Daria V. Berdnikova

Regiospecific C–N Photocyclization of 2-Styrylquinolines

Regiospecific C-N photocyclization of 2-styrylquinolines resulting in formation of potentially biologically active quino[1,2-a]quinolizinium derivatives was investigated. The presence of strong electron-donating groups in the phenyl ring reveals to be a crucial factor managing photocyclization effectiveness. Introduction of a crown ether moiety allows changing the photoreaction parameters by means of complexation with Mg(ClO4)2.

Interaction of Crown Ether‐Annelated Styryl Dyes with Double‐Stranded DNA

DNA‐binding properties of 15‐crown‐5‐derived mono‐ and bis‐styryl dyes were investigated in the presence of calf thymus DNA. To access the factors that influence the DNA association in the series of these ligands, the structure of the molecules was varied by either changing size of the heterocyclic moiety or altering the position of the styryl substituents. The major binding mode for the monostyryl dyes is intercalation. Notably, binding of the dyes to the nucleic acids leads to a fluorescence enhancement by a factor of up to 54. Therefore, these cationic styryl derivatives may be applied as fluorescent “light‐up” probes for DNA detection.

Sedimentation stability of aqueous dispersions of nanodiamond agglomerates

The electric conductivity and sedimentation stability of aqueous dispersions of nanodiamond agglomerates are studied. The properties and stability of dispersions were shown to be significantly affected by the pretreatment of particles. The particle size distribution was determined by means of optical microscopy. The sedimentation kinetics of nanodiamond particles in aqueous solutions was studied. The sedimentation kinetic curves showed two sections of fast and slow sedimentation. The obtained results are necessary to develop the technology of nanoporous carriers in analytical and preparative chromatography

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

3-Hydroxynaphtho[1,2-b]quinolizinium was synthesized by cyclodehydration route and its optical properties in different media were investigated. The absorption and emission spectra of this compound depend on the pH of the solution. Thus, at higher pH values the deprotonation yields a merocyanine-type dye that exhibits significantly red-shifted absorption bands and causes a dual emisson, i.e., a combination of emission bands of the hydroxyquinolizinium and its deprotonated form. Whereas this compound is a weak acid in the ground state (pK a = 7.9), it has a strongly increased acidity in the excited state (pK a * = 0.4). As a result, the blue-shifted fluorescence of the hydroxyquinolizinium becomes dominant only under strongly acidic conditions. In addition, it is shown that 3-hydroxynaphtho[1,2-b]quinolizinium binds to cucurbit[7]uril (CB[7]) with moderate affinity (K b = 1.8 × 104 M−1, pH 5) and that the pK a and pK a * values of this ligand increase by about two to three orders of magnitude, respectively, when bound to CB[7].

Protonation-Gated Dual Photochromism of a Chromene–Styryl Dye Hybrid

A novel hybrid bisphotochromic system involving a chromene residue and a styryl dye fragment is described. Initially, the compound shows almost no photochromism due to intramolecular energy and electron transfer between the chromophores. Protonation of the hybrid system blocks the transfer processes and unlocks a dual photochromic activity that includes ring opening of the chromene fragment and E-Z-isomerization of the styryl dye residue. Deprotonation of any photoinduced form resets the system to the initial photoinactive form.