Hydrogen‐Bonded Shape‐Persistent Aryl Hydrazide Polymers: Side‐Chain‐Tuned Formation of Vesicles and Organogels

Zhou, Chunjiang; Cai, Wei; Wang, Gui-Tao; Zhao, Xin; Li, Zhan‐Ting

doi:10.1002/macp.201000259

Cited by 12 publications

(6 citation statements)

References 72 publications

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“…Herein we report the synthesis of completely flat, rigid-rod-like bis-TEGylated poly(p-benzamide)s, which molecularly dissolve in organic solvents. To the best of our knowledge this is the first report on alkyloxy-bis-substituted poly(p-benzamide)s so far, joining the class of already described bis-substituted aromatic hydrazide polymers 10 and poly(1,4-phenylene terephthalamide)s. 11 The most commonly described polymerization techniques for aromatic polyamides rely on a step-growth mechanism, which ideally leads to a polydispersity index of 2. In the original process the polycondensation is mediated by the reaction of amines with acid chlorides derived from the corresponding carboxylic acids in situ (depending on AB or AA/BB systems from the amino acid or diacid, respectively).…”

Section: ■ Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 86%

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Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

et al. 2013

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The synthesis of perfectly planar, bis-substituted aromatic polyamides is reported herein. With highly flexible triethylene glycol chains attached and conformational restriction through intramolecular, bifurcated hydrogen bonds these are among the most shape-persistent yet organo-soluble polymers to date. Starting from 4-nitrosalicylic acid, our group developed a route to phenyl-2,5-bis-TEGylated aminobenzoate, which could be polymerized by addition of lithium bis(trimethylsilyl)amide (LiHMDS). Since this technique has not been applied to step-growth polycondensations of polyaramides so far, the influence of two different solvents and an N-protective group was investigated. Therefore, substituted phenyl aminobenzoate derivatives carrying a free amine or an N-protective group have been polymerized. Additionally, the tendency for self-assembly of the readily soluble bis-TEGylated poly(p-benzamide) was observed by transmission electron microscopy (TEM) in the dried state. Dynamic light scattering (DLS) measurements of chloroform solutions did not indicate the formation of aggregates. Thus, intermolecular interactions, which other aromatic polyamides typically exhibit, are prevented. The access to bis-substituted, entirely rigid poly(p-benzamide)s via this new polycondensation method paves the way for exciting new structures in materials science and supramolecular chemistry.

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Section: ■ Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 86%

Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

et al. 2013

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“…Hydrogen bonding-induced aromatic amide and hydrazide foldamers adopt crescent or helical conformations and thus resemble large discotic molecules to stack into vesicles or organogels, which are solvent-responsive. − Hydrazide foldamers could generate responsive host–guest organogels that exhibited unique time-dependent chirality transfer and amplification that are not observed for single-component organogels . Compounds 13a – f , which bear two arene units of varying size at the ends, strongly gelated organic solvents of varying polarity.…”

Section: Binding-responsive Chirality Transfer and Amplification In O...mentioning

confidence: 99%

Aromatic Amide and Hydrazide Foldamer-Based Responsive Host–Guest Systems

2014

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CONSPECTUS: In host-guest chemistry, a larger host molecule selectively and noncovalently binds to a smaller guest molecule or ion. Early studies of host-guest chemistry focused on the recognition of spherical metal or ammonium ions by macrocyclic hosts, such as cyclic crown ethers. In these systems, preorganization enables their binding sites to cooperatively contact and attract a guest. Although some open-chain crown ether analogues possess similar, but generally lower, binding affinities, the design of acyclic molecular recognition hosts has remained challenging. One of the most successful examples was rigid molecular tweezers, acyclic covalently bonded preorganized host molecules with open cavities that bind tightly as they stiffen. Depending on the length of the atomic backbones, hydrogen bonding-driven aromatic amide foldamers can form open or closed cavities. Through rational design of the backbones and the introduction of added functional groups, researchers can regulate the shape and size of the cavity. The directionality of hydrogen bonding and the inherent rigidity of aromatic amide units allow researchers to predict both the shape and size of the cavity of an aromatic amide foldamer. Therefore, researchers can then design guest molecules with structure that matches the cavity shape, size, and binding sites of the foldamer host. In addition, because hydrogen bonds are dynamic, researchers can design structures that can adapt to outside stimuli to produce responsive supramolecular architectures. In this Account, we discuss how aromatic amide and hydrazide foldamers induced by hydrogen bonding can produce responsive host-guest systems, based on research by our group and others. First we highlight the helical chirality induced as binding occurs in solution, which includes the induction of helicity by chiral guests in oligomeric and polymeric foldamers, the formation of diastereomeric complexes between chiral foldamer hosts and guests, and the induction of helical chirality by chiral guests into inherently flexible backbones. In addition, molecular or ion-pair guests can produce supramolecular helical chirality in the organogel state. Such structures exhibit remarkable time-dependence and a "Sergeants and Soldiers" effect that are not observed for other two-component organogels that have been reported. We further illustrate that the reversible folding behavior of an aromatic amide foldamer segment can modulate the switching behavior of donor-acceptor interaction-based [2]rotaxanes. Finally we show that a folded oligomer can induce folding in one or two attached intrinsically flexible oligomers, an example of a solvent-responsive intramolecular host-guest system.

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“…[38] These polymers adopted extended conformations that were also stabilized by intramolecular N-H···O=C hydrogen bonding. These rigid polymers also gelated organic solvents as a result of strong stacking of the backbones.…”

Section: Aromatic Urea and Hydrazide Backbonesmentioning

confidence: 98%

“…Hydrazide polymers were also prepared from 4,6‐dialkoxyisophthalohydrazides and 4,6‐dialkoxyisophthalic acids that bear different alkoxyl side chains by using the Yamazaki polymerization conditions . These polymers adopted extended conformations that were also stabilized by intramolecular N–H···O=C hydrogen bonding.…”

Section: Construction Of Hydrogen‐bonding‐driven Aromatic Foldamersmentioning

confidence: 99%

Hydrogen‐Bonding‐Driven Aromatic Foldamers: Their Structural and Functional Evolution

Zhang

Wang

2014

The Chemical Record

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This Personal Account summarizes the development of the design of hydrogen-bonding-driven aromatic foldamers and their applications in supramolecular chemistry. This account begins with a short, non-exhaustive description of the background in the study of hydrogen-bonded aromatic foldamers. The construction of foldamers from discrete aromatic residues, including amide, urea, hydrazide and 1,2,3-triazole units, is then described. In the following parts, the applications of such compact aromatic oligomers in supramolecular chemistry, including the development of acyclic receptors, the construction of hybrid helical sequences through intramolecular stacking, the promotion of the formation of covalently and noncovalently bonded macrocycles, the tuning of the mechanical properties of copolymers, and the regulation of the shuttling behavior of [2]rotaxanes and the controlled release of dye from reverse vesicles formed from them, are described. In the final part, the binding-induced folding of conformationally flexible aromatic amide oligomers and their self-binding are described.

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Hydrogen‐Bonded Shape‐Persistent Aryl Hydrazide Polymers: Side‐Chain‐Tuned Formation of Vesicles and Organogels

Cited by 12 publications

References 72 publications

Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

Aromatic Amide and Hydrazide Foldamer-Based Responsive Host–Guest Systems

Hydrogen‐Bonding‐Driven Aromatic Foldamers: Their Structural and Functional Evolution

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