Chemistry in the 20th Century: Materials, Methods, Residues During the 20th century, chemistry expanded through its methods into many neighboring scientific fields. At the same time, the enormous growth of chemical production, coupled with globalization, led to an increasingly troublesome chemical pollution and severe environmental problems. In my talk, I will present historiographical methods in order to tackle these developments. Bonn JCF will host a reception following the lecture. Come meet other chemists over drinks and snacks!
What layered iron compounds can offer, and more ... I will introduce recently-found 2D inorganic compounds based on layers of Fe2+ (S=2) ions, in order to highlight how they form a unique platform for new paradigms on spin-dynamics and magneto-dielectric couplings. Here, depending on the crystal structure, the spin-degrees of freedoms and fine anionic compositions are the key-ingredients to tune the exchanges, crystal field ... etc. Especially, I will show in a specific 2D-Ising-ferromagnet (BaFe2(PO4)2) the occurrence of giant magneto-crystalline anisotropy. It results in the collective freezing of magnetic domains which mediates the passage from a soft to a ‘super-hard’ magnet. This unique situation offers various unexpected peculiarities including the ability to imprint any unreturnable magnetization to the sample within simple temperature/field cycles.
Catalytic Enantioselective Pictet-Spengler Reaction of Ketones: Development and Applications in the Total Synthesis of Indole Alkaloids The asymmetric Pictect-Spengler reaction (PSR) between tryptamine and aldehydes is now well-developed. Conversely, catalytic enantioselective PSR of ketone is essentially unexploited. In this presentation, we will present our work on the catalytic enantioselective PSR of tryptamine with 1,2-diones, α-ketoesters and α-ketoamide for the synthesis of enantioenriched 1,1-Disubstituted tetrahydro-β-carboline (THBC) and their application in the total synthesis of monoterpene indole alkaloids.
Stefan Flesch Photolytical formation of a nitrido-iron(V) complex tracked by ultrafast mid-IR spectroscopy Hagen Neugebauer Toward reliable quantum chemical modeling of homogeneous 3d transition metal electrocatalysis Lea Schmidt Mixed-metal monophosphate tungsten bronzes containing divalent transition metal ions (M<sup>2</sup>: Fe, Co, Ni) and tungsten(VI) Houchao Xu The Mysterious Case of Sodorifen Biosynthesis Anschliessend BBQ
Hybridizing Light and Matter – Consequences for Chemical and Material Sciences Over the past decade, the possibility of manipulating material and chemical properties by using hybrid light-matter states has stimulated considerable interest. Such hybrid light-matter states can be generated by strongly coupling the electronic or the vibrational transitions of a material, to the spatially confined electromagnetic field of an optical resonator. Most importantly, this occurs even in the dark because the coupling involves the zero-point electromagnetic fluctuations of the resonator, the vacuum field. After introducing the fundamental concepts, examples of modified properties of strongly coupled systems, such as chemical reactivity, charge and energy transport, and magnetism will be given to illustrate the broad potential of light-matter states.
Breaking it and fixing it: new chemistry with nitrogen Atmospheric N<sub>2</sub> is a cheap, abundant resource with great potential for energy storage and chemical escribe the challenges and opportunities of nitrogen fixation, as well as my students' disynthesis, but it is difficult to convert it into other compounds ("fixing" nitrogen). This seminar will dscoveries of how to break the N–N bond of N<sub>2</sub> using homogeneous transition-metal complexes. In addition to new catalysts for producing ammonia, we have identified a new mechanism for sequential C-H activation and N-N activation to create C-N bonds. Detailed mechanistic studies reveal a cyclic reaction, which gives a route from atmospheric N<sub>2</sub> and petroleum-derived arenes to substituted anilines. This is an important step toward preparing useful chemicals using air as a starting material.
Universität Münster - "On Discovery and Sensitivity in (Photo)Catalysis" - Beginn: 16:00 Uhr - Hörsaal 2
This manuscript must either be drastically reduced or fully oxidized—scientific publishing from 1980 - 2030 . Scientific publishing has undergone in less than a generation a transformation from an all paper-and-print based to a fully digital/online business. In the future artificial intelligence will bring about further significant changes affecting authors, referees, and readers alike. From 1980 until today the number of annually published scientific manuscripts has increased from ca. 450.000 to ca. 4.5 Mio. 10% of which originate from chemistry. This growth is at the origin of discussions about all aspects of scientific publishing including peer review, open access and ethical problems. The lecture will touch on many of the issues and will provide facts and figures as well as food for thought—interspersed with anecdotes from the life of an Editor.
Copper makes the difference: Developing Sustainable Photoredox Catalyzed Transformations Synthetic organic chemistry undertakes significant efforts to develop new catalytic transformations that utilize greener reagents and avoid stoichiometric additives. In this regard, visible-light photoredox catalysis offers a unique activation mode of molecules, which serves as an alternative to many thermal transition-metals catalyzed reactions. The vast majority of photoredox-catalyzed processes capitalizes on heavy metals, namely, Ru(II) or Ir(III)-complexes which can serve as single electron oxidants or reductants in their photoexcited states.
Low-valent silicon complexes and their analogues: surprising and peculiar behaviors For over ten years, we have been developing the chemistry of low-value silicon complexes with a unique phosphine ligand system. These complexes exhibit special properties (somewhat like transition metals). When this ligand system is applied to synthesize other stable complexes of low-valent main-group elements, they also exhibit peculiar and surprising behaviors, allowing us to develop even more amusing chemistry. In my talk, I'll present some recent results on their chemistry.
Bio-inspired catalysts for clean H<sub>2</sub> production Hydrogen production through water splitting emerges as a pertinent solution in the long run for renewable energy storage. Hydrogenases, which are organometallic enzymes containing iron and/or nickel metal centers, exhibit catalytic performances that rival platinum for hydrogen evolution. Their fascinating properties make them the ideal inspiration for designing molecular catalysts for technological devices. During this presentation, the bio-inspired strategy will be illustrated: How can this approach be at the origin of efficient systems that achieve H<sub>2</sub> production in a catalytic manner? How can it provide helpful information regarding the catalytic mechanism of the enzymes?
Chemistry Bachelor Award Ceremony BASF´s Net Zero Accelerator In Mar of 2021 BASF presented their plans to reduce the scope 1&2 CO2 emissions in 2030 by 25% and develop a pathway towards net zero emissions until 2050. In order to drive this global transformation, the department Net Zero Accelerator was founded in Jan 2022 with the task to coordinate and accelerate the transformation. I will present, how BASF is approaching the reduction of scope 1&2 emissions and talk about the importance of creating transparency and understanding thermodynamic principles to identify the major technological challenges. I will explain, why -with regard to scope 1 & 2- we need an energy transformation in order to be able to achieve the -80% to -90% emission reduction goals, what technological opportunities & challenges there are by electrification of chemical processes & utilities and what BASF is doing in order to get access affordable renewable energy, which is a key enabler for the electrification.
Making, Seeing, and Using Subvalent Nitrogen Species Direct C H amination chemistry via electrophilic subvalent nitrogen intermediates could radically simplify access to nitrogen containing small molecules by providing the chemical tools to selectively convert ubiquitous C H bonds to valuable C N bonds At present, challenges in chemoselectivity sustainability, and synthetic versatility prevent realization of the synthetic potential of C H amination.This talk will describe recent efforts from the Powers Laboratory that advance 1 new strategies to structurally characterize transient intermediates in C H functionalization reactions, 2 novel metal free approaches to the sustainable generation of strong oxidants needed in C H functionalization reactions, and 3 bifunctional reagent platforms that enable rapid elaboration of the primary products of C H amination Future directions and challenges will be discussed.
Using NMR Spectroscopy to Evaluate Actinide-Ligand Bond Covalency Understanding actinide-ligand covalency is at the center of efforts to design new separations schemes for spent nuclear fuel, and thus features considerable practical importance. NMR spectroscopy is a widely available means of measuring 5f covalency that is complementary to more established methods, such as optical spectroscopy and XANES. However, its use for this purpose is still in its infancy. Herein, I will discuss our efforts to develop 1H and 13C NMR spectroscopy for the evaluation of An-L covalency in a wide variety of diamagnetic actinide complexes, including thorium allenylidenes and thorium hydrides.
Quantum Travellers – the Role of the Radical Pair Mechanism in Avian Magnetoreception Here we report that the photochemistry of cryptochrome 4 from the night-migratory European robin (Erithacus rubecula, ErCry4) is indeed magnetically sensitive in vitro, and compare the results to those found for Cry4 from two non-migratory bird species, chicken and pigeon. Site-specific mutations of ErCry4 in combination with Electron Paramagnetic Resonance studies are used to demonstrate the roles of four successive flavin-tryptophan radical pairs in generating magnetic field effects and in stabilising potential signalling states. Reference: Xu J. et al., Nature, 2021, 594, 535-540.
Supramolecular Gels & Polymers: From Superhydrophobic and Slippery Surfaces to Directional Transport along Gradients In the first part, a very simple production procedure for superhydrophobic and slippery surfaces is reported. The deposition of a gel leads to the surface roughness needed for superhydrophobicity and in a way mimics the Lotus leaf effect. The second part of the talk discusses approaches to chemically and light-switchable mono- and multilayers of rotaxanes on gold surfaces. With alternating layer-by-layer deposition of the tetralactam macrocycles or the corresponding rotaxanes and various connecting metal ions, coordination oligomers with well-defined sequences can be built that are anchored on one end on the surface. The third part discusses how to use a supramolecular polymer self-assembling from easy-to-synthesize monomers as a supramolecular machine for the directional transport of particles as their cargo over millimeter distances.
Vorträge der Preisträger Anna Kny: Chemical bonding of Merocyanines on the Ag(100) surface - An investigation at the synchrotron light source Anne Müller-Feyen: Synthesis of Bidentate Ligands for Metallo-supramolecular Pd Cages Prof. Dr. Klaus Müllen, MPI für Polymerforschung Mainz: A Discovery Tour from Synthesis to Function Anschließend Snacks und Getränke mit dem JCF Bonn
Professor Dr. Karl Gademann, Universität Zürich Microbiome Metabolites: Syntheses and Surprises The microbiome is composed of different microorganisms such as bacteria that live on or in a complex host, such as e.g. humans or plants. Estimates suggest that bacterial cells outnumber their human host cells by as much as 10:1, leading directly to the question: Who is in control? Interactions, and ultimately control of the microbiome with their host might involve the trading and trafficking of chemicals. We will present recent studies from our group investigating small molecule chemicals that serve as signals for bacterial communication, cyclitols for chemical offense, and a recent total synthesis of peyssonnoside A which might be produced by the microbiome of red algae, complemented with other terpene syntheses.
Prof. Dr. Erwin Reisner, University of Cambridge, UK: Sunlight-Powered Circular Chemistry Solar panels are well established to produce electricity as photovoltaic cells and are already in advanced development to photo-catalyse overall water splitting to produce green hydrogen as artificial leaves or photocatalyst sheets. This presentation will introduce solar chemistry panels as an emerging technology to enable sunlight-powered circular carbon chemistry. Our progress in designing and constructing prototype solar devices for the direct conversion of carbon dioxide as well as the coupling to the valorisation of biomass and plastic waste streams into renewable fuels and higher-value chemicals will be presented.
Prof. Dr. Helmut Grubmüller, MPI für Multidisziplinäre Naturwissenschaften, Göttingen Microtubules' bends, cryo-cool ribosimes, and wet proteins The extraordinary diversity and complexity that evolution has produced over the course of around one to two billion years is simply amazing. We are fascinated by the very complex and highly specialized organs that are familiar to us -- such as the eye, muscles, and brain. Nevertheless, evolution has achieved its masterpieces much earlier on the molecular level: Without similarly complex biological macromolecules such as proteins, life would be impossible. Combining atomistic computer simulations and statistical mechanics approaches, we are beginning to gain a better understanding of how these highly specialized 'molecular machines' perform their very diverse functions.
GDCh-Kolloquium: Junge Forscherinnen und Forscher der Bonner Chemie stellen sich vor ..............................
