Controlled Formation of Polymer Nanocapsules with High Diffusion‐Barrier Properties and Prediction of Encapsulation Efficiency

Polymer nanocapsules with high diffusion‐barrier performance were designed following simple thermodynamic considerations. Hindered diffusion of the enclosed material leads to high encapsulation efficiencies (EEs), which was demonstrated based on the encapsulation of highly volatile compounds of different chemical natures. Low interactions between core and shell materials are key factors to achieve phase separation and a high diffusion barrier of the resulting polymeric shell. These interactions can be characterized and quantified using the Hansen solubility parameters. A systematic study of our copolymer system revealed a linear relationship between the Hansen parameter for hydrogen bonding (δ_h) and encapsulation efficiencies which enables the prediction of encapsulated amounts for any material. Furthermore EEs of poorly encapsulated materials can be increased by mixing them with a mediator compound to give lower overall δ_h values.     

Nanorattles or Yolk–Shell Nanoparticles—What Are They,How Are They Made,and What Are They Good For?

The development of nanotechnology has led to the design of cutting‐edge nanomaterials with increasing levels of complexity. Although “traditional” solid, uniform nanoparticles are still the most frequently reported structures, new generations of nanoparticles have been constantly emerging over the last several decades. The outcome of this nano‐art extends beyond nanomaterials with alternative compositions and/or morphologies. The current state‐of‐the‐art allows for the design of nanostructures composed of different building blocks that exhibit diverse properties. Furthermore, those properties can be a reflection of either individual features, which are characteristic of a particular building block alone, and/or synergistic effects resulting from interactions between building blocks. Therefore, the unique structures as well as the outstanding properties of nanorattles have attracted increasing attention for possible biomedical and industrial applications. Although these nanoparticles resemble core–shell particles, they have a distinctive feature, which is a presence of a void that provides a homogenous environment for the encapsulated core. In this Review, we give a comprehensive insight into the fabrication of nanorattles. A special emphasis is put on the choice of building blocks as well as the choice of preparation method, because those two aspects further influence properties and thus possible future applications, which will also be discussed.     

Covalent Protein Labeling by Enzymatic Phosphocholination

We present a new protein labeling method based on the covalent enzymatic phosphocholination of a specific octapeptide amino acid sequence in intact proteins. The bacterial enzyme AnkX from Legionella pneumophila has been established to transfer functional phosphocholine moieties from synthetically produced CDP‐choline derivatives to N‐termini, C‐termini, and internal loop regions in proteins of interest. Furthermore, the covalent modification can be hydrolytically removed by the action of the Legionella enzyme Lem3. Only a short peptide sequence (eight amino acids) is required for efficient protein labeling and a small linker group (PEG‐phosphocholine) is introduced to attach the conjugated cargo.     

Fragment‐Based De Novo Design Reveals a Small‐Molecule Inhibitor of Helicobacter Pylori HtrA

Sustained identification of innovative chemical entities is key for the success of chemical biology and drug discovery. We report the fragment‐based, computer‐assisted de novo design of a small molecule inhibiting Helicobacter pylori HtrA protease. Molecular binding of the designed compound to HtrA was confirmed through biophysical methods, supporting its functional activity in vitro. Hit expansion led to the identification of the currently best‐in‐class HtrA inhibitor. The results obtained reinforce the validity of ligand‐based de novo design and binding‐kinetics‐guided optimization for the efficient discovery of pioneering lead structures and prototyping drug‐like chemical probes with tailored bioactivity.     

Heterophase Photocatalysts from Water‐Soluble Conjugated Polyelectrolytes: An Example of Self‐Initiation under Visible Light

We herein report a new design route to stable, heterophase photocatalysts, which function as highly dispersible conjugated polymer nanoparticles and porous monoliths under visible light in aqueous medium. They were constructed by attachment of the ionic‐liquid species 1‐alkyl‐3‐vinylimidazolium bromide onto the side chains of a photoactive polymer. The structure configuration allows not only photocatalysis in aqueous environment but also a unique self‐initiation radical cross‐linking process to transform the water‐soluble photoactive polymer into a heterophase system, either as nanoparticles or a porous monolith. High photocatalytic activity and reusability of the heterophase system were demonstrated in the degradation of organic dyes and reduction of Cr^VI into Cr^III in water under visible‐light irradiation.     

Trialkylphosphine-stabilized copper(I) phenylchalcogenolate complexes--crystal structures and copper-chalcogenolate bonding

A series of trialkylphosphine-stabilized copper(I) phenylchalcogenolate complexes [(R(3)P)(m)(CuEPh)(n)] (R = Me, Et, (i)Pr, (t)Bu; E = S, Se, Te) has been prepared and structurally characterized by X-ray diffraction. Structures were found to be mono-, di-, tri-, tetra-, hexa-, hepta-, or decanuclear, depending mainly on size and amount of phosphine ligand. Several structural details were observed, including unusually long Cu-E bonds or secondary Cu-E connections, μ(4)-bridging, and planar bridging chalcogenolate ligands. Relatively rigid Cu-E-C angles were found to be of significant influence on the flexible molecular structures, especially for bridging chalcogenolate ligands, since in these cases a correlation results between the Cu-E-Cu angles and the inclination of the E-C bonds to their Cu-E-Cu planes. We further address some of these phenomena by means of density functional computations.     

Improved thermal stability of an organic zeolite by fluorination

The thermal stability of an organic zeolite material, namely 2,4,6-tris(4-bromo-3,5-difluorphenoxy)-1,3,5-triazin (Br-3,5-DFPOT), was improved by fluorination of 2,4,6-tris(4-bromophenoxy)-1,3,5-triazin (BrPOT). The open pore structure (van der Waals diameter of 10.5 Å) of the modified zeolite was observed up to 110 °C in comparison to 70 °C for BrPOT. Nitrogen sorption at low temperature showed a type I isotherm and derived pore volumes thereof are in agreement with structural data. It was observed here that Br-3,5-DFPOT crystals preserving the open pore structure could only be obtained below a typical size of about 50 μm. The improved thermal stability of the fluorinated system is attributed to an enhancement of the strength of the Br₃-synthon.