. The team systematically screens reaction parameters in order to find one that maximizes the amount of their desired porphyrin in the mixture. They then carry out the winning reaction on a larger scale and separate the porphyrin from byproducts. They typically obtain roughly 250 milligrams of their compound, the weight of approximately ten grains of rice. Even an amount this small is plenty for scientists to study. Collaborators Christopher Ziegler at the University of Akron and Victor Nemykin at the University of Manitoba help Geier learn how his porphyrin compounds interact with metals and with light — fundamental information that researchers need before they could use a porphyrin to design a device or a drug.

But Geier’s not making bold promises about his molecules’ applications. “When are we going to see them in a product? Maybe never. I don’t know,” he says. Fundamental research is like that. “It could be a chemical dead end. Or it could lead to fresh directions and be looked at in the future as the start of something big.” In the meantime, Geier’s strategy of providing straightforward blueprints for porphyrins is working. A research group at the University of Delaware picked up on one of Geier’s routes by reading about it in a scientific journal, and they’ve successfully used it to make porphyrins to test as light-harvesting molecules for solar energy production.

When the endpoint of your research is uncertain, it pays to enjoy the journey. And for Geier and his students, just getting to look at porphyrins every day is a delight. Like the natural porphyrins in blood and in plants, the human-made porphyrins are vividly colored. From purifications, deep green and red-wine liquids emerge. When they dry out, to students’ wonder, the liquids become shiny, purple, needle-shaped crystals. “You get this rich rainbow of colors,” Geier says. “It’s just beautiful, pretty chemistry.”