2 research outputs found
Phenylazothiazoles as Visible-Light Photoswitches
A novel class of photoswitches based on a phenylazothiazole
scaffold
that undergoes reversible isomerization under visible-light irradiation
is reported. The photoswitch, which comprises a thiazole heteroaryl
segment directly connected to a phenyl azo chromophore, has very different
spectral characteristics, such as a redshifted absorption maximum
wavelength and well-separated absorption bands of the trans and cis isomers, than conventional azobenzene and
other heteroaryl azo compounds. Substituents at the ortho and para positions of the phenyl ring of the photoswitch
resulted in a further shift to longer wavelengths up to 525 nm at
the absorption maximum with a small thermal stability compensation.
These photoswitches showed excellent photostationary distributions
of the trans and cis isomers, thermal
half-lives of up to 7.2 h, and excellent reductant stability. The
X-ray crystal structure analysis revealed that the trans isomers exhibited a planar geometry and the cis isomers exhibited a T-shaped orthogonal geometry. Detailed ab initio
calculations further demonstrated the plausible electronic transitions
and isomerization energy barriers, which were consistent with the
experimental observations. The fundamental design principles elucidated
in this study will aid in the development of a wide variety of visible-light
photoswitches for photopharmacological applications