Photoinduced Proton Coupled Electron Transfer in 2‑(2′-Hydroxyphenyl)-Benzothiazole

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 117; no. 25; pp. 5269 - 5279
• Main Authors: Luber, Sandra, Adamczyk, Katrin, Nibbering, Erik T. J, Batista, Victor S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 27-06-2013
• Subjects: Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Charge; Chemistry; Coupling (molecular); Density-functional theory; Electron transfer; Electronic structure of atoms, molecules and their ions: theory; Electronics; Exact sciences and technology; General and physical chemistry; Markers; Molecular structure; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Physics; Solvents; Spectroscopy; Real time systems; Sulfur nitrogen heterocycle; Photochemical reactions; Isomerization; Theoretical study; Electron transfer; Chromophores; Benzothiazole derivatives; Excited states; Keto enol tautomerism; Real time; Intramolecular charge transfer; Pump probe spectrometry; Density functional method
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp403342w

We characterize the structural and electronic changes during the photoinduced enol–keto tautomerization of 2-(2′-hydroxyphenyl)-benzothiazole (HBT) in a nonpolar solvent (tetrachloroethene). We quantify the redistribution of electronic charge and intramolecular proton translocation in real time by combining UV-pump/IR-probe spectroscopy and quantum chemical modeling. We find that the photophysics of this prototypical molecule involves proton coupled electron transfer (PCET), from the hydroxyphenyl to the benzothiazole rings, resulting from excited state intramolecular proton transfer (ESIPT) coupled to electron transfer through the conjugated double bond linking the two rings. The combination of polarization-resolved mid-infrared spectroscopy of marker modes and time-dependent density functional theory (TD-DFT) provides key insights into the transient structures of the molecular chromophore during ultrafast isomerization dynamics.