Editing Polycatenane (section)

{{Short description|Mechanically interlocked molecular architecture}}
[[File:Polycatenane (cropped).jpg|thumb|Polycatenane model.<ref name=":2">{{Cite journal |last1=Wu |first1=Qiong |last2=Rauscher |first2=Phillip M. |last3=Lang |first3=Xiaolong |last4=Wojtecki |first4=Rudy J. |last5=de Pablo |first5=Juan J. |last6=Hore |first6=Michael J. A. |last7=Rowan |first7=Stuart J. |date=2017-12-15 |title=Poly[ n ]catenanes: Synthesis of molecular interlocked chains |journal=Science |language=en |volume=358 |issue=6369 |pages=1434–1439 |doi=10.1126/science.aap7675 |pmid=29192134 |bibcode=2017Sci...358.1434W |s2cid=667951 |issn=0036-8075|doi-access=free }}</ref>]]
A '''polycatenane''' is a chemical substance that, like [[polymer]]s, is chemically constituted by a large number of units.<ref name=":0">{{cite journal | author = Z.Niu and Harry.W. Gibson | title = Polycatenanes | year = 2009 | journal = [[Chem. Rev.]] | volume = 109 | issue = 11 | pages = 6024–6046 |doi= 10.1021/cr900002h| pmid = 19670889 }}</ref> These units are made up of concatenated rings into a chain-like structure.

It consists of mechanically linked [[catenane]]<ref>{{Cite journal |last1=Gil-Ramírez |first1=Guzmán |last2=Leigh |first2=David A. |last3=Stephens |first3=Alexander J. |date=2015-05-07 |title=Catenanes: Fifty Years of Molecular Links |url=http://dx.doi.org/10.1002/anie.201411619 |journal=Angewandte Chemie International Edition |volume=54 |issue=21 |pages=6110–6150 |doi=10.1002/anie.201411619 |pmid=25951013 |pmc=4515087 |issn=1433-7851}}</ref> structures, via topological [[Hopf link]]s, resulting in a higher dimensionality than the repeating unit.<ref>{{Cite book |last=Flapan |first=Erica |url=https://www.cambridge.org/core/books/when-topology-meets-chemistry/1B5638674BE0A88BB598C78E18D831DA |title=When Topology Meets Chemistry: A Topological Look at Molecular Chirality |date=2000 |publisher=Cambridge University Press |isbn=978-0-521-66254-3 |series=Outlooks |location=Cambridge |doi=10.1017/cbo9780511626272}}</ref><ref>{{Cite journal |last1=Carlucci |first1=Lucia |last2=Ciani |first2=Gianfranco |last3=Proserpio |first3=Davide M. |date=November 2003 |title=Polycatenation, polythreading and polyknotting in coordination network chemistry |url=http://dx.doi.org/10.1016/s0010-8545(03)00126-7 |journal=Coordination Chemistry Reviews |volume=246 |issue=1–2 |pages=247–289 |doi=10.1016/s0010-8545(03)00126-7 |issn=0010-8545|url-access=subscription }}</ref> They are a class of catenanes where the number of [[macrocycle]]s is greater than two and as catenanes they belong to the big family of [[Mechanically interlocked molecular architectures|mechanically interlocked molecular architectures (MIMAs)]].<ref>{{Cite book |last1=Davis |first1=Frank |title=Macrocycles: construction, chemistry, and nanotechnology applications |last2=Higson |first2=Séamus |date=2011 |publisher=Wiley |isbn=978-1-119-98993-6 |location=Chichester}}</ref><ref name=":1">{{Cite journal |last1=Fang |first1=Lei |last2=Olson |first2=Mark A. |last3=Benítez |first3=Diego |last4=Tkatchouk |first4=Ekaterina |last5=Goddard III |first5=William A. |last6=Stoddart |first6=J. Fraser |date=2010 |title=Mechanically bonded macromolecules |url=http://xlink.rsc.org/?DOI=B917901A |journal=Chem. Soc. Rev. |language=en |volume=39 |issue=1 |pages=17–29 |doi=10.1039/B917901A |issn=0306-0012 |pmid=20023833}}</ref><ref>{{Cite journal |last1=Amabilino |first1=David B. |last2=Stoddart |first2=J. Fraser |date=December 1995 |title=Interlocked and Intertwined Structures and Superstructures |url=http://dx.doi.org/10.1021/cr00040a005 |journal=Chemical Reviews |volume=95 |issue=8 |pages=2725–2828 |doi=10.1021/cr00040a005 |issn=0009-2665|url-access=subscription }}</ref>

[[File:Catenane mobility.tif|thumb|Reciprocal degree of motion of polycatenanes rings.]] The characteristic feature of a polycatenane compound, that distinguishes it from other polymers, is the presence of mechanical bonds in addition to covalent bonds.<ref name=":1" /><ref>{{Cite journal |last=Stoddart |first=J. Fraser |date=2009 |title=The chemistry of the mechanical bond |url=http://xlink.rsc.org/?DOI=b819333a |journal=Chemical Society Reviews |language=en |volume=38 |issue=6 |pages=1802–1820 |doi=10.1039/b819333a |issn=0306-0012 |pmid=19587969|url-access=subscription }}</ref><ref>{{Cite book |last1=Bruns |first1=Carson J. |title=The nature of the mechanical bond: from molecules to machines |last2=Stoddart |first2=J. F. |last3=Stoddart |first3=James Fraser |date=2017 |publisher=John Wiley & Sons |isbn=978-1-119-04400-0 |location=Hoboken, New Jersey}}</ref> The rings in this chain-like structure can be separated only when high energy is provided to break at least a covalent bond of the macrocycle. [''n'']-Catenanes (for large n), which consist solely of the mechanically interlocked cyclic components, can be viewed as “optimized” polycatenanes. The main difference between poly-[''2'']-catenanes and poly-[''n'']-catenanes is the repeating unit, as a monomer is for the polymer.<ref>{{Cite journal |last1=Xing |first1=Hao |last2=Li |first2=Zhandong |last3=Wang |first3=Wenbo |last4=Liu |first4=Peiren |last5=Liu |first5=Junkai |last6=Song |first6=Yu |last7=Wu |first7=Zi Liang |last8=Zhang |first8=Wenke |last9=Huang |first9=Feihe |date=February 2020 |title=Mechanochemistry of an Interlocked Poly[2]catenane: From Single Molecule to Bulk Gel |journal=CCS Chemistry |volume=2 |issue=1 |pages=513–523 |doi=10.31635/ccschem.019.20190043 |s2cid=219164409 |issn=2096-5745|doi-access=free }}</ref><ref name=":2" /><ref>{{Citation |last=Geerts |first=Yves |title=Polycatenanes, Poly[2]catenanes, and Polymeric Catenanes |date=1999-06-24 |url=https://onlinelibrary.wiley.com/doi/10.1002/9783527613724.ch10 |work=Molecular Catenanes, Rotaxanes and Knots |pages=247–276 |editor-last=Sauvage |editor-first=J.-P. |access-date=2023-07-05 |edition=1 |publisher=Wiley |language=en |doi=10.1002/9783527613724.ch10 |isbn=978-3-527-29572-2 |editor2-last=Dietrich-Buchecker |editor2-first=C.|url-access=subscription }}</ref> In the first case the monomer is made of two interlocked rings that repeat continuously in the final polycatenane, while in the latter case there is only one ring that repeat the interlocking process for a large number of times. If the rings of the polycatenane are all of the same type, it can be defined as a homocatenane while if the subunits are different it is defined as heterocatenane.

As a chain, the degree of motion of these structures is very high, greater than the one of a usual polymer, because the rings possess a reciprocal rotational, elongational and rocking motion.<ref name=":2" /> This flexibility is retained even if the macrocycles themselves are very rigid units, because the mobility is given by the ability of the rings to move with respect to each other. This mobility influences the final properties of the material (mechanical, rheological and thermal), and provides a dynamic behavior.<ref name=":6">{{Cite journal |last1=Rauscher |first1=Phillip M. |last2=Schweizer |first2=Kenneth S. |last3=Rowan |first3=Stuart J. |last4=de Pablo |first4=Juan J. |date=2020-06-07 |title=Dynamics of poly[ n ]catenane melts |url=https://pubs.aip.org/jcp/article/152/21/214901/198671/Dynamics-of-poly-n-catenane-melts |journal=The Journal of Chemical Physics |language=en |volume=152 |issue=21 |page=214901 |bibcode=2020JChPh.152u4901R |doi=10.1063/5.0007573 |issn=0021-9606 |pmid=32505155 |s2cid=219537697|doi-access=free }}</ref>