UCLA

Dickerson Biochemistry Seminar - Ben Montpetit
2024-02-16 15:30 - 16:30 (America/Los_Angeles) | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States

Special Chemistry Seminar - Rigoberto Hernandez
2024-02-21 14:00 - 15:00 | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States
Hernandez Seminar Flyer

3D-Networked Nanoparticles for Autonomous Computing

Abstract: Over the last decade, it has become clear that conventional VLSI is reaching key scaling limits. Moreover, the energy efficiency of human-engineered electronic devices is many orders of magnitude lower as compared to biological computational structures. Such inefficiencies, for example, severely limit our ability to move from 2D to 3D architectures in materials systems as is needed to achieve high performance and span the complexity required for applications using big data or artificial intelligence. We therefore need a new class of materials that can enable computing, but which are not bound by the rules of conventional VLSI, and we are inspired by the fact that the brain is an existence proof for such low-energy high-computing materials that do not rely on a von Neumann architecture. We have pursued the use of polymer-networked nanoparticles as a possible alternative. We will summarize our progress on characterizing these materials and report the primitive structures that we have created computationally thus far.

Jeffrey I. Zink Inorganic Chemistry Seminar Series Prof. Robert Comito
2024-02-21 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Flyer: Prof. Robert Comito Flyer
Title: Bimetallic Main-Group Catalysts for the Synthesis of Advanced Biodegradable Polymers
Abstract: Aliphatic polyesters are biodegradable and biocompatible materials that could replace polyolefins in many applications. However, their synthesis with fine structural control remains challenging, limiting the ability to tailor these materials for specialty and advanced applications. Our laboratory has developed a class of bimetallic main group catalysts for lactone and lactide polymerization distinguished by their electronic and steric tunability. The catalysts are constructed from binucleating bis(pyrazolyl)alkane ligands, which we have prepared by a novel method. Targeting monomer selectivity, stereocontrol, and sequence control we have developed homobimetallic, heterobimetallic, and chiral analogues of these complexes. We show promising evidence for metal-metal cooperativity from significant enhancements in rate compared to monometallic analogues. Through systematic comparison of metal composition and ligand sterics, we have identified a highly selective catalyst for lactone incorporation into polylactide, providing copolymers with a highly alternating structure. We describe an unusual dilithium complex that polymerizes aldehydes with exceptional activity and selectivity, raising opportunities for more sophisticated and adaptable oxygenated polymers.

Special Inorganic Chemistry Seminar - Dr. Alec Follmer
2024-02-22 14:00 - 15:30 | Young Hall 2033
Flyer: Dr. Alec Follmer Flyer
Title: Controlling C-H Bond Activation: Structural and Dynamic Regulation of Reactive Intermediates in Cytochrome P450 Catalysis
Abstract: From metabolism and detoxification to the biosynthesis of steroids and natural products, cytochromes P450 (P450s) are heme-containing enzymes that utilize O2 for the activation of C–H bonds and serve ubiquitous roles in nearly all biological systems. Their enzymatic activity, however, requires the formation of highly reactive intermediates within their active sites that can lead to the generation of potentially harmful reactive oxygen species and/or deleterious effects to the protein itself. Accordingly, many P450s have evolved structural and dynamic mechanisms to regulate their catalytic activity that involve complex rearrangements of their protein scaffolds. Despite a general understanding and appreciation of this regulation, the specific mechanisms and the extent to which they can be generalized remains unclear. Here, I will highlight several new key insights into how the reactivity of P450s is the controlled by allosteric interactions far from the active site that were discovered using a combination of structural, spectroscopic, and computational methods. Together these studies provide a new perspective on the importance that conformational dynamics play in the regulation of P450 activity.

Houk-Jung Organic Colloquium 247: Dr. Eugene Kwan
2024-02-22 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Dickerson Biochemistry Seminar - Shashank Shekhar
2024-02-23 15:30 - 16:30

Physical Chemistry Seminar 228: Matthew Sheldon
2024-02-26 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Prof. Matthew Sheldon Flyer
Talk Title: Plasmonic Platforms for Polaritonic Chemistry
Abstract: We are developing experimental platforms to probe vibrational strong coupling (VSC) between molecules and resonant infrared (IR) nanophotonic architectures, in order to understand how this coupling can fundamentally control chemical reactivity, as well as enable new classes of light-matter interaction. This method of altering the potential energy surface of a chemical process via coherent, electromagnetic perturbation of vibrating bonds has also been termed “polaritonic chemistry”. We employ a combined experimental strategy leveraging expertise in (1) the design of IR “metasurfaces” composed of plasmonic metal substrates that provide tailorable VSC to molecules within their optical near-field; and (2) multiple continuous wave (CW) spectroscopic techniques that enable analysis of several non-equilibrium, dynamic electronic effects in the metal substrate. Taken together, these tools allow studies into new regimes of spectral bandwidth (e.g. simultaneous multi-mode coupling), coupling strength, and time domains (e.g. studies of long lived and steady-state phenomena) that have been inaccessible using conventional optical cavities and time-resolved spectroscopies performed to date. Vibrational strong coupling is fundamentally interesting because it is a coherent interaction between radiation and molecular motion. The direct manipulation of a molecular process using externally controlled forcefields to obtain a desired outcome, i.e. “coherent control” or “quantum control”, has been a long-standing goal connected to the central aims of chemical science. Thus, this presentation will discuss the limits of chemical analysis and chemical control at interfaces leveraging a framework based on coherent interactions between controllable features of the engineered surface geometry and the molecular systems under study.

Jeffrey I. Zink Inorganic Chemistry Seminar Series - Prof. Chong Liu
2024-02-28 16:00 - 17:00 | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States
Flyer: Prof. Chong Liu Flyer
Title: Materials Design for Critical Element Separation
Abstract: The development of renewable energy technologies and next-generation quantum and optoelectronic devices relies on the secured supply of critical elements. Traditional mining and separation methods are disruptive to the environment, consume large quantities of harsh chemicals, and are unable to access dilute resources due to low elemental selectivity. Therefore, the invention of new separation methods and the fundamental understanding of the separation processes are crucial to realizing sustainable mining while broadening minable resources. In this talk, I will first introduce a platform method, electrochemical intercalation, for selective ion separation. I will present several strategies to promote the separation of lithium and lanthanides based on the understanding of complex host behavior upon co-intercalation of competing ions. In the second part, I will introduce our efforts in developing methods to construct (sub)nanometer solid ionic channels and probe the water and ion transport behavior in confinement.

Chem 218 Student Exit Seminar: Zerina Mehmedović
2024-02-29 12:00 - 13:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Houk-Jung Organic Colloquium 247: Prof. Frank Glorius
2024-02-29 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Dickerson Biochemistry Seminar - Gulcin Pekkurnaz
2024-03-01 15:30 - 16:30 | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States

Physical Chemistry Seminar 228: Alexander Balandin
2024-03-04 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Houk-Jung Organic Colloquium 247: Prof. Peter Schultz
2024-03-07 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Dickerson Biochemistry Seminar - James Link
2024-03-08 15:30 - 16:30 | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States

Physical Chemistry Seminar 228: Douglas Rees
2024-03-11 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Prof. Doug Rees Flyer
Talk Title: Nitrogenase: Beyond the Resting State
Abstract: The enzyme nitrogenase has the remarkable ability to catalyze the reduction of dinitrogen to ammonia to under physiological conditions. The mechanistic questions related to how nitrogenase overcomes the kinetic stability of the NN triple bond to fix dinitrogen under ambient conditions have intrigued chemists for the past century. We have applied a structure-based approach to examine how nitrogenase uses iron-sulfur metalloclusters and ATP-dependent electron transfer to reduce dinitrogen and other substrates. A puzzling feature of the nitrogenase mechanism has been how to reconcile the relative stability of the FeMo-cofactor with the reactivity towards dinitrogen. Our studies have established that binding of ligands to nitrogenase under turnover conditions can be accompanied by the reversible displacement and rearrangements of sulfurs in the catalytic FeMo-cofactor; these rearrangements may provide clues how the active site is activated during the catalytic cycle. The complementary strengths of X-ray and electron scattering are being used to illuminate the structural foundations of this process.

Jeffrey I. Zink Inorganic Chemistry Seminar Series - Prof. Kwabena Bediako
2024-03-13 16:00 - 17:00 | Mani L. Bhaumik Centennial Collaboratory, 607 Charles E. Young Dr., East, Los Angeles, CA, 90095, United States
Flyer: Prof. Kwabena Bediako Flyer
Title: Superlattice Design of Solids and Interfaces
Abstract: Superlattice structures are a powerful means of tailoring physical and chemical properties of materials. The modification of electronic structures at electrode–electrolyte interfaces is fundamental to efficient electrochemical energy conversion processes, and the intercalation of magnetic ions between van der Waals layers tunes the correlated electronic phenomena in these quantum materials. This talk will describe how azimuthal misalignment of atomically thin layers produces moiré superlattices that manifest a strong twist angle dependence of heterogeneous electrochemical kinetics in the case of twisted bilayer and twisted trilayer graphene electrodes with the greatest enhancement observed near the ‘magic angles’. These effects are driven by the angle-dependent engineering of moiré superlattice flat bands that dictate the electron transfer processes with the solution-phase redox couple. In addition, the talk will discuss how transition metal dichalcogenides intercalated with open-shell transition metals represent a family of materials allowing fine control over the chemical and electronic structure of a magnetic material to tailor the interplay between (anti)ferromagnetic exchange, magnetocrystalline anisotropy, and anisotropic exchange (Dzyaloshinskii–Moriya interactions) to bring about exotic magnetic orders in two-dimensional materials or bulk crystals. The design and manipulation of superlattices structures is therefore shown to serve as an unparalleled platform for systematically interrogating and exploiting the dependence of physical and chemical phenomena on electronic structure.

Dickerson Biochemistry Seminar - John Albeck
2024-03-15 15:30 - 16:30

The Norma Stoddart Award for Exemplary Citizenship and Excellence in Graduate Research
2024-03-22 13:30 - 16:30 | Collaboratory Yoo Seminar & Conference Hall YH4222

Inorganic Chemistry Student Exit Talk: Yuto Katsuyama (The Kaner Lab)
2024-03-26 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Flyer: Yuto Katsuyama Flyer
Title: Next-Generation Battery Electrode Materials Using Earth-Abundant Elements
Abstract: Energy storage devices, especially batteries, are indispensable in modern society, providing power for electronic devices including smartphones and EVs, and storing renewable energies in the electric grid, etc. However, batteries still have a lot of problems, such as their limited energy density, slow charging speed, high cost, short cycle life, etc. In this talk, several important approaches to solve these issues will be discussed. First of all, the effect of 3D micro and macro structure of battery electrodes on the battery performance is discussed. The structure was mainly engineered by using a 3D printer, and the 3D electrodes were applied to sodium-ion batteries, supercapacitors, and lithium-metal anode for lithium-ion batteries (LIBs). Then, the synthesis methods of battery materials will be discussed because it greatly affects the cost of the materials. In this talk, two facile synthesis methods of silicon/carbon composites (laser synthesis and re-precipitation synthesis) will be proposed for low-cost, high-performance LIBs. At the end of the talk, the battery working mechanisms will be discussed for sodium-ion batteries and zinc-ion batteries, which are expected to become as important as lithium-ion batteries in the future, by throughout characterization techniques at various charge and discharge states.

Jeffrey I. Zink Inorganic Chemistry Seminar Series – Prof. Courtney Roberts
2024-03-27 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Flyer: Prof. Courtney Roberts Flyer
Title: Access to Inaccessible Arynes and Redox Chemistry Using Transition Metals
Abstract: Research in the Roberts group involves looking at unsolved problems in organic synthesis through the perspective of organometallic/inorganic chemistry. One main area of interest for the group is the synthesis of heterocycles through aryne intermediates. Despite their useful reactivity, a number of challenges still remain in the use of arynes including problems with regioselectivity and the synthesis of N-heterocyclic arynes. Using fundamental principles of Ni chemistry, our group is the first to be able to access previously “inaccessible” 5-membered heterocyclic arynes for the first time since they were hypothesized to exist 120 years ago. We are also the first group to demonstrate catalyst controlled regioselectivity in arynes, where all previous examples operated under substrate control. Another challenge in organic synthesis lies in alkyl–alkyl cross-coupling. This is due to challenges with oxidative addition and off cycle pathways such as beta-hydride elimination. Our group has pioneered the use of Group 3 metal catalysts supported by redox-active ligands to overcome some of these challenges. Using 10 mol% of a Sc, Y, or Lu tris(amido) catalyst, coupling partners that both have beta-hydrogens can be successfully cross-coupled for the first time using early transition metals. These improvements related to organic synthesis can only be accessed using inorganic/organometallic chemistry.

Physical Chemistry Seminar 228: Prof. Jeremy Johnson
2024-04-01 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Chem 218 Student Exit Seminar: Cameron Movassaghi
2024-04-03 12:00 - 13:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Jeffrey I. Zink Inorganic Chemistry Seminar Series – Prof. Amanda Cook
2024-04-03 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Flyer: Prof. Amanda Cook Flyer
Title: Alkene Functionalization Using Homogeneous and Heterogeneous Catalysts
Abstract: Surface Organometallic Chemistry is an approach to synthesizing heterogeneous catalysts with molecular precision and relies on knowledge of homogeneous organometallic reactions. In our lab, we aim to install active sites on surfaces using oxidative addition of low-valent metal centers to surface functional groups. This strategy is a complementary route to the more common approaches (e.g., protonolysis of metal-ligand bonds by acidic surface sites) taken in surface organometallic chemistry. Using our approach, we developed a heterogeneous nickel-hydride catalyst that is highly active and selective for alkene isomerization. This reaction development was enabled by our work on homogeneous N-heterocyclic carbene-nickel catalysts for both alkene isomerization and hydrosilylation, which both utilize a nickel-hydride complex as the active catalyst.

Chem 218 Student Exit Seminar: Katie White
2024-04-04 12:00 - 13:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Physical Chemistry Seminar 228: Professor Michael Zuerch
2024-04-08 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222

Special Biochemistry Seminar: Prof. Steffen Lindert
2024-04-09 11:00 - 12:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
Flyer: Prof. Steffen Lindert Flyer
Title: Using Computers to Derive Protein Structure from Sparse Data – A Case Study for Mass Spectrometry
Abstract: Mass spectrometry-based methods such as covalent labeling, surface induced dissociation (SID) or ion mobility (IM) are increasingly used to obtain information about protein structure. However, in contrast to other high-resolution structure determination methods, this information is not sufficient to deduce all atom coordinates and can only inform on certain elements of structure, such as solvent exposure of individual residues, properties of protein-protein interfaces or protein shape. Computational methods are needed to predict high-resolution protein structures from the mass spectrometry (MS) data. Our group develops algorithms within the Rosetta software package that use mass spectrometry data to guide protein structure prediction. These algorithms can incorporate several different types of mass spectrometry data, such as covalent labeling, surface induced dissociation, and ion mobility. We developed scoring functions that assess the agreement of residue exposure with covalent labeling data, the agreement of protein-protein interface energies with SID data and the agreement of protein model shapes with collision cross section (CCS) IM measurements. We subsequently rescored Rosetta models generated with de novo protein folding and protein-protein docking and we were able to accurately predict protein structure from MS labeling, SID and IM data. Future work is focusing on developing custom machine learning models to predict protein structure from MS data.

Jeffrey I. Zink Inorganic Chemistry Seminar Series – Prof. Guosong Hong
2024-04-10 16:00 - 17:00
Flyer: Prof. Guosong Hong Flyer
Title: Seeing the Sound: An Ultrasound-Mediated Intravascular Light Source Enabled by Mechanoluminescent Materials
Abstract: Light is used in a wide range of methods in chemistry, biology, and medicine, fluorescence imaging, optogenetics, photoactivatable gene editing, light-controlled immunotherapy, and photochemotherapy for treating cancers and viral infections. A critical challenge for all light-based methods in live biological tissues arises from the poor penetration of photons, largely due to scattering and absorption. This limitation frequently necessitates invasive procedures, such as physical sectioning of the tissue, insertion of optical fibers and endoscopes, as well as surgical removal of overlying tissues (e.g., craniotomy). To address these challenges, our lab has developed an ultrasound-mediated intravascular light source, leveraging the deep-tissue penetration of focused ultrasound. We capitalized on mechanoluminescent nanotransducers (MLNTs), which are colloidal nanoparticles of mechanoluminescent materials synthesized via a biomineral-inspired suppressed dissolution approach. These MLNTs can be delivered intravenously into blood circulation and emit light locally at the ultrasound focus. Owing to the deep penetration and fast temporal kinetics of ultrasound, we have demonstrated that this method can produce on-demand and dynamically programmable light emission patterns at elevated depths in different organs of live mice with millisecond precision. This ultrasound-mediated intravascular light source has allowed us to perform noninvasive “sono-optogenetic” neuromodulation in live mice, as well as brain-wide “scanning optogenetics” that activate different brain regions of the same mouse brain. I will conclude my talk by presenting an outlook on how advances in photonic materials may facilitate the development of next-generation brain-machine interfaces.

Houk-Jung Organic Colloquium 247: Julian West
2024-04-11 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
West Flyer
A Radical Approach to Organic Chemistry
Abstract: Synthetic chemists need ever better tools to synthesize the molecules of modern life, from life-changing pharmaceuticals to next generation materials. Further, there is increasing need for these transformations to be both step and atom efficient and sustainable, proceeding under mild conditions using earth abundant elements. Here we show how employing open shell intermediates strategically allows for challenging transformations to be achieved directly, from alkene difunctionalization to carboxylic acid deletion. Importantly, these reactions make use of earth abundant elements and proceed under mild conditions, with many being driven by light. Together, our studies demonstrate the versatility of radical reactions to achieve challenging disconnections that are sustainable and environmentally-responsible.

Dickerson Biochemistry Seminar – Stephen Jamieson (The University of Auckland)
2024-04-12 15:30 - 16:30 | Collaboratory Yoo Seminar & Conference Hall YH4222

Physical Chemistry Seminar 228: Professor James Rondinelli
2024-04-15 16:00 - 17:00 | Collaboratory Yoo Seminar & Conference Hall YH4222
