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81.
Sergey S. Golotvin Rostislav Pol Ryan R. Sasaki Asya Nikitina Philip Keyes 《Magnetic resonance in chemistry : MRC》2012,50(6):429-435
Automated structure verification using 1H NMR data or a combination of 1H and heteronuclear single‐quantum correlation (HSQC) data is gaining more interest as a routine application for qualitative evaluation of large compound libraries produced by synthetic chemistry. The goal of this automated software method is to identify a manageable subset of compounds and data that require human review. In practice, the automated method will flag structure and data combinations that exhibit some inconsistency (i.e. strange chemical shifts, conflicts in multiplicity, or overestimated and underestimated integration values) and validate those that appear consistent. One drawback of this approach is that no automated system can guarantee that all passing structures are indeed correct structures. The major reason for this is that approaches using only 1H or even 1H and HSQC spectra often do not provide sufficient information to properly distinguish between similar structures. Therefore, current implementations of automated structure verification systems allow, in principle, false positive results. Presented in this work is a method that greatly reduces the probability of an automated validation system passing incorrect structures (i.e. false positives). This novel method was applied to automatically validate 127 non‐proprietary compounds from several commercial sources. Presented also is the impact of this approach on false positive and false negative results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
82.
Molecular and morphological characterization of midblock‐sulfonated styrenic triblock copolymers 下载免费PDF全文
Kenneth P. Mineart Justin J. Ryan Byeongdu Lee Steven D. Smith Richard J. Spontak 《Journal of Polymer Science.Polymer Physics》2017,55(6):490-497
Midblock‐sulfonated triblock copolymers afford a desirable opportunity to generate network‐forming amphiphilic materials that are suitable for use in a wide range of emerging technologies as fuel‐cell, water‐desalination, ion‐exchange, photovoltaic, or electroactive membranes. Employing a previously reported synthetic strategy wherein poly(p‐tert‐butylstyrene) remains unreactive, we have selectively sulfonated the styrenic midblock of a poly(p‐tert‐butylstyrene‐b‐styrene‐b‐p‐tert‐butylstyrene) (TST) triblock copolymer to different extents. Comparison of the resulting sulfonated copolymers with results from our prior study provides favorable quantitative agreement and suggests that a shortened reaction time is advantageous. An ongoing challenge regarding the morphological development of charged block copolymers is the competition between microphase separation of the incompatible blocks and physical cross‐linking of ionic clusters, with the latter often hindering the former. Here, we expose the sulfonated TST copolymers to solvent‐vapor annealing to promote nanostructural refinement. The effect of such annealing on morphological characteristics, as well as on molecular free volume, is explored. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 490–497 相似文献
83.
Matthew Skinner Ryan Selhorst Todd Emrick 《Journal of polymer science. Part A, Polymer chemistry》2016,54(1):127-134
A series of water‐soluble siloxane polymers with pendent phosphorylcholine (PC) and sulfobetaine (SB) zwitterions was prepared using thiol‐ene “click” chemistry. Specifically, well‐defined vinyl‐substituted siloxane homopolymers and block copolymers were functionalized with small molecule zwitterionic thiols at room temperature. Rapid and quantitative substitution of the pendent vinyl groups was achieved, and zwitterionic polysiloxanes of narrow molecular weight distribution were obtained. The PC‐ and SB‐substituted polymers were found to be readily soluble in pure, salt‐free water. Critical micelle concentrations (CMCs) of these polymers in water were measured using a pyrene fluorescence probe, with CMC values estimated to be <0.01 g/L. Polymer aggregates were studied by dynamic light scattering, and the micelles generated from the PC block copolymers were visualized, after drying, by transmission electron microscopy. Aqueous solutions of these zwitterionic polysiloxanes significantly reduced the oil‐water interfacial surface tension, functioning as polymer amphiphiles that lend stability to oil‐in‐water emulsions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 127–134 相似文献
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Miao Yang Shannon J. Odelberg Zongzhong Tong Dean Y. Li Ryan E. Looper 《Tetrahedron》2013,69(27-28):5744-5750
Cationic Rh(II) complexes are able to catalyze the regioselective hydroamination of propargyl ureas in a 6-endo fashion. This transformation permits access to interesting substitution patterns of dihydropyrimidines, which have found use as nucleotide exchange factor inhibitors. 相似文献
86.
Ryan Guterman Valerio Molinari Elinor Josef 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13178-13184
Ionic liquid lignins are prepared from sodium lignosulfonate by a cation exchange reaction and display glass transition temperatures as low as ?13 °C. Diethyleneglycol‐functionalized protic cations inhibit lignin aggregation to produce a free‐flowing “ionic liquid lignin”, despite it being a high‐molecular‐weight polyelectrolyte. Through this approach, the properties of both lignin and ionic liquids are combined to create a dispersant and binder for cellulose+gluten mixtures to produce small microphases. Biocomposite testing pieces are produced by hot‐pressing this mixture, yielding a material with fewer defects and improved toughness in comparison to other lignins. The use of unmodified lignosulfonate, acetylated lignosulfonate, or free ionic liquid for similar materials production yields poorer substances because of their inability to maximize interfacial contact and complexation with cellulose and proteins. 相似文献
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Herein, we report a practical synthesis of 2-D-l-tryptophan via sequential Ir-catalyzed CH borylation, and Ir-catalyzed C-2-deborylative deuteration steps. In this synthetic sequence, deprotection of the Boc and methyl ester groups proved challenging, due to replacement of deuterium with hydrogen. However, mild deprotection conditions were developed to avoid this D/H scrambling. Further, 2-D-L-Tryptophan is stable in many buffers used for biological studies. 相似文献
89.
Rational design of methacrylate monomers containing oxadiazole moieties for single‐layer organic light emitting devices 下载免费PDF全文
Bogdan Zdyrko Yuriy Bandera Volodymyr Tsyalkovsky Christopher F. Huebner Jamie A. Shetzline Parul Rungta Ryan D. Roeder Charles Tonkin Stephen E. Creager Stephen H. Foulger 《Journal of Polymer Science.Polymer Physics》2015,53(23):1663-1673
Methacrylate derived monomers functionalized with pendant oxadiazole moieties were synthesized and copolymerized with carbazole containing monomers to form polymers with electron and hole transporting fragments in the same molecule. Substituents on the oxidazole moiety were varied with the purpose of bandgap tuning and performance optimization when employed in single‐layer organic light emitting devices (OLED). Quantum mechanical calculations of the HOMO‐LUMO levels of the oxidazole derivatives were used to down‐select promising candidates for chemical synthesis and testing in single‐layer OLEDs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1663–1673 相似文献
90.