Fundamental Investigations into Chirality in the Atmosphere

With the support of the Environmental Chemical Sciences (ECS) Program within the Division of Chemistry of the National Science Foundation (NSF), Professors Franz Geiger and Regan Thomson of Northwestern University and their students are investigating aspects of the fundamental chemical connections between plant-produced molecules and the Earth’s atmosphere. The unmistakable smell of a pine forest is produced by volatile chemical compounds made by trees. These chemicals, known as terpenes, are oxidized and transformed in the atmosphere, ultimately leading to the formation of particles and, in turn, clouds, which impact the global environment through processes such as rainfall and the reflection of sunlight. This project will explore the role that a particular chemical property of terpenes known as chirality, or "handedness" plays in the atmosphere. This project will investigate whether chirality affects the cloud-formation ability of the oxidation products. The project will provide interdisciplinary training to graduate students. In addition, educational outreach activities will target incarcerated students. The significance of chirality is well established in areas such as medicine where right or left-handed drugs often possess completely different medicinal properties. Chirality's role in atmospheric cloud formation remains largely unexplored. The research project will focus on the lab-based organic synthesis of chiral atmospherically relevant plant-derived terpenes in order to provide access to otherwise unavailable compounds for subsequent physical measurements. These measurements will probe key properties like surface tension, interfacial structure, and liquid-liquid phase separation (LLPS) to illuminate possible spontaneous resolution processes and higher-order hierarchical organization to discover new relationships between molecular-level organic structure and macroscopic atmospheric processes. Ultimately, the findings of the project will inform and update ongoing scientific efforts to better model and understand the Earth’s complex climate system. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.