Year: 2026
Type: preprint
Abstract: The long term stability of conjugated fluorescent and photochromic compounds is essential for their application in materials and devices, but is often highly sensitive to changes in molecular structure. This aspect is particularly prominent in the 6'-nitro-spiropyran and 6'-nitro-spirothiopyran photochromes, which differ only in a O/S atom at the spiro center but show remarkably different stability under UV irradiation. Here, we show, using femtosecond and nanosecond transient absorption and NIR emission spectroscopy supported by quantum chemical calculations, that from a photo-physical and -chemical perspective the two compounds are remarkably similar. Time-resolved NIR emission of 1 O 2 , gas chromatography and NMR spectroscopy, reveal that the difference in observed photostability is due to the greater quantum yield for 1 O 2 generation of the photodegradation products in the case of NSTP .
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funder: Rijksuniversiteit Groningen
OpenAlex ID: W7214928202