On the low-lying electronically excited states of azobenzene dimers
- Azobenzene-containing molecules may associate with each other in systems such as self-assembled monolayers or micelles. The interaction between azobenzene units leads to a formation of exciton states in these molecular assemblies. Apart from local excitations of monomers, the electronic transitions to the exciton states may involve charge transfer excitations. Here, we perform quantum chemical calculations and apply transition density matrix analysis to quantify local and charge transfer contributions to the lowest electronic transitions in azobenzene dimers of various arrangements. We find that the transitions to the lowest exciton states of the considered dimers are dominated by local excitations, but charge transfer contributions become sizable for some of the lowest pi pi* electronic transitions in stacked and slip-stacked dimers at short intermolecular distances. In addition, we assess different ways to partition the transition density matrix between fragments. In particular, we find that the inclusion of the atomic orbitalAzobenzene-containing molecules may associate with each other in systems such as self-assembled monolayers or micelles. The interaction between azobenzene units leads to a formation of exciton states in these molecular assemblies. Apart from local excitations of monomers, the electronic transitions to the exciton states may involve charge transfer excitations. Here, we perform quantum chemical calculations and apply transition density matrix analysis to quantify local and charge transfer contributions to the lowest electronic transitions in azobenzene dimers of various arrangements. We find that the transitions to the lowest exciton states of the considered dimers are dominated by local excitations, but charge transfer contributions become sizable for some of the lowest pi pi* electronic transitions in stacked and slip-stacked dimers at short intermolecular distances. In addition, we assess different ways to partition the transition density matrix between fragments. In particular, we find that the inclusion of the atomic orbital overlap has a pronounced effect on quantifying charge transfer contributions if a large basis set is used.…
Author details: | Evgenii TitovORCiDGND |
---|---|
DOI: | https://doi.org/10.3390/molecules26144245 |
ISSN: | 1420-3049 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/34299521 |
Title of parent work (English): | Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International |
Subtitle (English): | Transition density matrix analysis |
Publisher: | MDPI |
Place of publishing: | Basel |
Publication type: | Article |
Language: | English |
Date of first publication: | 2021/07/13 |
Publication year: | 2021 |
Release date: | 2023/01/23 |
Tag: | ADC(2); TD-DFT; azobenzene; charge transfer; dimer; excited states; exciton; transition density matrix |
Volume: | 26 |
Issue: | 14 |
Article number: | 4245 |
Number of pages: | 24 |
Funding institution: | Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)German Research Foundation (DFG) [454020933] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
Peer review: | Referiert |
Publishing method: | Open Access / Gold Open-Access |
DOAJ gelistet | |
License (German): | CC-BY - Namensnennung 4.0 International |