Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Molecular Electronics and Excited State Properties II

CPP 20.4: Talk

Monday, March 16, 2020, 15:45–16:00, ZEU 260

Optical absorption of azobenzene-derivatives in solution and in metal-organic frameworks via embedded orbital-tuned Bethe-Salpeter calculations — •Aseem Rajan Kshirsagar and Roberta Poloni — Univ. Grenoble-Alpes, CNRS, Grenoble-INP, SIMaP, Grenoble 38000, France

The use of UV-Vis light has been proposed as an energy-efficient strategy for capture and release of CO2 in azobenzene-functionalized metal-organic frameworks (MOFs). We recently demonstrated that the mechanism behind the observed reversible change in gas adsorption is metal-node blocking by the cis isomer upon UV-Vis excitation [1]. Large photo-isomerization yields are needed in order to achieve large changes in CO2 uptake, underlining the importance of a highly selective optical absorption by each isomer. For this, the Bethe-Salpeter formalism with a non-equilibrium embedding scheme has been employed to accurately compute the paradigmatic case of S1 band separation between cis and trans in azobenzene derivatives in solution. Besides embedding, we show that the choice of the DFT functional is critical, despite the iterative convergence of GW quasiparticle energies. In light of this result, we employ an environment-consistent orbital-tuning method to study 20 azobenzene derivatives in solution and then extend this approach to study the nature of the lowest energy excitons of MOF and the implications of using periodic versus non-periodic models of MOFs. [1] Yang, Kshirsagar, Eddin, Lin, Poloni, Chem. Eur. J. 24, 15167 (2018); [2] Kshirsagar, D’Avino, Blase, Li, Poloni, ChemRxiv (2019), url: https://chemrxiv.org/s/a7791c5ab68368b15dce.