
	Where results make sense

Topic: Rotaxane

Related Topics

Catenane

Polycatenane

Molecular electronics

Digital logic

DNA topology

Nanowire

Logic gate

Topological

Isomer

Nanotechnology

Knot theory

DNA

Electrical resistance

Topoisomerase

In the News (Sun 15 Nov 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Rotaxane - Wikipedia, the free encyclopedia
		The two components are kinetically trapped as the two end-groups of the dumbbell (often called stoppers) are larger than the internal diameter of the ring, and thus prevent dissociation (unthreading) since this would require significant distortion of the covalent bonds.
		The name, rotaxane, is derived from the Latin for wheel (rota) and axle (axis).
		Rotaxanes are most commonly constructed by preorganizing or threading the parts utilizing hydrogen bonding, metal coordination, hydrophobic forces, covalent bonds, or coulombic interactions.
	en.wikipedia.org /wiki/Rotaxane (740 words)

	study
		However, the synthesis of this type of rotaxane is rather difficult; in the preparation step, we must use a reaction that does not disturb hydrogen bonding interaction between ammonium salt and crown ether.
		Conjugate Addition-Approach to End-Capping of Pseudorotaxanes for Rotaxane Synthesis, Chem.
		Acylation of the pseudorotaxane by 3,5-dimethylbenzoic anhydride in the presence of tributylphosphine afforded corresponding rotaxane in 90% yield.
	www.chem.osakafu-u.ac.jp /ohka/takata/kihara/studye.html (650 words)

	e-Polymers (Site not responding. Last check: 2007-09-17)
		Synthesis and characterization of a new phenanthroline-triether copolymer with rotaxane architecture
		This paper is devoted to the preparation and characterization of a new phenanthroline-triether copolymer with rotaxane architecture by reaction of complexes of α- or ß- cyclodextrin and tri(ethylene glycol) ditosylatewith 2,9-di(4-hydroxyphenyl)-1,10-phenanthroline, which is large enough to prevent dethreading of cyclodextrin molecules.
		Rotaxane copolymer present bimodal molecular weight distribution attributed to the separation of the fractions with different content of cyclodextrin threaded on the copolymer chain.
	www.e-polymers.org /abstract_show.cfm/1570 (129 words)

	Geek.com Geek News - Rotaxane molecule could offer 100 Gbit/inch densities (Site not responding. Last check: 2007-09-17)
		Although rotaxane is an intriguing molecule, it is unlikely that any storage devices based on this technology will ever emerge for several reasons.
		Rotaxanes are a class of molecules, not just one kind of molecule.
		A rotaxane is a linear molecule with a ring shaped molecule around it (like a wheel on an axle).
	www.geek.com /news/geeknews/2003Jan/bch20030127018359.htm (803 words)

	rotaxane
		The resulting threaded rotaxane and catenane molecular systems have the potential, by virtue of their unique topological cavities, to exhibit unprecedented anion recognition, sensing and molecular machine-like properties, whereby anion binding controls molecular movement of the rotaxane/catenane constituent parts.
		This allows the formation of the rotaxane to be reported by fluorescence.
		The anion may be removed from the rotaxane structure to provide a novel anion receptor that is selective for hydrogen sulfate.
	www.chem.ox.ac.uk /icl/beergroup/rotaxane.htm (369 words)

	Science - Collier et al.
		In the absence of the rotaxanes, they are assumed to be constant (the DOS of metals at the Fermi level are essentially constant with respect to bias voltage).
		In our case, there are two contributions to the tunneling current: one is due to the resonant electronic states of the rotaxanes, and the other is a nonresonant, "background" contribution, which is always present.
		However, near -0.5 V the rotaxane energy levels become resonant with the Al electrode and the current in that device increases exponentially, relative to the control device.
	www.sciencemag.org /feature/data/1039735.dtl (1252 words)

	Bumpy surface stores data TRN 012903
		The rotaxane dots are a few molecules high, 20 to 40 nanometers wide and 100 nanometers apart.
		A nanometer is one millionth of a millimeter, or the span of 10 hydrogen atoms.
		In theory, data could be written to the rotaxane film bits in parallel, using a stamp or an array of probe tips.
	trnmag.com /Stories/2003/012903/Bumpy_surface_stores_data_012903.html (985 words)

	www.rotaxane.net
		Rotaxanes consist of macrocyclic rings trapped onto a linear unit (the “thread”) by two bulky substituents (“stoppers”).
		Rotaxanes, on the other hand, are NOT topological isomers of their un-interlocked components because by infinitely stretching the ring (obviously this is only mathematically, not physically, possible) it could slip over the stoppers and dissociate it from the thread (see Figure 3).
		Up until the early 1980s, catenanes, rotaxanes and other interlocked architectures were considered by most chemists to be academic curiosities with little potential for practical applications.
	www.s119716185.websitehome.co.uk /home/rotcatintro.html (431 words)

	Closer to a Real Nanocomputer (Site not responding. Last check: 2007-09-17)
		Other than the layer of rotaxane molecules (the triangular array) materials of this device aren't meant to be especially small.
		rotaxanes which can be modified to make a complete circuit; this layer is one molecule thick, unlike the other parts of this device.
		Finally, one problem with rotaxanes in their system is that switches become permanently set open or shut.
	pweb.jps.net /~cryocoo/periastron/jul99/nanocomputer.htm (695 words)

	Molecular complexes for use as electrolyte components - Patent 5538655
		The rotaxanes of the present invention are functionalized to impart properties required of an electrolytic cell, such as high ionic conductivity, high transport number, electrochemical stability and reduced crystallinity.
		Use of block copolymers permit the assembly of the rotaxane along a portion of the polymer which is susceptible to rotaxane formation (appropriate size and character, favorable interactions between the linear cyclic molecules, etc), followed by the addition of a bulky monomer to form a copolymer block which functions as the blocking end group.
		The requirement that the bulky end group be of a size and character to prevent dethreading of the rotaxane may be met by the polymerizable functional group in the polymerized state, rather than in the unreacted state.
	www.freepatentsonline.com /5538655.html (9377 words)

	CMS—Materials Science, Machines from Interlocking Molecules (Site not responding. Last check: 2007-09-17)
		(b) Rotaxanes are formed from a ring molecule threaded on an "axle" molecule capped by two molecular stoppers.
		A rotaxane consists of a long, straight molecule—an "axle"—ringed by a doughnut-shaped molecule.
		The team's physicists took spectra of powder samples of the crown ether rings, anthracene caps, and [3]rotaxane for reference as well as a spectrum of thiol attached to gold.
	www-cms.llnl.gov /s-t/machines.html (1913 words)

	Rotaxane molecules store data (January 2003) - News - nanotechweb.org (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-09-17)
		To make the devices, the team deposited films of rotaxane molecules of between 3 and 35 nm thick onto graphite and mica substrates.
		For example, varying the film thickness from 3 to 35 nm increased the interdot distance from 100 to 500 nm, the dot height from 1 to 20 nm and the dot full-width-half-maximum from 40 to 250 nm.
		The scientists say that the scanning AFM tip imparts energy to rotaxane molecules along the scan line so that they reorganize into nuclei, which grow to form the dots.
	www.nanotechweb.org.cob-web.org:8888 /articles/news/2/1/14/1 (311 words)

	Synthesis and Mass Spectrometry Studies of an Amphiphilic Polyether-Based Rotaxane That Lacks an Enthalpic Driving ...
		This pure MC-12 was used to synthesize a rotaxane composed of one MC-12 ring threaded with one end-capped poly(tetrahydrofuran) (PTHF) oligomer by equilibrating half an equivalent of the thread with an organized solution of MC-12 and end-capping the threads with excess 2-p-[tris(p-tert-butylphenyl)methyl]phenoxymethyl-4,4-dimethylazlactone.
		The rotaxane was positively identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry (MS), although the spectra showed a low abundance of the rotaxane ions and high abundances of unthreaded MC-12 and end-capped thread ions in the product isolated from the threading experiment.
		HPLC using silica columns and an eluant of THF with 0.3 wt % Aliquat 336 confirmed that a "further-purified" sample of the rotaxane mixture was composed of 66 wt % end-capped thread, 23 wt % MC-12, and 11 wt % rotaxane, in qualitative agreement with the corresponding MALDI-ToF mass spectrum.
	pubs.acs.org /cgi-bin/abstract.cgi/mamobx/2005/38/i07/abs/ma0476689.html (264 words)

	OhioLINK ETD: ZEHNDER, DONALD
		Rotaxane formation reactions demonstrated a tether with 4 methylenes between the amine and carboxylic acid produced rotaxane in a 73% yield.
		An extensive library of modified tethers were synthesized and screened for rotaxane forming ability.
		By introducing an azide functional group into the tether, we were able to attach fluorescein while maintaining high rotaxane yields.
	www.ohiolink.edu /etd/view.cgi?acc_num=ucin1051188602 (350 words)

	[nano] kurzweill: eurekalert: rotaxane-based nanovalve
		The valve is uniquely designed so one end attaches to the opening of the hole that will be blocked and unblocked, and the other end has the switchable rotaxanes whose movable component blocks the hole in the down position and leaves it open in the up position.
		The researchers used chemical energy involving a single electron as the power supply to open and shut the valve, and a luminescent molecule that allows them to tell from emitted light whether a molecule is trapped or has been released.
		Switchable rotaxanes are molecules composed of a dumbbell component with two stations between which a ring component can be made to move back and forth in a linear fashion.
	perfectpresence.com /pipermail/nano_polymathy.org/2005-July/000719.html (714 words)

	Synthesis and Characterization of a Persistent Paramagnetic Rotaxane Based on alpha-Cyclodextrin. (Site not responding. Last check: 2007-09-17)
		Complexation of sebacoyl chloride by alpha-cyclodextrin followed by reaction with a bulky aminonitroxide resulted in the trapping of the cyclodextrin, threaded by the alkyl chain, thus generating the rotaxane structure.
		The preparation and characterization of a solvent-switchable rotaxane that shuttles in the opposite direction to that expected are reported.
		Specific interactions in the ionic liquids, as well as between the spin-probe molecules and the constituents of the ionic liquids are reflected in the spectra of the spin probes, depending on their molecular structure.
	yoh.lib.bioinfo.pl /pmid:16674049 (1380 words)

	The Neighborhood Computer (Site not responding. Last check: 2007-09-17)
		First nanowires, which are so tiny that 5,000 of them could fit in a single human hair, are arranged into a grid pattern.
		Since electricity can only flow when the wires are close together, each rotaxane acts like a switch.
		That?s a pretty clever layout, but even better is that individual rotaxane molecules can be "blown-out," destroying the switch, so that "neighborhoods" of switches can be isolated from other "neighborhoods," yet still connected by nanowires.
	www.mos.org /cst-archive/article/2951/1.html (295 words)

	nanogloss.com - rotaxane (Site not responding. Last check: 2007-09-17)
		A kind of molecule which consists of independent portions (generally two) linked by a thread surrounded by a ring.
		Rotaxanes have specific properties that have raised great promises for the development of molecular chips.
		Seen as "electrically switchable molecules", they can be attached to nanowires to create what could become "complex logic nanoscale chips".
	www.nanogloss.com /defi/rotaxan.htm (77 words)

	Science Notes 2001: Atoms that Add
		When the molecule, called a rotaxane, sits between two wires, electrons flowing through one wire can hop onto the rotaxane and across to the other wire.
		But if a voltage is applied to the rotaxane, the interlocked ring slides to a new position on the dumbbell and blocks the electrical current.
		But since discovering the rotaxane switch, the researchers have come up with a dozen more molecular switches, including reversible ones.
	scicom.ucsc.edu /SciNotes/0101/atoms.html (3865 words)

	EETimes.com - Researchers close to delivering molecular circuits (Site not responding. Last check: 2007-09-17)
		The basic hardware design is simple: Organic molecules of rotaxane are introduced into a crossbar array of erbium disilicide nanowires.
		The wires do not have to be precisely aligned, because the rotaxane molecules will seek out the crosspoints wherever they occur.
		The rotaxane is able to mimic all the functions of an FPGA cell.
	www.eetimes.com /story/OEG20020215S0063 (1705 words)

	Amazon.com: "rotaxane assemblies": Key Phrase page (Site not responding. Last check: 2007-09-17)
		See all pages with references to rotaxane assemblies.
		molecules of rotaxane to self assemble molecular scale switches with very high differential "on-off" resistivities [90].
		The formation of the rotaxane assemblies, which are on the order of 10 nm for a single functional element, is coordinated by applied voltages which initiate...
	www.amazon.com /phrase/rotaxane-assemblies (544 words)

	International Union of Pure and Applied Chemistry
		Expanded definitions of rotaxanes, their components, and other terms concerning rotaxanes are given.
		Recommendations are provided for unambiguous description of rotaxane isomerism with special descriptors that include information about position and orientation of rotaxane components.
		Types of rotaxane isomerism and description of the location of simple macrocyclic components at different linear sections of a complex threading component and location of simple threading components in macrocyclic components with several threadable rings.
	www.iupac.org /reports/provisional/abstract05/yerin_300406.html (143 words)

	TAKATA Lab (Site not responding. Last check: 2007-09-17)
		Cooperative effect between the axle and wheel components of rotaxane makes easy the construction of specific reaction field on rotaxane molecule.
		In particular, the introduction of asymmetric point into rotaxane results in the formation of chiral rotaxane field for asymmetric reaction.
		When a functional group capable of catalyzing a reaction is introduced onto the axle end, the asymmetric space on the axle can be changed to more restricted one by the dynamic effect of the wheel component.
	www.op.titech.ac.jp /polymer/lab/takata/contents/research/research_doc/rotaxane/rotaxanefield_e.html (194 words)

	Amazon.com: "switchable rotaxane": Key Phrase page (Site not responding. Last check: 2007-09-17)
		144 An optoelectronic surface-bound switchable rotaxane is schematically described in Figure 7.38 (A).
		A switchable rotaxane based on acceptor-donor complexes [24].
		left) Is 'I (c) A switchable rotaxane based on acceptor- donor complexes I"I Before oxidation (bottom), the electron acceptor (ring) interacts preferentially with the benzidine nucleus (donor).
	www.amazon.com /phrase/switchable-rotaxane (461 words)

	Amazon.com: "rotaxane structure": Key Phrase page (Site not responding. Last check: 2007-09-17)
		See all pages with references to rotaxane structure.
		As a consequence, one can expect destabilization of the original rotaxane structure, followed by a displacement of the ring along the wire (in pseudorotaxanes, such a destabilization is expected to lead to...
		Multiple cationic groups stabilize the rotaxane structure by inhibiting the cyclodextrin ring from coming off.
	www.amazon.com /phrase/rotaxane-structure (443 words)

	rotaxane
		"Rotaxanes of Cyclic Peptides", V Aucagne, D A Leigh, J S Lock and A R Thomson, J Am Chem Soc, 128, 1784-1785 (2006).
		"Photoisomerization of a Rotaxane Hydrogen Bonding Template: Light-Induced Acceleration of a Large Amplitude Rotational Motion" F G Gatti, S Leòn, J K Y Wong, G Bottari, A Altieri, M A Farran Morales, S J Teat, C Frochot, D A Leigh, A M Brouwer and F Zerbetto, Proc.
		"Glycylglycine Rotaxanes - The Hydrogen Bond-Directed Assembly of Synthetic Peptide Rotaxanes ", D A Leigh, A Murphy, J P Smart and A M Z Slawin, Angew Chem, Int Ed Engl 36, 728-732 (1997).
	www.s119716185.websitehome.co.uk /publicats/pub2.html (4667 words)

	Catenane, Calixarene, Rotaxane: Organische Chemie
		Crystal structure of an azo dye rotaxane - PDF-Text and Images.
		Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes with Stopper Groups of Intermediate Size - PDF-Text and Images.
		Self-Assembly of [ n ]Rotaxanes Bearing Dendritic Stoppers - PDF-Text.
	www.infochembio.ethz.ch /links/orgchem_catenan.html (145 words)

	Chemistry International -- Newsmagazine for IUPAC
		The classification of rotaxanes and nomenclature principles for naming of different types of rotaxanes are described and illustrated with examples.
		Recommendations are provided for unambiguous description of rotaxane isomerism with special descriptors that include information about the position and orientation of rotaxane
		types of rotaxane isomerism and description of the location of simple macrocyclic components at different linear sections of a complex threading component and location of simple threading
	www.ibiblio.org /pub/academic/chemistry/iupac/Download/publications/ci/2006/2802/pr3_yerin.htm (127 words)

Try your search on: Qwika (all wikis)