Sebastian Beil

5+(5×5+5×6)=hemisphere: An omphalos pentagon was decorated with 5 pentagons and 5 hexagons to form a hemispherical molecule by a polygon assembling strategy. Thirty phenine units were assembled to afford a large C₂₂₀H₁₈₀ molecule with a phenine framework isoreticular to a hemispherical, bisected segment of C₆₀.

Abstract

A synthetic strategy to construct large geodesic structures of phenine (1,3,5‐trisubstituted benzene) was devised. In this strategy, five pentagons were assembled on an omphalos pentagon, and bridging peripheral pentagons furnished five additional hexagons. Thirty phenine units were synthetically assembled to afford a large C₂₂₀H₁₈₀ molecule with a phenine framework isoreticular to a hemispherical, bisected segment of C₆₀. Although a hemispherical structure of the phenine framework was suggested by solution‐phase NMR spectra, crystallographic analysis revealed an oval‐like deformation of the molecular shape. In‐depth structural analyses, including theoretical calculations, showed that structural fluctuations observed as variations in the biaryl torsion angles allowed structural deformations and, at the same time, that the dynamic fluctuations resulted in the spectroscopic observation of a hemisphere as a time‐averaged structure.

Nanorings : The first examples of cyclofluorenes possessing five constituting fluorene units were synthesized and studied. The electronic properties of [5]‐cyclofluorenes are drastically different from those of [4]‐cyclofluorenes, highlighting the key role played by the ring size in the cyclofluorene family.

Abstract

For the last ten years, ring‐shaped π‐conjugated macrocycles possessing radially directed π‐orbitals have been subject to intense research. The electronic properties of these rings are deeply dependent on their size. However, most studies involve the flagship family of nanorings: the cyclo‐para ‐phenylenes. We report herein the synthesis and study of the first examples of cyclofluorenes possessing five constituting fluorene units. The structural, optical and electrochemical properties were elucidated by X‐ray crystallography, UV‐vis absorption and fluorescence spectroscopy, and cyclic voltammetry. By comparison with a shorter analogue, we show how the electronic properties of [5]‐cyclofluorenes are drastically different from those of [4]‐cyclofluorenes, highlighting the key role played by the ring size in the cyclofluorene family.

Nature Chemistry, Published online: 13 April 2020; doi:10.1038/s41557-020-0454-z

Metal-mediated self-assembly in solution typically leads to small two- and three-dimensional architectures on scales smaller than 10 nm, but now a series of large, discrete, two-dimensional supramolecular hexagonal grids have been prepared through a combination of intra- and intermolecular coordination interactions. These 20-nm-wide grids have been imaged at submolecular resolution using scanning tunnelling microscopy.

Nature, Published online: 30 March 2020; doi:10.1038/d41586-020-00917-5

Productivity coaches, boot camps and online meet-ups teach researchers to avoid distractions and negative thoughts to get their writing projects done.

Nature, Published online: 30 March 2020; doi:10.1038/d41586-020-00971-z

Alyssa Frederick defended her thesis remotely before the coronavirus outbreak began. Here’s how.

A heat engine composed of a coordination cage, Fe^II ₄L₄, decorated with thermoresponsive chains is constructed. Upon heating and cooling, the chains expand and contract, thereby modulating the solubility preferences of the cage. Through application of a thermal gradient, the cage reversibly transfers between water and ethyl acetate, pumping its encapsulated molecular cargo along the length of a tube and back again.

Abstract

The directed motion of species against a chemical potential gradient is a fundamental feature of living systems, underpinning processes that range from transport through cell membranes to neurotransmission. The development of artificial active cargo transport could enable new modes of chemical purification and pumping. Here, a heat engine is described that drives chemical cargo between liquid phases to generate a concentration gradient. The heat engine, composed of a functionalized Fe^II ₄L₄ coordination cage, is grafted with oligoethylene glycol imidazolium chains. These chains undergo a conformational change upon heating, causing the cage and its cargo to reversibly transfer between aqueous and organic phases. Furthermore, sectional heating and cooling allow for the cage to traverse multiple phase boundaries, allowing for longer‐distance transport than would be possible using a single pair of phases.

Nature Communications, Published online: 30 March 2020; doi:10.1038/s41467-020-15316-7

Conducting polymers are promising materials for diverse applications but the fabrication of conducting polymers mostly relies on conventional fabrication techniques. Here the authors introduce a high performance 3D printable conducting polymer ink to take full advantage of advanced 3D printing.

Open, sesame ! A method for the quantitative assembly of the heterobimetallic cage, [PdPtL₄]⁴⁺, is described. The cage interacts with quinone guest molecules in a 1:1 fashion. The cage can be selectively and reversibly opened and then re‐closed at the Pd^II end by the sequential addition of base then acid. Guest molecules can be reversibly released/bound during this process.

Abstract

A strategy is presented that enables the quantitative assembly of a heterobimetallic [PdPtL₄]⁴⁺ cage. The presence of two different metal ions (Pd^II and Pt^II) with differing labilities enables the cage to be opened and closed selectively at one end upon treatment with suitable stimuli. Combining an inert Pt^II tetrapyridylaldehyde complex with a suitably substituted pyridylamine and Pd^II ions led to the assembly of the cage. ¹H and DOSY NMR spectroscopy and ESI mass spectrometry data were consistent with the quantitative formation of the cage, and the heterobimetallic structure was confirmed using single‐crystal X‐ray crystallography. The structure of the host–guest adduct with a 2,6‐diaminoanthraquinone guest molecule was determined. Addition of N,N′‐dimethylaminopyridine (DMAP) resulted in the formation of the open‐cage [PtL₄]²⁺ compound and [Pd(DMAP)₄]²⁺ complex. This process could then be reversed, with the reformation of the cage, upon addition of p ‐toluenesulfonic acid (TsOH).

Stiff‐stilbene is increasingly applied to reversibly control the properties and function of chemical as well as biological systems. In this Minireview an overview is provided of the basic properties of this promising photoswitch, which is followed by a survey of recent applications.

Abstract

Stiff‐stilbene, a sterically restricted fused ring analogue of stilbene, has been regularly used as a model compound in theoretical studies of stilbene photoisomerization. Lately, owing to its excellent photoswitching properties, it is increasingly being applied to reversibly control the properties and function of chemical as well as biological systems. Stiff‐stilbene photoswitches possess a number of advantageous properties including a high quantum yield for photoisomerization and a high thermal stability. Furthermore, they undergo a large geometrical change upon isomerization and their synthesis is straightforward. Herein, we provide an overview of the basic properties of stiff‐stilbene and of recent applications in supramolecular chemistry, catalysis, and biological systems.

Platinum is king ! A responsive‐at‐metal Pt^II emitter undergoes controlled supramolecular and redox transformations. Pt^II selectively oxidizes into Pt^III or Pt^IV, thus diversifying the structural and photophysical properties of the system. Delicate modulation of Pt⋅⋅⋅Pt interactions by solvent molecules results in strong solvatochromism for the Pt^II complex.

Abstract

We report the synthesis, characterization, and spectroscopic investigations of a new responsive‐at‐metal cyclometalated platinum(II) complex. With mild chemical oxidants and reductants, it was possible to obtain the same complex in three different oxidation states and each of these complexes was structurally characterized by single‐crystal X‐ray diffraction. We discovered that the platinum(II) complex displays strong solvatochromism in the solid state, which can be attributed to modulation of Pt⋅⋅⋅Pt interactions that results in switching between optical and photoluminescent states. Incorporating responsive‐at‐metal species as dynamic components in nanostructured materials might facilitate response amplification, sensing, actuation, or self‐healing processes.

A general efficient protocol for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates was developed. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation.

Abstract

A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)−B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.

This Review gives an overview of the various types of supramolecular self‐assembled artificial ion‐channels: capsules and cages, macrocyclic stacks, tubular helical architectures.

Abstract

Owing to their significant physiological functions, especially as selective relays for translocation of physiological relevant species through cellular membranes, natural ion channels play important role in the living organisms. During the last decades, the field of self‐assembled ion channels has been continuously developed. Convergent multidimensional self‐assembly strategies have been used for the synthesis of unimolecular channels or non‐covalent self‐organized channels, designed to mimic natural ion channel proteins and for which a rich array of interconverting or adaptive channel conductance states can be observed. In this review, we give an overview on the development of various self‐assembled artificial channels in a bottom‐up approach, especially their design, self‐assembly behaviour, transport activity in lipid bilayer membranes, mechanism of transport and comparison with natural ion channels. Finally, we discuss their applications, the potential challenges facing in this field as well as future development and perspectives.