Pi-Stacking SDAs for Large-Cage Molecular Sieve Synthesis
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Solution Overview
Problem
Existing molecular sieves with large cages, cavities, or pores require expensive and difficult-to-prepare structure directing agents (SDAs), limiting their commercial implementation.
Innovation Solution
The use of structure directing agents capable of intramolecular pi-stacking, such as Ar+-L-Ar, Ar+-L-Ar-L-Ar+, and Ar+-L-Ar-L-NR3+, which allow for the synthesis of molecular sieves with large cages and pores through a straightforward, low-cost process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If bulky quaternary ammonium or phosphonium molecules are used as structure directing agents to achieve large cage, large cavities, or large pores, then the molecular sieve properties are improved, but the synthesis complexity and cost increase
Solution Approach 1:
The patent divides the bulky SDA molecule into two separate aromatic rings connected by a flexible alkyl chain. This segmentation allows each ring to independently interact with framework-forming species while maintaining the overall bulkiness needed for large cage formation, simplifying the synthesis process
Solution Approach 2:
The patent introduces a flexible alkyl chain connector between two aromatic rings, adding a dimensional element that enables the molecule to achieve bulkiness in three-dimensional space without requiring complex polycyclic structures. This dimensional approach simplifies synthesis while maintaining the volume necessary for large cage formation
2Volume of moving object
If existing bulky SDAs are used to synthesize molecular sieves with large pores, then the pore size is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent employs readily available aromatic rings and simple alkyl chain connectors as building blocks for the SDA molecule. These components are inexpensive and easy to synthesize, making the overall SDA preparation process simple and cost-effective while still achieving the desired large pore volume
Solution Approach 2:
The patent changes the molecular parameters of the SDA by using aromatic rings with varying substituent patterns and different alkyl chain lengths. This allows optimization of the balance between molecule bulkiness (for large pores) and synthesis ease, achieving both large pore volume and manufacturing simplicity
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
This approach enables the production of molecular sieves with large cages and pores using inexpensive and safer synthesis methods, overcoming the limitations of previous SDAs and expanding the range of achievable frameworks.
Implementation Method 1
structure directing agents that are capable of assuming a bulky conformation as a result of intramolecular pi-stacking
Data Source
AI summary
A method of making a molecular sieve may include: reacting a source selected from the group consisting of: a source of a tetrahedral element in the presence of a structure directing agent (SDA) selected from the group consisting of: Ar+-L-Ar, Ar+-L-Ar-L-Ar+, Ar+-L-Ar-L-NR3+, and ArAr+-L-Ar+Ar, where Ar+ is to a N-containing cationic aromatic ring, Ar is to a non-charged aromatic ring, L is a methylene chain of 3-6 carbon atoms, NR3+ is to a quaternary ammonium, and ArAr+ and Ar+Ar are a fused aromatic ring structure comprising both a N-containing cationic portion and a non-charged portion, to produce the molecular sieve.