Pyridyl-phenylethynylene bis-urea macrocycles: self-assembly and utility as a nanoreactor for the selective photoreaction of isoprene

Salpage, Sahan R.; Xu, Yuewen; Som, Bozumeh; Sindt, Ammon J.; Smith, Mark D.; Shimizu, Linda S.

doi:10.1039/c6ra18681e

Cited by 12 publications

(11 citation statements)

References 38 publications

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“…Furthermore, the columnar assemblies have been shown to adsorb and organise small guest molecules that interact via H‐bonds [18] . The same group reported the preparation of a wider bis‐urea macrocycle, based on a pyridyl‐acetylene scaffold, capable of acting as nanoreactor for the polymerisation of isoprene [19] . Johnson and co‐workers synthesised a library of inherently fluorescent pyridine‐based urea receptors that were successfully employed in the sensing of Cl − and other anions [20–25] .…”

Section: Introductionmentioning

confidence: 99%

Multidentate, V‐Shaped Pyridine Building Blocks as Tectons for Crystal Engineering

Guagnini

Pedrini

Dalcanale

et al. 2021

Chemistry A European J

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The formation of supramolecular structural units through self‐assembly is a powerful method to design new architectures and materials endowed with specific properties. With the aim of adding a group of versatile tectons to the toolkit of crystal engineers, we have devised and synthesised four new V‐shaped building blocks characterised by an aryl acetylene scaffold comprising three substituted pyridine rings connected by two triple bonds. The judicious choice of different substituents on the pyridine rings provides these tectons with distinctive steric, electrostatic and self‐assembly properties, which influence their crystal structures and their ability to form co‐crystals. Co‐crystals of the tectons with tetraiododifluorobenzene were obtained both via traditional and mechanochemical crystallisation strategies, proving their potential use in crystal engineering. The energetic contributions of the supramolecular interactions at play in the crystal lattice have also been evaluated to better understand their nature and strength and to rationalise their role in designing molecular crystals.

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Section: Introductionmentioning

confidence: 99%

Multidentate, V‐Shaped Pyridine Building Blocks as Tectons for Crystal Engineering

Guagnini

Pedrini

Dalcanale

et al. 2021

Chemistry A European J

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“…The gelation properties of bis(pyridyl urea) compounds have extensively been studied due to their ease of synthesis, cost-effectiveness, flexibility towards structural modification, and stimuli-responsive properties [29,[37][38][39]. The presence of pyridyl groups could enhance the stimuli-responsive properties of bis(pyridyl urea) LMWGs in the presence of salts/ions [38].…”

Section: Introductionmentioning

confidence: 99%

Making and Breaking of Gels: Stimuli-Responsive Properties of Bis(Pyridyl-N-oxide Urea) Gelators

2021

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The structural modification of existing supramolecular architecture is an efficient strategy to design and synthesize supramolecular gels with tunable and predictable properties. In this work, we have modified bis(pyridyl urea) compounds with different linkers, namely hexylene and butylene, to their corresponding bis(pyridyl-N-oxide urea). The gelation properties of both the parent and the modified compounds were studied, and the results indicated that modification of the 3-pyridyl moieties to the corresponding 3-pyridyl-N-oxides induced hydrogelation. The stability of the parent and modified compounds were evaluated by sol-gel transition temperature (Tgel) and rheological measurements, and single-crystal X-ray diffraction was used to analyze the solid-state interactions of the gelators. The morphologies of the dried gels were analyzed by scanning electron microscopy (SEM), which revealed that the structural modification did not induce any prominent effect on the gel morphology. The stimuli-responsive behavior of these gels in the presence of salts in DMSO/water was evaluated by rheological experiments, which indicated that the modified compounds displayed enhanced gel strength in most cases. However, the gel network collapsed in the presence of the chloride salts of aluminum(III), zinc(II), copper(II), and cadmium(II). The mechanical strength of the parent gels decreased in the presence of salts, indicating that the structural modification resulted in robust gels in most cases. The modified compounds formed gels below minimum gel concentration in the presence of various salts, indicating salt-induced gelation. These results show the making and breaking ability of the gel network in the presence of external stimuli (salts), which explains the potential of using LMWGs based on N-oxide moieties as stimuli-responsive materials.

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“…Organocatalytic nanoreactors have emerged as an exciting area for novel organic syntheses, offering environmentally friendlier processes [13–18]. The distinct nanospace around the substrates, use of green solvents and catalyst recycling, makes them highly valuable in view of sustainable chemical applications.…”

Section: Introductionmentioning

confidence: 99%

“…Further, the potential of hydrogen-bond donation may be a vital issue for the stabilization of the activated complex by a hydrophobic catalyst [31]. Again, the efficiency of an organocatalyst could be enhanced by downsizing the catalyst at nanorange distribution (i.e., nanoreactor) [13–14]. This is because a nanoreactor allows for precise interactions with the reactants.…”

Section: Introductionmentioning

confidence: 99%

“…This is because a nanoreactor allows for precise interactions with the reactants. In fact, encapsulation can result in the stabilization of a specific transition state by stripping it out from solvent molecules [13–14]. Hence, in aqueous medium, the syntheses of nanoreactors with a covalent organic framework is important, which is indeed a difficult task due to their large aggregation tendency.…”

Section: Introductionmentioning

confidence: 99%

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A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

Sarkar¹,

Sarkar²,

Ghosh³

2019

Beilstein J. Org. Chem.

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Pyridyl-phenylethynylene bis-urea macrocycles: self-assembly and utility as a nanoreactor for the selective photoreaction of isoprene

Abstract: Porous organic crystals with one dimensional channels facilitate stereoselective polymerization to produce trans-1,4-polyisoprene with low PDI under mild UV-irradiation.

Cited by 12 publications

References 38 publications

Multidentate, V‐Shaped Pyridine Building Blocks as Tectons for Crystal Engineering

Multidentate, V‐Shaped Pyridine Building Blocks as Tectons for Crystal Engineering

Making and Breaking of Gels: Stimuli-Responsive Properties of Bis(Pyridyl-N-oxide Urea) Gelators

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

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