A polyoxometallate-templated coordination polymer: synthesis and crystal structure of [Cu3(4,4'-bipy)5(MeCN)2]PW12O(40).2C6H5CN

The spherical phosphotungstate ion, PW12O40(3-), has been used as a non-coordinating anionic template for the construction of a novel, three-dimensional Cu(I) coordination polymer.     

Reduction of RF-induced sample heating with a scroll coil resonator structure for solid-state NMR probes

Heating due to high power 1H decoupling limits the experimental lifetime of protein samples for solid-state NMR (SSNMR). Sample deterioration can be minimized by lowering the experimental salt concentration, temperature or decoupling fields; however, these approaches may compromise biological relevance and/or spectroscopic resolution and sensitivity. The desire to apply sophisticated multiple pulse experiments to proteins therefore motivates the development of probes that utilize the RF power more efficiently to generate a high ratio of magnetic to electric field in the sample. Here a novel scroll coil resonator structure is presented and compared to a traditional solenoid. The scroll coil is demonstrated to be more tolerant of high sample salt concentrations and cause less RF-induced sample heating. With it, the viable experimental lifetime of a microcrystalline ubiquitin sample has been extended by more than an order of magnitude. The higher B1 homogeneity and permissible decoupling fields enhance polarization transfer efficiency in 15N-13C correlation experiments employed for protein chemical shift assignments and structure determination.     

Dysregulation of Na+/K+ ATPase by amyloid in APP+PS1 transgenic mice

Background  

The pathology of Alzheimer's disease (AD) is comprised of extracellular amyloid plaques, intracellular tau tangles, dystrophic neurites and neurodegeneration. The mechanisms by which these various pathological features arise are under intense investigation. Here, expanding upon pilot gene expression studies, we have further analyzed the relationship between Na+/K+ ATPase and amyloid using APP+PS1 transgenic mice, a model that develops amyloid plaques and memory deficits in the absence of tangle formation and neuronal or synaptic loss.     

Desymmetrization of glycerol derivatives with peptide-based acylation catalysts

[reaction: see text] Nucleophile-loaded peptides have been evaluated as catalysts for the desymmetrization of glycerol derivatives through an enantioselective acylation process. Enantiomeric excesses of up to 97% have been obtained for the monoacylated products. A range of other substrates have been examined that shed light on the mechanistic basis of the desymmetrizations.     

Halide-induced supramolecular ligand rearrangement

A novel reaction involving the halide-induced rearrangement of ligands within supramolecular Rh(I) complexes containing hemilabile ligands is presented. Three analogous bis- and trishemilabile ligands have been synthesized to construct bi- and trimetallic Rh(I) macrocyclic complexes. An intentionally added halide source results in the formal rotation of only one hemilabile ligand along the axis that is perpendicular to the plane defined by the aryl backbone of the hemilabile ligands. X-ray structures, as determined by X-ray crystallography, of key intermediates and products are presented.     

Acid-promoted Prins cyclizations of enol ethers to form tetrahydropyrans

Trifluoroacetic acid efficiently catalyzes Prins cyclizations of enol ethers 8 to provide tetrahydropyrans 9 and 10. These tetrahydropyrans are isolated with combined yields of 42-85% and stereoselectivities at C(4) ranging from 95:5 to 50:50 depending on the nature of the substituent R. Unique byproducts of these cyclizations that reveal the presence of underlying equilibria have been isolated and identified. [reaction: see text]