Editing Rotaxane (section)

== Potential applications ==
[[File:Rotaxane Crystal Structure ChemComm page493 2001 commons.jpg|thumb|left|Structure of a rotaxane with an α-[[cyclodextrin]] [[macrocycle]].<ref>{{cite journal |title= Synthesis of fluorescent stilbene and tolan rotaxanes by Suzuki coupling |year= 2001 |journal= [[Chem. Commun.]] |issue= 5 |pages= 493–494 |doi= 10.1039/b010015n|last1= Stanier |first1= Carol A. |last2= o'Connell |first2= Michael J. |last3= Anderson |first3= Harry L. |last4= Clegg |first4= William }}</ref>]]

===Molecular machines===
[[Image:Rot.ogg|thumb|Animation of a pH-controlled molecular rotaxane shuttle]]
Rotaxane-based molecular machines have been of initial interest for their potential use in [[molecular electronics]] as logic [[molecular switch]]ing elements and as [[molecular shuttle]]s.<ref>{{cite journal |title= On the Way to Rotaxane-Based Molecular Motors: Studies in Molecular Mobility and Topological Chirality |year= 2001 |journal= [[Acc. Chem. Res.]] |volume= 34 |issue= 6 |pages= 465–476 |doi= 10.1021/ar000179i |pmid= 11412083 |last1= Schalley |first1= C. A. |last2= Beizai |first2= K |last3= Vögtle |first3= F }}</ref><ref>{{cite journal |author= Sauvage, J. P. |title= Transition Metal-Containing Rotaxanes and Catenanes in Motion: Toward Molecular Machines and Motors |year= 1999 |journal= ChemInform |volume= 30 |issue= 4 |pages= no |doi= 10.1002/chin.199904221}}</ref> These [[molecular motor|molecular machines]] are usually based on the movement of the [[macrocycle]] on the dumbbell. The [[macrocycle]] can rotate around the axis of the dumbbell like a wheel and axle or it can slide along its axis from one site to another. Controlling the position of the [[macrocycle]] allows the rotaxane to function as a molecular switch, with each possible location of the macrocycle corresponding to a different state. These rotaxane machines can be manipulated both by chemical <ref>{{cite journal |author1=Coutrot, F. |author2=Busseron, E. |title= A New Glycorotaxane Molecular Machine Based on an Anilinium and a Triazolium Station |year= 2008 |journal= [[Chem. Eur. J.]] |volume= 14 |pages= 4784–4787 |doi= 10.1002/chem.200800480 |pmid= 18409178 |issue= 16}}</ref> and photochemical inputs.<ref>{{cite journal |title= Exercising Demons: A Molecular Information Ratchet |year= 2007 |journal= [[Nature (journal)|Nature]] |volume= 445 |pages= 523–527 |doi= 10.1038/nature05452 |pmid= 17268466 |issue= 7127 |bibcode= 2007Natur.445..523S |last1= Serreli |first1= V |last2= Lee |first2= C. F. |last3= Kay |first3= E. R. |last4= Leigh |first4= D. A. |s2cid= 4314051 }}</ref> Rotaxane based systems have also been shown to function as molecular muscles.<ref>{{cite journal  |title= A New pH-Switchable Dimannosyl [c2]Daisy Chain Molecular Machine |year= 2008 |journal= [[Org. Lett.]] |volume= 10 |pages= 3741–3744 |doi= 10.1021/ol801390h |pmid= 18666774 |issue= 17  |last1= Coutrot |first1= F |last2= Romuald |first2= C |last3= Busseron |first3= E }}</ref><ref>{{cite journal |title= Bridging Rotaxanes' wheels – cyclochiral Bonnanes |year= 2006 |journal= [[Angew. Chem. Int. Ed.]] |volume= 45 |pages= 7296–7299 |doi= 10.1002/anie.200602002 |pmid= 17029314 |issue= 43|last1= Radha Kishan |first1= M |last2= Parham |first2= A |last3= Schelhase |first3= F |last4= Yoneva |first4= A |last5= Silva |first5= G |last6= Chen |first6= X |last7= Okamoto |first7= Y |last8= Vögtle |first8= F }}</ref> In 2009, there was a report of a "domino effect" from one extremity to the other in a Glycorotaxane Molecular Machine. In this case, the <sup>4</sup>''C''<sub>1</sub> or <sup>1</sup>''C''<sub>4</sub> chair-like conformation of the manno[[pyranoside]] stopper can be controlled, depending on the localization of the macrocycle.<ref>{{cite journal |author1=Coutrot, F. |author2=Busseron, E. |title= Controlling the Chair Conformation of a Mannopyranose in a Large-Amplitude [2]Rotaxane Molecular Machine |year= 2009 |journal= [[Chem. Eur. J.]] |volume= 15 |pages= 5186–5190 |doi= 10.1002/chem.200900076 |pmid= 19229918 |issue= 21 }}</ref> In 2012, unique pseudo-macrocycles consisting of double-lasso molecular machines (also called rotamacrocycles) were reported in Chem. Sci. These structures can be tightened or loosened depending on pH. A controllable jump rope movement was also observed in these new molecular machines.<ref>{{cite journal |title= Tightening or loosening a pH-sensitive double-lasso molecular machine readily synthesized from an ends-activated [c2]daisy chain |year= 2012 |journal= [[Chem. Sci.]] |volume= 3 |issue= 6 |pages= 1851–1857 |doi= 10.1039/C2SC20072D|last1= Romuald |first1= Camille |last2= Ardá |first2= Ana |last3= Clavel |first3= Caroline |last4= Jiménez-Barbero |first4= Jesús |last5= Coutrot |first5= Frédéric |hdl= 10261/60415 |hdl-access= free }}</ref>

=== Ultrastable dyes ===
Potential application as long-lasting dyes is based on the enhanced stability of the inner portion of the dumbbell-shaped molecule.<ref>{{cite journal|title= Rotaxane-encapsulated cyanine dyes: enhanced fluorescence efficiency and photostability |year= 2000 |journal= [[Chem. Commun.]] |issue= 11 |pages= 905–906 |doi= 10.1039/b001812k |last1= Buston |first1= Jonathan E. H. |last2= Young |first2= James R. |last3= Anderson |first3= Harry L. }}</ref><ref>{{cite journal |title= Rotaxane-Encapsulation Enhances the Stability of an Azo Dye, in Solution and when Bonded to Cellulose |year= 1998 |journal= [[Angew. Chem. Int. Ed.]] |volume= 40 |issue= 6 |pages= 1071–1074 |doi= 10.1002/1521-3773(20010316)40:6<1071::AID-ANIE10710>3.0.CO;2-5 |pmid= 11268077 |last1= Craig |first1= M. R. |last2= Hutchings |first2= M. G. |last3= Claridge |first3= T. D. |last4= Anderson |first4= H. L. |doi-access= free }}</ref> Studies with [[cyclodextrin]]-protected rotaxane [[azo dye]]s established this characteristic. More reactive [[squaraine dye]]s have also been shown to have enhanced stability by preventing [[nucleophile|nucleophilic attack]] of the inner squaraine [[Moiety (chemistry)|moiety]].<ref>{{cite journal |title= Squaraine-Derived Rotaxanes: Sterically Protected Fluorescent Near-IR Dyes |year= 2005 |journal= [[J. Am. Chem. Soc.]] |volume= 127 |issue= 10 |pages= 3288–3289 |doi= 10.1021/ja042404n |pmid= 15755140 |url=http://www.nd.edu/%7Ebsmith3/pdf/JACS2005e.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.nd.edu/%7Ebsmith3/pdf/JACS2005e.pdf |archive-date=2022-10-09 |url-status=live|last1= Arunkumar |first1= E |last2= Forbes |first2= C. C. |last3= Noll |first3= B. C. |last4= Smith |first4= B. D. |bibcode= 2005JAChS.127.3288A }}</ref> The enhanced stability of rotaxane dyes is attributed to the insulating effect of the [[macrocycle]], which is able to block interactions with other molecules.

=== Nanorecording ===
In a nanorecording application,<ref>{{cite journal|title= Stable, Reproducible Nanorecording on Rotaxane Thin Films |year= 2005 |journal= [[J. Am. Chem. Soc.]] |volume= 127 |issue= 44 |pages= 15338–15339 |doi= 10.1021/ja054836j |pmid= 16262375 |last1= Feng |first1= M |last2= Guo |first2= X |last3= Lin |first3= X |last4= He |first4= X |last5= Ji |first5= W |last6= Du |first6= S |last7= Zhang |first7= D |last8= Zhu |first8= D |last9= Gao |first9= H |bibcode= 2005JAChS.12715338F }}</ref> a certain rotaxane is deposited as a [[Langmuir–Blodgett film]] on [[indium tin oxide|ITO]]-coated glass. When a positive [[voltage]] is applied with the tip of a [[scanning tunneling microscope]] probe, the rotaxane rings in the tip area switch to a different part of the dumbbell and the resulting new [[conformational isomerism|conformation]] makes the molecules stick out 0.3 [[nanometer]] from the surface. This height difference is sufficient for a [[memory dot]]. It is not yet known how to erase such a nanorecording film.