The low-lying electronic states and ultrafast relaxation dynamics of the monomers and J-aggregates of meso-tetrakis (4-sulfonatophenyl)-porphyrins

Hui Fang; Michael J Wilhelm; Danielle L Kuhn; Zachary Zander; Hai-Lung Dai; George A Petersson

doi:10.1063/5.0174368

The low-lying electronic states and ultrafast relaxation dynamics of the monomers and J-aggregates of meso-tetrakis (4-sulfonatophenyl)-porphyrins

J Chem Phys. 2023 Oct 21;159(15):154302. doi: 10.1063/5.0174368.

Authors

Hui Fang¹, Michael J Wilhelm¹, Danielle L Kuhn², Zachary Zander², Hai-Lung Dai¹, George A Petersson³

Affiliations

¹ Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA.
² U.S. Army DEVCOM Chemical Biological Center, Research and Operations, Aberdeen Proving Ground, Aberdeen, Maryland 21010, USA.
³ Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA.

PMID: 37846956
DOI: 10.1063/5.0174368

Abstract

The electronic and vibrational spectra of the meso-tetrakis(4-sulfonatophenyl)-porphyrins (TSPP) have been studied computationally using the PFD-3B functional with time-dependent density functional theory for the excited states. The calculated UV-vis absorption and emission spectra in aqueous solution are in excellent agreement with the experimental measurements of both H2TSPP-4 (monomer) at high pH and H4TSPP-2 (forming J-aggregate) at low pH. Moreover, our calculations reveal an infrared absorption at 1900 cm-1 in the singlet and triplet excited states that is absent in the ground state, which is chosen as a probe for transient IR absorption spectroscopy to investigate the vibrational dynamics of the excited state. Specifically, the S2 to S1 excited state internal conversion process time, the S1 state vibrational relaxation time, and the lifetime of the S1 excited electronic state are all quantitatively deduced.