Interpenetration Control in Three-Dimensional Covalent Organic Frameworks: Architectural Modulation and cis-Imine
Ziqiu Ye1, Honglin Du2, Wenshu Tan1
1College of Chemistry and Molecular Sciences, Wuhan University, Wuhan430072, China.
Journal of the American Chemical Society
|July 27, 2026
Summary
Interpenetration in 3D covalent organic frameworks (COFs) is a tunable design parameter that controls architecture and dynamics. Minimally interpenetrated COFs exhibit unique cis-imine configurations, leading to significant framework flexibility and volume expansion.
Area of Science:
- Materials Science
- Supramolecular Chemistry
- Crystallography
Background:
- Interpenetration is common in 3D covalent organic frameworks (COFs) but often considered a passive assembly outcome.
- Tuning interpenetration offers a novel strategy for controlling COF properties.
Purpose of the Study:
- To demonstrate that interpenetration in 3D COFs can be deliberately tuned.
- To investigate how varying interpenetration affects COF architecture, dynamics, and functionality.
Main Methods:
- Synthesis of an isoreticular series of 3D COFs with varying substituents (-OMe, -OEt, -OiPr) maintaining the pts topology.
- Characterization of crystal structures to determine interpenetration levels (5-fold, 4-fold, 2-fold).
- Analysis of pore architecture, surface area, and guest-induced dynamic behavior.
Main Results:
- Reduced interpenetration led to enlarged pore apertures and increased accessible surface areas.
- The minimally interpenetrated COF featured a rare cis-imine linkage configuration.
- These cis-imine linkages underwent reversible guest-induced cis-to-trans isomerization, causing significant crystal expansion (~220%).
Conclusions:
- Interpenetration is a crucial, tunable parameter for designing 3D COFs.
- Controlling interpenetration allows for precise modulation of framework architecture and dynamic responses.
- This study highlights a new avenue for developing functional COFs with tailored properties.
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