Steric Repulsion Driven Formation of a 3D Covalent Organic Framework Polymorph with Exceptionally High Surface Area
10 affiliations
- 1Institute of Chemistry, Faculty of Natural Sciences II, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, Halle/Saale, Germany
- 2Department of Pure and Applied Chemistry
- 3University of Strathclyde
- 4Department of Chemical and Process Engineering
- 5Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
- 6Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany
- 7Biozentrum, Martin Luther University Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany
- 8Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle (Saale, Germany
- 9Institute of Chemical Biology
- 10National Hellenic Research Foundation
Abstract
Dimensional polymorphism, in which the same molecular building blocks form frameworks of different dimensionality, offers a direct route to distinct pore architectures in covalent organic frameworks (COFs). True 2D/3D polymorphism remains rare, since linkers capable of forming both 2D and 3D COFs tend to favor 2D structures. Accessing 3D polymorphs remains a challenge. We investigated the dimensional polymorphism in an imine-linked COF based on a terphenyl tetraaldehyde linker core, which is functionalized with two bulky methyl benzoate groups, and p-phenylenediamine. The tetraaldehyde linker can adopt planar or pseudo-tetrahedral conformations, while the methyl benzoate groups introduce steric crowding within the framework. Under a wide range of conditions, the system forms a 2D-kgm COF, whereas precise control over small amounts of water gives access to a second highly crystalline and highly porous 3D-dia COF. This phase is retained only after supercritical CO2 activation, while the 2D-kgm COF is retained with and without scCO2, highlighting the importance of activation in the search for 3D phases. The steric crowding appears to limit the degree of interpenetration, enabling the 3D-dia phase to reach a much higher BET surface area of up to 3883 m2 g-1 and a substantial high-pressure CO2 uptake of 31.9 mmol g-1 at 273 K and 19.5 bar compared with the 2D-kgm phase. These results show that steric interactions can shift the balance between competing dimensional polymorphs, while limiting the degree of interpenetration, leading to a compelling route towards materials with exceptionally high surface areas and high CO2 uptake.
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BibTeX
@misc{winter2026steric,
title = {{Steric Repulsion Driven Formation of a 3D Covalent Organic Framework Polymorph with Exceptionally High Surface Area}},
author = {Alena Winter and Simona Bassoli and Emma Regincós Martí and David J. Ashworth and Farzad Hamdi and Alaa Shaikhqasem and Thomas Kunze and Daniel Sebastiani and Panagiotis L. Kastritis and Gavin A. Craig and Ashleigh J. Fletcher and Frederik Haase},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009339/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009339/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Steric Repulsion Driven Formation of a 3D Covalent Organic Framework Polymorph with Exceptionally High Surface Area
AU - Alena Winter
AU - Simona Bassoli
AU - Emma Regincós Martí
AU - David J. Ashworth
AU - Farzad Hamdi
AU - Alaa Shaikhqasem
AU - Thomas Kunze
AU - Daniel Sebastiani
AU - Panagiotis L. Kastritis
AU - Gavin A. Craig
AU - Ashleigh J. Fletcher
AU - Frederik Haase
PY - 2026
DA - 2026/09/23
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009339/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009339/v1
AB - Dimensional polymorphism, in which the same molecular building blocks form frameworks of different dimensionality, offers a direct route to distinct pore architectures in covalent organic frameworks (COFs). True 2D/3D polymorphism remains rare, since linkers capable of forming both 2D and 3D COFs tend to favor 2D structures. Accessing 3D polymorphs remains a challenge. We investigated the dimensional polymorphism in an imine-linked COF based on a terphenyl tetraaldehyde linker core, which is functionalized with two bulky methyl benzoate groups, and p-phenylenediamine. The tetraaldehyde linker can adopt planar or pseudo-tetrahedral conformations, while the methyl benzoate groups introduce steric crowding within the framework. Under a wide range of conditions, the system forms a 2D-kgm COF, whereas precise control over small amounts of water gives access to a second highly crystalline and highly porous 3D-dia COF. This phase is retained only after supercritical CO2 activation, while the 2D-kgm COF is retained with and without scCO2, highlighting the importance of activation in the search for 3D phases. The steric crowding appears to limit the degree of interpenetration, enabling the 3D-dia phase to reach a much higher BET surface area of up to 3883 m2 g-1 and a substantial high-pressure CO2 uptake of 31.9 mmol g-1 at 273 K and 19.5 bar compared with the 2D-kgm phase. These results show that steric interactions can shift the balance between competing dimensional polymorphs, while limiting the degree of interpenetration, leading to a compelling route towards materials with exceptionally high surface areas and high CO2 uptake.
ER -