Professor Timothy Jackson named March 2025 Sutton Family Research Impact Award recipient
The Department of Chemistry congratulates Professor Timothy Jackson on receiving the March 2025 Sutton Family Research Impact Award!
The Sutton Award is a monthly competition among chemistry faculty. Every month, the Chemistry Department Chair and Associate Chairs review the peer-reviewed papers published by chemistry faculty from the three previous months to select a winner. The recipient receives a $500 cash prize and is featured on the departmental website.
For a full list of winners, visit our Sutton Family Research Impact Award webpage.
Formation and Reactivity of a MnIV(O)(ยต-O)CeIV Species: A Closest Mimic of Photosystem II
By Sikha Gupta, Pragya Arora, Zahra Aghaei, Baghendra Singh, Timothy A. Jackson, and Apparao Draksharapu
J. Am. Chem. Soc. 2025, 147, 619-626. https://doi.org/10.1021/jacs.4c12523
The oxygen gas that makes up 21% of the air on earth is primarily generated through photosynthesis in plants and algae. The enzyme responsible for generating oxygen from water, photosystem II, uses a cluster of manganese, oxygen, and calcium to remove protons and electrons from water and form a bond between two oxygen atoms. Despite the importance of this reaction, the specific details by which this occurs have remained elusive. One proposed reaction pathway involves the formation of a manganese center with a terminal oxygen atom and an oxygen atom that bridges to a calcium ion (Figure 1, right). This type of structure is highly unusual, and, until recently, there was a lack of molecules that closely mimic this motif.
Figure 1. A proposed structure for a key intermediate in photosystem II (PS II, right) and the new complex generated by the Jackson and Draksharapu labs (left).
Professor Tim Jackson and graduate student Zahra Aghaei worked in collaboration with Associate Professor Apparao Draksharapu from the Indian Institute of Technology Kanpur to generate a synthetic manganese complex that mimics the intermediate in photosystem II. The complex was generated by adding the strong oxidant cerium(IV) to a manganese(II) compound in the presence of water. This reaction yielded the complex shown in Figure 1, left, which contains a terminal oxygen atom and an oxygen atom that bridges the manganese and cerium centers. The Jackson lab performed X-ray absorption experiments at the Stanford Synchrotron Radiation Lightsource to probe the structure of this complex. These experiments provided conclusive evidence for the Mn-O-Ce portion of the molecule and provide support for the manganese oxidation state. The Draksharapu lab used Raman spectroscopy to probe molecular vibrations of the intermediate, which provided conclusive support for the terminal oxygen atom. This collaborative work also demonstrated that the manganese complex could convert water to oxygen, just like photosystem II.