Effect of Thionation of the Carbonyl Groups in Naphthalimide-Phenoxazine Electron Donor-Acceptor Dyads on the Excited- State Dynamics: Transient Optical and Electron Paramagnetic Resonance Spectral Studies.

ABSTRACT: We performed thionation of the electron acceptor naphthalimide (NI) moiety in donor-acceptor (D-A) dyads in a series of thio-substituted D-A dyads. Thionation significantly enhances the electron-accepting ability of the chromophore, facilitating the formation of low-lying charge-separated (CS) states. Femtosecond transient absorption spectra revealed intersystem crossing (ISC) rate constants of S-NI-PXZ (k_ISC = 3.8 × 10¹¹ s^-1) and DS-NI-PXZ (k_ISC = 2.4 × 10¹¹ s^-1), which are interestingly independent of the number of sulfur atoms. Generally, fluorescence quenching was observed due to the rapid ISC process. Native NI-PXZ exhibits thermally activated delayed fluorescence (TADF). Thionation increased the singlet-triplet energy

SUBMITTER: Zhang Y 

PROVIDER: S-EPMC12734687 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature