Cyclodextrin Hybrid Frameworks via Organic Counteranion Co-Assembly
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Solution Overview
Problem
The development of ultramicroporous metal-organic frameworks (MOFs) with organic anions is challenging due to intermolecular interactions that can disrupt crystallization and result in disordered guests within the pores, and existing MOFs often lose crystallinity during post-synthetic modifications, limiting their structural flexibility and porosity.
Innovation Solution
An organic counteranion co-assembly strategy is employed to introduce organic anions during the crystallization of cationic MOFs, forming hybrid frameworks with cyclodextrin and metal cations, utilizing coordinative, electrostatic, and dispersive forces to create ordered structures with ultramicroporous apertures, allowing for reversible structural transformations and enhanced porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inorganic anions are used as secondary building blocks in MOFs, then ultramicroporous structures can be generated, but the incorporation of organic anions is rare due to intermolecular interactions that disrupt crystallization and result in disordered guests
Solution Approach 1:
The patent employs inorganic anions as intermediary secondary building blocks that facilitate the formation of ultramicroporous structures without the disruptive intermolecular interactions that prevent organic anion incorporation. These inorganic anions act as mediators between the metal nodes and organic ligands, enabling ordered crystallization while maintaining the desired porous architecture.
Solution Approach 2:
The patent utilizes parameter changes in the assembly process, specifically controlling the ratio of inorganic anions to metal nodes and ligands, to achieve optimal crystallization. By adjusting these parameters, the system transitions from disordered to ordered structures, enabling the formation of ultramicroporous MOFs with well-defined frameworks.
2Adaptability or versatility
If post-synthetic modifications are performed on MOFs, then structural flexibility can be enhanced, but crystallinity is often lost during these modifications
Solution Approach 1:
The patent performs preliminary actions during the synthesis process itself, incorporating flexible components and pre-establishing reversible bonding mechanisms. This preliminary preparation allows subsequent post-synthetic modifications to be performed while maintaining crystallinity, as the structural framework is already optimized to accommodate further modifications without losing order.
Solution Approach 2:
The patent introduces dynamic and reversible bonding mechanisms into the MOF structure during synthesis, enabling the framework to adapt to post-synthetic modifications while maintaining crystallinity. These dynamic bonds allow the structure to flex and reconfigure during modifications without collapsing into amorphous states.
3Adaptability or versatility
If reversible structural transformations are achieved through guest molecule deformation, then structural flexibility is improved, but such transformations are only observed in MOFs constructed from paddle-wheel linkers with limited connectivity
Solution Approach 1:
The patent develops a universal approach to achieving reversible structural transformations that applies to MOFs constructed from various linker types, not just paddle-wheel linkers. By incorporating flexible components and reversible bonding mechanisms that work across different linker architectures, the system achieves multi-functionality in structural transformation regardless of the specific linker connectivity.
Solution Approach 2:
The patent utilizes parameter changes in the synthesis conditions and composition ratios to enable reversible structural transformations in MOFs with different linker connectivities. By adjusting these parameters, the system can achieve the desired flexibility and reversibility without being constrained to specific linker types, thereby reducing the complexity requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The strategy results in hybrid frameworks with improved stability and porosity, enabling selective gas adsorption and irreversible single-crystal to single-crystal transformations, expanding the design possibilities for ultramicroporous materials and skin care applications.
Implementation Method 1
assembled from chiral γ-cyclodextrin (γ-CD) building blocks and alkali metal ions
Implementation Method 2
the OH anions reside inside the porous channels of the frameworks, but in close proximity to the metal centers—to which they experience electrostatic attraction
Implementation Method 3
Reversible structural transformations in MOFs can also be achieved by deforming the coordination geometry of the metal ions in response to the presence of guest molecules
Implementation Method 4
a solid-state superstructure identical to that of CD-MOF-1, with a rearrangement of coordinated metal ions
Data Source
AI summary
An organic counteranion co-assembly strategy is employed to prepare a hybrid molecular framework. The hybrid molecular framework comprises an ordered arrangement of cyclodextrin (CD), metal cations, and organic anions.