A polycatenane is a chemical substance that, like polymers, is chemically constituted by a large number of units.[2] These units are made up of concatenated rings into a chain-like structure.
The characteristic feature of a polycatenane compound, that distinguishes it from other polymers, is the presence of mechanical bonds in addition to covalent bonds.[7][9][10] 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.[11][1][12] 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.[1] 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.[13]
Classification
Depending on the location of the catenane structures in the polymer chain, the polycatenanes can be divided into main-chain polycatenanes and side-chain polycatenanes.[2][7][14]
Main-chain polycatenanes are linear catenanes in which the rings are interlocked in a large number of units. They can also be a series of oligomers linked physically even if not interlocked together. The stability of the structure is not only given by mechanical bonds but also hydrogen bonds and π-π interactions between the rings.[2]
On the other hand, the side-chain polycatenanes are polycatenanes with ramifications where more oligomers are connected on the same cycle with respect to the main backbone. This type of catenane is synthesised, functionalising the macrocycles so that there is directionality with the possibility to control the ramification.[2]
There are other types of polycatenanes like the ones based on cyclic polymers, where the macrocyles are interlocked to the cyclic polymers, or the polycatenane networks, where catenanes are interlocked into a net.[15][16]
Catenated nanocages
The basic unit of the polycatenane can differ from the relatively simple organic macrocycle. When organic and inorganic building blocks come together, they can form coordination cages (or macromolecular cages) that can interlock with one another to form a polycatenane structure.[17] The mechanism is still unexplored but generally the subunits self-assemble into a 0D cage and, in a concerted process, interlock together into a linear or more intricate catenane structure.[18][19][20][21][22][23] Sometimes the catenated cages structure is more stable with respect to the monomeric cage state, and it can be formed passing through a favored reaction intermediate.[24] The synthesis can follow a statistical or a directed routes, forming more or less product, but there are some cases when post-synthetic modifications can increase the product yields.[25][26] Catenated cages can be applied in a wide range of application due to the high presence of voids.[27][28][29]
Synthesis and applications
Synthesis
The synthesis of polycatenanes is considered a challenging task with most of the reported examples being in the solution state and very few in the solid state.[30] The formation of poly-[2]-catenanes can be achieved by polymerisation of functionalised [2]-catenanes.[31] Also the synthesis of [3]-catenanes, [5]-catenanes, [6]-catenanes and [7]-catenanes is reported in many articles.[32][33] The synthesis of poly-[n]-catenanes has instead some practical issues.[34][35] To this purpose, molecular dynamic simulation is very used as a tool for the design of the optimal synthetic path toward the desired product by predicting the final topology.[36][13]
There are two main synthetic routes: the statistical approach and the template-directed approach.[37]
The statistical approach is based on a stochastic methodology.[38][39] When the reactants are together, there is a probability that they will fit together first and then close on top of each other in a process of cyclisation. The catenation of two rings into a catenane is already complex, thus, as expected, the interlocking of multiple cycles into a polycatenane is statistically improbable. Being an unfavored entropically process the product is obtained in very small amounts. Also, the cyclisation process requires high dilutions, but the elongation of the chain is favored at high concentrations, making the synthesis even more difficult.[38][39]
The template-directed approach is based on the host-guest interactions that can direct the cyclisation of pre-organised linear unit upon the existing macrocycle.[37][31] These interactions can be hydrogen bonds, π-π interactions, hydrophobic interactions or metal ions coordinations. In this way the synthesis can be enthalpy-driven, obtaining quantitative results.[37][31]
The yield and selectivity are restrained by the kinetic or thermodynamic control of the reaction.[40]
Generally the kinetic control induces the formation of a product after short reaction times because it is favoued by irreversible reactions (or equilibrium reaction moved very much toward the formation of the products).[25] The thermodynamic product is obtained for longer reaction times for reversible processes.[41] In this case the units have the time to rearrange themselves toward the most stable state, in a sort of error-checking process. This is obtained by breaking covalent and coordination bonds and forming the most stable ones.[42]
Applications
Given that polycatenanes are a relatively recent field of study, the properties of these materials are not yet fully explored and understood.[43] The type of bonds that characterize the whole structure (covalent, non-covalent or mechanical bonds), the degree of mobility of the chain, the interactions between different chains and the fraction of voids of the catenanes are all factors that contribute to the final properties. As they can be strictly related to the family of metal-organic frameworks, the catenanes share all the potential applications of this class of compounds. Among these, there are applications in biomedicine, catalysis, as conducting bridges or in electronic devices, sensing or in recent fields like molecular machines.[44][45][46][47][48][49][50]
^Bruns, Carson J.; Stoddart, J. F.; Stoddart, James Fraser (2017). The nature of the mechanical bond: from molecules to machines. Hoboken, New Jersey: John Wiley & Sons. ISBN978-1-119-04400-0.
^Amabilino, David B.; Ashton, Peter R.; Balzani, Vincenzo; Boyd, Sue E.; Credi, Alberto; Lee, Ju Young; Menzer, Stephan; Stoddart, J. Fraser; Venturi, Margherita; Williams, David J. (1998-04-28). "Oligocatenanes Made to Order1". Journal of the American Chemical Society. 120 (18): 4295–4307. doi:10.1021/ja9720873. ISSN0002-7863.
Questa voce sull'argomento calciatori burkinabé è solo un abbozzo. Contribuisci a migliorarla secondo le convenzioni di Wikipedia. Charles Kaboré Nazionalità Burkina Faso Altezza 181 cm Peso 75 kg Calcio Ruolo Centrocampista Squadra svincolato Carriera Giovanili 2003-2004 SONABEL2004-2007 Étoile Ouagadougou Squadre di club1 2007-2008 Libourne-St-Seurin26 (2)2008-2013 Olympique Marsiglia136 (2)2013-2015 Kuban'63 (0)2015-2019 Krasnodar86 (2)2019-202...
Species of bird White-tailed tropicbird Warwick Parish, Bermuda Conservation status Least Concern (IUCN 3.1)[1] Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Chordata Class: Aves Order: Phaethontiformes Family: Phaethontidae Genus: Phaethon Species: P. lepturus Binomial name Phaethon lepturusDaudin, 1802 The white-tailed tropicbird (Phaethon lepturus) is a tropicbird. It is the smallest of three closely related seabirds of the tropical oceans and smal...
Genre of alternative rock music ShoegazeStylistic origins Indie rock[1] alternative rock[2] noise pop[3][4] dream pop[5][6] psychedelia[6] neo-psychedelia[6] post-punk[5] ethereal wave[7] garage rock[6] space rock[8] Cultural originsLate 1980s, Ireland and United KingdomDerivative forms Chillwave[9] nu gaze Fusion genresBlackgazeOther topics Ambient ethereal wave list of musicians noise roc...
Daftar keuskupan di Pantai Gading adalah sebuah daftar yang memuat dan menjabarkan pembagian terhadap wilayah administratif Gereja Katolik Roma yang dipimpin oleh seorang uskup ataupun ordinaris di Pantai Gading. Konferensi para uskup Pantai Gading bergabung dalam Konferensi Waligereja Pantai Gading. Saat ini terdapat 15 buah yurisdiksi, di mana 4 merupakan keuskupan agung dan 11 lainnya merupakan keuskupan sufragan. Daftar keuskupan Provinsi Gerejawi Abidjan Keuskupan Agung Abidjan: Kardinal...
Administrative entry restrictions Not to be confused with Visa requirements for Republic of the Congo citizens. A Democratic Republic of the Congo passport Visa requirements for Democratic Republic of the Congo citizens are administrative entry restrictions by the authorities of other states placed on citizens of the Democratic Republic of the Congo. As of 2 July 2019,[update] Democratic Republic of the Congo citizens had visa-free or visa on arrival access to 41 countries a...
President of Bolivia variously in the 20th century This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Víctor Paz Estenssoro – news · newspapers · books · scholar · JSTOR (March 2016) (Learn how and when to remove this template message) In this Spanish name, the first or paternal surname is Paz and the ...
جزء من سلسلة مقالات سياسة أذربيجانأذربيجان الدستور الدستور حقوق الإنسان السلطة التنفيذية الرئيس مجلس الوزراء السلطة التشريعية البرلمان السلطة القضائية القضاء المحكمة العليا التقسيمات الادارية مقاطعات الانتخابات الانتخابات الأحزاب السياسية السياسة الخارجية العلاقات ...
Dakshinamurti StotraSculpture of Dakshinamurti, Tamil Nadu, Arthur M. Sackler GalleryInformationReligionHinduismAuthorAdi ShankaraLanguageSanskritVerses10Sanskrit hymn about Shiva The Dakshinamurti Stotra (Sanskrit: दक्षिणामूर्तिस्तोत्र, romanized: Dakṣiṇāmūrtistotra) is a Sanskrit religious hymn (stotra) to Shiva attributed to Adi Shankara.[1] It explains the metaphysics of the universe in the frame of the tradition of Advaita Vedant...
Amusement park in California This article is about the current Santa Monica, California amusement park that opened in 1996. For the former Santa Monica amusement park that operated from 1958 to 1967, see Pacific Ocean Park. For the Brooklyn, New York redevelopment project, see Pacific Park, Brooklyn. Pacific Park EntrancePacific Park entrance in 2004LocationSanta Monica, California, United StatesCoordinates34°00′30″N 118°29′53″W / 34.00833°N 118.49806°W / 3...
درع المجتمع الإنجليزي 2005 تفاصيل الموسم درع الاتحاد الإنجليزي النسخة 83 البلد المملكة المتحدة المنظم الاتحاد الإنجليزي لكرة القدم البطل نادي تشيلسي مباريات ملعوبة 1 الحضور الجماهيري 58014 درع الاتحاد الإنجليزي 2004 درع الاتحاد الإنجليزي 2006 تعديل ...
Data format News feed redirects here. For the Facebook feature, see News Feed. This article needs to be updated. Please help update this article to reflect recent events or newly available information. (July 2023) Common web feed icon On the World Wide Web, a web feed (or news feed) is a data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe a channel to it by adding the feed resource address to a ne...
Italian community in Tunisia Italian TunisianItalo-tunisini (Italian)Total population3,000 (by birth, 2006)Regions with significant populationsTabarka, La Goulette, Tunis Italian Tunisians living in Italy: Sicily, Rome (migrant descendants of those people, from Sicily), Naples (Sicilian Tunisian immigrants)LanguagesFrench, Italian, Tunisian Arabic, Sicilian, Neapolitan, other Italian dialectsReligionRoman Catholicism,[1] JudaismRelated ethnic groupsItalians, Italian Algerians, It...
Final Fantasy XV character Fictional character Noctis Lucis CaelumFinal Fantasy characterNoctis wielding the Engine Blade, as drawn by Tetsuya Nomura for Dissidia Final Fantasy NT.First appearanceBrotherhood: Final Fantasy XV (2016)First gameFinal Fantasy XV (2016)Created byTetsuya NomuraDesigned byTetsuya NomuraHiromu TakaharaYusuke NaoraVoiced byEnglishRay Chase[1]Hyrum Hansen (child)[1]JapaneseTatsuhisa Suzuki[1]Miyuki Satō (child)[1]Motion captureTakuma Ha...
8th-century Abbasid-era mosque and mausoleum of Ali ibn Abi Talib in Najaf, Iraq For the site of his assassination, see Great Mosque of Kufa. Not to be confused with Hazrat Ali Mazar. Imam Ali Mosque redirects here. For the mosque in Basra, see Imam Ali Mosque (Basra). Shrine of Imam Ali حَرَم ٱلْإِمَام عَلِيّ Ḥaram al-Imām ‘Alī Imām 'Alī Shrine, where 'Alī ibn Abī Tālib is buriedReligionAffiliationIslamProvinceNajaf GovernorateRiteMuslimsEcclesiastical or organ...
Halaman ini berisi artikel tentang pemerintahan Republik Tiongkok antara tahun 1927 dan 1948. Untuk pemerintahan tersebut sejak tahun 1948, lihat Pemerintahan Republik Tiongkok. Untuk pemerintahan kolaborasionis Wang Jingwei, lihat Pemerintahan Nasional Direorganisasi Republik Tiongkok. Republik Tiongkok中華民國Chunghwa Minkuo1925–1948 Bendera Lambang Lagu kebangsaan: 《中華民國國歌》Lagu Kebangsaan Republik Tiongkok (1937–1948) Lagu bendera nasional《中華民國國旗...
This article contains content that is written like an advertisement. Please help improve it by removing promotional content and inappropriate external links, and by adding encyclopedic content written from a neutral point of view. (August 2010) (Learn how and when to remove this template message) Ontario Hospital AssociationTypeNon-profit organizationIndustryHealth CareFoundedToronto, Canada (1924 (1924))HeadquartersToronto, CanadaKey peopleAnthony Dale (President and CEO)Marcia Visser (...
Chinese banker An editor has performed a search and found that sufficient sources exist to establish the subject's notability. These sources can be used to expand the article and may be described in edit summaries or found on the talk page. The article may include original research, or omit significant information about the subject. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Charles Li –&...
لمعانٍ أخرى، طالع جزيرة شاتر (توضيح). جزيرة شاترShutter Island (بالإنجليزية) البوستر السينمائيمعلومات عامةالصنف الفني القائمة ... فيلم رعب — فيلم إثارة — فيلم مقتبس من رواية — فيلم دراما — فيلم جريمة — فيلم غموض الموضوع حقيقة تاريخ الصدور 19 فبراير 2010مدة العرض 138دقيقةال...
هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (أبريل 2016) اضغط هنا للاطلاع على كيفية قراءة التصنيف القنفذي الحسوني المرتبة التصنيفية نوع التصنيف العلمي النطاق: حقيقيات النوى المملكة: النباتات الفرقة العليا: الن...
Alper ErturkBorn (1982-04-03) April 3, 1982 (age 41)EducationVirginia Polytechnic Institute and State University, METUScientific careerFieldsMechanical engineeringEngineering mechanicsInstitutionsGeorgia Institute of Technology, George W. Woodruff School of Mechanical Engineering Alper Erturk (born April 3, 1982) is a mechanical engineer and the Woodruff Professor in the George W. Woodruff School of Mechanical Engineering at Georgia Institute of Technology.[1] Research Erturk lea...