Stuck on sulfur : The first transition‐metal complexes with S? Br units are surprisingly stable. Solid 3 is stable for at least six months and under vacuum solid 2 does not lose Br2. The formation of the first structurally characterized transition‐metal arenesulfenyl bromide complex 3 occurs with a change of the spin ground state from S=2 to S=0.
Long live the OLED! Rational design and synthesis of IrIII complexes bearing two cyclometalated ligands (C N) and one 2‐(diphenylphosphino)phenolate chelate (P O) as well as the corresponding IrIII derivatives with only one (C N) ligand and two P O chelates are reported. According to the observed photophysical data, a P O ligand is found to be able to fine‐tune the light‐emitting electronic transition of these complexes.
Changing channels : The novel dynamic gas‐separation mechanism is demonstrated by a GC study for a flexible single crystal [Cu2(bza)4(pyz)]n, 1 . The single‐crystal host 1 , because of its flexibility, can separate various gases by adjusting its channel structure according to the features of the guest gaseous molecules.
Playing the sax : The enantioselective total syntheses of (?)‐ and (+)‐decarbamoyloxysaxitoxin (doSTX) and (+)‐saxitoxin (STX) are reported. A new methodology was developed for the synthesis of STXs, featuring discriminative reduction of the nitro group and N? O bond in nitroisoxazolidine.
Always on the move : Molecular dynamics of perylene cores in columnar structures influences the processability and self‐healing of these materials. A combination of X‐ray scattering and advanced solid‐state NMR methods show that these systems have restricted angular mobility of the cores even in the frozen phase, and a cooperative spiral type of motion in the liquid crystalline phase (see picture).
A unique example of macromolecular self‐assembly, where a mono‐component homopolyimide bearing carboxy end‐groups spontaneously forms nanopartilces with novel dimple‐like morphology in a single good solvent, is presented. The self‐assembly process is dramatically affected by the solution concentration and the temperature. It is proposed that such an unexpected self‐assembly behavior is a synergistic result of the self‐complementary hydrogen bonding between carboxy end‐groups and the propensity to parallel packing of polyimide chains through aromatic interactions.
Custom built : A promising new approach towards more efficient self‐assembled cage receptors through computer‐aided design is demonstrated. The resulting M4L6 tetrahedral cage, internally functionalized with accurately positioned urea hydrogen‐bonding groups (see structure; yellow: predicted, blue: experimental, space‐filling: SO42?), proved to be a remarkably strong sulfate receptor in water.
Ring any bells? The differential capacitance curve of Au(100) in neat [BMI]BF4 (BMI=1‐butyl‐3‐methylimidazolium) ionic liquid has a bell‐shaped feature (see picture). The adsorption of BMI+ shows a disorder–order transition and depends on the structure of the surface. Ordered adsorption in a micelle‐like structure stabilizes the underlying Au surface.
“My favorite subject at school was tennis. When I was eighteen I wanted to be a chemist…?.!” This and more about Manfred T. Reetz can be found on page 3731.
Sensitive functional groups such as COR, CHO, or CH2OH can be present in benzylic indium reagents prepared by the direct insertion of indium in the presence of LiCl. These reagents undergo palladium‐catalyzed cross‐coupling reactions in the presence of a protic cosolvent after activation with iPrMgCl⋅LiCl (see scheme). Remarkable chemoselectivities are achieved by using various electrophiles containing NH or OH groups.
Additional cyclization : Dicyanonitrosomethanide, [C(CN)2(NO)]? undergoes nucleophilic addition and cyclization of 1,2‐diaminoethane and 1,3‐diaminopropane on the nitrile groups to form imidazolinyl and 1,4,5,6‐tetrahydropyrimidinyl groups, respectively. Ethanolamine has lower reactivity and fails to cyclize.
Well‐defined polymethylene‐block‐polystyrene (PM‐b‐PS) diblock copolymers were synthesized via a combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) of styrene. A series of hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight and narrow molecular weight distribution were prepared using living polymerization of ylides following efficient oxidation in a quantitive functionality. Then, the macroinitiators (PM‐MIs ( = 1 900–15 000; PDI = 1.12–1.23)) transformed from PM‐OHs in ≈ 100% conversion initiated ATRPs of styrene to construct PM‐b‐PS copolymers. The GPC traces indicated the successful extension of PS segment ( of PM‐b‐PS = 5 000–41 800; PDI = 1.08–1.23). Such copolymers were characterized by 1H NMR and DSC.
Unstable? We're able! 1,n‐Glycols serve as synthetic equivalents to unstable dialdehydes in two‐directional carbonyl allylation from the alcohol oxidation level under iridium‐catalyzed transfer hydrogenation conditions. Iterative asymmetric allylation employing 1,3‐propanediol enables the rapid assembly of protected 1,3‐polyol substructures with exceptional levels of stereocontrol.
How are dihydropyridines like indoles? Both groups of compounds have similar nucleophilicity parameters N and are therefore suitable substrates for iminium‐catalyzed reactions of α,β‐unsaturated aldehydes. The N parameters of 1,4‐dihydropyridines were derived from the rates of hydride transfer reactions to benzhydrylium ions (see scheme).
Preferred protonation : Does electrospray ionization mass spectrometry produce gas‐phase or liquid‐phase structures? The preferred protonation site in p‐aminobenzoic acid depends upon the medium, and the structure of its conjugate acid varies with the solvent used during spraying.
Fleetingly formyl : A new rhodium‐catalyzed hydroformylation reaction of N‐allyl oxazolidines, carried out under a CO/H2 atmosphere, followed by a diastereoselective deformylative cyclization affords hexahydropyrrolo[2,1‐b]oxazoles in good yields. The reaction proceeds by a unique hydroformylation–deformylation sequence in which the formyl group virtually substitutes for the {CH2? O} fragment of the oxazolidine heterocycle.
A supramolecular complex between an ionic monomer 3‐sulfopropyl methacrylate (SPMAK) and crown ether 18‐crown‐6 (18C6) has been employed to prepare a strong anionic cylindrical polyelectrolyte brush poly(potassium 3‐sulfopropyl methacrylate) (PSPMAK) by atom transfer radical polymerization (ATRP) in polar solvent dimethyl sulfoxide (DMSO). This strategy solved the problem of the solubilities of the incompatible hydrophobic poly‐initiator and hydrophilic ionic monomer. The formation of the PSPMAK brush is well proven by 1H NMR, aqueous gel permeation chromatography (GPC), dynamic light scattering (DLS), static light scattering (SLS), atomic force microscopy (AFM), and cryogenic transmission electron microscopy (cryo‐TEM) measurements. Cleavage of the side chains and further analysis reveal that the initiating efficiency of the polymerization is as low as 0.35.
Bulking up: The thermal barrier to rearrangement of a vic‐disulfoxide is significantly increased through steric buttressing about the (O)S? S(O) bond. Whereas the title compounds represent the most thermally stable vic‐disulfoxides known to date, they also undergo a novel photomediated epimerization at room temperature (see scheme).
Doped up : The incorporation of Zn2+ dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn0.4Mn0.6)Fe2O4 nanoparticles exhibit the highest magnetization value among the metal ferrite nanoparticles. Such high magnetism results in the largest MRI contrast effects (r2=860 mm?1 s?1) reported to date and also huge hyperthermic effects.
