From imines to amines through catalysis by IrI complexes of a new type of P,N ligand (see scheme): This reaction affords the corresponding optically active amines with up to 98 % ee and has also been used with perfect stereoselectivity in the asymmetric synthesis of sertraline ( 1 ), an important antidepressant chiral drug.
Helical superstructures : A series of luminescent chiral alkynylplatinum(II)–terpyridyl complexes has been successfully synthesised and shown to be capable of forming metallogels that show helical fibrous nanostructures. The chiral supramolecular structure and the spectroscopic properties are found to depend on the extent of aggregation through Pt???Pt and π–π interactions in various counteranions, as revealed by UV/Vis, circular dichroism (CD), and luminescence studies (see picture).
In a new light : The NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR; see structure, green Pchlide, yellow NADPH) is a good model to investigate catalytical processes in enzymes, as its light activation allows an immediate start of the catalyzed reaction. By irradiation with weak, short laser pulses it is possible to detect conformation changes during the reaction and thus to uncover the elementary steps of the catalytic process.
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.
X‐ray vision : Single‐crystal XRD experiments (see picture) reveal the excited‐state structure of the photomagnetic heterobimetallic title complex. The system shows a decrease in all the iron–ligand bond lengths, suggesting that photoexcitation involves a ligand‐to‐metal charge transfer or a change in the superexchange coupling between the metal centers.
Unusual {3 3 ?5 9 ?6 3 }‐lcy topology has been found in an uncommon 3D six‐connected, two‐fold interpenetrated {33 ? 59 ? 63}‐lcy net (illustrated). The coordinated SO42? anions in this framework can undergo a full exchange with Cl? anions, in the course of which the crystals change color as shown. The process has a solvent‐mediated rather than a solid‐state mechanism.
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).
Film studies : Epitaxial films of BaZrN2 (see TEM image) and BaHfN2 are grown by polymer‐assisted deposition on SrTiO3 (STO) substrates. The films are phase‐pure, allowing the intrinsic physical properties of the ternary nitrides to be studied. From 5 to 300 K, the films exhibit metallic‐like resistivity–temperature behavior, with large residual resistivity ratios.
A novel sialon phosphor is characterized by an unusual silicate framework, built up of edge‐ and vertex‐sharing tetrahedra (orange and green). Owing to pronounced pseudotranslations, the compound is highly disordered. It was investigated in detail by X‐ray diffraction and electron microscopy. Despite the disorder, all Sr atoms (yellow spheres) exhibit very similar coordination spheres, and doping with Eu2+ results in efficient green luminescence (see inset; Em.=emission, Exc.=excitation, Refl.=reflection).
Number of members makes a difference : The [2+2+2] intramolecular cyclotrimerisation of a new series of 20‐ and 25‐membered azamacrocycles catalysed by the Wilkinson's catalyst are reported (see scheme). The 20‐ and 25‐membered azamacrocycles show different reactivity. Why? Theoretical calculations give insight into the reactivity differences observed for the 20‐ and 25‐membered macrocycles.
Get selective! A selective oxidation of 1,2‐diols to α‐hydroxyketones catalyzed by organotin compounds has been developed (see scheme). Invaluable chemo‐ and stereoselectivity were found in the reaction. The catalytic system has been achieved by electrochemical and chemical oxidation.
The many faces of crystals : Silica mesoporous crystals were synthesized by using a co‐structure directing method. Structural defects in the crystals with Fdm symmetry—described as tetrahedrally close‐packed and consisting of 512 and 51264 polyhedra—were found (see figure). These defects were explained through the use of simulated TEM images. The defect formation is also discussed.
