4,643 research outputs found
An efficient approach to mechanically planar chiral rotaxanes
No full textWe describe the first method for production of mechanically planar chiral rotaxanes in excellent enantiopurity without the use of chiral separation techniques and, for the first time, unambiguously assign the absolute stereochemistry of the products. This proof-of-concept study, which employs a chiral pool sugar as the source of asymmetry and a high-yielding active template reaction for mechanical bond formation, finally opens the door to detailed investigation of these challenging target
Biologically targeted probes for Zn2+: a diversity oriented modular “click-SNAr-click” approach
Get PDFWe describe a one-pot strategy for the high yielding, operationally simple synthesis of fluorescent probes for Zn2+ that bear biological targeting groups and exemplify the utility of our method through the preparation of a small library of sensors. Investigation of the fluorescence behaviour of our library revealed that although all behaved as expected in MeCN, under biologically relevant conditions in HEPES buffer, a plasma membrane targeting sensor displayed a dramatic switch on response to excess Zn2+ as a result of aggregation phenomena. Excitingly, in cellulo studies in mouse pancreatic islets demonstrated that this readily available sensor was indeed localised to the exterior of the plasma membrane and clearly responded to the Zn2+ co-released when the pancreatic beta cells were stimulated to release insulin. Conversely, sensors that target intracellular compartments were unaffected. These results demonstrate that this sensor has the potential to allow the real time study of insulin release from living cells and exemplifies the utility of our simple synthetic approac
Spin-labelled mechanically interlocked molecules as models for the interpretation of biradical EPR spectra
Get PDFBiradical spin probes can provide detailed information about the distances between molecules/regions of molecules because the through-space coupling of radical centres, characterised byJ, is strongly distance dependent. However, if the system can adopt multiple configurations, as is common in supramolecular complexes, the shape of the EPR spectrum is influenced not only byJbut also the rate of exchange between different states. In practice, it is often hard to separate these variables and as a result, the effect of the latter is sometimes overlooked. To demonstrate this challenge unequivocally we synthesised rotaxane biradicals containing nitronyl nitroxide units at the termini of their axles. The rotaxanes exchange between the available biradical conformations more slowly than the corresponding non-interlocked axles but, despite this, in some cases, the EPR spectra of the axle and rotaxane remain remarkably similar. Detailed analysis allowed us to demonstrate that the similar EPR spectral shapes result from different combinations ofJand rates of conformational interconversion, a phenomenon suggested theoretically more than 50 years ago. This work reinforces the idea that thorough analysis must be performed when interpreting the spectra of biradicals employed as spin probes in solution
Cadiot-Chodkiewicz active template synthesis of rotaxanes and switchable molecular shuttles with weak intercomponent interactions
No full textThe Sacramental Theory in John 19:26-27
Get PDFAbout the author: Father Theodore Koehler, S.M., of the Seminaire Marianiste at the University of Fribourg, Switzerland, studied under Father Neubert
Christian Insight
Get PDFVery Rev . John A. Elbert, S.M., is Graduate Dean of Arts and Sciences, Professor of Philosophy, creator of the Interdisciplinary Seminar, former President of the University of Dayton. He is the author of a number of books
Mary and American Protestants
Get PDFAbout the author: Father William Cole, S.M., is Professor and director of graduate work in Theological Studies at the University of Dayton. He has long been associated with the Marian Library
Overcoming the Obstacles to Counselling Research
Get PDFThe author of this article, Brother Marion F. Belka, S.M., is Vice President of St. Mary\u27s University in San Antonio, Texas, and President of the National Catholic Guidance Conference
Active metal template synthesis of [2]catenanes
No full textThe synthesis of [2]catenanes by single macrocyclization and double macrocyclization strategies using Cu(l) ions to catalyze covalent bond formation while simultaneously acting as the template for the mechanically interlocked structure is reported. These "active metal template" strategies employ appropriately functionalized pyridine ether or bipyridine ligands and either the CuAAC "click" reaction of azides with terminal alkynes or the Cul(l)-mediated Cadiot-Chodkiewicz heterocoupling of an alkyne halide with a terminal alkyne. Using one macrocyclic and one acyclic building block, heterocircuit (the rings are constitutionally different) [2]catenanes are produced via the single macrocyclization route in up to 53% yield by optimizing the reaction conditions and relative stoichiometry of the starting materials. Alternatively, with the active template CuAAC reaction, a single acyclic unit can be used to form a homocircuit (two identical rings) [2]catenane in 46% yield through a one-pot, double macrocyclization, procedure. Remarkably, <7% of the corresponding noninterlocked macrocycle is isolated from this reaction, indicating the efficacy of Cu(l) as both a template for the catenane and a catalyst for covalent bond formation in the reaction
In Vivo Acticity of Bupropion at the Human Dopamine Transporter as Measured by Positron Emission Tomography
No full textArticle title: In vivo acticity of bupropion at the human dopamine transporter as measured by positron emission tomography. Reference: BPS7603 Journal title: Corresponding author: Dr. S.M. Learned-Coughlin First author: Dr. S.M. Learned-Coughlin Citation</p
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