(687f) Workflow Automation in Predicting Exciplex Formation in Arene-Amine Complexes

The formation of excited-state complexes or exciplexes in specific acceptor-donor systems leads to prominent red-shifted emission peaks in the fluorescence spectra. In particular, the photon absorbed excited state of oligo-(p-phenylene) (OPP*) forms the exciplex with the ground state triethylamine (TEA)[1]. The red-shifted emission peak is broader than that of isolated OPP*, indicating that the exciplex is likely comprised of an ensemble of structures. Identification of even a single exciplex geometry requires significant computational effort towards geometry optimization with time-dependent density functional theory (TDDFT) and user-intervention to ensure that the optimization always follows the correct excited state. To address this problem for the ensemble of structures, we construct automated workflows for TDDFT optimization as implemented in Q-Chem [2]. Our workflow takes advantage of FireWorks[3] for job handling, Pymatgen[4] for input/output parsing, and Custodian[5] for error handling, in addition to our in-house excited-state properties parsing code. The exciplexes are verified by new emission bands at longer wavelengths, otherwise absent in the spectra of isolated molecules. We also analyze the effect of solvent dielectrics on emission bands. The developed workflow can be employed to study the emission intensity variation with the electron-donor concentration.

References:

1. K. J. Kron et al, The Journal of Physical Chemistry A (page and volume not assigned yet) (2022).

2. Y. Shao et al., Molecular Physics, 113(2), 184-215 (2015).

3. A. Jain et al., Concurrency and Computation: Practice and Experience, 27(17), 5037-5059 (2015).

4. S. P. Ong et al., Computational Materials Science, 68, 314–319 (2013).

5. K. Mathew et al., Computational Materials Science, 139, 140-152 (2017).