Chemistry seminars

Apurba Bhatacharya discusses the intellectual and aesthetic rewards of organic synthesis: devising a retrosynthetic plan and then realizing it experimentally. The talk considers how the distinct chemical properties of elements allow synthetic chemists to construct complex molecular networks. It connects this molecular craftsmanship with academic innovation and the sustained practical work of synthesis, presenting beauty and simplicity as ways to understand its apparent complexity. Speaker: Dr. Apurba Bhatacharya, Professor Emeritus, Department of Chemistry, Texas A and M University–Kingsville. Hosted by the School of Math and Physical Sciences, Chemistry Seminar Series. Wednesday 30 September 2026, 15:00–16:00 America/Chicago (CDT). The university invites attendees to Nierman Hall, Room 251, Texas A and M University–Kingsville, Kingsville, Texas, USA. Those attending remotely can use the public Zoom link or Join Stream button on the official event page.

Leonardo Fernandes Fraceto explores the development of nanoherbicides for more efficient, sustainable weed control. This Spanish-language webinar covers design strategies, interactions between nanomaterials and plants, controlled release, reduced herbicide doses and potential reductions in environmental impact. It examines how these principles could support more precise crop management and discusses the practical benefits, barriers and opportunities associated with adopting nanoherbicides in real agricultural systems. Speaker: Dr. Leonardo Fernandes Fraceto, Universidade Estadual Paulista, Brazil. The registration page also lists Dr. Ingrid Montes, Universidad de Puerto Rico, Recinto de Río Piedras. Co-produced by ACS Webinars and Sociedad Química de México. Wednesday 30 September 2026, 14:00–15:00 America/New_York (EDT); the live registration page confirms 20:00 CEST. Online via Zoom Events, free registration required. Follow Regístrese Gratuitamente on the ACS event page to the verified Zoom Events registration page. A free ACS ID may be required. Slides are scheduled to be available on the webinar day.

Chemistry seminar by Prof. Yves Geerts (Université Libre de Bruxelles) on historical attempts by Pasteur and Curie to direct chiral symmetry breaking with external fields, why they failed, and how chirality-induced spin selectivity (CISS) under non-equilibrium conditions now enables enantiomer separation and control of molecular handedness.

Debashree Ghosh discusses quantum-chemistry approaches for strongly correlated polyaromatic hydrocarbons, including acenes and carotenoids. The talk examines why large valence active spaces are needed to describe optical properties and singlet–triplet gaps, and how density-matrix renormalization-group methods address these systems. Changes in molecular topology and odd-membered rings are connected to spin frustration and optical behaviour. The seminar also covers neural-network configuration interaction, connections between artificial neural networks and matrix-product-state wavefunctions, and restricted-Boltzmann-machine approaches to quantum wavefunctions. Applications include singlet fission and multiexcitonic phenomena. The hybrid event takes place in ICTP’s Euler Lecture Hall and online; the official event page provides the registration link.

Bispidines (3,7-diazabicyclo[3.3.1]nonane) and their derivatives act as bifunctional chelators (BFC), combining the advantages of multidentate macrocyclic and acyclic ligands e.g. high kinetic inertness, rapid radiolabelling under mild conditions. This bicyclic chelator system shows a great diversity in terms of its denticity and type of functional groups, yielding a wide range of multidentate ligands that can bind a variety of different metal ions. In addition, they allow a facile functionalisation of targeting molecules such as peptides, peptidomimetics, and bispeci􀄀c antibodies. Herein, examples of various bispidine complexes labelled with [64Cu]Cu2+, [111In]In3+, [ 177Lu]Lu3+ or [ 225Ac]Ac3+ will be presented which provide a picture of how different substituents in􀄁uence the coordination mode. Target-speci􀄀c radiolabelled bispidine-based conjugates (e.g. peptides, antibody fragments, antibodies) investigated in vivo by positron emission or single-photon emission computed tomography will be presented and discussed in terms of their suitability for nuclear medicine applications.

The question of the origin of homochirality of living matter, or the dominance of one handedness for all molecules of life across the entire biosphere, is a long-standing puzzle in the research on the Origin of Life. In the fifties, Frank proposed a mechanism to explain homochirality based on the properties of a simple autocatalytic network containing only a few chemical species. Following this work, chemists struggled to find experimental realizations of this model, possibly due to a lack of proper methods to identify autocatalysis [1]. In any case, a model based on a few chemical species seems rather limited, because prebiotic earth is likely to have consisted of complex ‘soups’ of chemicals. To include this aspect of the problem, we recently proposed a mechanism based on certain features of large out-of-equilibrium chemical networks [2]. We showed that a phase transition towards an homochiral state is likely to occur as the number of chiral species in the system becomes large or as the amount of free energy injected into the system increases. Through an analysis of large chemical databases, we showed that there is no need for very large molecules for chiral species to dominate over achiral ones; it already happens when molecules contain about 10 heavy atoms. We also analyzed the various conventions used to measure chirality and discussed the relative chiral signs adopted by different groups of molecules [3]. We then proposed a generalization of Frank’s model for large chemical networks, which we characterized using random matrix theory. This analysis includes sparse networks, suggesting that the emergence of homochirality is a robust and generic transition. References: [1] A. Blokhuis, D. Lacoste, and P. Nghe, PNAS (2020), 117, 25230. [2] G. Laurent, D. Lacoste, and P. Gaspard, PNAS (2021) 118 (3) e2012741118. [3] G. Laurent, D. Lacoste, and P. Gaspard, Proc. R. Soc. A 478:20210590 (2022).