The manipulation of molecular electronic structure through chemical design to engineer a degree of control over intra- and inter- molecular electron transfer has become a prevalent topic of study, especially with regards to quantum interference (QI) effects. Experimental and computational studies have shown the capacity of a phenylene molecular bridge to transmit electrons between remote sites is dependent on not only site connectivity (e.g. meta vs para) but also substituent groups through manipulation of these QI effects.[1] It is especially prevalent in meta diethynyl benzene derivatives, whereby the charge transfer properties that are typically suppressed by destructive QI effects, can be enhanced through introduction of carefully positioned substituents. This has been demonstrated in both the through-molecule electron transfer process in molecular junctions,[2] and the charge transfer process within molecular mixed-valence systems,[3] prompting consideration of the broader significance of QI phenomena with optically induced electron transfer processes.[4] The potential for intramolecular coupling in mixed-valence systems to be used as predictive models for QI effects in molecular junctions and provide insight into the governing structure-property relationships will be discussed, and expanded to consideration of other models based on optically induced charge transfer processes.
References
[1] a) M. H. Garner, et al., J. Phys. Chem. C 2016, 120, 9097−9103. b) L. A. Zotti, et al., Phys. Chem. Chem. Phys. 2020, 22, 5638.
[2] F. Jiang, et al., Angew. Chem. Int. Ed. 2019, 58, 18987–18993.
[3] D. P. Harrison, et al., Angew. Chem. Int. Ed. 2022, 61
[4] J. P. Launay, Coord. Chem. Rev. 2013, 257, 1544–1554.