Enache Bogdan C, Hanganu Anamaria, Tablet Cristina, Anghel Catalin C, Popescu Codruta C, Paun Anca, Hădade Niculina Daniela, Mădălan Augustin M, Matache Mihaela
Research Centre of Applied Organic Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Faculty of Chemistry, University of Bucharest, 90 Panduri Street, 050663 Bucharest, Romania.
Department of Research and Development, SC Microsin SRL, 51-63 Pericle Papahagi Street, 032364 Bucharest, Romania.
ACS Omega. 2022 Oct 20;7(43):39122-39135. doi: 10.1021/acsomega.2c04984. eCollection 2022 Nov 1.
Arylazopyrazoles stand out among the azoheteroarene photoswitches due to their excellent properties in terms of stability of the least stable isomer and conversion between isomers, leading to their use in several interesting applications. We report herein the synthesis of arylazo-trifluoromethyl-substituted pyrazoles and their switching behavior under light irradiation. UV-vis and NMR experiments showed that arylazo-1-3,5-bis(trifluoromethyl)pyrazoles displayed very long half-lives in DMSO (days), along with reasonable values of other parameters that characterize a photoswitch. Inclusion of naphthyl moieties as aryl counterparts of the arylazopyrazoles is beneficial only in combination with trifluoromethyl groups, while extending the conjugation by grafting the pyrazole moiety with electron-donating or -withdrawing substituents positively affects the photoswitching behavior, in terms of isomerization yield and half-lives of the least stable isomer. The experimental values were correlated with theoretical calculations indicating the valuable influence of the trifluoromethyl groups onto the photoswitching behavior.
芳基偶氮吡唑在偶氮杂芳烃光开关中脱颖而出，因为它们在最不稳定异构体的稳定性以及异构体之间的转换方面具有优异的性能，这使得它们在一些有趣的应用中得到使用。我们在此报告芳基偶氮-三氟甲基取代吡唑的合成及其在光照下的开关行为。紫外可见光谱和核磁共振实验表明，芳基偶氮-1,3,5-双（三氟甲基）吡唑在二甲基亚砜中显示出非常长的半衰期（数天），同时具有表征光开关的其他参数的合理值。作为芳基偶氮吡唑的芳基对应物引入萘基部分仅在与三氟甲基结合时才有益，而通过用供电子或吸电子取代基接枝吡唑部分来扩展共轭，就异构化产率和最不稳定异构体的半衰期而言，对光开关行为有积极影响。实验值与理论计算相关，表明三氟甲基对光开关行为有重要影响。
