Spin‐restricted time‐dependent DFT for open‐shell systems is used to study the spin multiplicity dependence of nonlinear optical coefficients. Calculations are performed for various spin states of the pyrrole radical (see figure). The results indicate a substantial dependence on spin multiplicity of the NLO properties, which are sensitive to the basis set compared to closed shells at the DFT level of theory.
Introduction of strong intermolecular interactions leads to the observation of the LIESST effect even for iron(III) spin‐crossover (SCO) compounds. For LIESST iron(III) compounds, both stretching and bending modes are considered in the reaction coordinate diagram. The picture depicts the LIESST mechanism in the reaction coordinate diagram considering both stretching and bending modes for SCO iron(III) compounds. For more information see the Full Paper by S. Hayami, O. Sato et al. on page 3497 ff.
Secondary, but second to none : The use of secondary alkyl halides in transition‐metal‐catalyzed cross‐coupling reactions (see scheme) has advanced significantly over the last five years. Selected examples of these transformations are examined, including mechanistic and stereochemical aspects.
The ins and outs of spin : Using the microporous coordination polymer {Fe(pz)[Pt(CN)4]} ( 1 , pz=pyrazine), incorporating spin‐crossover subunits, two‐directional magnetic chemo‐switching is achieved at room temperature. In situ magnetic measurements following guest vapor injection show that most guest molecules transform 1 from the low‐spin (LS) state to the high‐spin (HS) state, whereas CS2 uniquely causes the reverse HS‐to‐LS transition.
A facile wet route was applied to prepare a series of chalcogenide semiconductor nanocrystals (see figure) in controllable shapes and sizes, while a general bottom‐up approach was adopted to transform these cyclohexane‐soluble monodisperse nanocrystals into water‐soluble colloidal spheres.
Spin‐noise appeal : Detection of NMR spin‐noise is very appealing when dilute hyperpolarized species are considered. Continuous monitoring of the noise absorption at the Larmor frequency enables determination of T1 and T2*, independently of the static magnetic field. An inductively coupled microcoil located inside the NMR tube (see picture) allows acquisition of 129Xe spin‐noise spectra without radio‐frequency excitation.
On edge : Self‐assembled monolayers of a bis(hydrazone)‐based molecular grid physisorbed on graphite are studied by scanning tunneling microscopy (see picture). High order is attained at the supramolecular level by thermal annealing of the grid‐based films. A preferential edge‐on configuration of the molecular grid with respect to the substrate is found.
Suprapolymers : The synthesis of symmetrically end‐functionalized polymers in a single step has been developed by means of ring‐opening metathesis polymerization by using a bimetallic ruthenium initiator and functional chain terminators. Self‐assembly of the resulting polymers allows for the formation of supramolecular alternating block copolymers (see figure).
Not blue but red‐brown : A [1]ferrocenophanium ion has been synthesized and isolated as a red‐brown crystalline salt, surprisingly different in color from characteristically blue‐green unstrained ferrocenium ions. Compared to the neutral iron(II) counterpart, the [1]ferrocenophanium ion displays a considerably higher ring tilt and an increased propensity for ring‐opening reactions.
Get into the groove : The first high‐resolution structure of a foldamer bound to a protein target is described (see picture; foldamer in sticks). The foldamer consists of α‐ and β‐amino acid residues and is bound to the anti‐apoptotic protein Bcl‐xL. The overall binding mode and key interactions observed in the foldamer/Bcl‐xL complex mimic those seen in complexes of Bcl‐xL with natural α‐peptide ligands. Additional contacts in the foldamer/Bcl‐xL complex involving β‐amino acid residues appear to contribute to binding affinity.
Fruity electrodes : A simple bottom‐up self‐assembly method was used to fabricate rambutan‐like tin–carbon (Sn@C) nanoarchitecture (see scheme, green Sn) to improve the reversible storage of lithium in tin. The mechanism of the growth of the pear‐like hairs is explored.
The moderate nucleophilicity of the axially chiral amino sulfonamide (S)‐ 1 suppresses the problematic side reactions, including aldol reactions, in the asymmetric Mannich reaction of N‐Boc‐protected imines with aldehydes. The corresponding adducts are obtained in good yield and excellent stereoselectivity (see scheme; Boc=tert‐butoxycarbonyl, Tf=trifluoromethanesulfonyl).
A new class of tetrathiafulvalene‐based microstructures fabricated by coordinative self‐assembly has been prepared by a solution process. Upon incorporation of Pb2+ and Zn2+ ions, 1D wirelike microstructures and spherical polymer particles were achieved, respectively (see picture). The neutral coordination polymers are conductive and magnetic at room temperature without external manipulation.
In quarantine : Nitroxide spin probes are encapsulated by hexameric resorcinarene molecular capsules in dichloromethane solutions (see picture). A substantial reduction in the tumbling rates occurs upon encapsulation of two cationic probes and one neutral probe. As the molecular volume of the probe increases, the tumbling rate of the probe reflects the overall tumbling rate of the entire supramolecular assembly.
Multistep in flow: The Seyferth–Gilbert reagent 1 has been applied in a flow system to rapidly synthesize terminal alkynes. The system has been further applied to synthesize triazole 3 from alcohol 2 in a three‐step oxidation/homologation/copper(I)‐catalyzed azide–alkyne cycloaddition sequence without isolation of intermediates (see scheme).
Step by step : By attaching anionic building blocks of variable bulk to a cationic metal–organic framework, stepwise channel‐size adjustment of the resulting porous three‐dimensional host framework is achieved (see picture). This method is a new and viable approach for materials with predesigned nanopores for application in molecular recognition and selective guest inclusion.
Codeposition of NO and O 2 diluted in Ne at 6 K yield a ON???OO complex that exhibit strong UV absorption. This complex is converted into NO3 radicals by UV irradiation, and is regenerated by radiation of visible light (see spectra).
Breaking the chain : Reaction of a zirconium hydrazinediide with organoazides gives 2‐pentazene‐1,4‐diyl complexes, such as [Zr(N2TBSNpy){N(Ad)N3NPh2}] (C gray, N blue, Si green, Zr turquoise), by formal [2+3] cycloaddition. Bonding within the N5 chain is investigated using density functional calculations. These complexes thermally eject N2 to give side‐on bonded diazenides.
