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May 25, 2021 Webinar Speakers

Updated: May 26, 2021

We hope that everyone's summer is off to a great start! Our next webinar will take place via the internet on Tuesday May 25th at 8PM EDT/1AM GMT. Sign up on our mailing list to receive the Zoom link!

We hope to see/hear from you all at one of our sessions or as one of the next speakers. If you are an early career scientist and would like to present your research, don't hesitate to submit an abstract today! For now, please learn more about our current speakers and their research below. We also thank the generous support from Cell Reports Physical Science.

Our featured speakers this week are Arundhati Deshmukh (graduate student, University of California, Los Angeles, USA) and Dr. Isaiah Speight (postdoc, University of California, Irvine, USA). The seminar will be guest moderated by Dr. L. C. Campeau from Merck.


ARUNDHATI DESHMUKH (on twitter @Anchemystry)

Biography: Arundhati is a PhD candidate at UCLA working with Prof. Justin Caram. A physical and materials chemist by training, her research interests lie in chemically tuning properties, as well as introducing new functionalities in materials. At UCLA, she focuses on manipulation of excitonic properties in supramolecular chromophore aggregates. She did a Master’s thesis on exploring chemosensing mechanism in conjugated polymers, earning a BS-MS degree at Indian Institute of Science Education and Research (IISER), Bhopal. She enjoys communicating science in and outside academia, aiming to make it more welcoming and supportive for everyone. Her latest favorite leisure pursuit is creating digital art.

Title of Talk: Molecular Aggregation for Tuning Excitonic Properties Across the Visible and Shortwave Infrared

Abstract: Molecular aggregates are non-covalent self-assemblies of chromophores wherein transition dipole moments of individual molecules couple coherently over long distances forming delocalized excitons. This imparts exciting photophysical properties such as extreme blue or red shifts (seen in H- or J-aggregates respectively), narrow linewidths and high molar absorptivities. We modulate the transition dipole couplings within an aggregate via molecular packing, topology, and disorder in order to tune and explore new photophysical behaviors. In this talk, I will discuss the unusual situation that arises from 2D transition dipole coupling in sheet-like aggregates. In addition to traditional H- and J-aggregation, we find a new case of ‘I-aggregation’ which shows intermediate characteristics of H- and J-aggregates. I will also describe how we use thermodynamics of self-assembly to control the aggregate packing and thereby, tune excitonic properties. Using a three-component equilibrium model, I will lay down general principles for selectively stabilizing H- or J-aggregates, allowing us to construct a library of 2D J-aggregates with absorptions spanning the visible and shortwave infrared (SWIR) regions. Finally, I will show how subtle differences in chromophore structures within this library modulate the aggregate packing and eventually lead to distinct excitonic band structures, that can be experimentally probed using temperature dependent spectroscopy. Overall, this work establishes molecular aggregation as a tunable avenue for accessing unusual photophysical properties and thus, opens up organic chromophores to new functionalities including SWIR imaging, plexitonics, and telecommunications.

DR. ISAIAH SPEIGHT (on twitter @IR_SP8)

Biography: Isaiah Speight was born in Portsmouth, Virginia and received his B.S. in chemistry at Norfolk State University. During his undergraduate studies, Isaiah performed research in the areas of polymer synthesis with Dr. Olufemi Oyesanya and synthetic organic chemistry with Dr. Steven Townsend. Isaiah then went on to Vanderbilt University to earn his Ph.D. in Chemistry under the mentorship of Dr. Timothy Hanusa with a focus on mechanochemistry. Currently, Isaiah is a postdoctoral scholar at University of California, Irvine working with Dr. Vy Dong focusing on complex organic synthesis. Isaiah has also worked in leadership positions with NOBCChE.

Title of Talk: One plus two is two many: Mechanochemical generation of group 2 amido complexes

Abstract: The use of solvents is common in most synthetic methods, due to their ability to promote the mixing of reagents, disperse heat, alter product selectivity, and influence equilibrium. Solvent use has its benefits, but the negative environmental implications of solvent waste and disposal are encouraging chemists to search for ‘greener’ methods of synthesis. One of these methods is mechanochemistry, an approach to synthesis that uses mechanical energy to promote chemical reactions, often by grinding or ball milling. The removal of solvent from reactions can provide new and unique compounds, unsolvated complexes, and new types of reactivity. The use of solvent-free methods to generate amide compounds can prevent the formation of metalate complexes as well as improve methods by reducing reaction time, the use of toxic reagents, and the formation of solvated complexes. We have used solvent-free methods to develop a synthesis of a calcium amide species while avoiding common solvent based pitfalls.

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