Synthesis of Styrylbenzazole Photoswitches and Evaluation of their Photochemical Properties.
Chemistry
; 30(39): e202401409, 2024 Jul 11.
Article
in En
| MEDLINE
| ID: mdl-38761405
ABSTRACT
Styrylbenzazoles form a promising yet under-represented class of photoswitches that can perform a light-driven E-Z isomerization of the central alkene double bond without undergoing irreversible photocyclization, typical of the parent stilbene. In this work, we report the synthesis and photochemical study of 23 styrylbenzazole photoswitches. Their thermal stabilities, quantum yields, maximum absorption wavelengths and photostationary state (PSS) distributions can be tuned by changing the benzazole heterocycle and the substitution pattern on the aryl ring. In particular, we found that push-pull systems show large redshifts of the maximum absorption wavelengths and the highest quantum yields, whereas ortho-substituted styrylbenzazole photoswitches exhibit the most favorable PSS ratios. Taking advantage of both design principles, we produced 2,6-dimethyl-4-(dimethylamino)-styrylbenzothiazole, a thermally stable and efficient P-type photoswitch which displays negative photochromism upon irradiation with visible light up to 470â
nm to obtain a near-quantitative isomerization with a very high quantum yield of 59 %. Furthermore, 4-hydroxystyrylbenzoxazole was demonstrated to be a pH-sensitive switch which exhibits a 100â
nm redshift upon deprotonation. Ortho-methylation of its benzothiazole analogue improved the obtained PSS ratio in its deprotonated state from E Z=53 47 to E Z=18 82. We anticipate that this relatively unexplored class of photoswitches will form a valuable expansion of the current family of photoswitches.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Chemistry
Journal subject:
QUIMICA
Year:
2024
Type:
Article
Affiliation country:
Netherlands