Oleg Borodin

What is it really like being a scientist who does not fit the ‘traditional’ image or the man in the white lab coat?

Structure‐guided optimization of existing macrocyclic platform for anions allows synthesis of novel neutral receptor with extraordinary anti‐Hofmeister type selectivity for chloride. A drawing discloses X‐ray structure of the free receptor and its DFT‐calculated complex with chloride. The hydrophobic interactions are crucial for achieving selectivity for this spherical guest. The capture and release of cargo is controlled by the hydrogen‐bonding power of solvent in a controllable manner.

A structure‐guided design, synthesis, and characterization of neutral unclosed cryptand functionalized with a bulky and hydrophobic 1‐methylene‐pyrene substituent is described. The host selectively binds spherical chloride (Cl^–) over bigger and more basic carboxylates (MeCO₂ ^–, PhCO₂ ^–) and dihydrogenphosphate (H₂PO₄ ^–) in a competitive [D₆]DMSO + 0.5 % H₂O solvent mixture. The capture of chloride is accompanied by formation of sandwich‐type complex stabilized by π–π and CH–π interactions. Step‐wise addition of MeOH triggers release of the cargo in a controllable manner.

Small peptides derived from alanine and aminobenzoic acid ferry cations across lipid membranes as ion carriers. The aromatic unit is essential for the transport activity. Such readily accessible peptides are attractive scaffolds for therapeutic use.

Low molecular weight di‐, tri‐ and tetrapeptide transmembrane ion transporters containing aminobenzoic acid and l/d alanine are reported. These short peptides transport alkali metal cations in preference to halides across the lipid bilayer most likely through a carrier mechanism. Easy access to these peptides and the ability to install diverse functional groups into the peptidic scaffold make them attractive scaffolds for therapeutic use.

Nature Communications, Published online: 04 August 2020; doi:10.1038/s41467-020-17736-x

The human antibacterial and immunomodulatory peptide LL-37 is a hCAP-18 protein cleavage product that self-assembles. Here, the authors present the human and gorilla LL-37 (17–29) crystal structures, revealing a self-assembly of amphipathic helices into a densely packed and elongated hexameric structure with a central pore and mutagenesis experiments support the role of self-assembly for antibacterial activity.

Publication date: 3 September 2020

Source: Tetrahedron Letters, Volume 61, Issue 36

Author(s): Debjit Das

The ligands L¹ and L² form trinuclear self‐assemblies with Cu²⁺ (i.e. [L ₂Cu₃]⁶⁺) both of which act as hosts to a variety of anions. Inclusion of long aliphatic chains on these ligands allows the self‐assemblies to extract anions from aqueous media into organic solvents. Phosphate anions can be removed from water efficiently and highly selectively in the presence of other anions.

Abstract

The ligands L¹ and L² form trinuclear self‐assembled complexes with Cu²⁺ (i.e. [(L¹ )₂Cu₃]⁶⁺ or [(L² )₂Cu₃]⁶⁺) both of which act as a host to a variety of anions. Inclusion of long aliphatic chains on these ligands allows the assemblies to extract anions from aqueous media into organic solvents. Phosphate can be removed from water efficiently and highly selectively, even in the presence of other anions.

Speeding addition to fullerenes: Similar to the Diels–Alder (DA) cycloaddition, the Bingel–Hirsch (BH) addition of bromomalonate to C₆₀ is accelerated by the presence of monocations (Li⁺, Na⁺, K⁺) encapsulated in the fullerene. However, at variance with the DA cycloaddition, the performance of the BH deteriorates when changing the monocations to dications (Mg²⁺, Ca²⁺) owing to the increase of the energy barriers in the last step of the BH addition.

Abstract

In the last 30 years, fullerene‐based materials have become popular building blocks for devices with a broad range of applications. Among fullerene derivatives, endohedral metallofullerenes (EMFs, M@C _x ) have been widely studied owing to their unique properties and reactivity. For real applications, fullerenes and EMFs must be exohedrally functionalized. It has been shown that encapsulated metal cations facilitate the Diels–Alder reaction in fullerenes. Herein, the Bingel–Hirsch (BH) addition of ethyl bromomalonate over a series of ion‐encapsulated M@C₆₀ (M=Ø, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, and Cl⁻; Ø@C₆₀ stands for C₆₀ without any endohedral metal) is quantum mechanically explored to analyze the effect of these ions on the BH addition. The results show that the incarcerated ion has a very important effect on the kinetics and thermodynamics of this reaction. Among the systems studied, K⁺@C₆₀ is the one that leads to the fastest BH reaction, whereas the slowest reaction is given by Cl⁻@C₆₀.

Alkyl groups matter: Complexes between diadamantyl ether (DAE) and water and alcohols with increasing side‐chain size have been studied by using rotational spectroscopy. DAE and the clustering molecules interact through an O−H⋅⋅⋅O hydrogen bond and London dispersion (LD) interactions. The H−C⋅⋅⋅H−C LD attractions take place between the alkyl groups of the alcohols and those of DAE. The LD interactions increase with increasing size of the alcohol.

Abstract

Diadamantyl ether (DAE, C₂₀H₃₀O) represents a good model to study the interplay between London dispersion and hydrogen‐bond interactions. By using broadband rotational spectroscopy, an accurate experimental structure of the diadamantyl ether monomer is obtained and its aggregates with water and a variety of aliphatic alcohols of increasing size are analyzed. In the monomer, C−H⋅⋅⋅H−C London dispersion attractions between the two adamantyl subunits further stabilize its structure. Water and the alcohol partners bind to diadamantyl ether through hydrogen bonding and non‐covalent O_{water/alcohol}⋅⋅⋅H−C_DAE and C−H_alcohol⋅⋅⋅H−C_DAE interactions. Electrostatic contributions drive the stabilization of all the complexes, whereas London dispersion interactions become more pronounced with increasing size of the alcohol. Complexes with dominant dispersion contributions are significantly higher in energy and were not observed in the experiment. The results presented herein shed light on the first steps of microsolvation and aggregation of molecular complexes with London dispersion energy donor (DED) groups and the kind of interactions that control them.

Nature, Published online: 29 July 2020; doi:10.1038/d41586-020-02110-0

Despite advances in therapies for people with the genetic disease, women seem to have poorer outcomes.

Nature, Published online: 29 July 2020; doi:10.1038/d41586-020-02105-x

Innovative therapies are bringing hope to people with this inherited lung disorder.

Nature, Published online: 29 July 2020; doi:10.1038/d41586-020-02111-z

After three decades of false starts, gene therapy against the disease is in new clinical trials — and there is even hope of a cure.

Adding complexity : The use of aromatic and nonpolar solvent mixtures for supramolecular polymerization of hydrogen‐bonded supermacrocycles results in complex paths attributed to the formation of competing extended hydrogen‐bonded motifs.

Abstract

Beyond phenomenon, self‐assembly of synthetic molecules, is now becoming an essential tool to design supramolecular materials not only in the thermodynamically stable state but also in kinetically trapped states. However, an approach to design complex self‐assembly processes comprising different types of self‐assembled states remains elusive. Herein, an example of such systems is demonstrated based on a unique supramolecular polymer mediated by supermacrocyclization of hydrogen‐bonding π‐conjugated molecules. By adding an aromatic solvent into nonpolar solutions of the monomer, spontaneous nucleation triggered by supermacrocyclization was suppressed so that isothermal supramolecular polymerization could be achieved from kinetically formed topological variants and amorphous agglomerates to afford helicoidal structures hitherto obtainable only with very slow cooling of a hot solution. By increasing the proportion of aromatic solvent further, another self‐assembly path was found, based on competing extended hydrogen‐bonded motifs affording crystalline nanowires.

Continuous addition of a chemical fuel allows for the autocatalytic formation of surfactant that aggregate into vesicles. These vesicles can be maintained out‐of‐equilibrium by adding a catabolic catalyst to introduce a second, coupled reaction cycle into the metabolic network.

Abstract

We report chemically fuelled out‐of‐equilibrium self‐replicating vesicles based on surfactant formation. We studied the vesicles’ autocatalytic formation using UPLC to determine monomer concentration and interferometric scattering microscopy at the nanoparticle level. Unlike related reports of chemically fuelled self‐replicating micelles, our vesicular system was too stable to surfactant degradation to be maintained out of equilibrium. The introduction of a catalyst, which introduces a second catalytic cycle into the metabolic network, was used to close the first cycle. This shows how coupled catalytic cycles can create a metabolic network that allows the creation and perseverance of fuel‐driven, out‐of‐equilibrium self‐replicating vesicles.

Why are some people allergic to cats? Why does cat pee smell so bad? And why do cats love catnip? This graphic looks at some of the answers! I’ve recently become a cat owner: meet Linus (Pawling)! He’s helped to confirm that my wife’s suspicion that she’s allergic to cats is entirely correct. He’s also […]

Nature Nanotechnology, Published online: 20 July 2020; doi:10.1038/s41565-020-0734-1

A diffusion-reaction system in a gel matrix shows that concentration gradients can lead to an overall enhanced catalytic activity.

Structure‐guided optimization of existing macrocyclic platform for anions allows synthesis of novel neutral receptor with extraordinary anti‐Hofmeister type selectivity for chloride. A drawing discloses X‐ray structure of the free receptor and its DFT‐calculated complex with chloride. The hydrophobic interactions are crucial for achieving selectivity for this spherical guest. The capture and release of cargo is controlled by the hydrogen‐bonding power of solvent in a controllable manner.

A structure‐guided design, synthesis, and characterization of neutral unclosed cryptand functionalized with a bulky and hydrophobic 1‐methylene‐pyrene substituent is described. The host selectively binds spherical chloride (Cl^–) over bigger and more basic carboxylates (MeCO₂ ^–, PhCO₂ ^–) and dihydrogenphosphate (H₂PO₄ ^–) in a competitive [D₆]DMSO + 0.5 % H₂O solvent mixture. The capture of chloride is accompanied by formation of sandwich‐type complex stabilized by π–π and CH–π interactions. Step‐wise addition of MeOH triggers release of the cargo in a controllable manner.

Photoregulatory azobenzene diamide‐based transporters are reported. The anionophores exhibited efficient chloride transport with quick photoresponse time. A carrier‐mediated chloride‐anion antiport mechanism was confirmed, and the supramolecular interactions involved in chloride recognition within the sandwich complex were revealed from theoretical studies.

Abstract

There has been a tremendous evolution for artificial ion transport systems, especially gated synthetic systems, which closely mimic their natural congeners. Herein, we demonstrate a trans‐azobenzene‐based photoregulatory anionophoric system that transports chloride by forming a sandwich dimeric complex. Further studies confirmed a carrier‐mediated chloride‐anion antiport mechanism, and the supramolecular interactions involved in chloride recognition within the sandwich complex were revealed from theoretical studies. Reversible trans–cis photoisomerization of the azobenzene was achieved without any significant contribution from the thermal cis →trans isomerization at room temperature. Photoregulatory transport activity across the lipid bilayer membrane inferred an outstanding off‐on response of the azobenzene photoswitch.

Power belt: This Minireview focuses on the strategies used in synthesizing carbon nanobelts and related belt‐shaped polycyclic aromatic hydrocarbons. Successful examples and representative synthetic trials are discussed.

Abstract

The development of carbon nanobelts and related belt‐shaped polycyclic aromatic hydrocarbons has gained momentum in recent years. This Minireview focuses on the synthetic strategies used in constructing these aesthetically appealing molecular nanocarbons. Examples of carbon nanobelts and related belt‐shaped polycyclic aromatic hydrocarbons reported in recent years as well as some representative synthetic attempts in earlier times are discussed.

Seeding CPL: Supramolecular polymerization of a sulfur‐substituted naphthalene‐diimide (NDI) derivative (S,S)‐NDI‐2 leads to the formation of highly fluorescent fibrillar nanostructures with the emergence of strong CPL signal and a very high luminescence dissymmetry factor (g _lum) of 4.6×10⁻². Seeded supramolecular polymerization with NDI‐2 as seed produced similarly intense CPL signal from a diastereomeric mixture of homologous NDI‐derivative (NDI‐1) via chirality induction.

Abstract

H‐bonding driven J‐type aggregation and cooperative supramolecular polymerization of a sulfur‐substituted chiral naphthalene‐diimide (NDI)‐derivative (S,S)‐NDI‐2 in decane leads to remarkable enhancement of fluorescence quantum yield (43.3 % from 0.5 % in the monomeric state) and intense CPL signal in the aggregated state with a high luminescence dissymmetry factor (g _lum) of 4.6×10⁻². A mixture of NDI‐2 with a structurally similar NDI‐derivative NDI‐1 (mixture of racemic (S,S)‐ and (R,R)‐ isomers and the achiral derivative) in 1:9 (NDI‐2/NDI‐1) ratio, when heated and slowly cooled to room temperature, showed no enhanced CD band, indicating lack of any preferential helicity. However, when a monomeric solution of the NDI‐1 in tetrahydrofuran (THF) was injected to preformed seed of NDI‐2 in decane, a prominent CD signal appeared, indicating chiral amplification resulting in induced CPL with high g _lum value of 2.0×10⁻² from mostly (>98.5 %) diastereomeric mixture.