H. Ihmels et al., New dyes based on amino-substituted acridizinium salts - Synthesis and exceptional photochemical properties, CHEM-EUR J, 6(15), 2000, pp. 2854-2864
The novel amino-substituted acridizinium salts 5a and 5b represent a new cl
ass of cyanine dyes which exhibit intense color along with efficient fluore
scence properties. These dyes show moderate solvatochromism in their absorp
tion and emission spectra. The absorption and emission shifts of the two ch
romophores display a reasonable correlation with solvent parameters such as
donor and acceptor number, It was found that the dyes 5a and 5b interact w
ith DNA, with quenching of the band intensies accompanied with a red shift
of the absorption and emission bands. Moreover, irradiation of salts 5a and
5b in the presence of DNA results in DNA damage. Solution photolysis of ac
ridizinium salt 5a gave the head-totail dimers as the major products (>95%)
, whereas the acridizinium salt 5b afforded the anti-head-to-tail dimer alo
ng with both head-to-head isomers. The latter are thermally labile and rapi
dly revert to the monomer.