Chromophore assemblies in light harvesting complexes have been shown to facilitate efficient energy transfer in natural photosynthesis and have led to extensive investigations of biomimetic supramolecular assemblies. Covalent organic frameworks (COFs) have emerged as a class of materials that have great potential for long-range energy migration owing to their controllable order, crystallinity, and modularity. However, there has been little characterization of the electronic processes of these materials using optical spectroscopy due to their poor solubility, which results in low signal to noise ratios in optical studies. Macrocycles derived from COFs retain most of the COF properties while also being solution stable, allowing for higher quality optical characterizations. Furthermore, addition of acid induces pi-stacking of the macrocycles, providing the ability to control their macromolecular structures. In this report, we explore the effects of assembly and long-range order on the excitonic properties of a COF-derived macrocycle nanotube using time-resolved photoluminescence, steady-state and transient absorption spectroscopies. We observe a bathochromic shift as well as a significant increase in the excited-state lifetimes in the nanotube due to the hinderance of internal conversion pathways. This report provides one of the first in-depth investigations of the excitonic properties of these materials.

Investigation of ultrafast excitonic processes in covalent organic framework-derived macrocycles

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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