3D Carboxylic Acid COF Synthesis via Imine Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current research on covalent organic frameworks primarily focuses on two-dimensional materials with limited active sites due to the introduction of target functional groups through post-modification, which often results in pore collapse and reduced specific surface area.
Innovation Solution
A three-dimensional carboxylic acid covalent organic framework is synthesized by connecting monomers to compounds via imine bonds, using a pre-modification method that involves mixing the monomers, a compound, and a catalyst in an organic solvent, followed by a sealed and heated reaction to form a framework with abundant active sites and high specific surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If post-modification method is used to introduce target functional groups, then functional groups can be introduced to the framework, but the harsh chemical environment causes pore collapse and drastically reduces specific surface area
Solution Approach 1:
The patent applies preliminary action by incorporating carboxyl groups and formyl groups directly into the monomer structure before framework assembly. The monomer is pre-functionalized with both carboxyl groups (providing active sites) and formyl groups (for imine bond formation), eliminating the need for subsequent harsh post-modification steps that would cause pore collapse. This pre-introduction of functional groups during the gentle condensation process maintains pore structure integrity while achieving the desired functionality.
2Adaptability or versatility
If post-modification method is used to introduce target functional groups, then functional groups can be introduced to the framework, but the process is incomplete and leads to decline in active sites
Solution Approach 1:
The patent ensures complete functional group introduction by pre-incorporating both carboxyl groups and formyl groups into the monomer structure before framework assembly. This preliminary functionalization ensures that all monomer units contribute to forming the complete framework with maximum active sites, eliminating the incompleteness issue of post-modification methods where only partial functionalization occurs.
3Productivity
If two-dimensional covalent organic frameworks are used, then research focus is established, but the number of active sites is limited
Solution Approach 1:
The patent transitions from two-dimensional COF structures to three-dimensional COF structures by using monomers with multiple functional groups that can form extended networks in three dimensions. The monomer contains both carboxyl groups (for catalytic activity) and formyl groups (for crosslinking), enabling the formation of 3D frameworks with significantly increased active site density and surface area compared to 2D analogs.
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 resulting three-dimensional carboxylic acid covalent organic framework exhibits excellent adsorption and catalytic functions, suitable for gas adsorption and metal ion extraction, with uniformly distributed pores and high specific surface area, overcoming the limitations of two-dimensional frameworks.
Implementation Method 1
formed by connecting a monomer to a compound via imine bonds formed by reacting formyl groups in the monomer with amino groups in the compound
Implementation Method 2
mixing the monomer, the compound, a first organic solvent, and a catalyst together, removing oxygen from the mixture, and then conducting a reaction in a sealed and heated state
Data Source
AI summary
The present application relates to a three-dimensional carboxylic acid covalent organic framework, a preparation method thereof, and an application thereof. The three-dimension carboxylic acid covalent organic framework is formed by connecting a monomer to a compound via imine bonds formed by reacting formyl groups in the monomer with amino groups in the compound. The monomer is represented by structural formula I, II, or III, wherein R1 is selected from C, Si, substituted or unsubstituted biphenyl, orwhere * denotes a linking site; R2 to R31 are independently selected from H, C1-C6 linear alkyl, C1-C6 branched alkyl, or C1-C6 alkoxyl. The compound is represented by structural formula IV or V, wherein R34 to R41 are independently selected from H, Cl, Br, F, I, carboxyl, nitro, hydroxyl, C1-C6 linear alkyl, C1-C6 branched alkyl, or C1-C6 alkoxyl, and at least one of R34 to R41 is carboxyl.