UCLA

NSF Center for Integrated Catalysis Webinar Series
2021-06-08 13:00 (America/Los_Angeles) | CA
The NSF Center for Integrated Catalysis is delighted to announce that it will be hosting a monthly webinar series. The next webinar of this series will be held on Tuesday, June 8th, 2021 at 1:00 PM. We are pleased to invite all students, postdocs, faculty, and staff.

Chem 268: Samantha Zink Kozlowski
2021-06-04 15:30
Rodriguez Group
“Probing amyloid structure and function through designed fibril cores”

The 2021 Organic Graduate Symposium
2021-06-04 13:00
On Friday, June 4, the 2021 Organic Graduate Symposium featured research talks by eleven of this year’s UCLA chemistry graduate students. The Organic Graduate Symposium is an event that provides a forum for organic chemistry graduate students who are within one year of obtaining their Ph.D. to present their dissertation research at UCLA to their peers, researchers, and faculty. The Organic Graduate Symposium is open to the UCLA Department of Chemistry and Biochemistry affiliates and their families.

Chem 218 Student Exit Seminar: Arkaprabha Basu
2021-06-03 12:00
“Quantifying the Actin Cytoskeleton: A non-invasive image quantification tool to identify and track sub-cellular processes in real-time”

Chem 278 Prof. Kaner Research Group Seminar
2021-06-02 16:00
Lisa Pangilinan
“Effects of Solubility and Grain Size Refinement on the Hardness of Transition Metal Borides”

Mit Muni

“Graphene for Capacitive Energy Storage”

POSTPONED - Chem 268: Paul Sieminski
2021-05-28 15:30
Zhou Group
“TBA”

Chemical Synthesis and Study of Noncanonical Membrane Lipids
2021-05-27 16:00
Lipid membranes are universal features of living systems, constituting inner and outer barriers of a biological construct and maintaining non-equilibrium states necessary for life. Evolution has produced a fascinating array of lipid structures that dictate the function of biological membranes, and organisms devote considerable energy to the synthesis and maintenance of such compositions. Our group has been studying some of the most exotic lipids observed to date, representing a radical departure from the canonical hydrocarbons that dominate almost all prokaryotic and eukaryotic membranes. While minute amounts have been obtainable from natural sources for structural characterization, pure quantities of such lipids for function-related studies have not. Our work has established strategies for accessing different classes of noncanonical membrane lipids. Success in this vein has resulted in controllable access to single enantiomers of amphiphilic molecules with routes that are flexible enough to allow for the additional production of non-natural analogues.

Chem 218 Student Exit Seminar: Yuting Miao
2021-05-27 12:00
Super-Resolution imaging of plasmonic Near-fields: Overcoming Emitter Mislocalizations

Chem 278: Prof. Sen Zhang
2021-05-26 16:00
“Atomically Precise Nanocrystal Surfaces and Interfaces for Electrocatalysis”
Catalysis at surfaces and interfaces where there exists bi- or multi-component cooperation has been identified as crucial for many processes related to energy and environmental applications. In this talk, I will highlight such cooperative catalysis can be synthetically controlled at the surface and interface of atomically precise nanocrystals, and can play critical roles in maximizing the benefit of oxygen-mediated energy conversion reactions: oxygen reduction reaction (ORR) for fuel cells and oxygen evolution reaction (OER) for water electrolyzer. The first example is M-Pt (M=non-precious metals) core-shell nanocrystals within which desirable/undesirable interfaces between non-precious metal M core and precious metal Pt shell were identified by theoretical calculations and were experimentally balanced by nanocrystal synthesis. The optimized core-shell nanocrystals exhibited favorable interfacial interaction through properly coupled electronic and strain effects, leading to an enhanced electrocatalytic efficiency towards oxygen reduction reaction (ORR). In the second example, we modulated the interaction of single-site Co, Fe, Ni catalytic centers and inorganic coordination environments in the surface of nanocrystals for electrochemical oxygen evolution reaction (OER). The seamless integration of controlled synthesis of nanocrystals, operando structural/catalytic characterization, and advanced theoretical calculation for oxygen electrocatalyst development will be discussed, which will also be extended to other electrocatalytic processes (e.g. CO2 reduction and biomass-derived molecule upgrading).

Modulating the conformation and function of disease-relevant RNA with small molecules
2021-05-25 16:00
Abstract: Small molecules offer a unique opportunity to target structural and regulatory elements in therapeutically relevant RNAs, but understanding functional selectivity has been a recurrent challenge in small molecule:RNA recognition. In particular, RNAs tend to be more dynamic and offer less chemical functionality than proteins, and biologically active ligands must compete with the highly abundant and highly structured RNA of the ribosome. Indeed, the first small molecule drug targeting RNA other than the ribosome was just approved by the US FDA in August of 2020. Our recent survey of the literature revealed little more than one hundred reported chemical probes that target non-ribosomal RNA in biological systems.
As part of our efforts to improve small molecule targeting strategies and gain fundamental insights into small molecule:RNA recognition, we have analyzed patterns in both RNA-biased small molecule chemical space and RNA topological space privileged for differentiation. We have applied these principles to functionally modulate conformations of 3’-triple helix of the long noncoding RNA MALAT1 as well as an enterovirus (EV71) IRES structure, the latter in collaboration with the labs of Blanton Tolbert (Case Western Reserve University) and Gary Brewer and Mei-Ling Li (Rutgers Robert Wood Johnson Medical School). We have recently translated our success in developing an RNA-targeted antiviral for EV71 to targeting regulatory RNA in SARS-CoV-2.

Chem 228: Prof. Zdenka Kuncic
2021-05-24 16:00
“Harnessing nano-scale functionality for next-generation biomedical and bio-inspired technologies”

Chem 268: Nicole Lynn
2021-05-21 15:30
Torres Group
“Functional characterization of the mammalian family of Katanin microtubule-severing enzymes”

Mechanism-guided discovery of photocontrolled materials and reactions
2021-05-20 12:00
Abstract: The Kalow lab interrogates and exploits the relationship between molecular reactivity and macroscopic properties to discover polymeric materials relevant to human health and sustainability. We approach “reactivity-property” relationships bidirectionally: in reactivity-directed materials discovery, we use synthesis and physical organic chemistry to tune reactions occurring within polymer networks. In polymer networks composed of reversible covalent bonds, we translate changes in reactivity into macroscopic responses, ranging from repair in self-healing elastomers to photocontrolled stiffness in adaptable hydrogels. In properties-directed reaction discovery, we design photochemical reaction mechanisms that target desirable photophysical properties. Based on this principle, we have discovered a catalyst-free photopolymerization to produce n-type π-conjugated polymers, and a selective photoinduced cross-coupling of polyhalogenated dyes. Across these projects, light provides precise, tunable, and noninvasive spatiotemporal control over molecular reactivity.

Chem 218 Student Exit Seminar: Andrew Dawson
2021-05-20 12:00
Enabling High Capacity Anodes and Cathodes for Li-Ion Batteries

Chem 278 Prof. Diaconescu Research Group Seminar
2021-05-19 16:00
Ruxi Dai “Redox switchable catalysts for the preparation of biodegradable copolymers with novel properties”
Amy Lai “Predicting redox-switchable reactivity for the ring opening polymerization of lactones and epoxides”

Synthetic polypeptide-based materials for biological applications
2021-05-18 16:00
Abstract: As more attention is focused on biomaterials for medical applications, synthetic polypeptides offer a useful approach towards designing novel biomimetic materials. Polypeptides are inherently biodegradable and biocompatible, and offer wide-ranging properties seen in living systems. The peptide backbone is enzymatically degradable while their side chain functionality can be modified to create an array of stimuli-responsive materials. Here, I will present work on unnatural amino acids incorporated into synthetic polypeptides to design new biomaterials, including vesicles, hydrogels, and coacervates. Synthesis of these materials are modular and can be processed into an assortment of self-assembled macromolecular structures through secondary structure and self-assembly, relevant for stem cell therapies, gene and protein therapeutics, and imaging guides, among many other biomedical applications.

Chem 228: Prof. Suzanne E. Paulson
2021-05-17 16:00
“Aerosol particles out in the world: Wildfire smoke, traffic hotspots, SARS CoV-19, & Cloud droplet chemistry.”

Chem 268: Samuel Demario
2021-05-14 16:00
Chanfreau Group
“Substrate specificity of the Yeast TRAMP complex”

CIC Careers in Green Chemistry Seminar Series
2021-05-13 13:00
The Center for Integrated Catalysis is hosting a new seminar series called the “Careers in Green Chemistry.” With these webinars, we aim to bring speakers from a wide variety of careers, linked through green chemistry, to come talk about their current job as well as the career path that led them to that position. We are pleased to invite all students, postdocs, and faculty.

Chem 218 Student Exit Seminar: Erin Avery
2021-05-13 12:00
Exploration of Chemical Functionality of Self-Assembled Carborane Derivatives

Synthesis in a Boron World
2021-05-13 12:00
Abstract: Nature has evolved highly sophisticated machinery for organic synthesis, many of which resemble molecular assembly-line processes. So far chemists have been able to apply this type of approach in the synthesis of peptides and oligonucleotides but in these reactions, simple amide (C‒N) or phosphate (P‒O) bonds are created. It is much more difficult to make C‒C bonds but this is central to the discipline of organic synthesis. This difficulty is why organic synthesis is challenging and why robust, iterative or automated methodologies have not yet emerged.
Here, we describe the application of iterative homologation of boronic esters using chiral lithiated carbamates and chloromethyllithium enabling us to grow carbon chains with control over both relative and absolute stereochemistry. Applications of this strategy to the synthesis of natural products will be demonstrated. In addition, the methodology is used to answer fundamental questions about nature and the specific role of methyl substituents in carbon chains. By understanding their role, I will show that molecules can be created with linear or helical conformations or hybrids of the two.
Finally, I will show new triggers for 1,2-metalate rearrangements of boronate complexes using strain release as an additional driving force and we use this chemistry to make functionalized cyclobutanes and azetidines.

OCDS Seminar: Prof. Rodney D. Priestley
2021-05-12 16:00
“Molecular Dynamics and Glass Formation of Nanoscopically Confined Polymer”
Many technological advances are driven by the ongoing emergence of nanostructured polymers as the critical component to enable innovation. Yet, from a materials design perspective, we cannot presume that the bulk properties of polymers define their behavior when physically confined to nanoscale dimensions. This is, in fact, not true, as there is now convincing evidence that the nanoscale properties of polymers, including the glass transition temperature, can be profoundly different from the bulk. Here, I discuss two overarching questions in the field: 1) What are the molecular dynamics at the free surface of polymer glasses? and 2) How can we overcome the effect of confinement on the reduction in the glass transition temperature? Regarding the first question, we introduce a time-resolved nano-creep experiment to probe the dynamics at the surface of polymer glasses. We reveal a new mode of molecular dynamic at the surface: pseudoentanglements. This phenomenon causes unentangled chains to exhibit surface mechanical response and dynamics that are characteristic of entangled polymers. For entangled chains, the phenomenon prolongs and stiffens the entangled response. In both cases, the breadth of the entangled response grows on cooling, leading to a breakdown of time-temperature-superposition at the surface. Counterintuitively, this new mode of slow surface dynamics emerges precisely because surface dynamics are accelerated relative to the bulk. Concerning the latter question, we demonstrate that ultrathin polymer films with an ultradense brush morphology – defined with respect to approaching the maximum theoretical value of crystalline chain packing – exhibits a significant enhancement in thermal stability, as manifested by an exceptionally high Tg and low expansivity. For instance, a 5 nm thick polystyrene brush film exhibits a ~ 75 K increment in Tg and ~ 90 % reduction in expansivity compared to a spin-cast film of comparable thickness. Our results establish how the film morphology can overcome confinement and interfacial effects in controlling material properties, and how this can be achieved by the dense packing and molecular ordering in the amorphous state of the ultradense brushes prepared by surface-initiated atom transfer radical polymerization in combination with a self-assembled monolayer of initiators.

Synthetic biology approaches to study and exploit RNA regulation
2021-05-11 16:00
Abstract: RNA transcribed from the genome in the nucleus bears little resemblance to the RNA polymer it will ultimately become in the cytoplasm where it is translated into protein. Well-known processes such as capping, splicing and polyadenylation, as well as the recently discovered and ever-expanding list of diverse chemical modifications and editing, significantly alter the properties and fates of a given RNA during the course of its lifetime. These alterations regulate critical aspects of RNA function such as stability, transport, protein binding, and translation. Especially in mammalian systems, these post-transcriptional gene expression regulatory processes are often a key determinant of genetic information flow. Moreover, from an engineering and therapeutic perspective these RNA regulatory processes represent new ways to control or retune gene expression at the RNA level, if they can be harnessed. I will present several technologies our group has developed to measure the chemical composition and localization of RNAs, and to measure and control protein-RNA interactions with an eye toward therapeutic development.

NSF Center for Integrated Catalysis Webinar Series
2021-05-11 13:00
The NSF Center for Integrated Catalysis is delighted to announce that it will be hosting a monthly webinar series. The next webinar of this series will be held on Tuesday, May 11th, 2021 at 1:00 PM. We are pleased to invite all students, postdocs, faculty, and staff.

Chem 228: Prof. Andreas Heinrich
2021-05-10 16:00
“Taking Electron Spin Resonance to the Single Atom and Molecule”

Chem 268: Hannah Bailey
2021-05-07 15:30
Quinlan Group
“Utilizing Drosophila melanogaster to understand the role of actin dynamics in oogenesis”

Strain molecules assist peptide and protein synthesis, a new venue for thiolactones
2021-05-06 16:00
Abstract: The broad application of macrocycles has illustrated significant potential as therapeutic agents. 12-membered ring cyclotetrapeptides are particularly attractive entities among all the cyclic peptides. Compared with macrocycles of larger ring size, the characteristic head-to-tail or end-to-end peptidyl backbone provides intrusive structural motif of circular peptides grants distinct biological properties such as resistance to degradation, enhanced conformational stability, and increased epitope interactions with other biomolecules. Ability to acquire a sufficient quantity of high purity of cyclo-tetrapeptide could significantly promote their chemical and biological studies.
It is worth noting that the traditional coupling methods to achieve chemical synthesis of macrocycles have been a formidable challenge, requiring fully protected linear precursors and harsh conditions to achieve activation of the C-terminal residue for the cyclization. The harsh activation conditions are required to overcome the entropy barrier during the coupling often lead to epimerization of the C-terminal amino acid residue and peptide oligomerization. The practical strategy to attain macrocycles with a consensus sequence of L-cyclo(Pro-Xxx-Pro-Xxx), where Xxx = Val, Tyr, Leu, Phe, are elusive. There is the urgent need to develop a strategy to prepare circular tetrapeptides. Based on our previously reported β-thiolactone mediated chemistry, iii we were able to construct tetra-cyclic peptides in high yields. The strategy could be applied to produce a broad number of all-L-cyclo-tetrapeptides and the reactions were performed at room temperature in the aqueous buffer. The β-thiolactone furnished cyclization protocol prevented the amino acid epimerization during the cyclization and proved as a powerful general strategy for cyclic peptide synthesis.

Chem 218 Student Exit Seminar: Jack Fuller
2021-05-06 12:00
Secondary Coordination Effects in Artificial Biotin-Streptavidin Metalloenzymes
Designing artificial metalloenzymes is of interest because they combine the catalytic activity of possibly non-physiological but highly catalytically potent metals and the selectivity and mild operational conditions enabled by the protein. This talk will focus on joint theory-experiment efforts to design Rh and Ir artificial metalloenzymes, catalyzing the formation of 5-membered and 6-membered N-heterocycles. The biotin-streptavidin system has been used as a relatively simple and robust platform to create metalloenzymes by embedding organometallic catalysts in the protein. The monomeric streptavidin is known to retain the fold upon many different mutations, thus enabling the control over the second coordination sphere of the metal and fine-tuning of the metal electronic properties in a variety of ways without losing the entire structure. Biotin-Sav artificial metalloenzymes prepared in this way and containing Rh/Ir(Cp*) have shown improved reactivity and selectivity over simpler organometallic catalysts. We aimed to both explain the improved activity and to enhance it further by strategic mutagenesis. We have analyzed the secondary coordination effects using quantum mechanistic calculations, bonding analysis, and hybrid quantum mechanical/molecular mechanical simulations. In collaboration with experiment, we probed a library of mutants. In particular, we show that the pi-pi interaction between the catalyst and a tyrosine sidechain decreases rate-determining barriers. Additional residues in the vicinity of Tyr contribute to the quality of the pi-pi contact and the reactivity tuning. More remote mutations within the protein scaffold affect the protein structure and dynamics slightly, and thus affect the pi-pi contact indirectly, also impacting the activity. Successful and failed strategic and accidental mutations were made with the goal of improving the pi-pi contact, and will be discussed. Finally, we demonstrated that the activity correlates the most with the properties of the ensemble of states within the protein dynamics, showcasing the need for rapid QM/MM sampling in this work.

Chem 278: Prof. Henry S. La Pierre
2021-05-05 16:00
“Electron (De) Localization in f-Element Systems: From Fundamental Questions to QIS Design Principles”
Abstract: The La Pierre group studies how collective magnetic, physical, and chemical properties arise from electron (de)localization phenomena in f-element systems. Our studies include the development of solid-state and solution methodologies for the synthesis of novel lanthanide and actinide (Th – Pu) materials and complexes. These synthetic efforts are paired with synchrotron and neutron spectroscopies and physical property studies to break down the challenge of understanding the electronic structure of f-element systems. Particularly in solid-state systems, the f-elements present unique valence electronic structures due the near degeneracies engendered in these systems and strong electron correlation. Our efforts to-date have focused on the synthesis and analysis of systems governed by one of three phenomena: magnetic super-exchange (i.e. exchange coupled systems), multi-configurational electronic structures (ground state degeneracy including hybridization with ligand/band states), and mixed-valence metal ions (i.e. mixed f/d occupancy and mixed-oxidation states). Understanding and controlling the manifestation of these phenomena in molecular systems is crucial for understanding the interplay of these phenomena underpinning topological insulators such as SmB6 and PuB6 and superconductors such as CeCoIn5 and PuCoGa5. In turn, the group has employed this expanded fundamental understanding of f-element electronic structure to construct components of quantum information technologies (e.g. qubits, single-molecule magnets).

Molecular recognition tools for chemistry in living systems
2021-05-04 16:00
Abstract: The introduction of unnatural functionality in biological systems coupled with detection using bioorthogonal chemical reactions revolutionized the field of chemical biology by enabling the investigation biological processes in live cells and simple organisms. However the translation to complex organisms has led to less than optimal results with high background noise due to cross reactivity with activated reagents. This work investigates the utilization of non-covalent chemistry and bioorthogonal host-guest pairs to obtain more efficient labeling of living systems. Complexation between a host and guest is diffusion-limited, hence can be efficient in dilute environments. The cucurbit[n]uril scaffold has been utilized to determine the minimum binding affinity required for efficient bioorthogonal complexation and investigate how guest size and charge affects the introduction of guests as unnatural metabolites. Carboranes, a cucurbit[7]uril guest class that can be removed “on demand” from the host cavity, were found compatible with metabolic glycoengineering and were successfully incorporated on the cell surface. The cucurbit[7]uril-carborane system serves as the first example of bioorthogonal complexation and answers fundamental questions required for the further development of bioorthogonal host-guest pairs.
