Pd 0 does the trick! Alkenyl silanes are efficiently cyclopropanated by diazoalkanes at low Pd loadings (see scheme). Clear evidence for the involvement of a Pd0 resting state for this reaction is given.
Protein roll call : Peptide‐based building blocks, in which both an α‐helix‐forming segment and a β‐sheet segment are located within a single macrocyclic structure, self‐assemble into α‐helix‐decorated artificial proteins. This approach provides a starting point for developing artificial proteins that can modulate α‐helix‐mediated interactions occurring in a multivalent fashion.
A novel screening approach based on an oligonucleotide‐addressing enzyme assay enables multiplexed simultaneous profiling of DNA polymerases in nanoliter volumes in terms of their different properties. This approach was used to identify enzymes with altered properties out of a library of protein mutants.
It's not easy being green : Real‐time visualization of labeled ribosomes and de novo synthesized green fluorescent protein molecules using single‐molecule‐sensitive fluorescence microscopy demonstrates that the mutant GFPem is produced with a characteristic time of five minutes. Fluorescence of the fastest GFP molecules appears within one minute (see picture).
A sustainable method for the fabrication of metallic surfaces with flower‐like fractal morphology was developed by using a three‐dimensional supramolecular assembly as a template. Modifying Au nanoflakes with self‐assembled monolayers or polymers allows the surface wettability to be adjusted from superhydrophobic to superhydrophilic (see figure). Furthermore, Au nanoflakes present excellent substrates for surface‐enhanced Raman spectroscopy (SERS).
Going fishing ! The sulfonium borane [ 1 ]+ complexes cyanide in pure water at the maximum allowable concentration of 50 ppb recommended by the European Union. The high cyanide ion affinity displayed by this compound arises from favorable Coulombic effects augmented by a direct bonding interaction between the cyano and sulfonio groups.
Divide and conquer : Polymer nanoparticles with phase‐separation structures prepared with block copolymers and homopolymer blends were used to fabricate unique suprapolymer structures by cross‐linking one polymer moiety and dissolving the other (see scheme; PI=polyisoprene, PSt=polystyrene).
Like penguins on ice , buckybowl molecules move closer together when cooled on a copper surface (see model of a corannulene molecule adsorbed on Cu(111)). Upon heating, the molecules spread out into the original crystal phase again. The lower density at room temperature can be explained by the increase in entropy owing to the excitation of bowl vibrations at the surface.
Healing hands : A complex interplay between colloidal and polymeric energetics in microgel self‐assembly behavior results in soft colloidal assemblies with self‐healing properties. Repulsive soft spheres can adopt highly compressed conformations in colloidal crystalline lattices without directly contacting the nearest neighbors (see picture). This distant action is directly responsible for the self‐healing of the assemblies.
Two activations are better than one : The chiral bifunctional guanidine 1 , which features an amino amide backbone, catalyzes the asymmetric Michael addition of a range of substrates and gives products with excellent stereoselectivities. The method also allows the efficient synthesis of optically pure β‐amino acid esters. Both the guanidine group and the NH proton of the amide were important for the dual activation.
Get the lead out : The title fluorescence receptor exhibits a high affinity and selectivity for Pb2+ over competing metal ions in water (see picture) with an overall emission change of approximately 8‐fold at the emission maximum for Pb2+. The fluorescence receptor can remove 96 % of 100 ppb Pb2+ from human blood, and can be useful and effective for the selective and rapid removal of Pb2+ in vivo.
