<br/>Covalent organic frameworks (COFs), a class of crystalline porous organic polymers, have attracted significant attention over the last decade due to their chemical versatility, high surface area, and unique electronic properties. Here, we present a systematic theoretical analysis, based on first-principles calculations, of both structural and electronic properties of new multilayered COFs with periodic electron donor-acceptor units which form π-columnar arrays. Within each layer, the electron donors (metallophthalocyanines with copper centers) are located at the nodes of square lattices whose edges correspond to the electron acceptors (pyromellitic diimides). We consider different stacking geometries, including an eclipsed configuration, where the donors line up with donors and the acceptors line up with acceptors in the neighboring layers, and two staggered configurations, where for staggered 1, the donors are on top of the acceptors from the neighboring layers, and for staggered 2, the donors are on top of the central pores of the neighboring layers. Our results show that different stacking geometries lead to significantly different unit cell dimensions and electronic properties. Specifically, we find that the eclipsed one is metallic and displays high charge mobility along the stacking direction, while the staggered1 displays highly localized charge states. Given these differences, we suggest that the eclipsed configuration may find applications in electronic devices, while the staggered 1 configuration may potentially be used as a catalyst. Overall, our analyses demonstrate that theoretical calculations provide molecular-level insights into composition-structure-property relationships of COFs which, complementing conductivity and spectroscopic measurements, can guide the design of new COFs tailored for specific applications.

Effect of interlayer stacking arrangements on band gap and transport properties of donor-acceptor COFs

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.