Solar Energy’s Future Brightens, Thanks to Purple Bacteria

For Professor Seogjoo Jang (GC/Queens College, Chemistry), studying how purple bacteria gather energy from sunlight is both a way to satisfy his curiosity and help solve larger problems.
“I started working on this as a postdoctoral researcher at MIT,” Jang says. “I considered it a fascinating topic that could help find answers for efficient solar energy conversion in the long term, while also helping me learn about complex biological systems. I jumped in and initiated the project in our group.”
The sun beams a huge amount of energy onto the earth every day. With the right tools, we can convert that energy into heat, fuel, or electricity, providing an alternative to fossil fuels. Scientists like Jang turn to photosynthetic organisms, such as plants, algae, and some bacteria, for inspiration.
Jang studies light harvesting complexes (LHCs), or the proteins involved in photosynthesis, in purple bacteria. LHCs absorb energy from sunlight and pass it to other molecules. Jang uses computational and theoretical techniques to uncover how the multiple LHCs in a purple bacterium capture energy and transfer that energy to each other.
Much of this research involves taking a look at how quantum mechanics — the strange physics of tiny particles — plays a role. Jang started to develop his skills in quantum theories and methods during his Ph.D. studies at the University of Pennsylvania about 20 years ago.
In a recent study in The Journal of Physical Chemistry Letters, Jang presented the culmination of the past two decades of research, examining energy transfers between LHCs. Researchers have investigated these transfers for decades, Jang says, but many details remained unknown.
“The paper provides the majority of such details for the first time,” Jang says, “and elucidates the key quantum mechanical effects that make the transfer as efficient as it is. This work can provide lessons and ideas for developing efficient solar energy conversion devices.”
In another study, featured on the cover of Reviews of Modern Physics, Jang and Benedetta Mennucci of the University of Pisa reviewed years of progress in their field. The researchers analyzed advances scientists have made toward understanding light-harvesting proteins, focusing on two types of bacteria and a group of algae. The article also brings up the need for new experimental techniques and quantum calculation methods.
“The article will serve as an essential resource for a broad range of scientists,” Jang says. “Research on LHCs has implications for understanding natural solar energy conversion, and it serves as a testing ground for modern physical and chemical theories.”
Jang plans to start studying larger LHCs and developing models based on these natural systems. He is also putting his chemistry expertise to use in a new project: the science of smell.
“My research has been focused on developing a theory to describe the activation of olfactory receptors,” Jang says. “It’s still in the early stage, but is already producing exciting outcomes.”

Submitted on: DEC 21, 2018

Category: Chemistry | Faculty | General GC News