Pinning Down Small Populations of Photoinduced Intermediates Using Transient Absorption Spectroscopy and Time-Dependent Density Functional Theory Difference Spectra to Provide Mechanistic Insight into Controlling Pyridine Azo Dynamics with Protons.

ABSTRACT: In this work, the impact of protonation on the photoisomerization (trans → cis) and reversion (cis → trans) of three pyridine-based azo dyes (PyrN) is investigated by using a combination of transient absorption spectroscopy and time-dependent density functional theory computed difference spectra. The photophysical behaviors of the PyrN dyes are altered by the addition of one or two protons. Protonation of basic pyridine nitrogens results in an ultrafast accelerated reversion mechanism after photoisomerization, while protonation of azo bond nitrogens restricts cis isomer formation entirely. Computed difference spectra provide spectral signatures that are critical for the assignment of low-population long-lived states, providing direct evidenc

SUBMITTER: Knepp ZJ 

PROVIDER: S-EPMC11440581 | biostudies-literature | 2024 Sep

REPOSITORIES: biostudies-literature