A.I. Tolmachev

Metallochromic merocyanines of 8-hydroxyquinoline series

Abstract A number of merocyanines based on the 5- and 7-substituted 8-hydroxyquinoline nucleus have been synthesized, and the metallochromic and some metallofluorochromic properties of the prepared dyes have been studied. The most pronounced metallochromic effects are observed for the dyes containing low-basicity end nuclei. Maximum metallofluorochromic effects were demonstrated by the 7-substituted derivatives of 8-hydroxyquinoline upon interaction with Zn 2+ , Cd 2+ , and Hg 2+ cations. A possible mechanism of metal binding is discussed.

Metallochromic merocyanines of 8-hydroxyquinoline series. II. Dyes with end nuclei of low basicity

Based on 5-substituted 8-hydroxyquinoline, a number of complexing merocyanines with the end nuclei of low basicity have been synthesized. Dyes of this kind exhibit the most pronounced metallochromic effects manifested by drastic bathochromic and hyperchromic shifts on complexation with the salts of heavy and transition metals as well as lanthanide salts. The spectral effects observed are of a complicated character and arise from the interaction of the dye, metal, and solvent.

Nature of absorption bands of thiazolopyrimidinium polymethine dyes

Abstract Both symmetric and asymmetric thiazolopyrimidinium monomethine-, carbo- and dicarbo-cyanines have been synthesized. The wavelengths of the first two long-wave absorption bands have been investigated by physical and quantum-chemical methods. Electron density distributions for the ground, the first excited and second excited singlet states have been calculated. The electron redistribution diagrams were used to analyze the localization of electron transitions. The first band has been shown to be localized in the polymethine chain (Kuhns chain) while the second band is mainly localized in the thiazolopyrimidinium end-group.

A study of the vinylene shifts in polymethine dyes with sulphur-containing end-groups

Abstract A series of polymethine dyes with sulphur-containing end-groups have been investigated by spectral and quantum-chemical methods. The shift in absorption maximum with lengthening of the polymethine chain has been shown to depend on the nature of the first member of the vinylene series. Possible causes of this are discussed and a correlation between the first vinylene shift and the electron density change on excitation at the sulphur atoms has been established.

A simple treatment of bridge-induced shifts of absorption for symmetric polymethine dyes with a bridged chromophore

Abstract A simple topological model is developed which accounts for the effects caused on the absorption region of symmetric polymethine dyes by a cyclic fragment of the C 2v symmetry incorporated in their main chromophore. In the context of the Green’s function formalism, relationships between the structure of a dye molecule (represented by additive topological parameters of end groups, bridge, and the polymethine chain) and bridge-induced shifts of absorption maxima are derived. The trends revealed in signs and magnitudes of the absorption shifts are exemplified by treatment of squaraine and thiosquaraine molecules. ©