Просмотр кода страницы Английская Википедия:Cyclobis(paraquat-p-phenylene)

{{Английская Википедия/Панель перехода}}
{{DISPLAYTITLE:Cyclobis(paraquat-''p''-phenylene)}}
{{Chembox
|Name = Cyclobis(paraquat-''p''-phenylene)
|ImageFile = Cyclobis(paraquat-p-phenylen).svg
|ImageSize = 250px
|Section1 = {{Chembox Identifiers
|CASNo = 117271-76-8 
|CASNo_Comment = <small>(Tetracation)</small>
|CASNo1 = 117271-78-0
|CASNo1_Comment = <small>(Tetrachloride)</small>
|PubChem = 4457151
|ChemSpiderID = 3655997
|SMILES = c1cc2ccc1C[n+]3ccc(cc3)-c4cc[n+](cc4)Cc5ccc(cc5)C[n+]6ccc(cc6)-c7cc[n+](cc7)C2
|InChI = 1/C36H32N4/c1-2-30-4-3-29(1)25-37-17-9-33(10-18-37)35-13-21-39(22-14-35)27-31-5-7-32(8-6-31)28-40-23-15-36(16-24-40)34-11-19-38(26-30)20-12-34/h1-24H,25-28H2/q+4
|InChIKey = URORLZXVTFVIPS-UHFFFAOYAV
|StdInChI = 1S/C36H32N4/c1-2-30-4-3-29(1)25-37-17-9-33(10-18-37)35-13-21-39(22-14-35)27-31-5-7-32(8-6-31)28-40-23-15-36(16-24-40)34-11-19-38(26-30)20-12-34/h1-24H,25-28H2/q+4
|StdInChIKey = URORLZXVTFVIPS-UHFFFAOYSA-N
}}
|Section2 = {{Chembox Properties
|Formula = C<sub>36</sub>H<sub>32</sub>N<sub>4</sub>
|MolarMass = 520.663 g·[[Mole (unit)|mol]]<sup>−1</sup>
|Appearance = white solid <ref name="stoddart">{{citation|last1=Masumi Asakawa|last2=Wim Dehaen|last3=Gerrit L’abbé|last4=Stephan Menzer|last5=Jan Nouwen|last6=Françisco M. Raymo|last7=J. Fraser Stoddart|last8=David J. Williams|periodical=[[The Journal of Organic Chemistry]]|title=Improved Template-Directed Synthesis of Cyclobis(paraquat-phenylene) |volume=61|issue=26|pages=9591–9595|issn=0022-3263|date= January 1996|doi=10.1021/jo961488i}}</ref>
}}
}}

'''Cyclobis(paraquat-''p''-phenylene)''' (formally a derivative of [[paraquat]]) belongs to the class of [[cyclophane]]s, and consists of [[aromatic]] units connected by [[methylene bridge]]s. It is able to incorporate small guest molecule and has played an important role in [[host–guest chemistry]] and [[supramolecular chemistry]].<ref name=":3">{{citation|last1=Jonathan C. Barnes|last2=Michal Juríček|last3=Nicolaas A. Vermeulen|last4=Edward J. Dale|last5=J. Fraser Stoddart|periodical=The Journal of Organic Chemistry|title=Synthesis of ExnBox Cyclophanes |volume=78|issue=23|pages=11962–11969|date=  2013|doi=10.1021/jo401993n|pmid=24128112}}</ref>

The cyclophane is also referred to as ''Stoddart's blue box'' because its inventor, [[J. Fraser Stoddart]], illustrates the [[Electrophile|electron-poor areas]] of molecules in a blue shade.<ref name=":0">{{cite book|last1=Atwood|first1=Jerry L.|last2=Steed|first2=Jonathan W.|title=Supramolecular chemistry|date=2013|publisher=Wiley|location=Hoboken, N.J.|isbn=978-1-118-68150-3}}</ref>

== Synthesis ==
For synthesis of cyclobis(paraquat-''p''-phenylene), [[4,4'-Bipyridine|4,4'-bipyridine]] is reacted with [[1,4-Bis(bromomethyl)benzene|1,4-bis(bromomethyl)benzene]] to 1,1′-[1,4-phenylenebis-(methylene)]bis(4,4′-bipyridine), which is reacted in a template synthesis again with 4,4′-bipyridine to the final product. A common template for this synthesis is 1,5-bis[2-(2-methoxyethoxy)ethoxy]naphthalene.<ref name="stoddart" />
:[[File:Synthesis of Cyclobis (paraquat-p-phenylene).svg|650px]]

== Host guest chemistry ==
Cyclobis(paraquat-''p''-phenylene) is able to incorporate small guest molecules forming a [[host–guest complex]]. The interactions required for complex formation are [[Charge-transfer complex|donor-acceptor interactions]] and [[hydrogen bonding]], their strength is highly dependent on the ability of the [[donor]] to provide [[Pi interaction|π-electron density]]. Also an enlargement of the π-system enhances the binding. The [[Chemical kinetics|kinetics]] of complex formation and dissociation depends on the bulkiness of the guest.<ref name=":1">{{cite journal|last1=Nielsen|first1=Mogens Brøndsted|last2=Jeppesen|first2=Jan Oskar| last3=Lau|first3=Jesper|last4=Lomholt|first4=Christian |last5=Damgaard|first5=Dorthe|last6=Jacobsen |first6=Jens Peter|last7=Becher|first7=Jan|last8=Stoddart|first8=J. Fraser |title=Binding Studies between Tetrathiafulvalene Derivatives and Cyclobis(paraquat-phenylene)|journal=The Journal of Organic Chemistry|year=2001|volume=66 |issue=10 |pages=3559–3563 |doi=10.1021/jo010173m|pmid=11348145}}</ref>

One molecule which is able to form stable complexes with cyclobis(paraquat-''p''-phenylene) is [[tetrathiafulvalene]] (TTF). Numerous derivatives are based on the chelating ability of tetrathiafulvalene. The modifications include mechanically entrapped compounds such as [[catenane]]s and [[rotaxane]]s, [[molecular switch]]es and larger supramolecular structures.<ref name=":1" />

The charge-transfer interactions, present in complexes of cyclobis(paraquat-''p''-phenylene), can be compared as structural motif with the more commonly used [[hydrogen bond]]s, especially in terms of directionality and complementarity ([[lock-and-key model]]). Charge-transfer complexes are easier to detect by [[spectroscopic]] methods and have a greater tolerance to various solvents, but also generally a lower [[association constant]]. Due to the lower association constant many fewer charge transfer complexes are known. Other non-covalent bonds such as [[solvophobic forces]], [[metal-ligand interaction]] can be used to increase the association constant; numerous structures based on this strategy are known in literature.<ref name=":2" />

It was shown that the choice of the [[counterion]] of cyclobis(paraquat-''p''-phenylene) has a large influence on the association constant of the corresponding host–guest complex.<ref>{{cite journal|last1=Andersen|first1=Sissel S.|last2=Jensen|first2=Morten|last3=Sørensen|first3=Anne|last4=Miyazaki|first4=Eigo|last5=Takimiya|first5=Kazuo|last6=Laursen|first6=Bo W.|last7=Flood|first7=Amar H.|last8=Jeppesen|first8=Jan O.|title=Anion effects on the cyclobis(paraquat-p-phenylene) host|journal=Chemical Communications|year=2012|volume=48|issue=42|pages=5157–5159|doi=10.1039/c2cc31225e|pmid=22516888}}</ref> It is often used as [[hexafluorophosphate]] salt because in this form it is soluble in organic solvents.

== Utilization ==
To create [[catenanes]], the cyclobis(paraquat-''p''-phenylene) can be used as a template to "thread" a [[crown ether]] with a π-donor component. Subsequently, its still open ends are linked with each other to obtain two closed rings.<ref>{{cite journal|last1=Miljanić|first1=Ognjen Š.|last2=Dichtel|first2=William R.|last3=Mortezaei|first3=Shahab|last4=Stoddart|first4=J. Fraser|title=Cyclobis(paraquat-phenylene)-Based [2]Catenanes Prepared by Kinetically Controlled Reactions Involving Alkynes|journal=Organic Letters|year=2006|volume=8|issue=21|pages=4835–4838|doi=10.1021/ol061864d|pmid=17020315}}</ref> A bistable catenane (a ring with two π-donor components) is already a simple example of a [[molecular switch]]. In the present example, a cyclic ether has been selected with a [[Tetrathiofulvalene|TTF]] and a [[Dinitrophenol|DNP]] moiety. While the cyclobis(paraquat-''p''-phenylene) surroundings the TTF unit in the rest position, the DNP unit is stable when the TTF is (reversible) is [[oxidized]]. The ring rotates in this case due to the [[coulomb repulsion]] around itself until the cyclobis(paraquat-''p''-phenylene) encloses the DNP unit. A reverse movement occurs when the TTF unit is reduced again. This first example that proved the general feasibility, many more have followed.<ref>{{cite journal|last1=Fahrenbach|first1=Albert C.|last2=Warren|first2=Scott C.|last3=Incorvati|first3=Jared T.|last4=Avestro|first4=Alyssa-Jennifer|last5=Barnes|first5=Jonathan C.|last6=Stoddart|first6=J. Fraser|last7=Grzybowski|first7=Bartosz A.|title=Organic Switches for Surfaces and Devices|journal=[[Advanced Materials]]|date=2013-01-18|volume=25|issue=3|pages=331–348|doi=10.1002/adma.201201912|pmid=22933356|bibcode=2013AdM....25..331F |s2cid=205246256}}</ref>

== Derivates ==
Numerous [[Derivative (chemistry)|derivatives]] of cyclobis(paraquat-''p''-phenylene) have been developed, including an enlarged version of the molecule, in the literature referred Ex<sup>n</sup>Box<sup>4+</sup>, where n is the number of [[Arene substitution pattern#Ortho.2C meta.2C and para substitution|p]]-[[phenylene]] rings (n = 0-3).<ref name=":3" /> These variants with larger apertures are capable to included larger, different sized molecules. Based on the charge-transfer complexation of CBPQT4 + many supramolecular structures have been created, including [[fibrillar gel]]s, [[micelles]], [[Vesicle (biology and chemistry)|vesicles]], [[nanotubes]], [[foldamers]] and liquid crystalline phases. In analogy to biological systems, which are assembled by hydrogen bonds to form supramolecular structures, the charge-transfer complexation is here an alternative.<ref name=":2">{{cite journal |last1=Das|first1=Anindita|last2=Ghosh|first2=Suhrit |title=Supramolecular Assemblies by Charge-Transfer Interactions between Donor and Acceptor Chromophores|journal=Angewandte Chemie International Edition|date=2014-02-17 |volume=53|issue=8 |pages=2038–2054|doi=10.1002/anie.201307756 |pmid=24573995}}</ref>

== References ==
<references />

[[Category:Aromatic compounds]]
[[Category:Quaternary ammonium compounds]]
[[Category:Pyridines]]
[[Category:Cyclophanes]]
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