A 1.5×10
-4M solution of trans-sodium 4, 4'-bis (2-anilino-4-monoethanolamino-1, 3, 5-triazin-6-ylamino) -2, 2'-stilbene disulfonate (2) was irradiated at 30±0.2°C with UV light (360 mμ), and the changes of the UV absorption spectra, fluorescence intensity, and TLC were examined. After a solution of (2) reached a photostationary state, cotton fabrics were dyed repeatedly, and a photochemical product was obtained from the residual solution. A solution of
trans-4, 4'-diaminostilbene-2, 2'-di-sulfonate (1) was irradiated with UV light (360 mμ), and a photochemical product was separated by fractional precipitation. NMR spectra proved that this product was
cis- (1).
Cis- (2), which was synthesized from
cis- (1), was proved to be identical with the product of irradiation of
trans- (2), by comparing their UV, IR, NMR spectra and TLC. When irradiated with UV light under the same conditions, the photochemical product of
trans- (2) reached a photostationary state with the same composition as in the case of
trans- (2) :
cis 88%,
trans 12%. The composition of the photostationary state was dependent on the wavelength of the light irradiated. It is to be presumed, from the NMR and UV spectra, that the photochemical product of
trans- (2) was not a dimerization or cyclization product.
It was concluded from the processes described above that solutions of (2) undergo
cis-trans isomerization upon irradiation.
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