Picosecond Switchable Azo Dyes. Issue 32 (9th May 2019)

• Record Type: Journal Article
• Authors: Garcia‐Amorós, Jaume; Maerz, Benjamin; Reig, Marta; Cuadrado, Alba; Blancafort, Lluís; Samoylova, Elena; Velasco, Dolores
• Is Part Of: Chemistry. Volume 25:Issue 32(2019)
• Page Start: 7726
• Page End: 7732
• Publication Date: 2019-05-09
• Subjects: ab initio calculations -- azo compounds -- isomerization -- molecular switches -- ultrafast spectroscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201900796
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Azo dyes that combine electron‐withdrawing thiazole/benzothiazole heterocycles and electron‐donating amino groups within the very same covalent skeleton exhibit relaxation times for their thermal isomerization kinetics within milli‐ and microsecond timescales at room temperature. Notably, the thermal back reaction of the corresponding benzothiazolium and thiazolium salts occurred much faster, within the picosecond temporal domain. In fact, these new light‐sensitive platforms are the first molecular azo derivatives capable of reversible switching between their trans and cis isomers in a subnanosecond timescale under ambient conditions. In addition, theoretical calculations revealed very low activation energies for the isomerization process, in accordance with the fast subnanosecond kinetics that were observed experimentally. Abstract : cis / trans Isomerization : Amino‐azothiazolium and amino‐azobenzothiazolium salts are the first molecular azo dyes capable of reversible switching between their trans and cis isomers in a subnanosecond timescale under ambient conditions (see scheme).