From blue to red: While four π‐conjugated nitrophenolates absorb within a relatively narrow region in solution, they cover the entire visible spectrum when isolated in vacuo (see picture). The work combines gas‐ and solution‐phase spectroscopy and provides the first benchmark of theoretical excitation energies for nitrophenolates.
Cage me! A linear dumbbell‐shaped bipyridinium molecule can template cage formation around itself through sixfold imine bond formation to give an interlocked [2]rotaxane as the single product (see picture). This highly efficient [2+3] clipping occurs despite the symmetry mismatch between the template and the formed macrobicycle.
Fast moving : A new pentad (see figure) composed of silicon phthalocyanine (SiPc), as electron donor, that is connected with two units of naphthalenediimide (NDI) and fullerene C60, as electron acceptors, undergoes fast and efficient charge‐separation processes via the NDI and SiPc singlet excited states.
Stop the breathing : As the organic bridging ligands become more elaborate and large, the resulting MOFs tend to experience significant framework distortion (i.e., breathing) upon solvent removal. Rigidification of MOFs that are built from elongated tetracarboxylate bridging ligands by unusual interlocking and interpenetration leads to highly porous and robust hybrid materials.
Silica scaffolding : By employing functionalized mesoporous SBA‐15 silica, novel fluorescent cruciform‐silica hybrid materials are generated which preserve the desirable solution properties of cruciforms in the solid state for potential use in sensory schemes.
Entering the fold : A common structural motif in hydrolytic enzymes is the α,β‐hydrolase fold. The interconversion of one enzyme into another by introduction of mechanistically important residues is not enough; only substitution of a loop allows epoxide hydrolase activity in the esterase scaffold to be formed (see picture; structure comparison of epoxide hydrolases (green) with the esterase (orange)). The result is an enantioselective chimeric enzyme.
A sense of cell‐being : Single‐walled carbon nanotubes (SWNTs) are functionalized with bioactive monosaccharides to enable their use as biosensors. The glycosylated nanotube network is biocompatible and can interface with living cells (see scheme) to electronically detect biomolecular release with high temporal resolution and high sensitivity.
Tell your guests when it's time to go : When avidin caps are attached to biotinylated colloidal mesoporous silica, the four subunits of the protein avidin can each bind to a biotin moiety attached to the surface (see picture). The resulting material is a promising candidate for the design of smart detergents or drug‐delivery systems. The caps can be opened to release guest molecules by controlled enzymatic hydrolysis of the protein.
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.
Perfluorination: The fully fluorinated analogue of pentaphenylborole (see structure; B gray, C black, F green) has been prepared using successive transmetallation reactions involving Zr and Sn heterocycles. The highly moisture‐sensitive borole is a new member of the perfluoroaryl borane family, a class of antiaromatic compounds of fundamental significance to concepts of aromaticity.
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.
Bigger isn't better : Gold nanoclusters exhibit enhanced electrocatalytic activity in oxygen reduction when the core size decreased from Au140 to Au11, as reflected by the onset potential Eonset and peak current density JK (see picture). The increasing fraction of surface atoms with low coordination numbers and the shift of the d‐band center to the Fermi level facilitate oxygen adsorption.
