Resnick Institute

Past 2018 Seminars

Marcus Drover PhD

Marcus Drover, PhD
Postdoctoral Fellow (Peters Group)

Canvassing New Ligand Space: A Tale of Boron-based Allyl Equivalents and a Marriage between PPh3 and BPh4-

Ligand design is imperative to the formulation of new catalysts, molecules that serve to accelerate chemical reactions, without themselves being consumed – a cornerstone of the green chemistry movement. As part of our group’s ongoing efforts into the catalytic reduction of robust small-molecules (e.g., N2, CO, CO2 etc.) for access to high-value chemical feedstocks, we have stressed judicious ligand choice as key to achieving selective and sustainable reactivity.

This presentation will focus on the design, synthesis, characterization, and ensuing coordination chemistry of two new ligand scaffolds (with an eye toward application in small-molecule activation). First, the reactivity of a diphosphinoborane with nickel and platinum precursors will be highlighted, generating eta(3)-P,B,P complexes - the first examples of P,B,P-based allyl analogues. Secondly, the 9-phosphatriptycene-10-borate anion will be introduced. A fusion of two ubiquitous organometallic reagents, triphenylphosphine and tetraphenylborate, the synthesis, characterization, and coordination behavior of this species with iron and cobalt will be provided.

Matt Wellborn PhD

Matt Welborn, PhD
Postdoctoral Fellow (Miller Group)

Projection-based Embedding Applied to a Co-centered CO2 Reduction Catalyst

Small molecules – such as N2, H2 and CO2 – are key players in a sustainable economy, acting as feedstocks and fuels. Due to their inert nature, catalytic conversion of these molecules is critical, and transition metal complexes have proven effective for this task. However, designing effective catalysts is difficult: small molecule transformations involve many redox steps, proton transfers, and fleeting intermediates. Due to these challenges, theory is critical for elucidating and characterizing catalytic mechanisms. However, Density Functional Theory (DFT) — the workhorse computational method for describing the structure and reactivity of molecules — can be inaccurate for transition metal complex catalysts.

Projection-based embedding offers a simple framework for achieving the higher accuracy of wavefunction theories at a low cost comparable to that of DFT. In this talk, we apply projection-based embedding to a Co-centered CO2-to-CO reduction catalyst. We examine the key step of CO2 binding to the complex and determine the role of intramolecular hydrogen bonds in stabilizing bound CO2. Contrary to proposed mechanisms for similar complexes, we demonstrate that intramolecular hydrogen bonding is unfavorable and does not play a role in the catalysis.

Weilai Yu

Weilai Yu
Graduate Fellow (Lewis Group)

Understanding Semiconductor Corrosion Chemistry for Sustainable Solar Fuel Generation

Photoelectrochemical (PEC) solar fuel generation, including water splitting and CO2 reduction, represents a promising scheme for large-scale renewable energy production. Our desired PEC systems integrate semiconducting light-absorbers with electro-catalytic materials allowing for direct and efficient solar-to-fuel conversion. Unfortunately, many state-of-art semiconductors suffer from serious material corrosion and are not considered structurally robust when immersed in aqueous electrolytes, despite their superior photovoltaic performance.

Herein, starting from Ⅲ-Ⅴ semiconductors, we probe corrosion chemistry at the electrode/electrolyte interface under different pH/potential conditions. Thus, the regions where the chemical, electrochemical and photoelectrochemical corrosion occur are identified. Furthermore, both the detailed corrosion pathway and quantitative corrosion kinetics are comprehensively evaluated and measured. Equipped with this understanding, common principles may be devised to minimize/protect the semiconductor surface from rapid corrosion and enable construction of stable PEC devices for sustainable solar fuel production.

Tina Boville, PhD

Tina Boville, PhD
Postdoctoral Fellow (Arnold Group)

Engineered Biosynthesis of Amino Acids

The twenty standard proteinogenic, or protein creating amino acids grant access to a myriad of chemistries that harmonize to give rise to life. If nature can make such wondrous things with only these limited building blocks, new tools should allow us to accomplish even more. Indeed, expanding the protein code beyond the standard amino acids to include non-canonical amino acids (ncAAs) has unveiled pharmaceutical intermediates, biological probes, and natural products. Yet despite their obvious utility, synthesis of ncAAs remains challenging as strict chirality, multiple reactive functional groups, and poor yields stymie effective routes.

Biocatalysis has emerged as a versatile method to overcome these challenges by supplanting nature’s existing machinery to synthesize ncAAs. In conjunction with directed evolution, biocatalysis allows us to access an expanded amino acid alphabet using simple, green chemistries that are accessible to researchers from a broad array of backgrounds and means. My research aims to evolve useful biocatalysts to expand nature’s toolbox, providing a simple and environmentally benign platform for preparation of new tryptophan analogs.

Armeen Taeb

Armeen Taeb
Graduate Fellow (Chandrasekaran Group)

From Data Science to Hydrology, California Reservoirs During Drought

Water is a precious commodity, especially in the state of California. Our state frequently experiences cycles of major state-wide precipitation deficits – most notably the 2012–2015 drought which was the worst to occur in the past 1200 years.

The focus of this work is to develop a state-wide model of the California reservoir network to address the following scientific questions: 1) What are the dependencies among reservoirs? 2) Are there unmodeled phenomena (denoted as latent variables) that are influencing the network globally -And could these latent variables cause a system-wide catastrophe (e.g. exhaustion of multiple large reservoirs)?

For the first time, we developed a statistical model of the California reservoir network that address these questions. Using this model we can obtain a clearer picture of the demands placed on reservoirs during drought, and propose guidelines for policies that can lead to more sustainable water resources.

Austin Chadwick

Austin Chadwick
Graduate Fellow (Lamb Group)

The Role of Channel Avulsion in Mediating Land Loss on Drowning River Deltas

Land loss on river deltas is dictated by the rates of sea level rise, land subsidence, and sediment deposition. Existing models are based on sustainability of the entire delta; however, land loss can vary spatially because river avulsions periodically and abruptly shift the river course changing the distribution of sediment.

We present new theory and scaled physical experiments demonstrating that the extent of land loss is set by a competition between the avulsion frequency of active distributary channels and the rate of retreat on sediment-starved coastlines.

Results indicate that avulsions occur more frequently under more rapid rates of sea-level rise and land subsidence. More frequent avulsions, in turn leads to reduced durations of lobe abandonment and more even distributions of sediment. Thus, although rates of land loss are greater on average for deltas undergoing higher rates of sea-level rise, the local extremes are muted, resulting in transiently reduced rates of land loss.

Application of our theory to published field data suggests that sustaining modern delta area through the century will require more sediment than previously estimated.

Hao Zhao

Hao Zhao
Graduate Fellow (Rosenthal Group)

Water Institutions and Groundwater Sustainability in California

This talk addresses two questions: (1) How Southern California urban water users can achieve sustainability in groundwater basins; and (2) How will agricultural water users in the Central Valley adjust to a sustainable regime of groundwater pumping.

The first part of the talk will discuss the effectiveness of adjudication, a legal settlement among groundwater pumpers, in managing groundwater basins in Southern California. As a form of self-governance, adjudication generally leads to higher water levels in the adjudicated basins. Counter-intuitively however, there is a problem with dynamic efficiency because when compared to competitive pumpers, pumpers in adjudicated basins actually have less efficient extraction patterns in response to surface water availability.

The second part of the talk will discuss the response of the agricultural community to water supply changes in the Central Valley. We explore how reallocation of water through water markets may lead to greater efficiency.

Julian West, PhD

Julian West, PhD
Postdoctoral Fellow (Gray Group)

Making Sustainably: Designing Organic Chemistry for the 21st Century

Society relies on organic chemistry to make game-changing molecules for modern life, including high-performance materials, crop-boosting agrochemicals, and life-saving pharmaceuticals. All of these products are essential for life in the 21st century, but the ways we manufacture them are often not sustainable nor environmentally-conscious. Further, there are many remaining grand challenges that can be solved by inventing new molecules, though methods for making them do not yet exist. We need fundamentally better chemical tools to let us make new and old molecules more efficiently, sustainably, and environmentally-consciously.

Our research focuses on developing new tools, catalysts, for making molecules better. We take inspiration from nature in our designs, seeking to use sustainable and abundant solar electricity to drive our reactions just as plants use photosynthetic chemical potential to drive theirs. Our catalytic reactions enable efficient and environmentally-conscious ways to make old molecules and will be useful for inventing new ones.

Past 2017 Seminars

Xiaoqui Ren, Sebastian Lee

Xiaoqi Ren

A Market Approach to Increase Power Infrastructure Utilization in Multi-Tenant Data Centers

Sebastian Lee

Quantum Embedding Methods for the Better Design of Liquid Electrolytes in Lithium-ion Batteries

Jinglin Huang, Carlos Read

Jinglin Huang

Carbon Nanotubes for Seawater Desalination Application

Carlos G. Read, PhD

Growth and Characterization of Single-Crystalline Photocatalytic Materials for the Production of Solar Fuels