Inspired by jigsaw puzzles, Prof. Zhao Yanchuan and his research team from the Shanghai Institute of Organic Chemistry (SIOC) of the Chinese Academy of Sciences have developed a stable, porous molecular crystal (PMC) through a method they call “interdigitation-directed self-assembly.”
As described in their journal article Cell Reports Physical Sciencethe researchers used a propeller-shaped molecule, triptycene, known for its ability to create porosity and its unique concave-convex structure, as a building block to construct the molecular assembly.
PMC—a fascinating, crystalline, porous material—is formed from discrete organic molecules through noncovalent interactions. Its unique properties, such as high solubility, self-healing capabilities, and structural flexibility, have attracted increasing interest.
However, compared to well-established networked porous materials such as metal-organic frameworks and covalent organic frameworks, the relatively weak and less directional noncovalent interactions make PMC less stable, which poses a major obstacle to the production of stable porous materials.
In this study, the team’s findings, validated by single-crystal X-ray diffraction, show that this self-assembly is driven by interdigitation and maintained by weak van der Waals interactions, thus acting like pieces of a molecular jigsaw puzzle.
The resulting PMC has a Brunauer–Emmett–Teller specific surface area of 752 m2/ Mr. The stepwise adsorption and substantial hysteresis of the nitrogen sorption isotherms confirm the flexibility of this synthesized PMC, a fact further confirmed by structural simulations carried out in collaboration with Prof. Zhou Wei from the National Institute of Standards and Technology in the US.
In addition, this synthesized PMC shows excellent thermal and chemical resistance, maintaining its crystallinity and specific surface area even after immersion in highly concentrated NaOH, HCl, or boiling water.
In preliminary application tests, this PMC showed excellent adsorption capacity of rhodamine B in water (707 mg/g) and high CO.2/N2 choice.
This novel strategy of interdigitation-directed assembly offers significant potential for tailoring different building blocks. This could pave the way for the construction of porous architectures using weak van der Waals interactions, thus stimulating further innovation and development in the field.
More information:
Nie Fang et al, Layered porous molecular crystals by interdigitation-directed assembly, Cell Reports Physical Science (2023). DOI: 10.1016/j.xcrp.2023.101508
Awarded by the Chinese Academy of Sciences
Citation: Crafting molecular puzzles: A strategic approach to developing stable porous molecular crystals (2023, July 20) retrieved 20 July 2023 from https://phys.org/news/2023-07-crafting-molecular-puzzles-strategic-approach.html
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