A Bistable Poly[2]catenane Forms Nanosuperstructures

Olson, Mark A.; Braunschweig, Adam B.; Fang, Lei; Ikeda, Taichi; Klajn, Rafał; Trabolsi, Ali; Wesson, Paul J.; Benítez, Diego; Mirkin, Chad A.; Grzybowski, Bartosz A.; Stoddart, J. Fraser

doi:10.1002/anie.200804558

Cited by 75 publications

(52 citation statements)

References 87 publications

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“…radius of gyration (R g ) of the polymer aggregates experiences a contraction upon catenation, despite having a larger molar mass [6·nPF 6 R g = 100.1(AE0.4) nm; 8·nPF 6 R g = 74.2-(AE0.1) nm] of the CBPQT 4+ side-chains, suggesting that intra-and interchain [p···p] stacking interactions are occurring in solution. A SEC-MALS conformation plot of log r g as a function of log M w for 8·nPF 6 yields ( Figure 2) a slope of 0.97(AE0.01), a value which is consistent [25] with rodlike polymer aggregates being present in solution, whereas 6·nPF 6 yields a slope of 0.32(AE0.01), suggesting the existence [11,25] of spherically shaped polymer aggregates. The contraction of the R g is paralleled by a contraction of hydrodynamic radius (R h ) and an increase in the diffusion coefficient (D o ), as determined ( Figure 3 [2]catenanes are distributed along the polymer side-chains since the two rings do not dissociate upon dilution as would be the case for a pseudorotaxane.…”

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confidence: 85%

“…In an effort to improve upon the processibility of switchable bistable catenanes, they have been incorporated into polymeric scaffolds [10] in the form of side-chain poly [2]catenanes. [11,12] The weakness of this approach to the localizing of bistable catenanes on the sides of polymer chains is that their implantation relies upon kinetic control with its inherent absence of proof-reading and error-checking. [13] An attractive alternative, which is potentially much more modular and open to (complex) structural variation, is one in which multiple catenations are carried out under templation [14] on a reactive polymer itself under thermodynamic control.…”

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confidence: 99%

“…In theory at least, the same approach (Scheme 1) should be applicable to the formation of polycatenanes [19] of the main-chain, [20] pendant, [21] bridged, [22] and side-chain [11,12] Scheme 1. The synthesis of the degenerate [2]catenane 3·4PF 6 and the degenerate bis [2]catenane 5·8PF 6 .…”

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confidence: 99%

“…R g /R h (1) is a parameter [31] that describes qualitatively how the polymer chains are interacting in real space. Prior to catenation, this parameter 1 is calculated to be 0.74 approaching 0.77, a range which is consistent [32] with spherical aggregates of uniform density-i.e., the polyCBPQT 4+ 6·nPF 6 behaves [11] almost like a large micelle in which the tetracationic cyclophanes most likely protrude (Figure 4 a) outwards on account of Coulombic repulsions, leaving the relatively hydrophobic backbone to reside in the interior. Following catenation to give 8·nPF 6 , 1 becomes equal to 1.4 approaching 1.5, a range which is consistent [32] with random coils and linear chains, which are semi-flexible and much smaller in size.…”

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Polycatenation under Thermodynamic Control

et al. 2010

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Molecular switches based on mechanically interlocked molecules [1,2] have been shown to operate just as effectively in condensed phases [3] as in solution. Thus, we have witnessed these bistable donor-acceptor catenanes and rotaxanes [2] serving as the switchable components [4] in molecular electronic devices, [4] nanoelectromechanical systems, [5] plasmonic devices, [6] and mechanized nanoparticles. [7,8] To date, fabrication has relied on the formation of self-assembled monolayers [9] of one sort or another. In an effort to improve upon the processibility of switchable bistable catenanes, they have been incorporated into polymeric scaffolds [10] in the form of side-chain poly[2]catenanes. [11,12] The weakness of this approach to the localizing of bistable catenanes on the sides of polymer chains is that their implantation relies upon kinetic control with its inherent absence of proof-reading and error-checking. [13] An attractive alternative, which is potentially much more modular and open to (complex) structural variation, is one in which multiple catenations are carried out under templation [14] on a reactive polymer itself under thermodynamic control. [15] Here, we describe the synthesis of a side-chain poly[2]catenane using a synthetic protocoltested first of all on monomeric and dimeric analogues as models-in which nucleophilic substitutions, rendered dynamic under catalytic control, [16] are responsible for multiple catenations occurring all along the polymer chain, entirely driven in a synergistic fashion to completion by the intra-and intermolecular side-chain [p···p] stacking interactions of contiguous and interdigitated catenanes.Donor-acceptor [2]catenanes comprised of the tetracationic cyclophane, cyclobis(paraquat-p-phenylene) [17] (CBPQT 4+ ), as the p-electron accepting ring interlocked mechanically with a p-electron-donating crown ether are typically formed by a clipping procedure [18] to make the mechanical bond with the simultaneous formation of the [2]catenane. This route, although much employed, suffers from the weakness of being irreversible, i.e., should reactive sites come together by mistake, the product is committed effectively, to becoming contaminated with constitutional defects. Circumventing kinetic control requires a process in which proof-reading and error-checking ultimately lead to the designed transformations-and avoid introducing constitutional anomalies in the case of chemically modified polymers-under equilibrium control. This process relies upon dynamic covalent chemistry, [13] wherein covalent bonds are formed and broken reversibly until the thermodynamically most stable outcome is obtained.Recently, we have reported [16] the synthesis of donoracceptor [2]-and [3]catenanes using an iodide-catalyzed thermodynamically reversible nucleophilic substitution to open and close one of the rings, namely the tetracationic cyclophane. In theory at least, the same approach (Scheme 1) should be applicable to the formation of polycatenanes [19] of the main-chain, [20] pendant, [21] ...

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Polycatenation under Thermodynamic Control

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“…More recently, Li et al [251] employed hb poly(ether ether ketone) (hb-PEEK) at 1-5 wt% as a rheology modifier towards linear poly(ether ether ketone) (LPEEK) for improving the melt processability. Interestingly, the crystallization temperatures (T c ) of LPEEK/hb-PEEK blends were higher than that of pure LPEEK (T c ¼ 283 C), and the T c of LPEEK/hb-PEEK blends gradually increased from 288 to 294 C with increasing hb-PEEK content in the blends.…”

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Porous Carbons – Hyperbranched Polymers – Polymer Solvation

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2015

Advances in Polymer Science

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Self‐Assembly of Macromolecular Threaded Systems

Tachibana¹,

Nakazono²,

Takata³

2012

Supramolecular Chemistry

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Recently, a polyrotaxane network material has been practically used, for the first time, as a coating material for mobile phones in Japan. This is an epoch‐making event in the science and technology of interlocked molecules, macromolecules, and related materials. Polymers possessing interlocked structures as key skeletons are, therefore, the most promising and intriguing materials, especially in the application fields. Polyrotaxanes and polycatenanes are characterized by the specific features based on the unique mobility of the noncovalently bonded components in their special polymer structures, such as molecular rotaxanes and catenanes, leading to the construction of a variety of sophisticated systems. In particular, when wheel components and a chain polymer form a macromolecular threaded system (i.e., polyrotaxane), combining the wheel components of different molecules results in producing the cross‐linked points that can move on the chain. Such a type of “topological cross‐linking” of polyrotaxane network can provide special mobility to the polymer chains, as de Gennes suggested in his paper entitled “Sliding Gels.” The topological cross‐linking is clearly distinguished from both physical and chemical cross‐linkings with little mobility of polymer chains. Thus, the research area of interlocked polymer systems has collected much attention from the fields of both supramolecular and polymer sciences, and the active investigation on them must be continued in the future, judging from the enthusiastic activity in materials science fields today. In a whole research trend of interlocked polymers, being parallel to the development of the synthetic methods of interlocked polymers, various applications of them have been studied simultaneously. This chapter overviews the development of synthetic methods and applications of interlocked polymers such as polyrotaxane, polycatenane, and their networks that have been reported in these two decades. The works introduced are mainly the original ones. Owing to the limited space for this chapter, the authors cannot refer to the details of each work, although most works are very interesting. The detailed explanation of the important works published up to 2009 can be found in many reviews, including two comprehensive articles of Gibson and Stoddart on polyrotaxanes and polycatenanes in addition to a lot of review articles and books on the rotaxanes and catenanes that devote a small space for the polymers.

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A Bistable Poly[2]catenane Forms Nanosuperstructures

Cited by 75 publications

References 87 publications

Polycatenation under Thermodynamic Control

Polycatenation under Thermodynamic Control

Porous Carbons – Hyperbranched Polymers – Polymer Solvation

Self‐Assembly of Macromolecular Threaded Systems

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