Program

May 12, 2021 : Start Minisymposium 2021
08:30 - 09:00

Conference Platform Open - Morning Coffee

Have your morning coffee together within our virtual conference venue! Networking rooms open to meet up with other participants. Posters available for viewing. Technical support can be contacted if needed.

May 12, 2021 : Session 1 (Chair: M. R. Buchmeiser)
09:00 - 09:15

Welcome

  • Prof. Michael R. Buchmeiser  

Welcome and technical announcements.

09:15 - 10:00

Catalytic Access to a New Class of Enabling Compounds: Trisubstituted Olefins with a Fluoro-Chloro Terminus

  • Prof. Amir H. Hoveyda  

Organofluorine compounds are vital to drug discovery, development of agrochemicals, and materials science. Particularly sought after are trisubstituted alkenyl fluorides, which, among other functions, are secondary amide bond mimics in one stereoisomeric form and help induce peptide turn in the other. Yet, accessing fluoro-alkenes by laboratory synthesis, which is the only way of obtaining them, is severely limited. In this Lecture we will discuss a broad-ranging strategy by which trisubstituted alkenes with a stereochemically defined fluoro and chloro terminus can be synthesized. The core transformation is catalytic and unprecedented: cross-metathesis between two trisubstituted olefins, one of which is a purchasable but rarely utilized trihalo alkene. Reactions are typically promoted by a commercially available organometallic complex, furnishing products that can be efficiently converted to many trisubstituted alkenyl fluorides in either stereoisomeric or regioisomeric form. The utility of the advance will be highlighted by concise syntheses of a variety of fluoro-organic molecules that are of considerable value to therapeutic and materials science.

10:00 - 10:15

Break/ Meet the Speaker - Hoveyda

  • Break for coffee and more in-depth individual discussions.   Prof. Amir H. Hoveyda  

Participants can ask more specific questions in a direct video conference. Please join the speaker actively in the announced virtual room if you would like to ask questions.

10:15 - 10:45

Ru-Catalyzed Alkylation of Amines using Alcohols – Borrowing Hydrogen Catalysis in Confined Geometries as a Case Study for Tandem Catalysis

  • Prof. Bernd Plietker  

The direct alkylation of amines using alcohols as alkylating agents is commonly done under acid catalysis, which limits the application scope. The concept of borrowing hydrogen (or hydrogen autotransfer) catalysis has more recently shown to be a promising new strategy to overcome this limitation. The overall process of alcohol dehydrogenation, condensation and hydrogenation is a prime example for a tandem catalysis, it is more step economic and avoids formation of stoichiometric amounts fo problematic side products such as salts, bases, etc. In the vast majority of reported cases the intermediate condensation reaction is the rate limiting step, a problem which is commonly addressed through addition of either alcohol or amine in large excess. Only a very few examples for a stoichiometric reaction are reported. In this lecture the results of hydrogen autotransfer catalysis inside mesoporous materials using molecular heterogenous Ru-catalysts will be discussed. Both concepts for the selective “inner-pore” functionalization but also the influence of linker rigidity, linker length and pore wall hydrophilicity will be presented.

10:45 - 11:15

Asymmetric Rh(Diene)-Catalyzed Nucleophilic Additions under Confinement: Taking Initial Steps from Homogeneous Conditions to Mesoporous Solids

  • Prof. Sabine Laschat  

Chiral dienes have been developed into highly promising ligands, which can effectively control the stereochemistry of a variety of Rh-, Ir- and Pd-catalyzed reactions, mostly conjugate additions, nucleophilic additions to carbonyl analogues, cycloadditions, rearrangements and several other reactions.[1,2,3] However, the performance of chiral metal diene complexes under confined conditions has not been explored. Therefore, we developed two sets of chiral diene ligands with complementary polarity and investigated them under homogeneous conditions in the Rh-catalyzed 1,2-addition of boroxines to tosylimines and 1,4-additions of boronic acids to enones. When the reactions were performed in microemulsions significant rate acceleration was observed due to the liquid confinement.[4] Further mechanistic and theoretical studies provided insight into the role of the neutral vs. cationic Rh catalysts,[5] which finally helped us to tailor suitable solid confinements. ____________________________________________________________________________ [1] a) C. Defieber, H. Grützmacher, E. M. Carreira, Angew. Chem. Int. Ed. 2008, 47, 4482. B) J. B. Johnson, T. Rovis, Angew. Chem. Int. Ed. 2008, 47, 840. [2] S. Helbig, S. Sauer, N. Cramer, S. Laschat, A. Baro, W. Frey, Adv. Synth. Catal. 2007, 349, 2331. [3] T. Mühlhäuser, A. Savin, W. Frey, A. Baro, A. J. Schneider, H.-G. Döteberg, F. Bauer, A. Köhn, S. Laschat, J. Org. Chem. 2017, 82, 13468. [4] M. Deimling, M. Kirchhof, B. Schwager, Y. Qawasmi, A. Savin, T. Mühlhäuser, W. Frey, B. Claasen, A. Baro, T. Sottmann, S. Laschat, Chem. Eur. J. 2019, 25, 9464. [5] M. Kirchhof, K. Gugeler, F. R. Fischer, M. Nowakowski, A. Bauer, S. Alvarez-Barcia, K. Abitaev, M. Schnierle, Y. Qawasmi, W. Frey, A. Baro, D. P. Estes, T. Sottmann, M. R. Ringenberg, B. Plietker, M. Bauer, J. Kästner, S. Laschat, Organometallics 2020, 39, 3131.

11:15 - 11:30

Break/ Meet the Speakers - Plietker/ Laschat

  • Break for coffee and more in-depth individual discussions.   Prof. Bernd Plietker   Prof. Sabine Laschat  

Participants can ask more specific questions in direct video conferences with the speakers. Please join the speaker of your choice actively in the announced virtual room.

May 12, 2021 : Session 2 (Chair: J. van Slageren)
11:30 - 12:15

The Performance of Molecular Water Oxidation Catalysts Confined on Conductive and Semiconductive Surfaces

  • Prof. Antoni Llobet  

The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research has been devoted to this topic recently. Nature has been using sunlight as the primary energy input to oxidize water and generate carbohydrates (a solar fuel) for over a billion years. Inspired, but not constrained by nature, artificial systems[1] can be designed to capture light and oxidize water and reduce protons, CO2 or other compounds to generate useful chemical fuels and feedstocks. In this context, this contribution will describe the preparation of efficient molecular water oxidation catalysts both in homogeneous phase and confined into solid conductive or semiconductive supports. Further the nature of the anchoring strategy on the performance of these molecular (photo)anode will be further discussed as well their implications for the generation of solar fuels.[2] ____________________________________________________________________________ [1] (a) Berardi, S.; Drouet, S.; Francàs, L.; Gimbert-Suriñach, C.; Guttentag, M.; Richmond, C.; Stoll, T.; Llobet, A. Chem. Soc. Rev., 2014, 43, 7501-7519. (b) Matheu, R.; Ertem, M. Z.; Gimbert-Suriñach, C; Sala, X.; Llobet, A. Chem. Rev. 2019, 119, 3453–3471. (c) Matheu, R.; Garrido Barros, P.; Gil Sepulcre, M.; Ertem, M. Z.; Sala, X; Gimbert-Suriñach, C; Llobet, A. Nat. Rev. Chem. 2019, 3, 331–341. [2] (a) Creus, J.; Matheu, R.; Llobet, A. et al., Angew. Chem. Int. Ed. 2016, 55, 15382-15386. (b) Matheu, R.; Gray, H. B.; Brunschwig, B. S.; Llobet, A; Lewis, N. S. et al., J. Am. Chem. Soc. 2017, 139, 11345-11348. (c) Garrido-Barros, P.; Gimbert-Suriñach, C.; Llobet, A. et al., J. Am. Chem. Soc. 2017, 139, 12907–12910. (d) Hoque, Md. A.; Gil-Sepulcre, M.; Llobet, A. et al. Nat. Chem. 2020, 12, 1060–1066. (e) Schindler, D.; Gil‐Sepulcre, M.; Llobet, A.; Würthner, F. Adv. Energy Mater. 2020, 2002329.

12:15 - 12:30

Break/ Meet the Speaker - Llobet

  • Break for coffee and more in-depth individual discussions.   Prof. Antoni Llobet  

Participants can ask more specific questions in a direct video conference. Please join the speaker actively in the announced virtual room if you would like to ask questions.

12:30 - 13:00

2D Covalent Organic Frameworks as Molecularly Precise Platforms for Catalysis in Confinement

  • Prof. Bettina V. Lotsch  

Covalent Organic Frameworks (COFs) have emerged as a new generation of crystalline polymers with 2D or 3D network topologies and ordered micro- or mesoporosity. Their molecularly and spatially defined backbone opens up unique opportunities for catalysis, as a precise arrangement of molecular catalysts in the pore walls or pore interior - akin to the active sites of enzymes – is within reach. In photocatalysis, COFs have already left their fingerprint as a new generation of metal-free semiconductors and put a new spin on the development of “all-single-site” heterogeneous photocatalysts owing to their tunable optoelectronic properties, combined with ordered porosity. To advance our understanding of what drives photocatalytic activity and to translate this knowledge into rational catalyst design, detailed insights into the interplay between local and long-range structure as well as the role of confinement are necessary. In this talk I will present our recent progress towards the development of COF photocatalysts for the hydrogen evolution reaction and discuss the structural (local and long range), optoelectronic and catalytic boundary conditions guiding our design of all-single-site COF photocatalysts. Moving towards “designer pores” with covalently immobilized molecular catalysts, I will discuss the potential of COF-catalyst hybrids for molecular heterogeneous catalysis under confinement, specifically in the context of the hydrogen evolution reaction and alkene metathesis.

13:00 - 13:15

Break/ Meet the Speaker - Lotsch

  • Break for coffee and more in-depth individual discussions.   Prof. Bettina V. Lotsch  

Participants can ask more specific questions in a direct video conference. Please join the speaker actively in the announced virtual room if you would like to ask questions.

13:15 - 14:15

Lunch Break/ Poster Session

Please join the presenters in their individual virtual rooms via the announced conference platform.

May 12, 2021 : Session 3 (Chair B. V. Lotsch)
14:15 - 14:30

Award Ceremony - Best Master´s Thesis

14:30 - 15:15

Diffusion, Flow and Reaction in Hierarchical Silica Monoliths: From Morphological Reconstruction to Pore Scale Simulations to Continuous Flow Applications

  • Prof. Ulrich Tallarek  

Hierarchical, macro–mesoporous silica monoliths with domain sizes (sum of mean macropore size and skeleton thickness) of ~1 μm are highly efficient supports in solid–liquid catalysis. Their unprecedented performance regarding low backmixing, the elimination of internal and external diffusive transport limitations, as well as the simultaneous realization of a large (internal and external) surface area of the monolith skeleton allow reactor operation under exclusive reaction control in on-line coupled reaction–separation–analysis systems. It enables the precise, fully automated adjustment and control of all relevant reaction parameters and promises a boost in the rapid, reproducible determination of the intrinsic reaction kinetics, in general. Hydrodynamic and reaction kinetic parameters identify extreme plug-flow conditions with this high-surface-area, compact type of microreactor and quasi-homogeneous operation in continuous-flow mode. Relevant transport properties (effective diffusion coefficients and accessible porosities in the mesoporous skeleton; hydrodynamic dispersion coefficients in the interstitial macropore space) are derived through pore-scale simulations of hindered diffusion and advection–diffusion in realistic geometrical models of mesopore space and macropore space, respectively, obtained by tomographic methods. These complementary approaches to the transport and reaction dynamics define a general route to quantitative morphology–transport–functionality relationships in hierarchically structured materials.

15:15 - 15:30

Break/ Meet the Speaker - Tallarek

  • Break for coffee and more in-depth individual discussions.   Prof. Ulrich Tallarek  

Participants can ask more specific questions in a direct video conference. Please join the speaker actively in the announced virtual room if you would like to ask questions.

15:30 - 16:00

Atom Probe Tomography: A New Tool for Analysis of Soft Matter, Porous and Hybrid Materials?

  • Prof. Guido Schmitz  

Laser-assisted atom probe tomography is a cutting edge tool of microscopic analysis that has been well established in the study of hard matter such as metals, semi-conductors and ceramics. Single atoms are field-desorbed from the apex of needle-shaped samples. Subsequent to the measurement, time of flight spectroscopy and a dedicated computer processing deliver 3D maps of the atomic arrangement in single atom sensitivity and resolution. By contrast, the application of atom probe tomography to liquids, soft matter or macromolecular materials remains still a widely unexplored landscape. With new cyrogenic preparation methods, we recently opened a way to particularly study this exciting material class. Even the investigation of liquids, in the form of shock-frosted needles, has become now a regular option. It turned out that the field desorption characteristics of soft materials is fundamentally different from conventional solid materials. In response to lower bonding forces, the critical field strength for desorption is almost an order of magnitude less and as a consequence of this, complex mass spectra deliver a variety of larger molecular fragments. On the one hand, large fragments degrade the spatial resolution but on the other, they enable the promising option of identifying molecular moieties. The talk presents measurements of desorption fields of polar and unipolar solvents and of short linker molecules attached to metal or oxide surfaces. Desorbed fragments are compared to DFT calculations and simulations of the measurement process. It is shown how the size of detected fragments may be controlled by the measurement conditions. By quantitative interpretation of the mass spectra even different bonding strengths may be quantified. Isotope effects are discussed at example measurements of H2O and D2O. Strong variations in the evaporation field thresholds require a particular treatment in the tomographic reconstruction. New reconstruction algorithms are presented that are based on a statistical evaluation of many detection events and allow a realistic volume representation even in the case of complex hetero-structures.

16:00 - 16:30

Olefin Metathesis in Constraint Geometries Using Group 6 and 8 Metal Alkylidenes

  • Prof. Michael R. Buchmeiser  

Macrocyclic compounds can be synthesized via ring-closing olefin metathesis. However, for entropic reasons, syntheses at high substrate concentrations are impeded by competing oligomerization via acyclic diene metathesis (ADMET) oligomerization. Using a Hoveyda-Grubbstype catalyst, immobilized in the pores of mesoporous silica, a variety of macrocyclization reactions have been accomplished under spatial confinement.[1] For a successful implementation of the confinement concept, a selective fixation of catalyst inside the pore system turned out to be vital (Scheme 1). Scheme 1. Selective immobilization of a catalyst inside mesopores for macrocyclization in confined geometries. Under confined conditions, macro(mono)cyclization (MMC) efficiency was increased from 35% obtained with the homogeneous catalyst, to 60%. A correlation between the MMC efficiency and the substrate-to-pore-size ratio was successfully established. Silanization of the inner pore surface allowed to fine-tune the effective pore size and to reverse surface polarity, which resulted in a further increase of MMC efficiency to 68%. Reactions carried out under continuous flow[2] allowed for monitoring accessible porosity and effective diffusion coefficients resulting from steric and hydrodynamic interactions between tracers and pore space confinement. Time-resolved analysis of the reaction mixture revealed that no higher oligomers are formed inside the pores. Also, the time needed to reach the ring-chain equilibrium was identified. In an extension of this work, novel Moimido, W-imido and W-oxo alkylidene N-heterocyclic carbene (NHC) complexes, which constitute a new class of catalysts for alkene metathesis,[3] have been selectively immobilized in mesoporous SBA-15. With these catalysts, MMC reactions can be run at high substrate concentration (0.1 M) reaching >80% MMC selectivity.[4] __________________________________________________________________________ [1] F. Ziegler, J. Teske, I. Elser, M. Dyballa, W. Frey, H. Kraus, N. Hansen, J. Rybka, U. Tallarek, M. R. Buchmeiser, J. Am. Chem. Soc. 2019, 141, 19014. [2] a) U. Tallarek, J. Hochstrasser, F. Ziegler, X. Huang, C. Kübel, M. R. Buchmeiser, ChemCatChem 2021, 13, 281 ; b) F. Ziegler, M. Pyschik, T. Roider, C. P. Haas, D. Wang, U. Tallarek, M. R. Buchmeiser, submitted 2021. [3] a) M. Benedikter, J. Musso, M. K. Kesharwani, K. L. Sterz, I. Elser, F. Ziegler, F. Fischer, B. Plietker, W. Frey, J. Kästner, M. Winkler, J. van Slageren, M. Nowakowski, M. Bauer, M. R. Buchmeiser, ACS Catal. 2020, 10, 14810 ; b) M. J. Benedikter, F. Ziegler, J. Groos, P. M. Hauser, R. Schowner, M. R. Buchmeiser, Coord. Chem. Rev. 2020, 415, 213315. [4] F. Ziegler, M. J. Benedikter, H. Kraus, K. Weißer, N. Hansen, M. Dyballa, M. R. Buchmeiser, unpublished 2021.

16:30 - 16:45

Break/ Meet the Speakers - Schmitz/ Buchmeiser

  • Break for coffee and more in-depth individual discussions.   Prof. Guido Schmitz   Prof. Michael R. Buchmeiser  

Participants can ask more specific questions in a direct video conference. Please join the speaker of your chooice actively in the announced virtual room if you would like to ask questions.

May 12, 2021 : Session 4 (Chair B. Plietker)
16:45 - 17:30

Photocatalysis within Supramolecular Hydrogel Scaffolds

  • Prof. Samuel I. Stupp  

17:30 - 17:35

Final Remarks

17:35 - 17:50

Meet the Speaker - Stupp

  • Break for coffee and more in-depth individual discussions.   Prof. Samuel I. Stupp  

Participants can ask more specific questions in a direct video conference with the speaker. Please join the speaker actively in the announced virtual room.

17:50 - 18:30

Poster Session

Please join the presenters in their individual virtual rooms via the announced conference platform.

Invited Speakers

We are pleased to announce that eminent experts representing catalysis, materials science and spectroscopy, have agreed to give key note lectures.