Ultrafast Photo-Dynamics of a Reversible Photochromic Spiropyran

Abstract

We report the first ultrafast ring closure kinetics of the merocyanine (MC) of a reverse photochromic spiropyran 1′,3′,3′-trimethyl-6,8-dinitrospiro[2H-1-benzopyran-2,2-indoline] (6,8-dinitro BIPS) and its 1′-(2-carboxyethyl) substituted derivative. The reaction is fast and essentially over in a few hundred picoseconds. The rate of MC-S 1 state decay evaluated from transient absorbance can be correlated directly with the MC-S 1 state lifetime as determined using stimulated and ordinary emission measurements. The recovery of the MC-S 0 state from MC-S 1 has a component with a lifetime of 60-78 ps in acetonitrile with a second component of 350-470 ps probably due to a metastable intermediate. We can further establish that the excited MC-S 1 state takes on the order of 500 fs to form from higher-energy states after photoexcitation with 390 nm light. † Part of the special issue "Noboru Mataga Festschrift".

Useful Spectrokinetic Methods for the Investigation of Photochromic and Thermo-Photochromic Spiropyrans

“…the decay of excited MC, 1 MC * → SP) has also been investigated by time resolved techniques [53,54]. The phototransformation of MC is believed to proceed via similar types of decay routes (i.e.…”

Transient absorption spectroscopy on spiropyran monolayers using nanosecond pump—probe Brewster angle reflectometry

“…The built-in EP 3 goniometer, which has a 0.01°angle resolution and a reproducibility of 0.001°, makes it possible to establish the Brewster angle of the monolayer very accurately. The precision of this value is important to get better estimations of monolayer thickness and initial refractive index from simulations.…”

“…Spiropyran (SP) to merocyanine (MC) conversion (Scheme 1) [1][2][3] in thin films and monolayers has attracted a lot of attention in recent years because of potential applications in photoswitching devices. Studies include light-induced phase transitions that induce conformational and pressure changes, [4][5][6] and changing the wettability of surfaces.…”

Preparation, Characterization, and Application of Optical Switch Probes

“…Excitation of the MC‐state of NitroBIPS with 546‐nm light generates the MC‐excited state that can decay via two independent processes, each with a unique quantum yield. The first process is an excited state intramolecular reaction that reforms the SP‐state and has a high quantum yield (Hobley et al, ), whereas the second process involves a return to the ground state with the emission of a red photon with a low quantum yield between 0.05 and 0.1 (Chibisov and Görner, ). However, even though weak, the MC‐fluorescence of NitroBIPS is useful for imaging and analysis of the progress of optical switching in cells and tissue (Mao et al, ; Marriott et al, ; Sakata et al, ).…”

“…Excitation of MC with 546-nm light generates the MC-excited state, which decays by one of two independent processes. The Þrst process is the excitedstate intramolecular reaction that reforms the SP-state and proceeds with a quantum yield as high as 0.8 in apolar solvents (Hobley et al, 2002). The competing process involves the return of the excited MC to the same MC-ground state with emission of a red photon at ∼618 nm.…”