Upcoming Seminars & Events

Professor Todd Hyster
Department of Chemistry
Princeton University

Emergent Mechanisms in Photoenzymatic Catalysis

Enzymes are exquisite catalysts for chemical synthesis, capable of providing unparalleled levels of chemo-, regio-, diastereo- and enantioselectivity. Unfortunately, biocatalysts are often limited to the reactivity patterns found in nature. In this talk, I will share my groups efforts to use light to expand the reaction mechanisms available to natural enzyme families. In our studies, we found photo excitation of common biological cofactors, such as NADH, PLP, and FMN, to be a general strategy for revealing these novel functions. In many cases, we have identified unexpected mechanisms available to reactions occurring within the protein microenvironment that are not observed in solution- based photochemistry. Using these approaches, we can develop biocatalysts to solve long-standing selectivity challenges in chemical synthesis.

Todd Hyster

Professor Hyster is a native of Minnesota and received his B.S. in Chemistry from the University of Minnesota and his Ph.D. from Colorado State University under Tomislav Rovis. He was a Marie Curie Fellow with Thomas Ward at the University of Basel and an NIH Postdoctoral Fellow with Frances Arnold at Caltech. He began his independent career at Princeton in 2015, moved to Cornell University in 2021, and returned to Princeton as Professor of Chemistry in 2023. Professor Hyster’s research group develops new biocatalytic strategies to address long- standing reactivity and selectivity challenges in organic synthesis. The Hyster lab is broadly focused on enabling enzymes to catalyze reactions that are currently unknown in nature, then applying directed evolution to optimize these catalysts for efficient, selective chemical transformations. The group is particularly known for pioneering photoenzymatic catalysis, using visible light to unlock new catalytic functions from known enzyme families.

Hosted by Professor Christopher Douglas

Sponsored by Organic Syntheses, Inc. 

Sean Ross, Ph.D.
Senior Scientist II
AbbVie

Enabling chemistry at the interface of late discovery and early development

At AbbVie, the process chemistry group works in collaboration with our discovery and product development science and technology groups to develop active pharmaceutical ingredients (API) from their discovery to market. Critical early deliveries of API to enable preclinical studies requires the development of enabling routes to accelerate drug development. This talk will describe the rapid development of an enabling route to a preclinical target across discovery and process chemistry. The focus of the talk will include the development of a cross electrophile coupling approach to install a key C-C bond, as well as the development of a C-O cross coupling to form the penultimate intermediate This collaborative effort successfully delivered API that was supported a wide range of pre-clinical studies.

Sean Ross

Sean began his formal chemistry education at the University of Nevada, Reno where he obtained his B.S. in chemistry. During this time, he performed undergraduate research with Professor Bob Sheridan on the matrix isolation of carbenes, and with Professor Mazal on the synthesis of 1.1.1 propellanes. This later led him to pursue a Ph.D. in organic chemistry from the University of Minnesota. At the University of Minnesota, Sean joined the lab of Professor Tom Hoye working on the development of methodologies utilizing thermally generated benzynes. After defending his Ph.D. in 2011, Dr. Ross moved to the University of Utah where he joined the group of Professor Matt Sigman. There he worked on applying data science techniques to the redox-relay Heck reaction. In 2021, Sean joined AbbVie as a part of the Process Chemistry team. His current work is focused on the development of enabling chemistry to facilitate the kilo-scale manufacture of active pharmaceutical ingredients for late preclinical and early clinical studies.

Hosted by Professor Christopher Douglas
Sponsored by AbbVie

Professor Zhen-Gang Wang
Department of Chemical Engineering
California Institute of Technology

Self-Assembly of End-Charged Block Copolymers and Blends: Effects of Ion Clustering

Introducing a small number of ionic groups at polymer chain ends — whether within a single diblock copolymer or across two different homopolymers in a blend — has emerged as a promising strategy for directing self-assembly, with applications ranging from compatibilizing immiscible polymer blends to templating functional and ion-conducting nanostructures. We study the effects of these end charges on the self-assembly of diblock copolymers and binary polymer blends using a self-consistent field theory that incorporates strong ion correlations. Under the low-dielectric conditions typical of polymer melts, the charged ends aggregate into multi-ion clusters, which reshapes the self- assembly of both systems. In the case of end-charged diblock copolymers, the resulting clusters act as compact, curvature- favoring foci around which the chains radiate, unlocking complex network morphologies, such as the single primitive and single gyroid phases, that are normally inaccessible to neutral melts. In binary blends with oppositely charged termini, the electrostatic attraction between chain ends suppresses the macroscopic phase separation in the corresponding uncharged blend and results in microphase separation instead. Interestingly, the resulting phase diagram is simpler — dominated by lamellar and cylindrical phases — than expected based on the pairwise-bonded effective diblock picture previously invoked to describe these systems. We attribute this difference to the difference in the location of the ion clusters in the two systems: in the diblock they act as compact foci to organize the chains around them, while in the blend they are confined to the interface separating the two species, where they resist curvature rather than favor it. Finally, for both systems, ordered microphase structures can appear at segregation strengths significantly lower than that required for the corresponding uncharged diblock copolymers.

Zhen-Gang Wang

Zhen-Gang Wang received his B.Sc. in Chemistry in 1982 from Beijing (Peking) University, and his Ph.D. in Chemistry in 1987 from the University of Chicago. He did postdoctoral research first in Exxon Research and Engineering Company and then at UCLA. Since 1991 he has been on the Chemical Engineering faculty at the California Institute of Technology, where he is currently the Dick and Barbara Dickinson Professor. He has also served as Executive Officer (department chair) for Chemical Engineering for 6 years. 

Wang’s research is the theoretical and computational study of structure, phase behavior, interfacial properties and dynamics of polymers, soft materials, and biophysical systems. His current activities revolve around three main themes: charged systems, including polyelectrolytes, salt-doped polymers, and electric double layers; nucleation or more generally barrier crossing in polymers and soft matter; and nonlinear rheology of polymer gels and entangled polymers. 

Wang is a fellow of the American Physical Society and a member of the U. S. National Academy of Engineering. He is recipient of several significant awards and honors, including the Camille Dreyfus Teacher–Scholar Award (1995), the Alfred P. Sloan Award (1996), the Braskem Award from the American Institute of Chemical Engineers (AIChE) (2018), the AIChE Alpha Chi Sigma Award (2023), and the American Physical Society Polymer Physics Prize (2024). In addition, he was awarded the Richard P. Feynman Prize for Excellence in Teaching (2008), Caltech’s highest teaching honor. 

Wang has served on the editorial advisory boards of Journal of Theoretical and Computational Chemistry, Macromolecules, ACS Macro Letters, Giant, Acta Physicochimica Sinica, and Science in China B (Chemistry). He is currently an associate editor for the ACS Journal Macromolecules.

Hosted by Professor Timothy Lodge

Professor Vicki Wysocki
School of Chemistry & Biochemistry
Georgia Institute of Technology

Professor Vicki Wysocki
School of Chemistry & Biochemistry
Georgia Institute of Technology

Professor Vicki Wysocki
School of Chemistry & Biochemistry
Georgia Institute of Technology

Professor Evan Williams
Department of Chemistry
University of California, Berkeley

Professor Bess Vlaisavljevich
Department of Chemistry
University of Iowa

High-Valent f-element Coordination Complexes: Connecting Quantum Chemical Modelling to Measured Properties

The electronic structure of the coordination chemistry of the 4f-elements typically involves metal-centered valence orbitals and weak ligand fields. However, stabilizing unusually high formal oxidation states requires designing ligands that fall outside this classical paradigm. This talk explores how a combined use of density functional theory (DFT) and multiconfigurational methods can be used to understand recently synthesized high-valent praseodymium complexes. By characterizing the pseudo-tetrahedral [Pr(IV)(NPtBu3)3] complex, we examine the interplay between crystal field splitting and spin-orbit coupling. Comparisons between this complex and its isoelectronic Ce(III) analogue are attributed to differences in crystal field splitting, based on EPR measurements and theory. Moreover, this complex has an accessible Pr5+/4+ redox couple allowing it to be oxidized to form a molecular praseodymium complex in the formal +5 oxidation state, specifically [Pr(V)(NPtBu3)3]+. The complex has a multiconfigurational singlet ground state resulting from an inverted ligand field. To place the electronic structure of the 4f species in context, this talk will draw parallels to the inverted ligand fields observed in high-valent transition metal chemistry, specifically in Cu(II) species. The comparison between the 4f and 3d metals will lead into a conversation about the high- valent actinides. Specifically, the dramatic change in molecular geometry observed for a uranium(V) oxo complex. By invoking the concept of an “inverse trans influence”, we can understand the different behavior with soft-donor sulfur groups compared to the analogous oxo-donating ligands. This final section of the talk will focus on how experimental observables like structure and spectra cannot always be used alone to assign bonding but provide important metrics that, only when computed, can be used to provide the full picture of what stabilizes the structure.

Bess Vlaisavljevic

Bess Vlaisavljevich is from St. Paul, Minnesota. She received her B.A. in chemistry from the University of Minnesota Morris in 2007. She then received her M.S. and Ph.D. degrees working with Prof. Laura Gagliardi from the Department of Chemistry at the University of Minnesota Twin Cities in 2010 and 2013, respectively. Her PhD work focused on studying the electronic structure of the f-elements with multiconfigurational methods. Following this, she worked as a postdoctoral scholar at the University of California Berkeley with Prof. Berend Smit using molecular simulation and density functional theory to study gas separations and adsorption in nanoporous materials. Later, at Northwestern University with Prof. Toru Shiozaki, she was involved in developing the (X)MS-CASPT2 analytical gradient code in the program package BAGEL. In 2017, she began her independent career at the University of South Dakota. Her research focuses on using multireference quantum chemistry theories for a variety of problems in transition metal and actinide chemistry. She was recently awarded a Department of Energy Early Career Awards and USD’s Early/Mid- Career President’s research award for her efforts. In 2023, she was awarded tenure and promoted to Associate Professor. In 2024, she moved to the University of Iowa as an Associate Professor.

Hosted by Professor Anthony Schlimgen

Professor Jodi Hadden-Perilla
Chemistry and Biochemistry Department
University of Delaware

Professor Jeffrey Lipshultz
Department of Chemistry
Stony Brook University

Hosted by Professor Ian Tonks