Protonation of chiral porous materials introduces a Brønsted acid centre, the structure of which is unique to the heterogeneous phase requiring pore wall confinement for stable isolation.

Challenging couplings of hindered carboxylic acids with non-nucleophilic amines to form amide bonds can be accomplished in high yields, and in many cases, with complete retention of the adjacent stereogenic centers using the combination of N, N, N', N'-tetramethylchloroformamidinium hexafluorophosphate (TCFH) and N-methylimidazole (NMI). This method allows for in situ generation of highly reactive acyl imidazolium ions, which have been demonstrated to be intermediates in the reaction. The reagent delivers high reactivity similar to acid chlorides with the ease of use of modern uronium reagents.

Knockout mice deficient in the gap junction gene connexin43 exhibit developmental anomalies associated with abnormal neural crest, primordial germ cell, and proepicardial cell migration. These migration defects are due to a loss of directional cell movement, and are associated with abnormal actin stress fiber organization and a loss of polarized cell morphology. To elucidate the mechanism by which Cx43 regulates cell polarity, we used a wound closure assays with mouse embryonic fibroblasts (MEFs) to examine polarized cell morphology and directional cell movement. Studies using embryonic fibroblasts from Cx43 knockout (Cx43KO) mice showed Cx43 deficiency caused cell polarity defects as characterized by a failure of the Golgi apparatus and the microtubule organizing center to reorient with the direction of wound closure. Actin stress fibers at the wound edge also failed to appropriately align, and stabilized microtubule (Glu-tubulin) levels were markedly reduced. Forced expression of Cx43 with deletion of its tubulin-binding domain (Cx43dT) in both wildtype MEFs and neural crest cell explants recapitulated the cell migration defects seen in Cx43KO cells. However, forced expression of Cx43 with point mutation causing gap junction channel closure had no effect on cell motility. TIRF imaging revealed increased microtubule instability in Cx43KO cells, and microtubule targeting of membrane localized Cx43 was reduced with expression of Cx43dT construct in wildtype cells. Together, these findings suggest the essential role of Cx43 gap junctions in development is mediated by regulation of the tubulin cytoskeleton and cell polarity by Cx43 via a nonchannel function.

Two neutral and four-coordinate vanadium(V)-nitrido complexes have been prepared via the thermolysis of metastable vanadium(III)-azido precursors. All complexes have been fully characterized by multinuclear NMR, FT-IR, isotopic labeling, and, in most instances, single crystal X-ray diffraction. On the basis of activation parameters, N(2) extrusion to form the V[triple bond]N moiety is proposed to occur via an ordered and early transition state having three- or four-triazametallacycle frameworks. In addition, we demonstrate the nitrido ligand to undergo incomplete N-atom transfer to CO and CN{2,6-Me(2)-C(6)H(3)) to form the bent V-N=C=X (X = O, N{2,6-Me(2)-C(6)H(3)}) ligands with concomitant 2e(-) reduction at the vanadium center.

Aryl-triazole pentads have been preorganized with intramolecular hydrogen bonds to enhance chloride binding. This outcome highlights the dual hydrogen bond donor and acceptor properties of 1,2,3-triazoles.