Study of tribenzo[ b, d, f]azepine as donor in D-A photocatalysts

Abstract

Since the discovery of donor-acceptor (D-A) type molecules in the field of materials science, they have found great applicability in the field of photocatalysis. Most of these compounds are based on complex D-A-D structures or multi-D-A systems, such as 4CzIPN. Whereas these systems have been widely studied and applied as photocatalysts, simpler D-A structures remain less explored. Nevertheless, the simplicity of D-A structures makes them the ideal structures to further understand the structure-property relationship of D-A molecules for optimizing their photocatalytic performance by simpler modification of the different D-A subunits. In particular, D-A structures featuring sulfur-based acceptors and nitrogen donors have gained increasing attention for their use as photoredox catalysts. This study introduces a new family of D-A molecules by exploring various sulfur-based acceptors and nitrogen donors, including a novel tribenzo[b,d,f]azepine (TBA) unit and 5H-dibenz[b,f]azepine (IMD). Our findings demonstrate that these simple D-A structures exhibit promising photocatalytic properties, comparable to those of more complex D-A-D systems.

Keywords: donor–acceptor system; organic photocatalyst; photocatalyst design; photoredox catalysis.

Figure 1

D–A–D organic PCs previously reported and our new D–A bimodal organic PCs.

Figure 2

Selected frontier MOs and relative calculated energies of D–A photocatalysts (4a,5a–e, and 6a). Absorption and emission profiles of D–A compounds (4a,5a–e, and 6a) measured in MeCN.

Figure 3

Comparison of the ground state redox potential of the acceptor moieties (4–6), the donor moieties (a–e), and D–A compounds (4a, 5a–e, and 6a).