Oleksandr

Nature Chemistry. doi:10.1038/nchem.2540

Authors: Wenyan Liu, Jonathan Halverson, Ye Tian, Alexei V. Tkachenko & Oleg Gang

A broadly applicable strategy that can control the self-assembly of nanoparticles into a predefined structure has been reported. Integrating nanoparticles with DNA constructs creates individual modules that can be assembled into complex planar architectures. The approach combines nanoparticles with the selectivity and directionality of bonds provided by DNA.

An autonomous chemically fuelled small-molecule motor

Nature 534, 7606 (2016). doi:10.1038/nature18013

Authors: Miriam R. Wilson, Jordi Solà, Armando Carlone, Stephen M. Goldup, Nathalie Lebrasseur & David A. Leigh

Molecular machines are among the most complex of all functional molecules and lie at the heart of nearly every biological process. A number of synthetic small-molecule machines have been developed, including molecular muscles, synthesizers, pumps, walkers, transporters and light-driven and electrically driven rotary motors. However, although biological molecular motors are powered by chemical gradients or the hydrolysis of adenosine triphosphate (ATP), so far there are no synthetic small-molecule motors that can operate autonomously using chemical energy (that is, the components move with net directionality as long as a chemical fuel is present). Here we describe a system in which a small molecular ring (macrocycle) is continuously transported directionally around a cyclic molecular track when powered by irreversible reactions of a chemical fuel, 9-fluorenylmethoxycarbonyl chloride. Key to the design is that the rate of reaction of this fuel with reactive sites on the cyclic track is faster when the macrocycle is far from the reactive site than when it is near to it. We find that a bulky pyridine-based catalyst promotes carbonate-forming reactions that ratchet the displacement of the macrocycle away from the reactive sites on the track. Under reaction conditions where both attachment and cleavage of the 9-fluorenylmethoxycarbonyl groups occur through different processes, and the cleavage reaction occurs at a rate independent of macrocycle location, net directional rotation of the molecular motor continues for as long as unreacted fuel remains. We anticipate that autonomous chemically fuelled molecular motors will find application as engines in molecular nanotechnology.

Chemistry: No turning back for motorized molecules

Nature 534, 7606 (2016). doi:10.1038/534187a

Authors: Jonathan Clayden

Two molecular motors have been developed that use chemical energy to drive rotational motion in a single direction. The findings bring the prospect of devices powered by such motors a tantalizing step closer. See Letter p.235

An accommodating host: The iminium-catalyzed 1,4-reduction of unsaturated aldehydes can be performed inside a supramolecular host. Only catalytic amounts of the supramolecular capsule are required. The intermolecular, noncovalent interactions inside the host system dramatically improve enantioselectivity for several amine catalysts.

[Communication]
Thomas M. Bräuer, Qi Zhang, Konrad Tiefenbacher
Angew. Chem. Int. Ed., June 03, 2016, DOI: 10.1002/anie.201602382. Read article

Nature Chemistry. doi:10.1038/nchem.2543

Authors: Beatrice S. L. Collins, Jos C. M. Kistemaker, Edwin Otten & Ben L. Feringa

Control of motion at the molecular level is an integral requirement for the development of future nanoscale machinery. Now, governed by the fundamental reactivity principles of organometallic chemistry, a biaryl rotor is shown to exhibit 360° unidirectional rotary motion driven by the conversion of two simple fuels.

Artificial photosynthetic systems can store solar energy and chemically reduce CO2. We developed a hybrid water splitting–biosynthetic system based on a biocompatible Earth-abundant inorganic catalyst system to split water into molecular hydrogen and oxygen (H2 and O2) at low driving voltages. When grown in contact with these catalysts, Ralstonia eutropha consumed the produced H2 to synthesize biomass and fuels or chemical products from low CO2 concentration in the presence of O2. This scalable system has a CO2 reduction energy efficiency of ~50% when producing bacterial biomass and liquid fusel alcohols, scrubbing 180 grams of CO2 per kilowatt-hour of electricity. Coupling this hybrid device to existing photovoltaic systems would yield a CO2 reduction energy efficiency of ~10%, exceeding that of natural photosynthetic systems. Authors: Chong Liu, Brendan C. Colón, Marika Ziesack, Pamela A. Silver, Daniel G. Nocera

Nature Chemistry. doi:10.1038/nchem.2526

Authors: Shoji Onogi, Hajime Shigemitsu, Tatsuyuki Yoshii, Tatsuya Tanida, Masato Ikeda, Ryou Kubota & Itaru Hamachi

Designing self-sorting events, and understanding their dynamics, in synthetic supramolecular assembly is a promising route towards complex, functional artificial systems. The formation of self-sorted supramolecular nanofibres has now been imaged in situ, in real time, by confocal laser microscopy. A stochastic, non-synchronous fibre formation through a cooperative mechanism was observed.

Nature Chemistry. doi:10.1038/nchem.2520

Authors: Michał S. Dutkiewicz, Joy H. Farnaby, Christos Apostolidis, Eric Colineau, Olaf Walter, Nicola Magnani, Michael G. Gardiner, Jason B. Love, Nikolas Kaltsoyannis, Roberto Caciuffo & Polly L. Arnold

Probing the chemistry of transuranic elements is notoriously challenging. Now, three neptunium(III) organometallic sandwich complexes have been prepared using a flexible macrocycle as ligand, and their molecular and electronic structures characterized, adding to our understanding of the behaviour of f-elements and suggesting that the lower oxidation state Np(II) may be chemically accessible.

A modular strategy for the synthesis of surface-confined supramolecular copolymers is reported by P. Besenius, B. J. Ravoo, and co-workers in their Communication (10.1002/anie.201601048). The sequential addition of aqueous solutions containing the anionic or cationic comonomer enables the stepwise growth of alternating copolymers from gold surfaces. Charge regulation passivates the growing chain end and yields kinetically trapped chiral copolymers with a tunable height of 5–19 nm.

[Cover Picture]
Hendrik Frisch, Eva-Corinna Fritz, Friedrich Stricker, Lars Schmüser, Daniel Spitzer, Tobias Weidner, Bart Jan Ravoo, Pol Besenius
Angew. Chem. Int. Ed., May 20, 2016, DOI: 10.1002/anie.201604416. Read article

Iron(III)-catalysed carbonyl–olefin metathesis

Nature 533, 7603 (2016). doi:10.1038/nature17432

Authors: Jacob R. Ludwig, Paul M. Zimmerman, Joseph B. Gianino & Corinna S. Schindler

The olefin metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic olefin metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl–olefin metathesis reaction can also be used to construct carbon–carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl–olefin metathesis has been reported. Here we demonstrate a catalytic carbonyl–olefin ring-closing metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by olefin metathesis.

Nature Chemistry. doi:10.1038/nchem.2517

Authors: Zimou Wang, Weiliang Xu, Lei Liu & Ting F. Zhu

A mirror-image polymerase—a version of African swine fever virus polymerase X made from D-amino acids—has now been chemically synthesized. This polymerase can catalyse template-directed L-DNA replication and transcription from L-DNA into L-RNA. These reactions represent two key steps in the central dogma of molecular biology—but demonstrated using the opposite chirality.

Machine-learning-assisted materials discovery using failed experiments

Nature 533, 7601 (2016). doi:10.1038/nature17439

Authors: Paul Raccuglia, Katherine C. Elbert, Philip D. F. Adler, Casey Falk, Malia B. Wenny, Aurelio Mollo, Matthias Zeller, Sorelle A. Friedler, Joshua Schrier & Alexander J. Norquist

Inorganic–organic hybrid materials such as organically templated metal oxides, metal–organic frameworks (MOFs) and organohalide perovskites have been studied for decades, and hydrothermal and (non-aqueous) solvothermal syntheses have produced thousands of new materials that collectively contain nearly all the metals in the periodic table. Nevertheless, the formation of these compounds is not fully understood, and development of new compounds relies primarily on exploratory syntheses. Simulation- and data-driven approaches (promoted by efforts such as the Materials Genome Initiative) provide an alternative to experimental trial-and-error. Three major strategies are: simulation-based predictions of physical properties (for example, charge mobility, photovoltaic properties, gas adsorption capacity or lithium-ion intercalation) to identify promising target candidates for synthetic efforts; determination of the structure–property relationship from large bodies of experimental data, enabled by integration with high-throughput synthesis and measurement tools; and clustering on the basis of similar crystallographic structure (for example, zeolite structure classification or gas adsorption properties). Here we demonstrate an alternative approach that uses machine-learning algorithms trained on reaction data to predict reaction outcomes for the crystallization of templated vanadium selenites. We used information on ‘dark’ reactions—failed or unsuccessful hydrothermal syntheses—collected from archived laboratory notebooks from our laboratory, and added physicochemical property descriptions to the raw notebook information using cheminformatics techniques. We used the resulting data to train a machine-learning model to predict reaction success. When carrying out hydrothermal synthesis experiments using previously untested, commercially available organic building blocks, our machine-learning model outperformed traditional human strategies, and successfully predicted conditions for new organically templated inorganic product formation with a success rate of 89 per cent. Inverting the machine-learning model reveals new hypotheses regarding the conditions for successful product formation.

Nature Chemistry. doi:10.1038/nchem.2511

Authors: Subhabrata Maiti, Ilaria Fortunati, Camilla Ferrante, Paolo Scrimin & Leonard J. Prins

Dissipative self-assembly processes are energetically uphill and require the continuous consumption of energy. Now, by using ATP as a chemical fuel, the dissipative self-assembly of vesicles has been demonstrated. These transiently formed supramolecular assemblies are able to sustain a chemical reaction and it is shown that the yield depends on the lifetime of the vesicles.

Nature Chemistry. doi:10.1038/nchem.2503

Authors: Marcus Schulze, Valentin Kunz, Peter D. Frischmann & Frank Würthner

Designing improved catalysts is predicated on understanding how they work. Now, by positioning three ruthenium centres in a macrocyclic framework, a remarkable acceleration of catalytic water oxidation has been achieved. Detailed mechanistic studies revealed that the catalyst operates through the ‘water nucleophilic attack’ pathway—similar to the natural oxygen-evolving cluster of photosystem II.