Projects

Metalloenzymes

This project aims to find the best computational method for studying enzymes that contain metal atoms, e.g. as part of their active site. In DFT, many different types of approximations exist, and it’s unclear which is most accurate for complex metalloenzymes. To find the most reliable and accurate computational tool, we use the MME55 benchmark set, a realistic test set designed to mimic reactions in metalloenzyme active sites. An example 3D model of a structure from this set is shown below:

Specifically, we test a promising but previously unevaluated class of DFT methods called local hybrid (LH) functionals. Previous work has shown that certain LHs show advantages for describing transition metals (see Further Reading). The question is whether this transfers to the more complex enzyme environment.

Further Reading:

Fullerenes

Fullerenes are carbon-based cages that have gained considerable interest in chemistry and related disciplines due to their remarkable electronic and structural properties.

Computational methods are essential to fullerene research because they are very challenging to synthesize. DFT calculations thus enable us to predict what number of carbon atoms and what cage structure would be favorable for use in applications such photodynamic cancer therapy or organic photovoltaics. However, achieving accurate results with DFT for these special molecules is difficult and we explore the new class of range-separate local hybrids for it

Further Reading:
S. Fürst, M. Haasler, R. Grotjahn, M. Kaupp. Full Implementation, Optimization, and Evaluation of a Range-Separated Local Hybrid Functional with Wide Accuracy for Ground and Excited States. J. Chem. Theory Comput. 2023, 19, 488.

Photoredox Catalysis

Photoredox catalysis harnesses visible light to drive redox reactions via single-electron transfer, enabling transformations under mild conditions with high selectivity. Understanding these processes often requires investigating molecular orbitals (MOs). MOs look like clouds around a molecule and give us a sense of where an electron is most likely to be found or, if added, could be found in the molecule. The Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) are often particularly important:

3Dmol.js Cube Viewer

Closer analysis of these orbitals reveals charge-transfer pathways and catalytic activity. Density Functional Theory (DFT) provides important insights into orbital energies, excited-state dynamics, and reaction energetics, guiding the molecular design of new catalysts.

In systems involving heavy transition metals, such as iridium, the metal nuclei are so highly charged that some electrons move close to the speed of light. Thus, we need to account for the effects of Einstein’s theory of special relativity in our calculations. Have you ever seen a phosphorescent material glow in the dark? You have seen the effects of special relativity in action. Phosphorescence and its associated quantum excited states play a significant role in photoredox catalysis because these states are long-lived, which gives the catalyst enough time to interact with the correct molecule in the reaction mixture and advance the reaction.

Further Reading:
E. Bednářová, R. Grotjahn, C. Lin, K. A. Xie, Y. Karube, J. S. Owen, C. L. Joe, B. C. Lainhart, T. C. Sherwood, T. Rovis. From Structure to Function: Designing Iridium Catalysts with Spin-Forbidden Excitation for Low-Energy Light-Driven Reactions. J. Am. Chem. Soc. 2025, 147, 12511.