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A set of inexpensive and pedagogically rich experiments focusing on S[subscript N]1, E1, and E2 reactions have been updated to include modern computational and spectroscopic analyses. The S[subscript N]1 experiment involves treatment of "tert"-amyl alcohol with hydrochloric acid to generate the corresponding alkyl chloride, which is used as the starting material for the subsequent E2 reaction. The E1 experiment involves reaction of "tert"-amyl alcohol with sulfuric acid. Both elimination reactions generate a pair of isomeric methylbutenes, with the ratio being dependent on the reaction mechanism. The combination of computational chemistry and a recently developed fast heteronuclear single-quantum correlation spectroscopy method (ASAP-HSQC), in tandem with [superscript 1]H and [superscript 13]C NMR and GC-MS analysis, allows the E1 and E2 product mixtures to be fully analyzed by students.

Quantitative [superscript 13]C NMR provides a straightforward method of analyzing edible oils in undergraduate chemistry laboratories. [superscript 13]C spectra are relatively easy to understand, and are much simpler to analyze and workup than corresponding [superscript 1]H spectra. Average chain length, degree of saturation, and average polyunsaturated fatty acid content of common edible oils are obtained directly using integrals of the proper regions in the [superscript 13]C 1D spectra. These spectra segue to 2D [superscript 1]H - [superscript 13]C HSQC experiments that provide an excellent path for students to verify assignments, in particular those associated with polyunsaturated fatty acids. Data acquisition and analysis can be completed in one to two lab sections, although spectrometer scheduling may be necessary for groups of students greater than six. [superscript 13]C relaxation measurements of common oils are presented that enable accurate quantitative [superscript 13]C data to be obtained in reasonable amounts of time (30-40 min per sample) on modern 400 MHz NMR spectrometers.

Nobel Prize in Medicine awarded in December 2003 to chemist Paul C. Lauterbur and physicist Peter Mansfield for the development of magnetic resonance imaging (MRI), a long overdue recognition of the huge impact MRI has had in medical diagnostics and research is mentioned. MRI was derived, and remains an extension of nuclear magnetic resonance (NMR) developed primarily to solve the structures of organic molecules, into an enormously valuable medical tool.

The metastable purple [(Py5Me2)RuIII(N3)]2+ ion reacts with PPh3 at room temperature to form the phosphinimine complex [(Py5Me2)RuII(N(H)PPh3)]2+ and free [H2NPPh3]+ in a combined 23% conversion. Mechanistic studies suggest that this is the first metallo-Staudinger reaction of a late transition metal that bypasses the nitrido mechanism and instead utilizes a Ru–N＝N＝N–PPh3 phosphazide intermediate. [ABSTRACT FROM AUTHOR]

The synthesis and the properties of various glass-forming materials including 1,3,5-tris(napthyl)benzene and its derivatives are discussed.

Solution-state NMR typically requires 100 μM to 1 mM samples. This limitation prevents applications to mass-limited and aggregationprone target molecules. Photochemically induced dynamic nuclear polarization was adapted to data collection on low-concentration samples by radiofrequency gating, enabling rapid 1D NMR spectral acquisition on aromatic amino acids and proteins bearing aromatic residues at nanomolar concentration, i.e., a full order of magnitude below other hyperpolarization techniques in liquids. Both backbone H1-C13 and side-chain resonances were enhanced, enabling secondary and tertiary structure analysis of proteins with remarkable spectral editing, via the 13C PREPRINT pulse sequence. Laser-enhanced 2D NMR spectra of 5 μM proteins at 600 MHz display 30-fold better S/N than conventional 2D data collected at 900 MHz. Sensitivity enhancements achieved with this technology, denoted as low-concentration photo- CIDNP (LC-photo-CIDNP), depend only weakly on laser intensity, highlighting the opportunity of safer and more cost-effective hypersensitive NMR applications employing low-power laser sources. [ABSTRACT FROM AUTHOR]

Discusses the use of various techniques to measure the anisotropic electrical conductivity of carbon-fiber/epoxy resin composites. Approximate analysis; Experimental details and results; Measurements of the nuclear magnetic resonance imaging.

Nanoparticles are frequently modified with polymer layers to control their physical and chemical properties, but litde is understood about the morphology and dynamics of these polymer layers. We report here an NMR-based investigation of a model polymer-modified nanoparticle, using multiple NMR techniques including ¹H NMR, diffusion-ordered spectroscopy (DOSY), total correlation spectroscopy (TOCSY), and T2 relaxometry to characterize the dynamics of the nanoparticle—polymer interface. Using 5 run detonation nanodiamond covalently linked to poly(allylamine) hydrochloride as a model system, we demonstrate the use of NMR to distinguish between free and bound polymer and to characterize the degree to which the segments of the nanoparticle-wrapping polymer are mobile (loops and tails) versus immobile (trains). Our results show that the polymer-wrapped nanoparticle contains a large fraction of highly mobile polymer segments, implying that the polymer extends well into solution away from the nanoparticle surface. Flexible, distal polymer segments are likely to be more accessible to extended objects such as cell membranes, compared with polymer segments that are in close proximity to the nanoparticle surface. Thus, these flexible segments may be particularly important in controlling subsequent interactions of the nanoparticles. While reported here for a model system, the methodology used demonstrates how NMR methods can provide important insights into the structure and dynamics at nanoparticle—polymer interfeces, leading to new perspectives on the behavior and interactions of polymer-functionalized nanoparticles in aqueous systems. [ABSTRACT FROM AUTHOR]

Quantitative 13C NMR provides a straightforward method of analyzing edible oils in undergraduate chemistry laboratories. 13C spectra are relatively easy to understand, and are much simpler to analyze and workup than corresponding ¹H spectra. Average chain length, degree of saturation, and average polyunsaturated fatty acid content of common edible oils are obtained directly using integrals of the proper regions in the 13C 1D spectra. These spectra segue to 2D ¹H-13C HSQC experiments that provide an excellent path for students to verify assignments, in particular those associated with polyunsaturated fatty acids. Data acquisition and analysis can be completed in one to two lab sections, although spectrometer scheduling may be necessary for groups of students greater than six. 13C relaxation measurements of common oils are presented that enable accurate quantitative 13C data to be obtained in reasonable amounts of time (30-40 min per sample) on modern 400 MHz NMR spectrometers. [ABSTRACT FROM AUTHOR]

Hydroxamic acids (HAs) perform tasks in medicine and industry that require bidentate metal binding. The two favored conformations of HAs are related by rotation around the C(=O)-N bond. The conformations are unequal in stability. Recently, we reported that the most stable conformation of a small secondary HA in water places the oxygen atoms anti to one another. The barrier to C-N bond rotation may therefore modulate metal binding by secondary HAs in aqueous media. We have now determined the activation barrier to C-N rotation from major to minor conformation of a small secondary HA in D2O to be 67.3 kJ/mol. The HA rotational barrier scales with solvent polarity, as is observed in amides, although the HA barrier is less than that of a comparable tertiary amide in aqueous solution. Successful design of new secondary HAs to perform specific tasks requires solid understanding of rules governing HA structural behavior. Results from this work provide a more complete foundation for HA design efforts. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two novel trialkyl-substituted aromatic acids, solwaric acids A and B, were isolated from a marine Solwaraspora sp. cultivated from the ascidian Trididemnum orbiculatum. Solwaric acids A and B were isotopically labeled with U-13C glucose, and analysis of a 13C-13C COSY allowed for unambiguous determination of the location of the phenyl methyl group. The two novel compounds demonstrated antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). [ABSTRACT FROM AUTHOR]