Simple Mechanical Molecular and Supramolecular Machines: Photochemical and Electrochemical Control of Switching Processes
摘要:
AbstractPhotochemical control of a self‐assembled supramolecular 1:1 pseudorotaxane (formed between a tetracationic cyclophane, namely the tetrachloride salt of cyclobis(paraquat‐p‐phenylene), and 1,5‐bis[2‐(2‐(2‐hydroxy)ethoxy)ethoxy]naphthalene) has been achieved in aqueous solution. The photochemical one‐electron reduction of the cyclophane to the radical trication weakens the noncovalent bonding interactions between the cyclophane and the naphthalene guest—π‐π interactions between the π‐electron‐rich and π‐electron‐poor aromatic systems, and hydrogen‐bonding interactions between the acidic α‐bipyridinium hydrogen atoms of the cyclophane and the polyether oxygen atoms of the naphthalene derivative—sufficiently to allow the guest to dethread from the cavity; the process can be monitored by the appearance of naphthalene fluorescence. The radical tricationic cyclophane can be oxidized back to the tetracation in the dark by allowing oxygen gas into the system. This reversible process is marked by the disappearance of naphthalene fluorescence as the molecule is recomplexed by the tetracationic cyclophane. This supramolecular system can be chemically modified such that the π‐electron‐rich unit, either a naphthalene derivative or a hydroquinone ring, and the tetracationic cyclophane are covalently linked. We have demonstrated that the π‐electron‐rich residue in this system is totally “self‐complexed” by the cyclophane to which it is covalently attached. Additionally, the self‐complexation can be switched “off” and “on” by electrochemical two‐electron reductions and oxidations, respectively, of the tetracationic cyclophane component. Thus, we have achieved the construction of two switches at the nanoscale level, one driven by photons and the other by electrons.
Die Synthese von 2-Methyl-5-phenacyl-1,3,4-thiadiazolen / The Synthesis of 2-Methyl-5-phenacyl-1,3,4-thiadiazoles
作者:Willi Kantlehner、Erwin Haug、Willy Kinzy、Oliver Scherr、Ivo C. Ivanov
DOI:10.1515/znb-2004-0403
日期:2004.4.1
Keywords 2,5-Dimethyl-1,3,4-thiadiazole (1a) reacts which aromatic carboxylic acid esters 8a - u in the presence of excessive sodium hydride under condensation to give sodium enolates which afford on hydrolysis the phenacyl-1,3,4-thiadiazoles 9a - u. The action of aromatic carboxylic acid chlorides on 1a in the presence of triethylamine gives rise to the formation of mixtures of diacylated thiadiazole
Diarylcycloalkyl derivatives, processes for their preparation and their use as pharmaceuticals
申请人:——
公开号:US20040122069A1
公开(公告)日:2004-06-24
Diarylcycloalkyl derivatives and their physiologically acceptable salts and physiologically functional derivatives are disclosed. The compounds include those of formula I,
1
in which the radicals are as defined, and their physiologically acceptable salts and processes for their preparation. The compounds typically have lipid- and/or triglyceride-lowering properties and are suitable, for example, for the treatment of disorders of lipid metabolism, of type II diabetes, and of syndrome X.
Thermodynamic forecasting of mechanically interlocked switches
作者:Mark A. Olson、Adam B. Braunschweig、Taichi Ikeda、Lei Fang、Ali Trabolsi、Alexandra M. Z. Slawin、Saeed I. Khan、J. Fraser Stoddart
DOI:10.1039/b911874h
日期:——
Mechanically interlocked molecular (MIM) switches in the form of bistable [2]rotaxanes and [2]catenanes have proven to be—when incorporated in molecular electronic devices (MEDs) and in nanoelectromechanical systems (NEMS)—a realistic and viable alternative to the silicon chip density challenge. Structural modifications and chemical environment can have a large impact on the relaxation thermodynamics
Synthesis of a new class of π-electron-deficient tetracationic cyclophane ring, cyclobis(paraquat-p-phenylene), carrying one or two paramagnetic side-arms based on 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) moiety has been achieved in five steps starting from 2,5-dimethyl benzoic acid. The possibility of exploiting the proposed cyclophanes as hosts in rotaxane-like structures was tested preparing
Substituierte Prop-2-in-1-ol- und Prop-2-en-1-ol-Derivate
申请人:Bayer CropScience AG
公开号:EP2510786A1
公开(公告)日:2012-10-17
Die Erfindung betrifift substituierte Prop-2-in-1-ol- und Prop-2-en-1-ol-Derivate der allgemeinen Formel (I),
wobei die Reste R1, R2, R3, R4, R5, [X-Y] und Q die in der Beschreibung angegebenen Definitionen besitzen,
Verfahren zu deren Herstellung und ihre Verwendung zur Steigerung der Stresstoleranz in Pflanzen gegenüber abiotischem Stress, sowie zur Stärkung des Pflanzenwachstums und/oder zur Erhöhung des Pflanzenertrags.