To bend about : The conformations of three phenyl‐C‐galactosides in solution were evaluated by using theoretical calculations and NMR spectroscopic studies. The α‐CF2 derivative (see scheme) showed significant flexibility of the pyranose ring and around the pseudoanomeric center, whereas the other two analogues more closely resemble the natural galactosides. Regardless, all three compounds bind to a plant lectin.
Getting stuck in : A hydrophobic molecular rod with terminal fluorescent moieties has been synthesized. The insertion of the rod into membranes was investigated and shown to incorporate efficiently into model and biological membranes (see picture; gray C, blue N, red O). Those rods can be used as stable membrane‐associated anchors for functionalization of membrane surfaces.
A boost from the branches : Incorporation of the dithieno[3,2‐b:2′,3′‐d]phosphole system as a core in oligo(phenylenevinylene) dendrimers (an example is shown here) provides materials that exhibit energy‐transfer features relaying incoming photons from the dendrons towards the core, which in turn shows enhanced emission intensity. The optical properties and self‐assembly features of the dendrimers can be impacted by the terminal groups (‐H, ‐CF3, or ‐NPh2) employed.
Stereocontrolled access to the hexacyclic core of FD‐594 has been achieved. The key steps include the intramolecular SNAr reaction for construction of the densely functionalized xanthone skeleton, the stereoselective lactone cleavage using a chiral nucleophile to induce the axial stereochemistry, and the SmI2‐mediated pinacol cyclization for the stereocontrolled conversion of axially chiral biaryl dialdehyde into the corresponding trans diol.
Large, larger, …? Replacement of 1,4‐benzenedicarboxylate by 2,6‐naphthalenedicarboxylate in the MIL‐101 structure leads to an isoreticular mesoporous framework containing cages with diameters of 39 and 46 Å. High‐throughput methods are employed to determine appropriate reaction conditions. The microcrystalline compound is characterized by molecular simulation techniques, powder X‐ray diffraction, N2‐sorption, and TEM investigations.
Losing the grip : The synthesis of multivalent low‐molecular‐weight dendrons with lysine branching units coupled to disulfide‐linked spermine surface groups is described. It is furthermore demonstrated that the dendrons bind DNA with good affinity (see image), but are also able to release the DNA in a reductive environment.
Available in small print : Block copolymer lithography has great potential for reducing the size and fabrication time of integrated circuits. Hydrogen‐bonding‐mediated molecular recognition in self‐assembly processes can be used to produce highly ordered square arrays of block copolymers on the surface of a silicon substrate (see picture).
From nanocrystals to atomic clusters : Fluorescent gold clusters (Au8) are synthesized by etching gold nanocrystals with the assistance of biomolecules, such as amino acids, peptides, proteins, and DNA (see picture). The gold clusters exhibit strong blue fluorescence as well as solvent‐dependent emission properties when dissolved in various organic solvents. They show potential applications in biological labeling and photoluminescence‐based sensors.
Two members of a family of pyrrole–imidazole marine alkaloids, (+)‐dibromophakellin and the nonnatural congener (+)‐phakellin, were synthesized enantioselectively from 4‐hydroxy‐L ‐proline. The chiral aminal at C10 was constructed efficiently by means of an Overman‐type [3,3] sigmatropic rearrangement of an enamide (see scheme).
The assembly line : Hexabenzocoronene amphiphiles appended with pyridyl‐terminated triethylene glycol side chains, in combination with trans‐[Pt(PhCN)2Cl2], lead to the formation of graphitic nanotubes. The structural features and dimensions of the nanotubes depend on the assembly conditions. A platinum(II)‐bridged cyclic dimer having two HBC units self‐assembles into a nanotubular structure.
Shining metal cups : A luminescent tube of triangular cross‐section and stoppered by a silver ion (see picture: Re yellow, N blue, O red) is formed in two steps from commercial materials. The silver ion can be removed to give a tube, and both species are potential hosts for small ions and molecules; a change in luminescence is triggered by the encapsulation of silver.
A black whole : The black insoluble biopolymer eumelanin is prepared through the oxidative polymerization of 5,6‐dihydroxyindoles (see scheme). It has a largely unknown heterogeneous structure and unique optoelectronic properties. Current structural models are presented and possible applications are discussed.
Economical atoms : 2‐Cyclopenten‐1‐ones, 5‐alkylidenefuran‐2(5 H)‐ones and indan‐1‐ones have been synthesized by atom‐economic reductive cyclocarbonylation of internal alkynes with carbon monoxide catalyzed by [{RhCl(CO)2}2]/CO(NH2)2 in the presence of water (see scheme).
Fast detection of cellular thiols in aqueous medium was achieved using a newly developed fluorescence probe (see picture). Based on this probe, a high‐throughput fluorescence assay for glutathione reductase was developed.
Exciton migration! Spectroscopic analyses and extensive molecular dynamics studies revealed a well‐defined 41 helix in which the perylene molecules (see figure) form four “helter‐skelter‐like” overlapping pathways along which excitons and electrons can rapidly migrate.
A bicycle built for two : The title reaction affords cis‐fused bicyclo[4.3.0]nonenes from readily available 1,5‐bisallenes with structurally diverse propargylic carbonates and arylboronic acids (see scheme; X=NTs, C(E1)2 with E1=CO2Bn, SO2Ph, dba=trans,trans‐dibenzylidenacetone). The reaction may involve a sequential oxidative addition, two different types of three carbopalladations, and a Suzuki‐type coupling.
Self‐control : endo‐Sulfoxide products can be synthesized selectively by the oxidation of thia‐capped cyclodextrins using m‐chloroperoxybenzoic acid (m‐CPBA) in water. The reaction occurs by the formation of an oxidant–cyclodextrin inclusion complex. Operating in organic media preferentially leads to exo‐sulfoxide products.
Surface‐hopping simulations are used to study the nonradiative relaxation of 9H‐guanine. Two distinct S1→S0 (ππ*→gs) decay channels, both of which pass through a conical intersection (CI), are found to be responsible for the experimentally observed double‐decay behavior (see schematic diagram).
Efficiency simplified : A synthetic strategy has been developed to prepare single‐crystalline hollow Pd/Pt nanocubes (right, see picture; left: nanocubes). Compared to the solid Pd/Pt nanocubes of similar sizes, the hollow Pd/Pt nanocubes increase accessible surface area and therefore improve electrocatalytic activity in formic acid oxidation.
Quick on the uptake : A multiscale theoretical method predicts that the gravimetric adsorption capacities of H2 in Li‐doped covalent organic frameworks based on the building blocks shown (Li violet, H white, B pink, C green, O red, Si yellow) can reach nearly 7 % at T=298 K and p=100 bar, suggesting that these Li‐doped materials are promising adsorbents for hydrogen storage.
