Probing machine learning models based on high throughput experimentation data for the discovery of asymmetric hydrogenation catalysts.

Enantioselective hydrogenation of olefins by Rh-based chiral catalysts has been extensively studied for more than 50 years. Naively, one would expect that everything about this transformation is known and that selecting a catalyst that induces the desired reactivity or selectivity is a trivial task. Nonetheless, ligand engineering or selection for any new prochiral olefin remains an empirical trial-error exercise.

Dimethyl carbonate synthesis from CO and methanol over CeO: elucidating the surface intermediates and oxygen vacancy-assisted reaction mechanism.

Surface intermediate species and oxygen vacancy-assisted mechanism over CeO catalyst in the direct dimethyl carbonate (DMC) synthesis from carbon dioxide and methanol are suggested by means of transient spectroscopic methodologies in conjunction with multivariate spectral analysis. How the two reactants, CO and methanol, interact with the CeO surface and how they form decisive surface intermediates leading to DMC are unraveled by DFT-based molecular dynamics simulation by precise statistical sampling of various configurations of surface states and intermediates. The atomistic simulations and uncovered stability of different intermediate states perfectly explain the unique DMC formation profile experimentally observed upon transient operations, strongly supporting the proposed oxygen vacancy-assisted reaction mechanism.

Dynamics of hydroxide-ion-driven reversible autocatalytic networks.

In living systems adaptive regulation requires the presence of nonlinear responses in the underlying chemical networks. Positive feedbacks, for example, can lead to autocatalytic bursts that provide switches between two stable states or to oscillatory dynamics. The stereostructure stabilized by hydrogen bonds provides an enzyme its selectivity, rendering pH regulation essential for its functioning.

2,5-Furandicarboxaldehyde as a bio-based crosslinking agent replacing glutaraldehyde for covalent enzyme immobilization.

In the quest for a bio-based and safer substitute for glutaraldehyde, we have investigated 2,5 diformylfuran (DFF) as bifunctional crosslinking agent for the covalent immobilization of glucoamylase on amino-functionalized methacrylic resins. Immobilization experiments and systematic comparison with glutaraldehyde at four different concentrations for the activation step showed that DFF leads to comparable enzymatic activities at all tested concentrations. Continuous flow experiment confirms a similar long term stability of the immobilized formulations obtained with the two crosslinkers.

Light-driven biocatalytic oxidation.

Enzymes are the catalyst of choice for highly selective reactions, offering nature-inspired approaches for sustainable chemical synthesis. Oxidative enzymes (, monooxygenases, peroxygenases, oxidases, or dehydrogenases) catalyze a variety of enantioselective oxyfunctionalization and dehydrogenation reactions under mild conditions. To sustain the catalytic cycles of these enzymes, constant supply with or withdrawal of reducing equivalents (electrons) is required.

Dual promotional effect of Cu O clusters grown with atomic layer deposition on TiO for photocatalytic hydrogen production.

The promotional effects on photocatalytic hydrogen production of Cu O clusters deposited using atomic layer deposition (ALD) on P25 TiO are presented. The structural and surface chemistry study of Cu O/TiO samples, along with first principles density functional theory simulations, reveal the strong interaction of ALD deposited Cu O with TiO, leading to the stabilization of Cu O clusters on the surface; it also demonstrated substantial reduction of Ti to Ti on the surface of Cu O/TiO samples after Cu O ALD. The Cu O/TiO photocatalysts showed remarkable improvement in hydrogen productivity, with 11 times greater hydrogen production for the optimum sample compared to unmodified P25.

CO Hydrogenation to Methanol over Cd/TiO Catalyst: Insight into Multifunctional Interface.

Supported metal catalysts have shown to be efficient for CO conversion due to their multifunctionality and high stability. Herein, we have combined density functional theory calculations with microkinetic modeling to investigate the catalytic reaction mechanisms of CO hydrogenation to CHOH over a recently reported catalyst of Cd/TiO. Calculations reveal that the metal-oxide interface is the active center for CO hydrogenation and methanol formation via the formate pathway dominates over the reverse water-gas shift (RWGS) pathway.

Utilizing Design of Experiments Approach to Assess Kinetic Parameters for a Mn Homogeneous Hydrogenation Catalyst.

Homogeneous hydrogenation catalysts based on metal complexes provide a diverse and highly tunable tool for the fine chemical industry. To fully unleash their potential, fast and effective methods for the evaluation of catalytic properties are needed. In turn, this requires changes in the experimental approaches to test and evaluate the performance of the catalytic processes.

Fuel-driven macromolecular coacervation in complex coacervate core micelles.

Fuel-driven macromolecular coacervation is an entry into the transient formation of highly charged, responsive material phases. In this work, we used a chemical reaction network (CRN) to drive the coacervation of macromolecular species readily produced using radical polymerisation methods. The CRN enables transient quaternization of tertiary amine substrates, driven by the conversion of electron deficient allyl acetates and thiol or amine nucleophiles.

Compartmentalized cross-linked enzyme nano aggregates (-CLEAs) toward pharmaceutical transformations.

A new immobilization strategy using compartmentalized nanoreactors is herein reported for two biocatalytic processes: (1) -acetylneuraminate lyase (NAL) is internalized in NAL--CLEAs and used in a continuous flow aldol condensation of -acetyl-d-mannosamine with sodium pyruvate to -acetylneuraminic acid; (2) two hydroxysteroid dehydrogenases (HSDH) 7α- and 7β-HSDH are incorporated in -CLEAs and used in a two-step cascade batch synthesis of ursodeoxycholic acid (UDCA). The versatile use of -CLEA demonstrates that this immobilization methodology is a valuable addition to the toolbox of synthetic chemists.

Immobilization strategies for porphyrin-based molecular catalysts for the electroreduction of CO.

The ever-growing level of carbon dioxide (CO) in our atmosphere, is at once a threat and an opportunity. The development of sustainable and cost-effective pathways to convert CO to value-added chemicals is central to reducing its atmospheric presence. Electrochemical CO reduction reactions (CORRs) driven by renewable electricity are among the most promising techniques to utilize this abundant resource; however, in order to reach a system viable for industrial implementation, continued improvements to the design of electrocatalysts is essential to improve the economic prospects of the technology.

Greener and facile synthesis of Cu/ZnO catalysts for CO hydrogenation to methanol by urea hydrolysis of acetates.

Cu/ZnO-based catalysts for methanol synthesis by CO hydrogenation are widely prepared co-precipitation of sodium carbonates and nitrate salts, which eventually produces a large amount of wastewater from the washing step to remove sodium (Na) and/or nitrate (NO ) residues. The step is inevitable since the remaining Na acts as a catalyst poison whereas leftover NO induces metal agglomeration during the calcination. In this study, sodium- and nitrate-free hydroxy-carbonate precursors were prepared urea hydrolysis co-precipitation of acetate salt and compared with the case using nitrate salts.

: exploration of chemical space by automated functionalization of molecular scaffold.

Exploration of the local chemical space of molecular scaffolds by post-functionalization (PF) is a promising route to discover novel molecules with desired structure and function. PF with rationally chosen substituents based on known electronic and steric properties is a commonly used experimental and computational strategy in screening, design and optimization of catalytic scaffolds. Automated generation of reasonably accurate geometric representations of post-functionalized molecular scaffolds is highly desirable for data-driven applications.

Room temperature synthesis of perylene diimides facilitated by high amic acid solubility.

A novel protocol for the synthesis of perylene diimides (PDIs), by reacting perylene dianhydride (PDA) with aliphatic amines is reported. Full conversions were obtained at temperatures between 20 and 60 °C, using DBU as the base in DMF or DMSO. A "green" synthesis of PDIs, that runs at higher temperatures, was developed using KCO in DMSO.

Spatial reactant distribution in CO electrolysis: balancing CO utilization and faradaic efficiency.

The production of value added C1 and C2 compounds within CO electrolyzers has reached sufficient catalytic performance that system and process performance - such as CO utilization - have come more into consideration. Efforts to assess the limitations of CO conversion and crossover within electrochemical systems have been performed, providing valuable information to position CO electrolyzers within a larger process. Currently missing, however, is a clear elucidation of the inevitable trade-offs that exist between CO utilization and electrolyzer performance, specifically how the faradaic efficiency of a system varies with CO availability.

The Impact of Computational Uncertainties on the Enantioselectivity Predictions: A Microkinetic Modeling of Ketone Transfer Hydrogenation with a Noyori-type Mn-diamine Catalyst.

Selectivity control is one of the most important functions of a catalyst. In asymmetric catalysis the enantiomeric excess (e.e.

Nickel-iron layered double hydroxides for an improved Ni/Fe hybrid battery-electrolyser.

The transition to renewable electricity sources and green feedstock implies the development of electricity storage and conversion systems to both stabilise the electricity grid and provide electrolytic hydrogen. We have recently introduced the concept of a hybrid Ni/Fe battery-electrolyser (battolyser) for this application. The hydrogen produced during the Ni/Fe cell charge and continued electrolysis can serve as chemical feedstock and a fuel for long-term storage, while the hybrid battery electrodes provide short term storage.

Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade.

Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant.

Photo cleavable thioacetal block copolymers for controlled release.

We present a new light cleavable polymer containing -nitrobenzene thioacetal groups in the main chain. By conjugation to a PEG block, we synthesized block copolymers capable of forming nanoparticles in aqueous solution. We studied drug encapsulation and release using the model drug Nile Red.

On the use of catalysis to bias reaction pathways in out-of-equilibrium systems.

Catalysis is an essential function in living systems and provides a way to control complex reaction networks. In natural out-of-equilibrium chemical reaction networks (CRNs) driven by the consumption of chemical fuels, enzymes provide catalytic control over pathway kinetics, giving rise to complex functions. Catalytic regulation of man-made fuel-driven systems is far less common and mostly deals with enzyme catalysis instead of synthetic catalysts.

Nickel-Iron Hydrogenase 1 Catalyses Non-native Reduction of Flavins: Demonstration for Alkene Hydrogenation by Old Yellow Enzyme Ene-reductases.

A new activity for the [NiFe] uptake hydrogenase 1 of Escherichia coli (Hyd1) is presented. Direct reduction of biological flavin cofactors FMN and FAD is achieved using H as a simple, completely atom-economical reductant. The robust nature of Hyd1 is exploited for flavin reduction across a broad range of temperatures (25-70 °C) and extended reaction times.

Transient Supramolecular Hydrogels Formed by Aging-Induced Seeded Self-Assembly of Molecular Hydrogelators.

Here, transient supramolecular hydrogels that are formed through simple aging-induced seeded self-assembly of molecular gelators are reported. In the involved molecular self-assembly system, multicomponent gelators are formed from a mixture of precursor molecules and, typically, can spontaneously self-assemble into thermodynamically more stable hydrogels through a multilevel self-sorting process. In the present work, it is surprisingly found that one of the precursor molecules is capable of self-assembling into nano-sized aggregates upon a gentle aging treatment.

Operando Modeling of Multicomponent Reactive Solutions in Homogeneous Catalysis: from Non-standard Free Energies to Reaction Network Control.

Optimization and execution of chemical reactions are to a large extend based on experience and chemical intuition of a chemist. The chemical intuition is rooted in the phenomenological Le Chatelier's principle that teaches us how to shift equilibrium by manipulating the reaction conditions. To access the underlying thermodynamic parameters and their condition-dependencies from the first principles is a challenge.

cross-linked enzymatic -aggregates (-CLEA) for efficient in-flow biocatalysis.

Nano-sized enzyme aggregates, which preserve their catalytic activity are of great interest for flow processes, as these catalytic species show minimal diffusional issues, and are still sizeable enough to be effectively separated from the formed product. The realization of such catalysts is however far from trivial. The stable formation of a micro-to millimeter-sized enzyme aggregate is feasible the formation of a cross-linked enzyme aggregate (CLEA); however, such a process leads to a rather broad size distribution, which is not always compatible with microflow conditions.

Efficient and Practical Transfer Hydrogenation of Ketones Catalyzed by a Simple Bidentate Mn-NHC Complex.

Catalytic reductions of carbonyl-containing compounds are highly important for the safe, sustainable, and economical production of alcohols. Herein, we report on the efficient transfer hydrogenation of ketones catalyzed by a highly potent Mn(I)-NHC complex. Mn-NHC is practical at metal concentrations as low as 75 ppm, thus approaching loadings more conventionally reserved for noble metal based systems.