Official websites use. Share sensitive information only on official, secure websites. Azoheteroarene photoswitches have attracted attention due to their unique properties. We present the stationary photochromism and ultrafast photoisomerization mechanism of thiophenylazobenzene TphAB. Therefore, the adoption and disruption of the orthogonal geometry requires significant movement along the inversion reaction coordinates CNN and NNC angles. Our results establish TphAB as an excellent photoswitch with versatile properties that expand the application possibilities of AB derivatives.
Keywords: isomerization mechanisms, photochromism, photoswitches, thiophenylazobenzene, time-resolved spectroscopy. The operation of molecular photoswitches is based on the reversible transformation of the switching molecule between states of different physicochemical properties for example, geometrical structure, dipole moment, absorption spectrum, or redox potential. Azobenzenes AB are a prominent group of widely utilized photoswitches.
Also, additional pathways may be involved, making a clear distinction between the timescales of the relaxation pathways in the ultrafast data hard. Furthermore, due to distortions because of steric effects, the spectral properties of azoheteroarenes are altered.
Moreover, the presence of heteroatoms permits new functional designs previously unavailable in conventional ABs. Therefore, azoheteroarenes offer an untapped potential for further optimization and expansion of the capabilities of AB photoswitches. In this work, we explore a different azoheteroarene design, where one of the phenyl groups of a conventional AB is substituted by a thiophenyl group. We present its synthesis along with the theoretical and experimental investigation of the photoisomerization of this thiophenylazobenzene TphAB photoswitch.
All spectroscopic experiments with TphAB were performed in acetonitrile. The QY determination see Supporting Information and ref. This is in stark contrast to AB 4 and the related azothiophene, 19 where both rings are twisted away from the CNNC plane. Interestingly, it was found that in these compounds, the orthogonal geometry is disfavored when a bulky substituent is present in ortho position to the CNNC group. Nevertheless, the contribution of the twisted geometry to the experimental spectrum is negligible as this configuration is essentially not present at room temperature see above.
