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21.
Krow GR Liu N Sender M Lin G Centafont R Sonnet PE DeBrosse C Ross CW Carroll PJ Shoulders MD Raines RT 《Organic letters》2010,12(23):5438-5441
CD spectra for homooligomers (n = 4, 6, 8) of (1S,4R,5R)-5-syn-carboxy-2-azabicyclo[2.1.1]hexane (MPCA), a methano-bridged pyrrolidine β-carboxylic acid, suggest an ordered secondary structure. Even in the absence of internal hydrogen bonding, solution NMR, X-ray, and in silico analyses of the tetramer are indicative of conformations with trans-amides and C(5)-amide-carbonyls oriented toward the C(4) bridgehead. This highly constrained β-amino acid could prove useful in the ongoing development of well-defined foldamers. 相似文献
22.
Parkesh R Vasudevan SR Berry A Galione A Dowden J Churchill GC 《Organic & biomolecular chemistry》2007,5(3):441-443
A chemo-enzymatic synthesis of novel caged NAADP+ without the formation of multiple cage compounds has been achieved. The biological activity of the caged NAADP+ was demonstrated by its fast uncaging in intact sea-urchin eggs. 相似文献
23.
Our struggles and ultimate success in achieving a total synthesis of phomactin A are described. Our strategy features an intramolecular oxa-[3 + 3] annulation to construct its unique ABD-tricyclic manifold. Although the synthesis would constitute a distinctly new approach with the 12-membered D-ring of phomactin A being assembled simultaneously with the 1-oxadecalin at an early stage, the ABD-tricycle represents a unique structural topology that would pose a number of unprecedented challenges. One challenge concerned elaborating this tricycle to have oxygenation at the proper carbon atoms. To overcome this, we would utilize a Kornblum-DeLaMare ring-opening of a peroxide bridge as well as a challenging late-stage 1,3-allylic alcohol transposition. Further, the structural intricacies of the ABD-tricycle were uncovered by a conformational analysis that would be critical for the C5a-homologation. 相似文献
24.
Trevor M. Grant David S. Josey Kathleen L. Sampson Thanmayee Mudigonda Timothy P. Bender Benoît H. Lessard 《Chemical record (New York, N.Y.)》2019,19(6):1093-1112
Organic photovoltaics (OPVs) have experienced continued interest over the last 25 years as a viable technology for the generation of power. Phthalocyanines are among the oldest commercial dyes and have been utilized in some of the earliest examples of OPVs. In recent years, the use of boron subphthalocyanines (BsubPcs) and silicon phthalocyanines (SiPcs) has attracted a flurry of interest with some examples of fullerene‐free devices reaching power conversion efficiencies >8 %. Unlike other more common divalent phthalocyanines such as copper or zinc, BsubPcs and SiPcs contain additional axial groups that can easily be functionalized without significantly affecting the optoelectronic properties of the macrocycle. This handle facilitates our ability to tune the solid‐state arrangement and other physical characteristics such as solubility ultimately giving us the ability to improve the thin film processing and final device performance. This review covers recent studies on the development of BsubPcs and SiPcs for use as active materials in organic photovoltaics. 相似文献
25.
Carolyn J. Koester James F. Blankenship Patrick M. Grant 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2015-2019
Using cyanoacrylate or “superglue” fuming to develop latent dermatoglyphic prints significantly altered the volatile and semivolatile compounds within the material of polyethylene zip-lock bags. Comparisons of SPME-GC/MS analyses of poly bags obtained before and after application of a glue fuming fingermark-developing technique resulted in markedly different material profiles of the bags. Not only were species added to the chemical composition of a bag, but other compounds that had been initially present were removed. These effects are particularly important for nuclear forensic investigations in the realm of route (pathway) analyses, and may also be of general interest to criminalistics laboratories that examine illicit drugs and their packaging. 相似文献
26.
27.
A series of substituted 2-azadiene systems has been prepared and characterized by reactivity, structure, and photoelectron-spectroscopic studies. An attempt has been made to employ photo-electron spectroscopy as a tool for predicting sites of chemical reactivity for these azadiene systems. Although such correlations can be tenuous, they seem to be useful in this limited study. 相似文献
28.
Julio C. Facelli David M. Grant Josef Michl 《International journal of quantum chemistry》1987,31(1):45-55
A new method is presented to analyze the IGLO (individual gauge for localized orbitals) bond contributions in 13C chemical shielding. The IGLO bond contributions calculated in the molecular frame are rotated to a local bond frame, in which one component is selected along the bond. This procedure removes the explicit angular dependence of the IGLO bond contributions and allows a comparison of the bond contributions in different molecules. The results provide a new method to study the electronic basis of shielding interactions. The problems associated with the multiple gauge origins used in the IGLO method are discussed in their relationship to the bond contribution analysis. 相似文献
29.
Michael P. Hartshorn Richard G. Jensen A. Grant Waller Graeme J. Wright 《Tetrahedron letters》1987,28(52):6701-6704
Reaction of the 15N-4-nitrodienone (1) with excess nitrogen dioxide in benzene for 16 h gives the 4,5,6-trinitro ketone (2), labelled (15NO2) at C6 but not at C4, and recovered 4-nitrodienone (1) in which extensive loss of 15NO2 has occurred. The mechanistic implications of these and related results are discussed. 相似文献
30.
McNamara N Benham D Sleep D Grant H Stott A 《Rapid communications in mass spectrometry : RCM》2002,16(23):2165-2171
We describe the development of a novel mobile field laboratory, purposely designed for the automated capture and subsequent stable isotopic analyses of multiple gas samples. The multiple capture system is integrated into a mobile laboratory that is fully capable of measuring the concentration of carbon dioxide, methane and nitrous oxide trace gases in a flow-through system connected to a gas chromatograph fitted with both electron capture and flame ionisation detectors. The capture of gases is achieved by routing samples through a series of 135 mL gas flasks that are sealed by micro-solenoid valves triggered by a timing system. Trace gas light stable isotope ratio mass spectrometry can then be carried out on gas samples collected by the system (NERC (15)N Stable Isotope Facility). The excitingly unique potential of the system to the ecological research field is that it will allow the collection of cyclical data for three different trace gases both in real-time and in situ. We present data arising from the validation of this mobile system as well as a preliminary experimental assessment of this technique. This technique was used to measure delta(13)C in CO(2) and CH(4) in soil gases released from waterlogged cores and delta(13)C-CH(4) values were significantly depleted in wet cores compared with dry ones (p < 0.001). 相似文献