14691-88-4Relevant academic research and scientific papers
Immobilization of catalysts in poly(p-xylylene) nanotubes
Hepperle, Johannes A.M.,Mitschang, Fabian,Bier, Anna K.,Dettlaff, Barbara K.,Greiner, Andreas,Studer, Armido
, p. 25976 - 25981 (2013)
This paper describes the immobilization of a TEMPO-derivative and a copper catalyst in ethinyl-functionalized poly(p-xylylene) nanotubes which are readily prepared by the Tubes by Fiber Templates (TUFT) process. Catalyst conjugation to the nanotubes is achieved via the Cu-catalyzed azide alkyne cycloaddition (CuAAC). The TEMPO-functionalized nanotubes are successfully used as recyclable catalysts for oxidation of benzyl alcohol. Recycling studies show that the TEMPO-modified nanotubes can be reused 20 times without loss of catalytic activity. Conjugation of the nanotubes with a bipyridine moiety provides a material that allows for immobilization of metal catalysts. Treatment with a Cu(i)-salt leads to a hybrid material, which shows high activity as a recyclable catalyst in the CuAAC. Recycling experiments reveal that these Cu-nanotubes can be reused for 18 runs.
Design, Synthesis, EPR-Studies and Conformational Bias of Novel Spin-Labeled DCC-Analogues for the Highly Regioselective Labeling of Aliphatic and Aromatic Carboxylic Acids
G?lz, Jan Philipp,NejatyJahromy, Yaser,Bauer, Mirko,Muhammad, Ashraf,Schnakenburg, Gregor,Grimme, Stefan,Schiemann, Olav,Menche, Dirk
, p. 9591 - 9598 (2016)
Novel types of spin-labeled N,N′-dicyclohexylcarbodiimides (DCC) are reported that bear a 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) residue on one side and different aromatic and aliphatic cyclohexyl analogues on the other side of the diimide core. These readily available novel reagents add efficiently to aliphatic and aromatic carboxylic acids, forming two possible spin-labeled amide derivatives with different radical distances of the resulting amide. The addition of aromatic DCC analogues proceeds with excellent selectivity, giving amides where the carboxylic acid is exclusively connected to the aromatic residue, while little or no selectivity was observed for the aliphatic congeners. The usefulness of these adducts in structural studies was demonstrated by EPR (electron paramagnetic resonance) measurements of biradical adducts of biphenyl-4,4′-dicarboxylic acids. These analyses also reveal high degrees of conformational bias for aromatic DCC derivatives, which further underlines the powerfulness of these novel reagents. This observation was further corroborated by quantum chemical calculations, giving a detailed understanding of the structural dynamics, while detailed information on the solid state structure of all novel reagents was obtained by X-ray structure analyses.
Urushiol detection using a profluorescent nitroxide
Braslau, Rebecca,Rivera, Frank,Lilie, Erin,Cottman, Mariellen
, p. 238 - 245 (2013)
A method to visually detect minute amounts of urushiol, the toxic catechol from poison oak, poison ivy, and poison sumac, has been developed utilizing the reaction of a profluorescent nitroxide with the B-n-butylcatecholboronate ester formed in situ from urushiol and B-n-butylboronic acid. The resulting N-alkoxyamine is strongly fluorescent upon illumination with a fluorescent lamp, allowing the location of the toxic urushiol contamination to be visualized. This methodology constitutes the groundwork for the future development of a spray to detect urushiol to avoid contact dermatitis, as well as to detect catecholamines for biomedical applications.
Spin-labelled diketopiperazines and peptide-peptoid chimera by Ugi-multi-component-reactions
Sultani, Haider N.,Haeri, Haleh H.,Hinderberger, Dariush,Westermann, Bernhard
, p. 11336 - 11341 (2016)
For the first time, spin-labelled coumpounds have been obtained by isonitrile-based multi component reactions (IMCRs). The typical IMCR Ugi-protocols offer a simple experimental setup allowing structural variety by which labelled diketopiperazines (DKPs) and peptide-peptoid chimera have been synthesized. The reaction keeps the paramagnetic spin label intact and offers a simple and versatile route to a large variety of new and chemically diverse spin labels.
EPR Studies of V-ATPase with Spin-Labeled Inhibitors DCC and Archazolid: Interaction Dynamics with Proton Translocating Subunit c
G?lz, Jan Philipp,Bockelmann, Svenja,Mayer, Kerstin,Steinhoff, Heinz-Jürgen,Wieczorek, Helmut,Huss, Markus,Klare, Johann P.,Menche, Dirk
, p. 420 - 428 (2016)
Vacuolar-type H+-ATPases (V-ATPases) have gained recent attention as highly promising anticancer drug targets, and therefore detailed structural analyses and studies of inhibitor interactions are very important research objectives. Spin labeling of the V-ATPase holoenzyme from the tobacco hornworm Manduca sexta and V-ATPase in isolated yeast (Saccharomyces cerevisiae) vacuoles was accomplished by two novel methods involving the covalent binding of a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) derivative of N,N′-dicyclohexylcarbodiimide (DCC) to the essential glutamate residue in the active site and the noncovalent interaction of a radical analogue of the highly potent inhibitor archazolid, a natural product from myxobacteria. Both complexes were evaluated in detail by electron paramagnetic resonance (EPR) spectroscopic studies and double electron-electron resonance (DEER) measurements, revealing insight into the inhibitor binding mode, dynamics, and stoichiometry as well as into the structure of the central functional subunit c of these medicinally important hetero-multimeric proton-translocating proteins. This study also demonstrates the usefulness of natural product derived spin labels as tools in medicinal chemistry. Near and DEER: Electron paramagnetic resonance (EPR) and double electron-electron resonance (DEER) studies of V-ATPase in complex with spin-labeled inhibitors DCC and archazolid have enabled insight into the noncovalent binding dynamics and analysis of the enzyme′s key functional subunit c. These studies also demonstrate the general utility of natural product derived spin labels as innovative tools for chemical biology.
Multi-responsive copolymers: Using thermo, light- and redox stimuli as three independent inputs towards polymeric information processing
Schattling, Philipp,Jochum, Florian D.,Theato, Patrick
, p. 8859 - 8861 (2011)
We report on triple responsive polymers, exhibiting a distinct and reversible lower critical solution temperature in water that can be altered by light and redox stimuli, and we suggest their evaluation for molecular information processing.
THE OXIDATION OF SECONDARY AMINES BY ALKANESULFONIC PERACIDS
Safiullin, R. L.,Enikeeva, L. R.,Bukin, I. I.,Mukhametova, G. A.,Shishlov, N. M.,et al.
, p. 1045 - 1047 (1990)
Alkanesulfonic peracids are efficient oxidation agents for the conversion of secondary amines to the corresponding nitroxyl radicals.
Preparation and properties of biphenyl and cholesterol derivatives with nitroxide radicals
Nakatsuji,Mizumoto,Kitamura,Akutsu,Yamada
, p. 33 - 40 (2001)
Series of biphenyl as well as cholesterol derivatives with nitroxide radicals have been prepared to investigate their magnetic/liquid crystalline characters. Weak antiferromagnetic interactions in the low temperature region with no liquid crystalline character have been observed in all cholesterol and several biphenyl derivatives prepared while a cyanobiphenyl derivative with TEMPO substituent have been found to show ferromagnetic interactions in the low temperature region on the one hand and smectic liquid crystalline behavior at elevated temperatures on the other hand.
Hierarchically structured, blue-emitting polymer hybrids through surface-initiated nitroxide-mediated polymerization and water templated assembly
Leone, Giuseppe,Giovanella, Umberto,Bertini, Fabio,Hoseinkhani, Sajjad,Porzio, William,Ricci, Giovanni,Botta, Chiara,Galeotti, Francesco
, p. 6585 - 6593 (2013)
A facile and robust approach for fabricating structured, blue-emitting polymer hybrids is explored by grafting poly(styrene) incorporating π-conjugated oligo(fluorene) side-chains, to fluoromica silicate layers through surface-initiated nitroxide-mediated polymerization (SI-NMP). It is expected that the polymer intercalation can effectively reduce π-stacking, chain-chain interactions, twists and bends, and interfacial effects, leading to significant difference in the electronic/optoelectronic properties, and improved optical, thermal and chemical stability of the materials. The experimental results indicate that the bottom-up strategy is rational and efficacious. The hybrids exhibit a blue photoluminescence quantum yield (PL-QY) as high as 0.90, even in the solid, which makes the materials appealing for polymer light-emitting devices (PLEDs). The materials also show significantly enhanced thermal, and chemical stabilities with respect to the organic precursors. If processed under specific controlled conditions, the hybrids spontaneously assemble into highly ordered microporous films, where an organization of matter at different length scales is obtained. Since the introduction of surface patterning in the active layer could enhance the extraction of light generated in the device, this hierarchical organization is a promising tool for the further development of optimized hybrid PLEDs.
A Simple Synthesis of 4-Amino-2,2,6,6-tetramethyl-1-piperidinyloxy Radical
Bushmakina, N. G.,Misharin, A. Yu.
, p. 966 (1986)
A simple synthesis of the title compound starting from 4-hydroxy-2,2,6,6-tetramethyl-1-piperidyloxy radical (2) based on sulfonate-azide exchange method is described.
