Cycloparaphenylene

Last updated
Interactive 3D model of [5]cycloparaphenylene Cycloparaphenylene 3D Model.stl
Interactive 3D model of [5]cycloparaphenylene
Space-filling model of an [8]cycloparaphenylene molecule. Cycloparaphenylene-3D-spacefill.png
Space-filling model of an [8]cycloparaphenylene molecule.

A cycloparaphenylene is a molecule that consists of several benzene rings connected by covalent bonds in the para positions to form a hoop- or necklace-like structure. Its chemical formula is [C6H4]n or C
6nH
4n Such a molecule is usually denoted [n]CPP where n is the number of benzene rings.

Contents

An "armchair" carbon nanotube and a cycloparaphenylene molecule. CNT CPP.png
An "armchair" carbon nanotube and a cycloparaphenylene molecule.

A cycloparaphenylene can be considered as the smallest possible armchair carbon nanotube, and is a type of carbon nanohoop. [2] Cycloparaphenylenes are challenging targets for chemical synthesis due to the ring strain incurred from forcing benzene rings out of planarity.

History

In 1934 by V. C. Parekh and P. C. Guha described the first published attempt to synthesize a cycloparaphenylene, specifically [2]CPP. They connected two aromatic rings with a sulfide bridge, and hoped that removal of the latter would yield the desired compound. However, the attempt failed as the compound would have been far too strained to exist under anything but extreme conditions. [3]

First attempts at a CPP Product S.png
First attempts at a CPP

By 1993, Fritz Vögtle attempted to synthesize the less-strained [6]CPP and [8]CPP by the same approach. He produced a hoop of phenyl rings, bridged together by a sulfur atom. However, his attempts to remove the sulfur failed too. They also synthesized a macrocycle that upon dehydrogenation would yield a CPP, but could not perform this final step. [5] [4]

In the year 2000, Chandrasekhar and others concluded, by computational analysis, that [5]CPP and [6]CPP should be significantly different in their aromaticity. [6] However, the synthesis in 2014 of [5]CPP refuted this conclusion. [1] [7] [8] [9]

In 2008 the first cycloparaphenylenes were synthesized by Ramesh Jasti during his post doctoral research in the lab of Carolyn Bertozzi. He used cyclohexa-1,4-dienes which are closer in oxidation state to the desired phenylene than the cyclohexanes used previously by Vögtle. The first cycloparaphenylenes that were reported and characterized were: [9]CPP, [12]CPP, and [18]CPP. [10] In 2009, the Itami group would report the selective synthesis of [12]CPP, and shortly thereafter Yamago synthesized [8]CPP in 2010. [11] [12] The Jasti Group then synthesized all increasingly smaller CPPs using new methodology that allowed [7]CPP, [13] [6]CPP, [14] and finally [5]CPP [1] to be reported in relatively quick succession.

Properties

Structure

The normal configuration of each phenylene element would be planar, with the bonds in the para position pointing opposite to each other in a straight line. Therefore, the cycloparaphenylene molecule is strained, and the strain increases as the number of units decreases. The strain energy of [5]CPP was calculated as 117.2 kcal/mol. In spite of the strain, the phenyl rings retain their aromatic character, even in the [5]CPP. [1] [15] However, as the size of the CPP decreases the HOMO-LUMO gap also decreases. This trend opposite to that observed in linear polyparaphenylenes where the HOMO-LUMO gap decreases as size increases. [9] [12] This causes a red-shift of the fluorescent emission. [9]

Solid-state packing

Cycloparaphenylenes with 7 to 12 rings all adopt a herringbone-like packing in the solid state. A similar but denser structure was observed for [5]CPP, whereas [6]CPP forms columns. [14] This columnar packing structure has been of interest due to a potentially high internal surface area. By partial fluorination, it was found that this packing geometry could be engineered. [16]

Synthesis

There are three main methods used for cycloparaphenylene synthesis.

Suzuki Coupling of Curved Oligophenylene Precursors

In the initial synthesis, cycloparaphenylenes with n = 9, 12, and 18 have been synthesized starting from macrocycles containing 1,4-syn-dimethoxy-2,5-cyclohexadiene units as masked aromatic rings. Lithium–halogen exchange with p-diiodobenzene followed by a two-fold nucleophilic addition reaction with 1,4-benzoquinone yielded a syn-cyclohexadiene moiety. Borylation of this material followed macrocyclization under Suzuki–Miyuara cross-coupling with an equivalent of the diiodide produced macrocycles in low yields which could be separated by column chromatography. These macrocycles were then reductively aromatized using sodium naphthalenide to yield [n]cycloparaphenylenes. Since this initial synthesis uses symmetric building blocks it is challenging to use it to make smaller CPPs. Therefore, instead of benzoquinone, benzoquinone monomethyl ketal was used to allow the use of asymmetric building blocks. This innovation allowed the selective synthesis of [12]CPP to [5]CPP. [17]

[5]CPP is synthesized with an intramolecular boronate homocoupling technique that was originally seen as an undesired by-product of Suzuki-Miyaura cross-coupling reactions in the synthesis of [10]CPP. [1] [15] Cycloparaphenylenes now have selective, modular, and high yielding synthetic pathways.

Reductive Elimination of Platinum Macrocycles

A quicker route to [8-13]CPPs starts by selectively building [8]CPP and [12]CPP from the reaction of 4,4′-bis(trimethylstannyl)biphenyl and 4,4′ ′-bis(trimethylstannyl)terphenyl, respectively, with Pt(cod)Cl2 (where cod is 1,5-cyclooctadiene) through square-shaped tetranuclear platinum intermediates. [12] A mixture of [8-13]cycloparaphenylenes can be obtained in good combined yields by mixing biphenyl and terphenyl precursors with the platinum sources. [12]

[2+2+2]Cycloaddition of Alkynes

A third method for the synthesis of cycloparaphenylenes developed in the Wegner group is based on rhodium-catalyzed [2+2+2]cycloadditions of substituted alkynes. [18] The method has been further investigated by the Tanaka group, which have used the rhodium-catalysed cyclotrimerisation of alkynes as a core strategy. [19] [20]

Potential applications

Potential applications of cycloparaphenylenes include host–guest chemistry, [10] seeds for carbon nanotube growth, and hybrid nanostructures containing nanohoop-type substituents. [21] A cycloparaphenylene can be seen as minimal single-walled carbon nanotube of the armchair type. As such, a cycloparaphenylene may be a seed for synthesis of longer nanotubes. [10] [12] [22] Their electronic properties may also be useful. [23] [24]

Fullerene binding

Cycloparaphenylenes have shown affinity to fullerenes and other carbonaceous molecules, [10] with interactions similar to those in carbon peapods. Potential applications of these structures include nanolasers, single electron transistors, spin-qubit arrays for quantum computing, nanopipettes, and data storage devices. [25] [26] [27]

Specifically, the π-π interactions and the concave interior of the cycloparaphenylenes is expected to bind to π conjugated systems with convex surfaces that can fit inside the ring. Indeed, [10]CPP has been shown to selectively bind a C60 fullerene within its hole, thus producing a "molecular bearing". [10] The fullerene remains in the ring long enough to be observed on the NMR timescale. [28] The fluorescence of [10]CPP is quenched upon complexation with C60, which suggests its potential as a C60 sensor. [10] In 2018 this affinity was exploited to create CPP-fullerene rotaxanes. [29]

It has been observed that such "ball-in-hoop" interactions are stronger for endohedral metallo-fullerenes, in which a positively charged metal ion is trapped inside a fullerene cage and makes it more electronegative. [30] [22] Specifically, [12]CPP was found to preferentially enclose metallo-fullerenes instead of "empty" fullerenes, reducing their solubility in toluene; which provides a convenient separation method for the two species. [28]

As the synthesis of CPPs has become easier, derivative structures have begun to be synthesized as well. In 2013 the Itami group reported the synthesis of a nanocage made completely of benzene rings. This compound was especially interesting because it could be viewed as a junction of a branched nanotube structure. [31]

Other chiral derivatives of cycloparaphenylenes (which may serve as chemical templates for synthesizing chiral nanotubes) have also been characterized. Similar to the original (n,n) cycloparaphenylenes, these chiral nanorings also exhibit unusual optoelectronic properties with excitation energies growing larger as a function of size; however, the (n+3,n+1) chiral nanoring exhibits larger photoinduced transitions compared to the original (n,n) cycloparaphenylenes, resulting in more readily observable optical properties in spectroscopic experiments. [32]

In 2012 the Jasti Group reported the synthesis of dimers of [8]CPP linked by arene bridges. [33] This synthesis was followed two years later by the synthesis of a directly connected dimer of [10]CPP from chloro[10]CPP by the Itami group. [34]

Donor–acceptor functionalization

CPPs are unique in that their donor–acceptor properties can be adjusted with the addition or removal of each phenyl ring. In the all-carbon nano-hoop systems a reduction in width corresponds to a higher HOMO and a lower LUMO. Additional donor–acceptor selectivity was observed by the addition of an aromatic heterocycles into the larger ring. N-methylaza[n]CPP showed that a lowering of the LUMO could be enhanced by decreasing the ring size, while the HOMO energy level remained the same. [35]

Related Research Articles

<span class="mw-page-title-main">Porphyrin</span> Heterocyclic organic compound with four modified pyrrole subunits

Porphyrins are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). In vertebrates, an essential member of the porphyrin group is heme, which is a component of hemoproteins, whose functions include carrying oxygen in the bloodstream. In plants, an essential porphyrin derivative is chlorophyll, which is involved in light harvesting and electron transfer in photosynthesis.

A nanoring is a cyclic nanostructure with a thickness small enough to be on the nanoscale. Note that this definition allows the diameter of the ring to be larger than the nanoscale. Nanorings are a relatively recent development within the realm of nanoscience; the first peer-reviewed journal article mentioning these nanostructures came from researchers at the Institute of Physics and Center for Condensed Matter Physics in Beijing who synthesized nanorings made of gallium nitride in 2001. Zinc oxide, a compound very commonly used in nanostructures, was first synthesized into nanorings by researchers at Georgia Institute of Technology in 2004 and several other common nanostructure compounds have been synthesized into nanorings since. More recently, carbon-based nanorings have been synthesized from cyclo-para-phenylenes as well as porphyrins.

Dynamic covalent chemistry (DCvC) is a synthetic strategy employed by chemists to make complex molecular and supramolecular assemblies from discrete molecular building blocks. DCvC has allowed access to complex assemblies such as covalent organic frameworks, molecular knots, polymers, and novel macrocycles. Not to be confused with dynamic combinatorial chemistry, DCvC concerns only covalent bonding interactions. As such, it only encompasses a subset of supramolecular chemistries.

In organic chemistry, a cyclophane is a hydrocarbon consisting of an aromatic unit and a chain that forms a bridge between two non-adjacent positions of the aromatic ring. More complex derivatives with multiple aromatic units and bridges forming cagelike structures are also known. Cyclophanes are well-studied examples of strained organic compounds.

<span class="mw-page-title-main">Prato reaction</span> Example of the well-known 1,3-dipolar cycloaddition of azomethine ylides to olefins

The Prato reaction is a particular example of the well-known 1,3-dipolar cycloaddition of azomethine ylides to olefins. In fullerene chemistry this reaction refers to the functionalization of fullerenes and nanotubes. The amino acid sarcosine reacts with paraformaldehyde when heated at reflux in toluene to an ylide which reacts with a double bond in a 6,6 ring position in a fullerene via a 1,3-dipolar cycloaddition to yield a N-methylpyrrolidine derivative or pyrrolidinofullerene or pyrrolidino[[3,4:1,2]] [60]fullerene in 82% yield based on C60 conversion.

In chemistry, mechanically interlocked molecular architectures (MIMAs) are molecules that are connected as a consequence of their topology. This connection of molecules is analogous to keys on a keychain loop. The keys are not directly connected to the keychain loop but they cannot be separated without breaking the loop. On the molecular level, the interlocked molecules cannot be separated without the breaking of the covalent bonds that comprise the conjoined molecules; this is referred to as a mechanical bond. Examples of mechanically interlocked molecular architectures include catenanes, rotaxanes, molecular knots, and molecular Borromean rings. Work in this area was recognized with the 2016 Nobel Prize in Chemistry to Bernard L. Feringa, Jean-Pierre Sauvage, and J. Fraser Stoddart.

In chemistry, transfer hydrogenation is a chemical reaction involving the addition of hydrogen to a compound from a source other than molecular H2. It is applied in laboratory and industrial organic synthesis to saturate organic compounds and reduce ketones to alcohols, and imines to amines. It avoids the need for high-pressure molecular H2 used in conventional hydrogenation. Transfer hydrogenation usually occurs at mild temperature and pressure conditions using organic or organometallic catalysts, many of which are chiral, allowing efficient asymmetric synthesis. It uses hydrogen donor compounds such as formic acid, isopropanol or dihydroanthracene, dehydrogenating them to CO2, acetone, or anthracene respectively. Often, the donor molecules also function as solvents for the reaction. A large scale application of transfer hydrogenation is coal liquefaction using "donor solvents" such as tetralin.

<span class="mw-page-title-main">Acene</span> Class of chemical compounds

In organic chemistry, the acenes or polyacenes are a class of organic compounds and polycyclic aromatic hydrocarbons made up of benzene rings which have been linearly fused. They follow the general molecular formula C4n+2H2n+4.

<span class="mw-page-title-main">Fullerene chemistry</span>

Fullerene chemistry is a field of organic chemistry devoted to the chemical properties of fullerenes. Research in this field is driven by the need to functionalize fullerenes and tune their properties. For example, fullerene is notoriously insoluble and adding a suitable group can enhance solubility. By adding a polymerizable group, a fullerene polymer can be obtained. Functionalized fullerenes are divided into two classes: exohedral fullerenes with substituents outside the cage and endohedral fullerenes with trapped molecules inside the cage.

Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrate. While iron adopts oxidation states from Fe(−II) through to Fe(VII), Fe(IV) is the highest established oxidation state for organoiron species. Although iron is generally less active in many catalytic applications, it is less expensive and "greener" than other metals. Organoiron compounds feature a wide range of ligands that support the Fe-C bond; as with other organometals, these supporting ligands prominently include phosphines, carbon monoxide, and cyclopentadienyl, but hard ligands such as amines are employed as well.

<span class="mw-page-title-main">Catellani reaction</span>

The Catellani reaction was discovered by Marta Catellani and co-workers in 1997. The reaction uses aryl iodides to perform bi- or tri-functionalization, including C-H functionalization of the unsubstituted ortho position(s), followed a terminating cross-coupling reaction at the ipso position. This cross-coupling cascade reaction depends on the ortho-directing transient mediator, norbornene.

<span class="mw-page-title-main">Carbon peapod</span> Hybrid nanomaterial

Carbon peapod is a hybrid nanomaterial consisting of spheroidal fullerenes encapsulated within a carbon nanotube. It is named due to their resemblance to the seedpod of the pea plant. Since the properties of carbon peapods differ from those of nanotubes and fullerenes, the carbon peapod can be recognized as a new type of a self-assembled graphitic structure. Possible applications of nano-peapods include nanoscale lasers, single electron transistors, spin-qubit arrays for quantum computing, nanopipettes, and data storage devices thanks to the memory effects and superconductivity of nano-peapods.

Radical fluorination is a type of fluorination reaction, complementary to nucleophilic and electrophilic approaches. It involves the reaction of an independently generated carbon-centered radical with an atomic fluorine source and yields an organofluorine compound.

Cobalt(II)–porphyrin catalysis is a process in which a Co(II) porphyrin complex acts as a catalyst, inducing and accelerating a chemical reaction.

Carbonyl olefin metathesis is a type of metathesis reaction that entails, formally, the redistribution of fragments of an alkene and a carbonyl by the scission and regeneration of carbon-carbon and carbon-oxygen double bonds respectively. It is a powerful method in organic synthesis using simple carbonyls and olefins and converting them into less accessible products with higher structural complexity.

Natalia B. Shustova is a Peter and Bonnie McCausland Professor of Chemistry at the University of South Carolina. She focuses on developing materials for sustainable energy conversion, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and graphitic supramolecular structures.

<span class="mw-page-title-main">Carbon nanohoop</span>

Carbon nanohoops are a class of molecules consisting of aromatic sections curved out of planarity by the inherent cyclic geometry of the molecule. This class of molecules came into existence with the synthesis of cycloparaphenylenes by Ramesh Jasti in the lab of Carolyn Bertozzi and since then has been expanded into cyclonaphthylenes, cyclochrysenylenes, and even cyclohexabenzocoronenylenes. Moreover, several nanohoops containing such antiaromatic units as dibenzo[a,e]pentalene and pyrrolo[3,2-b]pyrrole are reported. Carbon nanohoops often map on to a certain chirality of carbon nanotube. If the diameter is adequate, these molecules can host a fullerene. For example, [10]cycloparaphenylene can host a C60 fullerene.

Ramesh Jasti is a professor of organic chemistry at the University of Oregon. He was the first person to synthesize the elusive cycloparaphenylene in 2008 during post doctoral work in the laboratory of Professor Carolyn Bertozzi. He started his laboratory at Boston University where he was the recipient of the NSF CAREER award. His early lab repeatedly broke the record for the synthesis of the smallest cycloparaphenylene known. In 2014, he moved his laboratory to the University of Oregon where he expanded his focus to apply the molecules he discovered in the areas of organic materials, mechanically interlocked molecules, and biology. He is the Associate Director of the Materials Science Institute at the University of Oregon.

<span class="mw-page-title-main">Allotropes of arsenic</span>

Arsenic in the solid state can be found as gray, black, or yellow allotropes. These various forms feature diverse structural motifs, with yellow arsenic enabling the widest range of reactivity. In particular, reaction of yellow arsenic with main group and transition metal elements results in compounds with wide-ranging structural motifs, with butterfly, sandwich and realgar-type moieties featuring most prominently.

Ellen Sletten is an American chemist who is the John McTague Career Development Chair at University of California, Los Angeles. Her research considers the use of physical organic chemistry for diagnostics and medical therapies.

References

  1. 1 2 3 4 5 Evans, Paul J.; Darzi, Evan R.; Jasti, Ramesh (May 2014). "Efficient room-temperature synthesis of a highly strained carbon nanohoop fragment of buckminsterfullerene". Nature Chemistry. 6 (5): 404–408. Bibcode:2014NatCh...6..404E. doi:10.1038/nchem.1888. ISSN   1755-4349. PMID   24755591.
  2. ↑ "Carbon Nanohoops: Molecular Templates for Precision Nanotube Synthesis". 19 August 2014.
  3. ↑ Parekh, V.C.; Guha, P.C. (1934). "Synthesis of p,p'-diphenylene disulfide". Journal of Indian Chemical Society. 11: 95–100.
  4. 1 2 Friederich, Rolf; Nieger, Martin; Vögtle, Fritz (1993-07-01). "Auf dem Weg zu makrocyclischen para-Phenylenen (On The Way to Macrocyclic Paraphenylenes)". Chemische Berichte. 126 (7): 1723–1732. doi:10.1002/cber.19931260732. ISSN   1099-0682.
  5. ↑ Miyahara, Yuji; Inazu, Takahiko; Yoshino, Tamotsu (1983). "Synthesis of [1.1.1.1]paracylophane". Tetrahedron Letters. 24 (47): 5277–5280. doi:10.1016/s0040-4039(00)88416-6.
  6. ↑ Jagadeesh, Mavinahalli N.; Makur, Anindita; Chandrasekhar, Jayaraman (2000-02-01). "The Interplay of Angle Strain and Aromaticity: Molecular and Electronic Structures of [0n]Paracyclophanes" (PDF). Molecular Modeling Annual. 6 (2): 226–233. doi:10.1007/s0089400060226. ISSN   0949-183X. S2CID   55092879.
  7. ↑ Bodwell, Graham J. (May 2014). "Closing the loop". Nature Chemistry. 6 (5): 383–385. doi:10.1038/nchem.1932. ISSN   1755-4349. PMID   24755587.
  8. ↑ Kayahara, Eiichi; Patel, Vijay Kumar; Yamago, Shigeru (2014-02-12). "Synthesis and Characterization of [5]Cycloparaphenylene". Journal of the American Chemical Society. 136 (6): 2284–2287. doi:10.1021/ja413214q. ISSN   0002-7863. PMID   24460371.
  9. 1 2 3 Wong, Bryan M. (2009-12-31). "Optoelectronic Properties of Carbon Nanorings: Excitonic Effects from Time-Dependent Density Functional Theory". The Journal of Physical Chemistry C. 113 (52): 21921–21927. arXiv: 0912.4707 . doi:10.1021/jp9074674. ISSN   1932-7447. PMC   3317592 . PMID   22481999.
  10. 1 2 3 4 5 6 Iwamoto, Takahiro; Watanabe, Yoshiki; Sadahiro, Tatsuya; Haino, Takeharu; Yamago, Shigeru (2011). "Size‐Selective Encapsulation of C60 by [10]Cycloparaphenylene: Formation of the Shortest Fullerene‐Peapod". Angewandte Chemie. 50 (36): 8342–8344. doi:10.1002/anie.201102302. ISSN   1521-3773. PMID   21770005.
  11. ↑ Yamago, Shigeru; Watanabe, Yoshiki; Iwamoto, Takahiro (2010-01-18). "Synthesis of [8]Cycloparaphenylene from a Square-Shaped Tetranuclear Platinum Complex". Angewandte Chemie International Edition. 49 (4): 757–759. doi:10.1002/anie.200905659. ISSN   1521-3773. PMID   20014269.
  12. 1 2 3 4 5 Iwamoto, Takahiro; Watanabe, Yoshiki; Sakamoto, Youichi; Suzuki, Toshiyasu; Yamago, Shigeru (2011-06-01). "Selective and Random Syntheses of [n]Cycloparaphenylenes (n = 8–13) and Size Dependence of Their Electronic Properties". Journal of the American Chemical Society. 133 (21): 8354–8361. doi:10.1021/ja2020668. ISSN   0002-7863. PMID   21542589.
  13. ↑ Sisto, Thomas J.; Golder, Matthew R.; Hirst, Elizabeth S.; Jasti, Ramesh (2011). "Selective Synthesis of Strained [7]Cycloparaphenylene: An Orange-Emitting Fluorophore". Journal of the American Chemical Society. 133 (40): 15800–15802. doi:10.1021/ja205606p. PMID   21913694.
  14. 1 2 Xia, Jianlong; Jasti, Ramesh (2012). "Synthesis, Characterization, and Crystal Structure of [6]Cycloparaphenylene". Angewandte Chemie International Edition. 51 (10): 2474–2476. doi:10.1002/anie.201108167. ISSN   1521-3773. PMID   22287256.
  15. 1 2 Omachi, Haruka; Matsuura, Sanae; Segawa, Yasutomo; Itami, Kenichiro (2010-12-27). "A Modular and Size-Selective Synthesis of [n]Cycloparaphenylenes: A Step toward the Selective Synthesis of [n,n] Single-Walled Carbon Nanotubes". Angewandte Chemie International Edition. 49 (52): 10202–10205. doi:10.1002/anie.201005734. ISSN   1521-3773. PMID   21105035.
  16. ↑ Leonhardt, Erik J.; Van Raden, Jeff M.; Miller, David; Zakharov, Lev N.; Alemán, Benjamín; Jasti, Ramesh (2018). "A Bottom-Up Approach to Solution-Processed, Atomically Precise Graphitic Cylinders on Graphite". Nano Letters. 18 (12): 7991–7997. Bibcode:2018NanoL..18.7991L. doi:10.1021/acs.nanolett.8b03979. PMID   30480454. S2CID   53754770.
  17. ↑ Darzi, Evan R.; Sisto, Thomas J.; Jasti, Ramesh (2012). "Selective Syntheses of [7]–[12]Cycloparaphenylenes Using Orthogonal Suzuki–Miyaura Cross-Coupling Reactions". The Journal of Organic Chemistry. 77 (15): 6624–6628. doi:10.1021/jo3011667. PMID   22804729.
  18. ↑ Tran-Van, Anne-Florence; Huxol, Elena; Basler, Jonathan M.; Neuburger, Markus; Adjizian, Jean-Joseph; Ewels, Chris P.; Wegner, Hermann A. (2014-03-21). "Synthesis of Substituted [8]Cycloparaphenylenes by [2 + 2 + 2] Cycloaddition". Organic Letters. 16 (6): 1594–1597. doi:10.1021/ol500194s. ISSN   1523-7060.
  19. ↑ Hayase, Norihiko; Miyauchi, Yuta; Aida, Yukimasa; Sugiyama, Haruki; Uekusa, Hidehiro; Shibata, Yu; Tanaka, Ken (2017). "Synthesis of [8]Cycloparaphenylene-octacarboxylates via Rh-Catalyzed Stepwise Cross-Alkyne Cyclotrimerization". Organic Letters. 19 (11): 2993–2996. doi:10.1021/acs.orglett.7b01231. PMID   28513181.
  20. ↑ Kohrs, Daniel; Volkmann, Jannis; Wegner, Hermann A. (2022-07-05). "Cycloparaphenylenes via [2+2+2] cycloaddition". Chemical Communications. 58 (54): 7483–7494. doi:10.1039/D2CC02289C. ISSN   1364-548X.
  21. ↑ Li, Penghao; Zakharov, Lev N.; Jasti, Ramesh (2017-05-02). "A Molecular Propeller with Three Nanohoop Blades: Synthesis, Characterization, and Solid-State Packing". Angewandte Chemie International Edition. 56 (19): 5237–5241. doi: 10.1002/anie.201700935 . ISSN   1521-3773. PMID   28374422.
  22. 1 2 Lewis, Simon E. (2015-04-10). "Cycloparaphenylenes and related nanohoops". Chemical Society Reviews. 44 (8): 2221–2304. doi: 10.1039/c4cs00366g . ISSN   1460-4744. PMID   25735813.
  23. ↑ Golder, Matthew R.; Wong, Bryan M.; Jasti, Ramesh (2013-09-30). "Photophysical and theoretical investigations of the [8]cycloparaphenylene radical cation and its charge-resonance dimer". Chemical Science. 4 (11): 4285. doi:10.1039/C3SC51861B. ISSN   2041-6539.
  24. ↑ Zabula, Alexander V.; Filatov, Alexander S.; Xia, Jianlong; Jasti, Ramesh; Petrukhina, Marina A. (2013-05-03). "Tightening of the Nanobelt upon Multielectron Reduction". Angewandte Chemie International Edition. 52 (19): 5033–5036. doi:10.1002/anie.201301226. ISSN   1521-3773. PMID   23564669.
  25. ↑ Service, Robert F. (2001-04-06). "Nanotube 'Peapods' Show Electrifying Promise". Science. 292 (5514): 45. doi:10.1126/science.292.5514.45. ISSN   0036-8075. PMID   11294210. S2CID   33284325.
  26. ↑ Kwon, Young-Kyun (1999). ""Bucky Shuttle" Memory Device: Synthetic Approach and Molecular Dynamics Simulations". Physical Review Letters. 82 (7): 1470–1473. Bibcode:1999PhRvL..82.1470K. doi:10.1103/physrevlett.82.1470.
  27. ↑ Utko, Pawel; Nygård, Jesper; Monthioux, Marc; Noé, Laure (2006). "Sub-Kelvin transport spectroscopy of fullerene peapod quantum dots". Applied Physics Letters. 89 (23): 233118. Bibcode:2006ApPhL..89w3118U. doi:10.1063/1.2403909. S2CID   120800423.
  28. 1 2 Matsuno, Taisuke; Kamata, Sho; Hitosugi, Shunpei; Isobe, Hiroyuki (2013-07-02). "Bottom-up synthesis and structures of π-lengthened tubular macrocycles". Chemical Science. 4 (8): 3179. doi:10.1039/c3sc50645b. ISSN   2041-6539. S2CID   98409330.
  29. ↑ Xu, Youzhi; Kaur, Ramandeep; Wang, Bingzhe; Minameyer, Martin; Gsänger, Sebastian; Meyer, Bernd; Drewello, Thomas; Guldi, Dirk; von Delius, Max (20 September 2018). "Concave–Convex π–π Template Approach Enables the Synthesis of [10]Cycloparaphenylene–Fullerene [2]Rotaxanes". Journal of the American Chemical Society. 140 (41): 13413–20. doi:10.1021/jacs.8b08244. PMID   30234982. S2CID   207194425.
  30. ↑ Iwamoto, Takahiro; Slanina, Zdenek; Mizorogi, Naomi; Guo, Jingdong; Akasaka, Takeshi; Nagase, Shigeru; Takaya, Hikaru; Yasuda, Nobuhiro; Kato, Tatsuhisa (2014-10-27). "Partial Charge Transfer in the Shortest Possible Metallofullerene Peapod, La@C82⊂[11]Cycloparaphenylene". Chemistry – A European Journal. 20 (44): 14403–14409. doi:10.1002/chem.201403879. ISSN   1521-3765. PMID   25224281.
  31. ↑ Matsui, Katsuma; Segawa, Yasutomo; Namikawa, Tomotaka; Kamada, Kenji; Itami, Kenichiro (2012-11-29). "Synthesis and properties of all-benzene carbon nanocages: a junction unit of branched carbon nanotubes". Chem. Sci. 4 (1): 84–88. doi:10.1039/c2sc21322b. ISSN   2041-6539.
  32. ↑ Wong, Bryan M.; Lee, Jonathan W. (2011-11-03). "Anomalous Optoelectronic Properties of Chiral Carbon Nanorings…and One Ring to Rule Them All". The Journal of Physical Chemistry Letters. 2 (21): 2702–2706. arXiv: 1110.2756 . doi:10.1021/jz2012534. ISSN   1948-7185. PMC   4047598 . PMID   24920994.
  33. ↑ Xia, Jianlong; Golder, Matthew R.; Foster, Michael E.; Wong, Bryan M.; Jasti, Ramesh (2012-12-05). "Synthesis, Characterization, and Computational Studies of Cycloparaphenylene Dimers". Journal of the American Chemical Society. 134 (48): 19709–19715. doi:10.1021/ja307373r. ISSN   0002-7863. PMID   23130993.
  34. ↑ Ishii, Yuuki; Matsuura, Sanae; Segawa, Yasutomo; Itami, Kenichiro (2014-04-18). "Synthesis and Dimerization of Chloro[10]cycloparaphenylene: A Directly Connected Cycloparaphenylene Dimer". Organic Letters. 16 (8): 2174–2176. doi:10.1021/ol500643c. ISSN   1523-7060. PMID   24689496.
  35. ↑ Van Raden, J. M.; Darzi, E. R.; Zakharov, L. N.; Jasti, R. (2016-06-15). "Synthesis and characterization of a highly strained donor–acceptor nanohoop". Organic & Biomolecular Chemistry. 14 (24): 5721–5727. doi:10.1039/c6ob00133e. ISSN   1477-0539. PMID   26881906.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.