A new pentafluorinated derivative of (dibenzoylmethanato)boron difluoride (5F-DBMBF2) was synthesized and studied as an “off–on” fluorescent probe for benzene derivatives with a reversible detection capability.
A method for the preparation of polydimethylsiloxanes with grafted methoxy-substituted dibenzoylmethanatoboron difluoride has been described. The structures of prepared polymers were confirmed using NMR, IR spectroscopy and gel permeation chromatography methods. Their thermal properties were investigated using thermal gravimetric analysis, differential scanning calorimetry and thermomechanical analysis. The prepared polymers had good thermal (Td5% up to 393 °C) and thermo-oxidative (Td5% = 413 °C) stability. The polymers started to transit in a viscous flow state at about 40 °C (for 3 a) and at about 20 °C (for 3 b). The viscoelastic characteristics of prepared polymers were determined in the sinusoidal oscillating vibrations mode. It was shown that the studied polymers at low frequencies at room temperature are viscoelastic fluids (G′ < G″). Increasing the frequency led to inversion (crossover) of dependences G′ and G″, which indicated the transition of polymers from viscous to elastomeric behavior characteristics, and the beginning of the formation of a physical network. Optical properties were studied using electron absorption, steady-state and time-resolved fluorescence spectroscopy. It was shown that intramolecular H-dimers exist in the ground state. The polymers studied had a bright fluorescence in the solution and in the solid state, consisting of bands of monomer and excimer emission. Thermally-activated delayed fluorescence was observed in the solution and the solid state. The prepared polymers possess intriguing properties that make them useful as optical materials, sensors or imaging agents.
A series
of new tetrachromophoric systems based on stereoregular
tetracyclosiloxanes and dibenzoylmethanatoboron difluoride derivatives
have been synthesized and characterized by a complex of physicochemical
methods. The photophysical properties of the synthesized compounds
are studied by electronic absorption, steady-state, and time-resolved
fluorescence spectroscopy. In the synthesized compounds, four dibenzoylmethanatoboron
difluoride (DBMBF2)-based fluorophores are in an all-cis
arrangement with respect to a cyclotetrasiloxane scaffold. DFT calculations
predict that they can form H-type dimers, trimers, or tetramers with
an antiparallel orientation of their ground-state dipole moments.
Under UV excitation, solutions of these compounds in polar and nonpolar
solvents exhibit complex fluorescence consisting of monomer- and excimer-like
emissions with different lifetimes. Global fitting analysis reveals
the presence of at least four kinetically distinguishable species
in the excited state. The studied compounds in solutions have CIE
chromaticity coordinates very close to the white color point and are
promising objects for the development of next-generation single-emission
materials for white illumination.
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