Dream Chemistry Lectures series


    Dr. Yujia Qing
University of Oxford

"Single-molecule covalent chemistry under confinement"

14 May 2020 [#18]
Abstract:Covalent chemistry can be observed at the single-molecule level by using engineered protein pores as nanoreactors. Individual bond-breaking and bond-making events are monitored in real-time as perturbations to the ionic current passing through the nanopores. Through this approach, we have detected short-lived intermediates of small-molecule reactions and determined the kinetic rate constants for their formation and breakdown. We have further exploited the nanoscale dimensions of protein nanoreactors to study chemistry under confinement. Site-selective control of chemistry on polymers confined within a nanoreactor has been established by spatial organisation of the reactants. The associated chemistry has been elaborated into a remarkable molecular machine, a molecular hopper, which takes directional sub-nanometre steps along a protein track while carrying a DNA cargo. The ability to ratchet individual biopolymers through a detector with chemical control might facilitate the development of a highly parallel universal sequencing platform.

 


    Prof. Timothy Noël
Eindhoven University of Technology, Department of Chemical Engineering & Chemistry, Micro Flow Chemistry & Synthetic Methodology, Eindhoven, The Netherlands

"Exploring new chemical territory through use of flow"

5 March 2020 [#17]
Abstract:
Until recently, many reactions have been exclusively performed in conventional batch LabWare. With the advent of microreactor technology, significant effort has been devoted to develop a wide variety of continuous-flow techniques to facilitate organic synthesis. Microreactor technology offers several advantages compared to traditional batch reactors, such as, enhanced heat- and mass-transfer, improved irradiation, safety of operation and the possibility to integrate several reaction steps and subsequent separations in a single streamlined process.

Our group has taken a great interest in assisting chemists by developing automated and flow-based reaction technologies capable of reducing manual labor, increasing the reproducibility of the results and accelerating reaction discovery. In this presentation, we will give an overview of our synthetic methodology development, exemplified by photoredox catalysis, cross-coupling and electrochemistry and how these synthetic methods were impacted by continuous-flow microreactor technology. Furthermore, we will discuss the developed technology and reaction models in detail.

 


    Prof. Matthias Heinemann
Faculty of Science and Engineering, University of Groningen, The Netherlands

"The limits to growth: The cellular challenge to dissipate Gibbs energy"

6 February 2020 [#16]
Abstract:
More than 1000 chemical reactions constitute the cellular metabolic network, which is responsible for the conversion of nutrient molecules into building blocks for new cells and energy. While the network itself is long known, we are still basically clueless on how molecules ‘travel’ through this network, what the regulatory mechanisms are that ‘steer’ the molecule fluxes through the network, and what the constraints and principles are that governs metabolism. Yet, understanding all this is important from a fundamental research point of view, but also for applications in biotechnology and biomedicine. Here, after a short introduction into the challenges in the field of metabolism, I will introduce a recently discovered physical constraint, which cellular metabolism apparently needs to obey. Specifically, through model-based analysis of experimental data, we recently have found that cellular metabolism is constrained by the rate with which cells can dissipate Gibbs energy to the environment. This finding could explain why certain organisms show a peculiar metabolism, such an aerobic fermentation, which is responsible in yeast cells for alcohol production and in cancer cells for lactate excretion. I will conclude with speculating of what the mechanistic, i.e. physical, basis of this uncovered limit could mean.

 


    Prof. Christian Klinke
Institute of Physical Chemistry, University of Hamburg
Chemistry Department, Swansea University
Institute of Physics, University of Rostock

"Semiconductor-like properties in metal particle films"

28 November 2019 [#15]
Abstract:
I will present a concept based on colloidal metal nanoparticles[1] and nanoclusters[2] on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. The combination of the high-quality chemically synthesis of the materials with scalable surface deposition methods and lithography techniques results in transistors, which show high on/off ratios, reliable transfer characteristics, and good room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties. The results demonstrate the potential of metal particles as solution processed materials for semiconducting devices.

[1] S.Willing, H.Lehmann, M.Volkmann, Ch.Klinke; Metal nanoparticle film-based room temperature Coulomb transistor , Science Advances 3 (2017) e1603191.
[2] M.Galchenko, A.Black, L.Heymann, Ch.Klinke; Field effect and photoconduction in Au25 nanoclusters films, Adv. Mater. (2019) 1900684, 10.1002/adma.201900684.

 


    Prof. Micheál D. Scanlon
The Bernal Institute and Department of Chemical Sciences,
School of Natural Sciences, University of Limerick, Ireland

"Photoelectrochemistry and Reversible H-J Interconversion of Porphyrin Nanostructures at an Electrified Soft Interface"

21 November 2019 [#14]
Abstract:
Certain soft interfaces formed between aqueous and organic electrolyte solutions of low miscibility ( e.g., trifluorotoluene) are electrochemically active in the sense that it is possible to precisely control the Galvani potential difference between the two adjacent liquids ( i.e., to “polarise” or electrify the interface), and thus drive charge transfer reactions. Such interfaces are denoted interfaces between two immiscible electrolyte solutions (ITIES). The ITIES can be controllably electrified by application of a potential either externally through the use of electrodes immersed in both phases or through a common ion dissolved in the organic and aqueous phases.
 
Synthetic molecular assemblies at soft interfaces exhibit macroscale long-range order and so provide routes to biomimetic analogues that minimise concentration quenching. In this presentation, I will describe a new route to the facile assembly of free-standing layered crystalline films of zinc(II) meso-tetrakis(4-carboxyphenyl)porphyrin interfacial nanostructures. I will demonstrate the reversible structural rearrangement of these porphyrin supramolecular structures floating at the liquid-liquid interface from a H- to J-type configuration upon varying the interfacial Galvani potential difference . The latter structural changes were observed in situ by UV/vis and potential modulated fluorescence spectroscopies (both under total internal reflection at the electrified soft interface).

The porphyrin interfacial nanostructures exhibit significant photocurrents in situ at an electrified liquid | liquid interface, providing a new paradigm for realisation of light-harvesting antennae in artificial photosynthetic technologies. To explore this possibility, photo-induced electron transfer between organic electron donors, like ferrocene derivatives, and aqueous electron acceptors, like O 2 , is achieved by controllably modulating the voltage across the interface (see Fig. 1).


Fig. 1 Schematic of “soft-photoconversion”; converting light energy to chemical energy using dye-sensitised electrified liquid | liquid interfaces. The donor species (D) is decamethylferrocene and the acceptor species (A) is O2. Light energy is converted to chemical energy in the form of the oxidised donor (D+) and reduced acceptor (A–) spatially separated on either side of the liquid | liquid interface.

 


    Dr. Krzysztof Fic
Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Poland

"Towards understanding the electrode/electrolyte interface for better electrochemical capacitors and energy storage systems"

24 October 2019 [#13]
Abstract:
This lecture will provide comprehensive insight on the application of the in-situ and operando techniques such as Raman spectroscopy, Quartz Crystal Microbalance (EQCM), Scanning Electrochemical Microscopy (SECM), On-line Electrochemical Mass Spectroscopy (OEMS) and Operando Contact Angle Measurements (oCAM). These techniques were applied for determination of charge storage phenomena and ageing factors in activated carbon-based supercapacitors, operating with aqueous electrolytes.
It has been already confirmed with in-situ Raman spectroscopy that activated carbon electrodes operating in neutral aqueous media like Li2SO4 or LiNO3 solutions are prone to a mild oxidation during cycling (vibration modes from oxygen-based functionalities found) whereas the surface chemistry of negative electrode appears to be unchanged. EQCM study confirmed significant frequency/mass variation of the positive electrode. However, SECM demonstrated that during positive and negative polarization, the thickness (and volume) of the negative electrode changes remarkably, even within the typical capacitive storage range. This might be related with the specific adsorption of the solvated Li+ specimen. Interestingly, oCAM indicated that the hydrophobic/hydrophilic properties of activated carbon surface change with the polarization direction and potential values. OEMS confirmed that for more hydrophilic surfaces, more CO and CO2 gases should be expected at elevated voltages. It has been also shown that redox-active electrolytes (e.g. solutions of alkali metal iodides, bromides, thiocyanates) might have a detrimental impact on the carbon electrode performance. An oxidation of carbon surface has been identified near the iodide/iodine redox activity potentials, being even more pronounced for bromide-based systems. While EQCM study confirmed the presence of various iodine species in the electrolyte, carbon ‘corrosion’ has been observed especially for more concentrated iodide solutions.

 


    Prof. Max von Delius
Institute of Organic Chemistry and Advanced Materials, University of Ulm, Germany

"Self-Assembly of Adaptive Orthoester Architectures"

13 June 2019 [#12]
Abstract:
Dynamic covalent chemistry (DCC) is a powerful tool for probing non-covalent interactions, identifying ligands for medicinally relevant biological targets, and for making use of the feature of “error correction” to achieve the synthesis of interesting molecules and materials.
In this talk, I will present our recent work on a previously ignored dynamic covalent reaction: the acid-catalyzed reaction of O,O,O-orthoesters with alcohols (Fig. a), which we were able to use for the one-pot synthesis of cryptates, in which orthoesters act as tripodal bridgeheads. Due to their unique structure (Fig. b), these compounds exhibit a range of unusual properties, including tunable, pH-dependent hydrolysis (Fig. c). Most notably, dynamic orthoester architectures offer an elegant entry to experiments, in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents (“adaptive host-guest systems”, Fig. d). Of particular relevance to the area of systems chemistry is our recent discovery that ammonium complexes of orthoester cryptands represent the first example of “fluxional supermolecules”, i.e. these host-guest complexes are inherently dynamic and adaptive.
I will close the talk by discussing our ongoing work towards extending the scope of suitable guest ions and using these compounds for the transport of ions across phospholipid membranes.

 


    Prof. Pawe³ Dydio
Institute of Science and Supramolecular Engineering, University of Strasbourg & CNRS

"Dual-catalytic systems for functionalization of unreactive sites of molecules"

6 June 2019 [#11]
Abstract:
Catalytic functionalization reactions occur readily at sites of starting materials that are both innately reactive and sterically accessible or that are predisposed by a functional group capable to direct a catalyst. However, selective reactions at unbiased sites of substrates remain challenging and typically require additional pre-activation or directing group installation steps, or the use of highly reactive reagents. Therefore, the synthetic methodologies enabling for direct and selective functionalization of typically unreactive sites are highly desired.
Here I will present our studies dedicated to the development of dual-catalytic systems that enable selective functionalization reactions of substrates at their unreactive sites, such as ubiquitous unactivated C-H bonds. Our strategy rests on merging a metal-catalyzed reversible reaction and a metal-catalyzed functionalization reaction. Due to the mild reagents and conditions of both the reversible reaction and the functionalization reaction, the devised methodologies are general and compatible with a broad scope of substrates, including natural product-like molecules. These studies highlight the potential of the multi-catalytic approach to address challenging transformations to circumvent multi-step procedures and use of highly reactive reagents in organic synthesis.

 


    Prof. Ville-Veikko Telkki
NMR Research Unit, Faculty of Science, University of Oulu, Finland

"Ultrafast Laplace NMR"

30 May 2019 [#10]
Abstract:
Relaxation and diffusion NMR (Laplace NMR) experiments provide versatile information about the dynamics and structure of substances. Like in traditional NMR spectroscopy, the resolution and information content of LNMR can be significantly increased by the multidimensional approach. However, long experiment time restricts the applicability of the multidimensional methods. As a solution for this problem, we are developing a broad range of ultrafast, single-scan multidimensional LNMR experiments, based on the principles of continuous spatial encoding that have been successfully applied in ultrafast multidimensional NMR spectroscopy. The method shortens the experimental time by one to three orders of magnitude as compared to the conventional method. Furthermore, it facilitates significantly the use of hyperpolarized substances to boost the sensitivity by several orders of magnitude. The method has many interesting applications in various disciplines. It is also feasible with low field, single-sided instruments, which are portable and much cheaper than the high-field spectrometers.

 


    Dr. Danny Müller
Institute of Applied Synthetic Chemistry, Vienna Uni of Technology, Austria

"Thermochemical energy storage for sustainable energy solutions"

23 May 2019 [#9]
Abstract:
Mapping the actual energy landscape, heat is the most ubiquitously used form of energy including electricity generation and industrial purposes. Only for the thermal generation of electricity, the International Energy Agency estimates the global energy loss through heat losses to account for 2/3 of the necessary primary energy. Thermal energy storage could reveal as a true game-changer, allowing for a notable decrease of necessary energy, thus reducing the energy footprint. This could assist a widespread acceptance and utilization of renewable energy, as well as the use of fluctuating energy sources.

Waste heat sources, but also natural energy sources such as the sun or wind suffer from a distinct temporal mismatch between energy production and consumption that needs to be overcome. The development of efficient heat storage concepts allows herein for a temporal shift, enabling utilization of excess heat, collected in times of high availability / low demand, during times of low availability / high demand. In other words, the success of many renewable energy concepts and waste heat recycling in today’s energy landscape is directly related to matching supply and demand and further, directly to development and availability of efficient heat storage technologies.

Dr. Danny Müller focusses together with his collaborators on the investigation of novel materials tailored for specific thermochemical storage applications. Based on a systematic selection process over 5,000 potential materials were screened and investigated for their potential in energy storage. In the last few years they developed according to the applied reactive gas (H2O, CO2, NH3, O2) various thermochemical storage solutions for different temperature levels allowing for application in housing, combination with solar thermal and industrial waste heat recycling. The contribution concentrates on the way from a systematic laboratory study to a first prototype of a storage system, the applicational potential of the technology and current obstacles on the way to a commercial use.

 


    Dr. Peter Korevaar
Institute for Molecules and Materials, Radboud University Nijmegen, The Netherlands

"Building life-like materials that self-organize at mesoscopic scale"

16 May 2019 [#8]
Abstract:
Living matter has unique properties that are a great source of inspiration to create materials with unprecedented characteristics. Departing from molecular self-assemblies that operate under equilibrium conditions, non-equilibrium systems are increasingly explored to introduce life-like behaviour into synthetic matter.
In our research group, we build chemical systems that pick up stimuli from their environment and process these into behavior that is programmed by (physico)chemical mechanisms. Inspired by slime molds that grow long wires and form networks while exploring surfaces to localize food, we developed a chemical system of amphiphiles that assemble into networks of centimeter-long filaments. These filaments coordinate as they grow, driven by Marangoni effects, the self-organization of droplets at aqueous surfaces. A simple model rationalizes different types of spatial self-organization, depending on the kinetic rates of amphiphile release and -depletion. Furthermore, insights from the model enable feedback mechanisms – positive and negative – to the growth of filaments, by manipulating the Marangoni flux upon controlled (de)-activation of surfactant molecules, which lead to adaptability of the network connections. We foresee that these principles will contribute to new classes of life-like materials, driven by autonomously operating systems that transfer chemical signals through spontaneously emerging and re-wiring self-assembled connections.

 


    Prof. Konrad Tiefenbacher
Dept. of Chemistry, University of Basel, Switzerland
Dept. of Biosystems Science and Engineering, ETH Zurich, Switzerland

"Terpene Biosynthesis as Inspiration for Supramolecular Catalysis"

25 April 2019 [#7]
Abstract:
Nature’s extraordinary elegance when performing chemical reactions has fascinated and inspired chemists for decades. Arguably, one of the most complex organic transformations performed in living organisms, is the tail-to-head terpene (THT) cyclization. It allows the construction of the most diverse class of natural products, namely terpenes, via nature’s way of combinatorial chemical synthesis. Thousands of different natural products are formed from just a handful of simple, acyclic starting materials: geranyl pyrophosphate (monoterpenes), farnesyl-PP (sesquiterpenes) and geranylgeranyl-PP (diterpenes). Nature utilizes enzymes, termed cyclases or terpene synthases, to carry out this complex transformation. Building upon our initial results, we explore possibilities to utilize supramolecular structures to mimic such complex transformations in the laboratory.

 


    Dr. M. Selim Hanay
Dept. of Mechanical Engineering, Bilkent University, Ankara, Turkey
National Nanotechnology Research Center (UNAM), Bilkent University, Ankara, Turkey

"Resonator-Based Spectroscopy: Sizing Cells and Large Molecules"

21 March 2019 [#6]
Abstract:
Mechanical and Electromagnetic Resonators at the micro/nanoscale can be used as exquisite sensors of physical changes, such as the mass and polarizability of a species. We will explore two such sensing paradigms in this talk:
1) Nanoelectromechanical Systems (NEMS) for the Mass Spectrometry of large single biomolecules and nanoparticles, and
2) Microfluidics-Integrated Microwave Sensors for sizing of single cells.

In the first half of the talk (NEMS based Mass Spectrometry), I will argue that conventional forms of Mass Spectrometry face certain challenges when the molecular weight of the species becomes larger than the MegaDalton range which is the regime for large biomolecules, organelles and viruses. In this mass range, nanomechanical devices can offer novel advantages in terms of mass spectrometry, and beyond —such as the simultaneous extraction of molecular shape information. The principles developed for the mechanical resonators can be extended to electromagnetic resonators. For instance, the microwave frequency range seems extremely advantageous for accurate sizing of single-cells in a microfluidic environment. Thus, in the second half of my talk, I will focus on this new approach, a radar for cells, for performing real-time single cell analysis.

 


    Dr. Jesús Campos
Institute for Chemical Research (IIQ), CSIC-University of Sevilla, Spain

"Developing new cooperative strategies for catalysis, or dreaming about it"

7 March 2019 [#5]
Abstract:
In the early 80s Chisholm proposed that “all the types of reactions which have been studied for mononuclear transition metal complexes will also occur for dinuclear transition metal complexes”. Almost 40 years later, continued research on the area of bimetallic systems has proven that claimed and gone beyond, even exploiting the chemistry of many polymetallic and cluster species. Regarding catalytic applications, there are many important transformations that require the concerted action of pairs of active metal sites, paralleling what is often found in metalloenzymes. This fertile area of research inspired us to start investigating less explored concepts in the field of cooperative chemistry with the aim of developing novel catalytic applications. In one of our approaches, we focused on late-transition bimetallic systems characterized by the use of sterically hindered phosphine ligands containing a terphenyl (2,6-C 6 H 3 -Ar 2 ) substituent. We now can tune the formation of M-M bonds versus M···M frustration with interesting outcomes in terms of reactivity. In a related approach and within a dreaming standpoint we have also tried to develop cooperative molecular materials that rely on Coulombic forces to produce heterogeneized catalysts. The two strategies, namely our future dreaming chemistry and also our down-to-Earth results on bimetallic pairs will be discussed.

 


    Dr. Thomas Juffmann
Max F.Perutz Laboratories, University of Vienna, Austria

"Can we image the folding conformation of a single protein?"

21 February 2019 [#4]
Abstract:
Optical phase contrast microscopy and cryo-electron microscopy are widely used in the study of cells and proteins, respectively. In both techniques, a specimen imparts a phase shift on the probe (photons or electrons), which can be measured using various interferometric techniques.
In this talk I will briefly discuss the physical basics and limits of phase microscopy, and will show ways how to improve on current techniques using wave-front shaping, cavity or quantum enhanced measurements. I will demonstrate how wave-front shaping can enable phase contrast imaging with optimized sensitivity all across the field of view, and how multi-passing the probe particles through a sample can be used for high sensitivity / low damage imaging. The latter could potentially allow for cryo-electron microscopy with unprecedented resolution.

 


    Prof. Dr. Pablo Rivera-Fuentes
Dept of Chemistry and Applied Bioscences, ETH Zürich, Switzerland

"Chemical tools for single-molecule imaging in live cells"

7 February 2019 [#3]
Abstract:
Single-molecule imaging enables the observation of cellular structures with nanometric resolution. In densely labeled samples, however, emission from molecules that are closer than the diffraction limit of light appear as a single signal. To enable the localization of such molecules beyond the diffraction limit, photoactivatable or photoswitchable dyes have been developed. In recent work, we extended this concept to combine photoactivation and other chemical processes to tackle some of the current challenges in single-molecule imaging. For example, we have developed probes that enable the observation of single molecules of enzymes based on their activity. We have also created fluorophores with a polarity-dependent photoactivation mechanism, allowing to image intracellular lipid domains with nanometric resolution. Moreover, dyes that combine photoactivation and fluxional equilibria have allowed us to perform very long time-lapse, super-resolved imaging of synaptic vesicles in live human neurons with minimal phototoxicity or photobleaching. These experiments have revealed details of the 3D compartmentalization of these vesicles.

 


    Dr. David Martinez-Martin
Dept of Biosystems Science and Engineering, ETH Zürich, Switzerland

"Tracking a cell's mass in real time: a new indicator of cell physiology"

24 January 2019 [#2]
Biography

  • Bachelor’s + Master’s degree in Physics (2005). University of Valladolid (Spain). Summa Cum Laude
  • PhD in Physics (2011). Autonomous University of Madrid (Spain). Summa Cum Laude
  • Postdoctoral EMBO Fellowship. ETH Zurich (2013-2015)
  • Scientist and Project Manager. ETH Zurich (2016-currently)
  • Senior Lecturer. University of Sydney (offer accepted)
  • Selected achievement: Technology to measure mass changes of a single living cell in real time.
 


    Dr. Dominik Kubicki
Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

"How Physical Chemistry advances Materials Science: solid-state NMR of lead halide perovskites for optoelectronics"

19 December 2018 [#1]
Abstract:
Organic-inorganic lead halide perovskites are a promising family of light absorbers for a new generation of LEDs and solar cells, with reported efficiencies currently exceeding 22%. The field of perovskite photovoltaics is largely driven by systematic optimization of numerous parameters affecting the performance of perovskite solar cells. Such a trial-and-error approach, not backed up by atomic-level understanding of the reasons behind successes and failures, makes rational design of new compositions with better properties extremely difficult. Here, I will show how we use high-field multi-nuclear (1H, 2H, 13C, 14N, 15N, 133Cs, 87Rb, 39K) solid-state magic angle spinning NMR to provide for the first time atomic-level understanding of the different doping strategies used to improve photovoltaic performance of lead halide perovskites. These advances were largely enabled by a new solid-state method of synthesizing highly pure and crystalline lead halide perovskites: mechanosynthesis.