Host–Guest Chemistry Within Cellulose Nanocrystal Gel Receptors

Zhang, Dongjie; Soto, Miguel A.; Lewis, Lev; Hamad, Wadood Y.; MacLachlan, Mark J.

doi:10.1002/ange.201913030

Cited by 3 publications

(2 citation statements)

References 50 publications

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“…4 To fit an assortment of applications, gels with versatile mechanical properties are highly desirable. Tuning of the mechanical properties of CNC gels has been realized by adding polymers, 26 solvents, 27 or salts 28,29 or via chemical functionalization; 30 however, these additives might hinder the biocompatibility of the resulting materials. Thus, alternative strategies to synthesize pristine CNC gels with tunable mechanical properties are of great interest.…”

Section: ■ Introductionmentioning

confidence: 99%

Cellulose Nanocrystal Gels with Tunable Mechanical Properties from Hybrid Thermal Strategies

Soto

Drummond

et al. 2023

ACS Appl. Mater. Interfaces

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Gels are useful materials for drug delivery, wound dressings, tissue engineering, and 3D printing. These various applications require gels with different mechanical properties that can be easily tuned, also preferably excluding the use of chemical additives, which can be toxic or harmful to the body or environment. Here, we report a novel strategy to synthesize cellulose nanocrystal (CNC) gels with tunable mechanical properties. Sequential freeze–thaw cycling and hydrothermal treatments were applied to CNC suspensions in different orders to give a series of pristine CNC hydrogels. Freeze-drying of the hydrogels also afforded a series of lightweight CNC aerogels. The mechanical properties of the hydrogels and aerogels were studied by rheological measurements and compression strength tests, respectively. Specifically, the complex modulus of CNC hydrogels ranged from 160 to 32,000 Pa among eight different hydrogels, while Young’s modulus of CNC aerogels was tuned from 0.114 to 3.98 MPa across five different aerogels. The microstructures of aerogels were also investigated by scanning electron microscopy and X-ray microtomography, which revealed remarkable differences between the materials. Solvent sorption–desorption tests showed that the reinforced networks have excellent stability over the basic CNC aerogels in ethanol, demonstrating a material enhancement from the preparation strategies we developed. Thermal conductivity and thermal stability for these materials were also investigated, and it was found that the lowest thermal conductivity was 0.030 W/m K, and all of the aerogels are generally stable below 280 °C. These characteristics also expand the potential applications of this family of CNC gels to lightweight supporting materials and thermal insulators.

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Section: ■ Introductionmentioning

confidence: 99%

Cellulose Nanocrystal Gels with Tunable Mechanical Properties from Hybrid Thermal Strategies

Soto

Drummond

et al. 2023

ACS Appl. Mater. Interfaces

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“…These additional stabilizing effects are crucial when it comes to raising the efficiency of template‐assisted syntheses of donor–acceptor catenanes. A large collection of π‐electron‐rich guests derived from HQ, [56] DN, [57] 1,5‐dithianaphthalene (DTN), [58] DAN, [48, 59] TTF, [60] bispyrrolotetrathiafulvalene [61] (BPTTF), biphenol, [62] benzidine, [63] azobenzene, [64] pentiptycene‐based crown ethers, [65] triptycene‐based cucurbiturils, [66] amino acids, [67] neurotransmitters, [68] and phenyl glucopyranosides [69] have all been investigated for their ability to complex with the little blue box [70]…”

Section: Cbpqt4+ As An π‐Electron‐deficient Host Moleculementioning

confidence: 99%

The Story of the Little Blue Box: A Tribute to Siegfried Hünig

Chen

Stoddart

2022

Angewandte Chemie

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The tetracationic cyclophane, cyclobis(paraquat-p-phenylene), also known as the little blue box, constitutes a modular receptor that has facilitated the discovery of many host-guest complexes and mechanically interlocked molecules during the past 35 years. Its versatility in binding small π-donors in its tetracationic state, as well as forming trisradical tricationic complexes with viologen radical cations in its doubly reduced bisradical dicationic state, renders it valuable for the construction of various stimuli-responsive materials. Since the first reports in 1988, the little blue box has been featured in over 500 publications in the literature. All this research activity would not have been possible without the seminal contributions carried out by Siegfried Hünig, who not only pioneered the syntheses of viologencontaining cyclophanes, but also revealed their rich redox chemistry in addition to their ability to undergo intramolecular π-dimerization. This Review describes how his pioneering research led to the design and synthesis of the little blue box, and how this redox-active host evolved into the key component of molecular shuttles, switches, and machines.

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The Story of the Little Blue Box: A Tribute to Siegfried Hünig

Chen

Stoddart

2022

Angew Chem Int Ed

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The tetracationic cyclophane, cyclobis(paraquat‐p‐phenylene), also known as the little blue box, constitutes a modular receptor that has facilitated the discovery of many host–guest complexes and mechanically interlocked molecules during the past 35 years. Its versatility in binding small π‐donors in its tetracationic state, as well as forming trisradical tricationic complexes with viologen radical cations in its doubly reduced bisradical dicationic state, renders it valuable for the construction of various stimuli‐responsive materials. Since the first reports in 1988, the little blue box has been featured in over 500 publications in the literature. All this research activity would not have been possible without the seminal contributions carried out by Siegfried Hünig, who not only pioneered the syntheses of viologen‐containing cyclophanes, but also revealed their rich redox chemistry in addition to their ability to undergo intramolecular π‐dimerization. This Review describes how his pioneering research led to the design and synthesis of the little blue box, and how this redox‐active host evolved into the key component of molecular shuttles, switches, and machines.

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Host–Guest Chemistry Within Cellulose Nanocrystal Gel Receptors

Cited by 3 publications

References 50 publications

Cellulose Nanocrystal Gels with Tunable Mechanical Properties from Hybrid Thermal Strategies

Cellulose Nanocrystal Gels with Tunable Mechanical Properties from Hybrid Thermal Strategies

The Story of the Little Blue Box: A Tribute to Siegfried Hünig

The Story of the Little Blue Box: A Tribute to Siegfried Hünig

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