Effect of Substituents on TICT Rate in Thioflavin T-Based Fluorescent Molecular Rotors

New fluorescent molecular rotors (FMRs) were developed by modification of the Thioflavin T (ThT) structure via introduction of methyl and methoxy groups. Effects of the substituents on fluorescence properties and twisted intramolecular charge transfer (TICT) rate in the excited state of the molecules were studied using steady-state fluorescence and time-resolved absorption spectroscopy. Quantum chemical calculations of the molecules in the ground and excited states were carried out to aid interpretation of the experimental results. Only cationic forms of ThT derivatives have FMR properties and exhibit viscosity-dependent fluorescence. The TICT rate was found to be affected by the size of the molecular fragments, which experience mutual rotation, dihedral angle [Formula: see text] between the fragments in the ground state as well as their donor/acceptor properties.

Sol–Gel Fabrication and Luminescence Properties of Multilayer Eu-Doped BaTiO3–SiO2 Xerogel Nanostructures

With the use of sol–gel method BaTiO3–SiO2 multilayer structures were fabricated on glass or fused silica substrates employing dipping or spinning procedure. The photonic stop band was observed in the reflection and transmission spectra of the multilayer structure annealed at [Formula: see text]C. It is redshifted with an increase of the thicknesses of BaTiO3 and SiO2 layers. For structures comprising Eu-doped BaTiO3 layers of different thicknesses photoluminescence with the main band at 614[Formula: see text]nm was detected. It is characterized with the double-exponential decay with the lifetimes of about 0.5[Formula: see text]ms and 1.1[Formula: see text]ms which do not depend significantly on the photonic stop band position.

Fast relaxation processes and structural changes in immunoactive biomolecules

Based upon an analysis of the absorption spectra, the fluorescence and fluorescence excitation spectra, and the lifetime of the excited states of aqueous solutions (pH 7.4) of 2,3-dimethoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dione, it is established that two centers of different type exist: one emits long-wave (L-centers) and the other short-wave (S-centers) fluorescence. Irradiation of solutions increases the number of L-centers and greatly decreases that of S-centers. Examination of the picosecond transient absorption spectra and their kinetics revealed that the initial photochemical stage is defined as the ionization of a considered molecule and the subsequent one, as the formation, most probably, of the dehydroderivative of a parent molecule.