Ultrafast photoinduced dynamics of halogenated cyclopentadienes: observation of geminate charge-transfer complexes in solution

Abstract

aThe photoinduced dynamics of the fully halogenated cyclopentadienes C 5 Cl 6 and C 5 Br 6 have been investigated in solution and gas phase by femtosecond time-resolved spectroscopy. Both in solution and in gas phase, homolytic dissociation into a halogen radical and a C 5 X 5 (X = Cl, Br) radical was observed.In liquid phase, solvent-dependent formation of charge transfer complexes between geminate radicals was observed for the first time. These complexes were found to be surprisingly stable and offered the opportunity to follow the dynamics of specific radical pairs. In the case of C 5 Cl 6 in trichloroethanol, a reaction of the chlorine radical with molecules from the solvent cage was observed.

Plant Sunscreens in the UV-B: Ultraviolet Spectroscopy of Jet-Cooled Sinapoyl Malate, Sinapic Acid, and Sinapate Ester Derivatives

“…We were unable to record DFL spectra for SMB, SM, and SDM due to the lack of laser desorption capabilities in our fluorescence chamber, but direct detection of broad, red-shifted emission in DFL of SM would certainly represent an important future step in confirming a CT-like mechanism. Alternatively, the presence and character of the second excited state responsible for the broadening should be apparent in the time evolution of the photoelectron spectrum. − Atomic charges and dipole moments of the three excited states at the ground state geometry were calculated by electrostatic potential (ESP) fitting, also revealing some nπ*/CT character, as summarized in the Supporting Information.…”