Spiropyran Degradation A Quantitative Approach

Under conditions of pulsed photolysis, the merocyanine optical density variation ADmc at wavelength X2 is 

Tobin 13. Quantum Yields 1q for Irreversible PhoiodcgradAlion of Sjiiropyrans in Toluene Is Not Dvpcntkni [)n the Presence of Oxygen and of lilt Degree ofConversion1 

SPs belonging to the dithiolane series (150-154) are thermally and photo-chemically unstable and decompose in the presence of acids, and it is thus not possible to compare their t d values to those of other spiropyrans. It is worth noting that for all nitrospiropyrans and a few other derivatives, bd changes during photolysis, for the nitrospiropyrans, it already changes beyond 5% conversion. 

For all nitro-substituted SPs, photooxidation processes are responsible for photodegradation. These compounds are characterized by a relatively long-lived 

TsiWp )6. Quantum yields C, for Irreversible Photodognsdaiion of spiiopyrans in Toluene Dj Increases as ihc Degree of Conversion of SP increases in the Presence or the Absence of 

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