Femtosecond Laser Photolysis Studies on Temperature Dependence of Cyclization and Cycloreversion Reactions of a Photochromic Diarylethene Derivative

Abstract

Temperature dependencies of cyclization and cycloreversion processes of a photochromic diarylethene derivative, 1,2-bis(2-methyl-3-benzothienyl)perfluorocyclopentene (BT), were investigated by steady-state spectroscopy and femtosecond laser photolysis methods. Steady-state measurements revealed that the cyclization reaction quantum yield and the fraction of the conformer with C 2v symmetry favorable for the cyclization (antiparallel, AP conformer) were independent of temperature in the range of 253−343 K. These results indicated that the cyclization reaction of the AP conformer in the open-ring isomer in the excited state had no apparent temperature dependence and suggested that the fate of the excited AP conformer in the open-ring isomer, such as cyclization or deactivation to the ground state, was determined at the conical intersection. On the other hand, the cycloreversion reaction was dependent on the temperature; the reaction quantum yield increased together with a decrease in the lifetime of the excited state of the closed-ring isomer with increasing temperature. On the basis of the adiabatic energy surface for the reaction profiles, it was deduced that the rapid deactivation into the ground state took place in the S 1 state in competition with the activated pathways leading to the conical intersection where the cycloreversion occurred.

Fluorescent Photoswitchable Diarylethenes for Biolabeling and Single-Molecule Localization Microscopies with Optical Superresolution

“…440−488 nm); in a spectral region where high quality synthetic markers are not abundant. Importantly, the photoswitching of DAEs involves singlet-excited states, 52 and thus the presence of blinking buffers is expected to strongly affect their photswitching behavior. 100 nm makes them almost unique, as in general long Stokes-shift markers for fluorescence microscopy are rare; in particular, in all superresolution techniques, including those based on STORM.…”

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

“…41 The cycloreversion quantum yield, on the other hand, increases at higher temperatures. According to theoretical investigations described in the previous section, the excited state of the closed-ring isomer has to go over an energy barrier to reach the branching conical intersection (CI), through which the open-ring isomer is produced.…”

Fast and Efficient Oxidative Cycloreversion Reaction of a π‐Extended Photochromic Terarylene

“…The photocyclization quantum yield has been raised to almost unity through efficient control of the molecular conformation by means of multiple noncovalent interactions ,. Since both the photocyclization and cycloreversion reactions proceed through an identical conical intersection on the potential energy surface, the efficiency of these reactions should be dependent on the nature of this conical intersection . Therefore, it seems difficult to obtain high quantum yields for both the photocyclization and the cycloreversion reactions simultaneously.…”