Our next webinar will take place via the internet on Tuesday September 13th at 10 AM EDT/3 PM BST. 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, Merck, Janssen, and the Royal Society of Chemistry.
Our featured speakers this week are Gargi Kundu (Graduate Student, National Chemical Laboratory, India), and Kostas Parkatzidis (Graduate Student, ETH Zurich, Switzerland).
LEARN MORE ABOUT THE SPEAKERS AND THEIR TALKS BELOW
GARGI KUNDU (on Twitter @gargikundu6)
Biography: Gargi Kundu is a doctoral researcher from CSIR-National Chemical Laboratory, Pune, India. She is working under the supervision of Dr. Sakya S. Sen, on designing and developing the chemistry of more nucleophilic saturated N-heterocyclic carbenes (SNHCs), such as five and six-membered carbenes. Her research area includes studying the chemistry of SNHCs in C-F bond activation and its further applications in tuning the diradical character of SNHC based Kekulé hydrocarbons. Her works also feature the reactivity of saturated 5/6-membered carbenes in NHC∙boron chemistry.
Title of Talk: Chemistry of Six-membered N-heterocyclic Carbene Borane
Abstract: The body of work on carbene-borane chemistry keeps growing thanks to pioneering works by the groups of Curran (1) and Braunschweig (2), but the carbene component is mainly restricted to two classes of carbenes: (a) Arduengo type five-membered NHC and (b) Cyclic alkyl amino carbene (CAAC). The reports of six-membered carbenes are limited in the literature partly due to their less thermal stability and structural rigidity, though they feature a higher HOMO and lower HOMO–LUMO gap compared to typical five-membered NHCs. Here, we have introduced a new NHC, 6-SIDipp for NHC·borane chemistry, and described a detailed study of substitution reactions of 6-SIDipp·BH3 (3). Direct electrophilic halogenation of 6-SIDipp·BH3 with a stoichiometric amount of I2 led to NHC boryl iodides, 6-SIDipp·BH2I and 6-SIDipp·BHI2, which were further reacted with various nucleophiles to give novel 6-SIDipp based mono and disubstituted boranes with triflate (OTf) or nitro (ONO2) functional groups. The addition of Br2/H2O to 6-NHC-BH3 smoothly results in a novel class of dihydroxyborenium cation which is the cationic analogue of phenyl boronic acid. We have also demonstrated the ability of a six-membered 6-SIDipp for stabilizing borenium cations (4). For this purpose, we have prepared 6-SIDipp·PhBCl2 adduct and reacted with AlCl3 which led to the formation of first borenium cation of composition [6-SIDipp·B(Ph)(Cl)]+. Analogous reaction with triflic acid resulted in [6-SIDipp·B(Ph)(OH)]+ which can be considered as the cationic analogue of less illustrated phenyl boronous acid. Attempts to do the Lewis base exchange reaction with 4-DMAP led to the formation of an unusual boroxine complex.
Reference:
1. Solovyev, A.; Chu, Q.; Geib, S. J.; Fensterbank, L.; Malacria, M.; Lacôte, E.; Curran, D. P. Substitution Reactions at Tetracoordinate Boron: Synthesis of N-Heterocyclic Carbene Boranes with Boron−Heteroatom Bonds. J. Am. Chem. Soc. 2010, 132, 15072− 15080.
2. Auerhammer, D.; Arrowsmith, M.; Braunschweig, H.; Dewhurst, R. D.; Jiménez-Halla, J. O. C.; Kupfer, T. Nucleophilic Addition and Substitution at Coordinatively Saturated Boron by Facile 1,2-Hydrogen Shuttling onto a Carbene Donor. Chem. Sci. 2017, 8, 7066–7071.
3. Kundu, G.; Ajithkumar, V. S.; Raj, K. V.; Vanka, K.; Tothadi S.; Sen, S. S. Substitution at sp3 Boron of a Six-membered NHC-BH3: Convenient Access to a Dihydroxyborenium Cation, Chem. Commun. (2022), DOI:10.1039/D1CC06816D
4. Kundu, G.; Balayan, K; Tothadi S.; Sen, S. S. Six-membered Saturated NHC Stabilized Borenium Cations: Isola-tion of a Cationic Analogue of Boronous Acid. (Manuscript under revision)
KOSTAS PARKATZIDIS (on Twitter @kostaspark)
Biography: Kostas finished his Material Science and Technology Studies at the University of Crete, in Greece, in collaboration with the institute of electronic structure and laser (IESL), in 2017. He then received his Master’s degree in Organic Chemistry from the same university in 2018 (supervised by Prof. Maria Vamvakaki and Dr. Maria Farsari). His research focused on synthesizing novel biocompatible materials for additive manufacturing (μ-3D printing) using the two-photon polymerization technique. Since 2019, he has been a PhD candidate at the Department of Material Science at ETH Zurich, Switzerland, under the supervision of Prof. Athina Anastasaki, focusing on control radical polymerization and its application in the synthesis of polymeric materials.
Title of Talk: Transformer-Induced Metamorphosis of Polymeric Nanoparticle Shape at Room Temperature
Abstract: Controlled polymerizations have enabled the synthesis of a wide range of amphiphilic block copolymers which can form nanostructured materials with different shapes exhibiting distinct properties and performance. Despite the importance of shape, current strategies that allow for the efficient morphological transformation are limited in polymer scope, often alter the chemical structure, operate at high temperatures, and can be fairly tedious and time-consuming. Herein we present a rapid and versatile morphological transformation strategy which operates at ambient temperature and without impairing the chemical structure of the resulting morphologies. By simply adding a small amount of a molecular transformer (i.e. small organic molecule) in an aqueous solution of polymeric nanoparticles, a rapid evolution to the next high-ordered morphology was observed within seconds, yielding a range of nanoparticles morphology from the same starting material. Significantly, this approach can be applied to nanoparticles produced by disparate block copolymers (i.e. with different cores and coronae) obtained by various synthesis techniques, including emulsion polymerization, polymerization-induced self-assembly and traditional solution self-assembly.