Insight into the crystallization of amorphous imine-linked polymer networks to 2D covalent organic frameworks

Smith, Brian J.; Overholts, Anna C.; Hwang, Nicky; Dichtel, William R.

doi:10.1039/c5cc10221a

Cited by 408 publications

(441 citation statements)

References 22 publications

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“…In 1993 she obtained her PhD degree in Organic Chemistry from the same university. 18 Thus, energetic synthetic reaction conditions and/or long reaction times seem to favour the thermodynamic control of COF formation and allow the error correction and crystallization. Her research interest is focused in different areas as organic photochemistry, organometallics and more recently, in materials chemistry.…”

Section: María J Mancheñomentioning

confidence: 99%

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Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

2016

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Covalent organic-frameworks (COFs) are an emerging class of porous and ordered materials formed by condensation reactions of organic molecules. Recently, the Schiff-base chemistry or dynamic imine-chemistry has been widely explored for the synthesis of COFs. The main reason for this new tendency is based on their high chemical stability, porosity and crystallinity in comparison to previously reported COFs. This critical review article summarizes the current state-of-the-art on the design principles and synthetic strategies toward COFs based on Schiff-base chemistry, collects and rationalizes their physicochemical properties, as well as aims to provide perspectives of potential applications which are at the forefront of research in materials science.

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Section: María J Mancheñomentioning

confidence: 99%

“…18 2.1.2 Hydrazone linkages. Thus, the network crystallizes to the 2D-COF under conditions that allow imine exchange, and does not require the presence of additional imine or aldehyde monomers.…”

Section: Solvothermal Reaction Conditionsmentioning

confidence: 99%

Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

2016

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“…[8,9] The rigidity and planarity of macrocycles lead to assemblies such as 2D networks, [10] liquid crystals, [11] or nanotubes with well-defined channels. [22] Here we evaluate the formation of hexagonal imine-linked macrocyclesa nd demonstrate that their assembly into layered structures slowsi mine exchange. [13][14][15] Macrocycle assemblies confer many of the same de-sirable features as COFs and offer superior processability and greater potential for stimuli-responsive functions.…”

mentioning

confidence: 98%

“…These soluble species are in equilibrium with hexagonal macrocycles, which aggregate into layered assemblies whose imines are far less dynamic, drivingm acrocycle formation in high yield. [22] As such, these macrocyclesa re informative models ystemsf or understandingimine-linked COF formation, in addition to being intriguing assembliest hemselves.The solubility of the macrocycles in the THF mobilep hase of the GPC experiments,j uxtaposed with their low solubility in 1,4-dioxane, led us to study the polymer/macrocycle equilibration in mixtureso ft he two solvents. The macrocycles may be solution cast into ordered, crystalline films with similar structuralp recision as COFs.…”

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confidence: 99%

Equilibration of Imine‐Linked Polymers to Hexagonal Macrocycles Driven by Self‐Assembly

Chavez

Evans

Flanders

et al. 2018

Chemistry A European J

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Macrocycles based on directional bonding and dynamic covalent bond exchange can be designed with specific pore shapes, sizes, and functionality. These systems retain many of the design criteria and desirable aspects of two-dimensional (2D) covalent organic frameworks (COFs) but are more easily processed. Here we access discrete hexagonal imine-linked macrocycles by condensing a truncated analogue of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthaldehyde (PDA). The monomers first condense into polymers but eventually convert into hexagonal macrocycles in high yield. The high selectivity for hexagonal macrocycles is enforced by their aggregation and crystallization into layered structures with more sluggish imine exchange. Their formation and exchange processes provide new insight into how imine-linked 2D COF simultaneously polymerize and crystallize. Solutions of these assembled macrocycles were cast into oriented, crystalline films, expanding the potential routes to 2D materials.

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“…42 Herein, the process included heating the powder material at 120°C in water, then filtering and drying under vacuum. The posttreatment duration was optimized based on the steric properties of the substituents, that is,~1 h for TpPa-NO 2 and a few minutes for TpPa-H.…”

Section: Resultsmentioning

confidence: 99%

Intensified synthesis and post-synthetic modification of covalent organic frameworks using a continuous flow of microdroplets technique

et al. 2018

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Covalent organic frameworks (COFs) are two-dimensional/three-dimensional crystalline polymeric materials with diverse molecular backbones and topologies and are strong candidates for numerous applications. However, the ready availability of these materials is a challenge. The key issues are slow production rates, harsher and longer reaction conditions, and a need for post-synthetic modification to obtain desired molecular functionalities. Only a few studies, including those using microfluidic techniques, have focused on refining these factors, but these reports lack synthetic continuity and scalability. Herein, we present a fast, intensified and continuous synthesis and post-synthetic modification of β-ketoenamine-linked COFs by confining organic building units into moving microdroplets in a transparent capillary. This study introduces a one-step, facile approach to serially modify NO 2 -to NH 2 -substituted COFs in a fraction of the time, effort and cost of traditional methods. These results may stimulate the development of novel COFs with unique chemistries and functions for various applications.

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Insight into the crystallization of amorphous imine-linked polymer networks to 2D covalent organic frameworks

Cited by 408 publications

References 22 publications

Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

Equilibration of Imine‐Linked Polymers to Hexagonal Macrocycles Driven by Self‐Assembly

Intensified synthesis and post-synthetic modification of covalent organic frameworks using a continuous flow of microdroplets technique

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