title: Novel hetarylazo dyes containing tetrazole and hydroquinoline moieties: spectral characteristics, solvatochromism and photochemistry.
abstract: Novel hetarylazo dyes containing tetrazole and tetra- or dihydroquinoline moieties were synthesized and their spectral properties in solvents of different polarities and H-bonding abilities were examined. The dyes exhibit solvatochromism dramatically depending on the proton accepting ability of solvents: (DMSO > H2O > MeOH > ACN > CH2Cl2) and the dye concentration. Upon dilution the absorption maximum of the visible band shows a blue shift and the absorption coefficient of the maximum decreases. This was accounted for by complex formation either between the dye molecules or between the dye and solvent molecules. The H-bond with partial proton transfer is formed between the acidic NH group of the tetrazole moiety of a dye molecule and the basic NH group of the hydroquinoline moiety of the other dye molecule or with a solvent with proton accepting ability. Upon dilution the equilibrium shifts to the complex with a solvent. The coexistence of several forms of the dye molecules with different absorption spectra was demonstrated in pulse photolysis upon excitation by light with different wavelengths. Three forms of cis-isomers were registered. The photogenerated cis-isomers decay with lifetimes from 200 μs to 5 ms. The fast cis-trans dark isomerization determines the photostability of the dyes.
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia. nekip@sky.chph.ras.ru.
authors.forename: Tatiana D
authors.initials: TD
authors.lastname: Nekipelova
authors.affiliation: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia.
authors.forename: Evgenii N
authors.initials: EN
authors.lastname: Khodot
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia. nekip@sky.chph.ras.ru.
authors.forename: Olga N
authors.initials: ON
authors.lastname: Klimovich Lygo
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia. nekip@sky.chph.ras.ru.
authors.forename: Lidiya N
authors.initials: LN
authors.lastname: Kurkovskaya
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia. nekip@sky.chph.ras.ru.
authors.forename: Irina I
authors.initials: II
authors.lastname: Levina
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia. nekip@sky.chph.ras.ru.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Kuzmin
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D007536:Isomerism; D010777:Photochemistry; D011804:Quinolines / Q000737:chemistry*; D012997:Solvents; D013777:Tetrazoles / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D011804:Quinolines; D012997:Solvents; D013777:Tetrazoles; C037219:quinoline