Simple, versatile and green : Diels–Alder “click” chemistry is a simple, versatile and “greener” approach in the design of a diverse range of dendritic macromolecules (see scheme).
Similarities and differences : Far‐infrared spectra of protic ionic liquids could be assigned to intermolecular bending and stretching modes of hydrogen bonds. The characteristics of the low‐frequency spectra resemble those of water. Both liquids form three‐dimensional network structures, but only water is capable of building tetrahedral configurations. EAN: ethylammonium nitrate, PAN: propylammonium nitrate, DMAN: dimethylammonium nitrate.
Building bridges : The title compound forms an unprecedented polymeric structure with bridging B–H–B three‐center two‐electron bonds in the solid state. This organoborane serves as an efficient precursor for the preparation of boron‐doped π‐conjugated polymers by hydroboration polymerization with a functionalized 1,4‐diethynylbenzene (see picture). These polymers form thin films that show intense green luminescence.
One step at a time : The in situ monitoring of the step‐by‐step formation of metal–organic frameworks (MOFs) by using surface plasmon resonance (SPR), allows the nucleation process and the formation of the secondary building units to be investigated. Growth rates on functionalized organic surfaces with different crystallographic orientations can also be studied.
A novel selective palladium catalyst system based on bidentate 2,2′‐heteroarylarylphosphines and p‐TsOH has been developed for hydroformylation reactions (see scheme). By applying optimal conditions good to excellent regioselectivity is obtained for the hydroformylation of aliphatic and aromatic olefins. It is shown that a low acid concentration is crucial for obtaining high degrees of the linear isomer.
Changing places : Intramolecular B(pin)/H exchange took place in the presence of a platinum–phosphane catalyst, giving synthetically useful cis‐β‐methyl‐substituted alkenylboronates stereoselectively (see scheme; B(pin)=4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl).
Ask a copper : A copper(II) salt/chiral dipyridylphosphine/PhSiH3 system (see scheme) acts as a very effective and practical catalyst for the asymmetric reduction of heteroaromatic and other types of ketones in air with good‐to‐excellent enantioselectivities (up to 94 %), giving many chiral alcohols that are intermediates for physiologically active compounds. Remarkable temperature effects were observed for some heteroaromatic ketones.
Tuning electronic properties and morphologies : We report a unique design platform of n‐type organic semiconductors based on asymmetrically substituted bisphenazines that enable tuning of both electronic properties and morphologies of 1D nanostructures (see figure) by using small substituents with various sizes and electronic demands.
Ultrafast light‐induced processes in a series of π‐conjugated mono‐, bis‐, tris‐ and tetrakis(terpyridine) derivatives are investigated by femtosecond time‐resolved spectroscopy. Non‐exponential excited‐state dynamics involving singlet–triplet intersystem crossing are observed which span from picoseconds to nanoseconds (see figure).
Attractive chlorine : Noncovalent interactions between chlorine or bromine atoms and aromatic rings in proteins open up a new method for the manipulation of molecular recognition. Substitution at distinct positions of two factor Xa inhibitors improves the free energy of binding by interaction with a tyrosine unit. The generality of this motif was underscored by multiple crystal structures as well as high‐level quantum chemical calculations (see picture).
Ligand design by‐pam : A ruthenium‐catalyzed asymmetric arylation of aldehydes with arylboronic acids has been developed, giving chiral diarylmethanols in good yields. The use of a chiral bidentate phosphoramidite ligand ((R,R)‐Me‐bipam) led to excellent enantioselectivities.
Chiral oxazaborolidines can be activated by N‐protonation using strong protic acids or by N‐coordination with AlBr3 to form very strong chiral Lewis acids. The resulting chiral boron electrophiles (see structure) are powerful chiral catalysts that effectively promote [4+2], [3+2], and [2+2]‐cycloaddition reactions with high enantioselectivity.
