abstract
A challenging aspect in the synthesis of covalent organic frameworks (COFs) that goes beyond the framework's structure and topology is interpenetration, where two or more independent frameworks are mechanically interlocked with each other. Such interpenetrated or interlocked frameworks are commonly found in three-dimensional (3D) COFs with large pores. However, interlocked two-dimensional (2D) COFs are rarely seen in the literature, as 2D COF layers typically crystallize in stacks that maximize stabilization through pi-stacking. The few interlocked 2D COFs described to date have been derived from monomers with aryl groups arranged perpendicularly. Herein, we report an interlocked 2D COF derived from a new class of monomers constituted of sterically overcrowded polycyclic aromatic hydrocarbons. The formation of such an interlocked structure is ascribed to the presence and the bulkiness of the substituents that directly interfere with interlayer pi-stacking. The microscopy, gas sorption, spectroscopic, and charge transport characterization are consistent with the absence of pi-stacking, as imposed by the interlocked architecture. This work evidences how the use of overcrowded aromatic systems as monomers can generate mechanically interlocked 2D COFs, offering new avenues for the design of COFs with unconventional topologies.
keywords
ELECTRON; DESIGN
subject category
Chemistry
authors
De Bolòs, E; Bera, S; Strutynski, K; Bardin, AA; Lodge, RW; Padial, N; Saeki, A; Martí-Gastaldo, C; Khlobystov, AN; Nannenga, BL; Melle-Franco, M; Mateo-Alonso, A
our authors
Karol Strutyński
Assistant Researcher
Manuel Melle-Franco
Principal Researcheracknowledgements
This work was carried out with support from the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country, Diputacion de Guipuzcoa, Gobierno Vasco (PIBA_2024_1_0030 and BERC programme) and Gobierno de Espana (Projects PID2021-124484OB-I00, CNS2022-135677, CEX2020-001067-M and Maria de Maeztu Excellence Unit CEX2023-001303-M financed by MCIN/AEI/10.13039/501100011033). This Project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (Grant Agreement No. 722951). This work was funded by the European Union under the Horizon Europe grant 101046231. Project (PCI2022-132921) funded by the Agencia Estatal de Investigacion through the PCI2022 and M-ERA.NET 2021 calls is acknowledged. Technical and human support provided by SGIker of UPV/EHU is acknowledged. The authors thank the Nanoscale and Microscale Research Centre (nmRC), University of Nottingham, for access to HRTEM facilities. The MicroED work was supported by the National Institutes of Health P41GM136508. Portugal National funds through FCT/MCTES (CICECO-Aveiro Institute of Materials DOI:10.54499/UIDB/50011/2020, DOI:10.54499/UIDP/50011/2020 & DOI:10.54499/LA/P/0006/2020) and the Scientific Employment Stimulus Program (2022.07534.CEECIND) are acknowledged. Adrian Moron-Blanco is gratefully acknowledged for preparing Figure d,e.