E. V. Fedorenko

Fluorescence quenching of silica gel-adsorbed (Dibenzoylmethanato)boron difluoride by polar solvent vapor

(Diketonato)boron difluoride dyes have beenwidely studied in the context of their use as laser dyesand materials for nonlinear optics, as well as components of solar collectors and electron diffraction materials [1]. Special recent attention has been given tounique optical properties of polylactides of (dibenzoylmethanato)boron difluoride (DBMBF

Crystal structure and luminescence of 2,2-difluoro-4,6-(4-methylphenyl)-1,3,2-dioxaborine

The crystal structure, luminescence properties of 2,2-difluoro-4,6-(4-methylphenyl)-1,3,2-dioxaborine (CH3C6H4COCHCOC6H4CH3BF2) crystals and solutions at different concentrations are examined at T 296 K and 156 K.

Luminescence of solvate of boron difluoride dibenzoylmethanate with benzene: Aggregates formation

The concentration dependence of spectral-luminescence properties of solutions boron difluoride dibenzoylmethanate (DBMBF2) in benzene and chloroform has been studied through stationary and time-resolved emission spectroscopy methods. The formation of J-aggregates in the solution of DBMBF2 in chloroform has been revealed and a crystalline adduct of DBMBF2 with benzene has been obtained. A bright blue adduct luminescence is due only to the luminescence of J-aggregates, unlike the crystals of DBMBF2, for which the luminescence of excimers and J-aggregates has been observed. The quantum chemistry simulation of geometric and electronic structure of the DBMBF2 С6Н6 solvate has been performed, and the absorption spectra of DBMBF2 and it is adduct have been calculated.

Crystal structure and luminescence properties of 4-(4-benzoyloxy-2-hydroxyphenyl)-2,2-difluoro-6-phenyl-1,3,2-dioxaborine

The crystal structure of 4-(4-benzoyloxy-2-hydroxyphenyl)-2,2-difluoro-6-phenyl-1,3,2-dioxaborine (1) was determined by X-ray diffraction analysis. π-π-Stacking interaction between the molecules results in joining the molecules into a three-dimensional layered framework. Luminescence of the aggregates is observed in concentrated solutions of compound 1. Two routes of excimer formation in crystal were revealed by steady-state and time-resolved luminescence spectroscopy: via excitation of single molecules and via excitation of aggregates.

Fluorescence Spectra and Structure of the Difluoro(dibenzoylmethanato)boron Monomers and Dimers Absorbed on Silica Gel

It has been shown that difluoro(dibenzoylmethanato)boron ((dbm)BF2) can be absorbed on silica gel in the form of fluorescent monomers and dimers with the emission properties that change in the presence of vapors of volatile organic compounds, such as ethanol, acetone, toluene, and meta-xylene. Fluorescence quenching was observed for the (dbm)BF2 monomers and dimers in the case of ethanol and acetone, whereas the formation of fluorescent exciplexes with monomers and enhancement of the dimer fluorescence were observed in the case of toluene and meta-xylene. Results of the quantum-chemical calculations of the structure of the (dbm)BF2 monomer complex with the matrix and toluene and (dbm)BF2 dimers with matrix are presented.

Fluorescence properties and conformation of dibenzoylmethanatoboron difluoride in solutions

The electronic absorption and fluorescence spectra of dibenzoylmethanatoboron difluoride (DBMBF2) in a number of polar and nonpolar solvents have been studied; the quantum yields and fluorescence lifetimes have been measured, and the vibrational structure of the spectra has been analyzed. The equilibrium configuration parameters of DBMBF2 in the ground state have been determined by the DFT method. It has been found that there is only one stable conformation of DBMBF2 in the ground state.

Boron difluoride dibenzoylmethane derivatives: Electronic structure and luminescence

Electronic structure and optical properties of boron difluoride dibenzoylmethanate and four of its derivatives have been studied by X-ray photoelectron spectroscopy, absorption and luminescence spectroscopy and quantum chemistry (DFT, TDDFT). The relative quantum luminescence yields have been revealed to correlate with charge transfers of HOMO-LUMO transitions, energy barriers of aromatic substituents rotation and the lifetime of excited states in the investigated complexes. The bathochromic shift of intensive bands in the optical spectra has been observed to occur when the functional groups are introduced into p-positions of phenyl cycles due to destabilizing HOMO levels. Calculated energy intervals between electronic levels correlate well with XPS spectra structure of valence and core electrons.

Nitrogen-Containing Analog of Dibenzoylmethanate of Boron Difluoride: Luminescence, Structure, Quantum Chemical Modeling, and Delay Fluorescence

AbstractBoron difluoride of 3-amino-1,3-diphenyl-2-propene-1-onate (1) has been synthesized and its crystal structure has been determined. The comparative studies of 1 and its oxygen analog 1,3-diphenyl-1,3-dionate (dibenzoylmethanate) of boron difluoride (2) have been performed using the methods of stationary and time-resolved spectroscopy and quantum chemical modeling. It was established that at the transition from solutions to crystals, a bathochromic shift of the spectra and a significant increase of luminescence intensity of 1 take place. The luminescent properties of solutions of 1 and 2 are similar. The peculiarities of crystal packings of 1 and 2 are responsible for differences in crystals luminescent properties. For crystals of 2, one observes the luminescence of J-aggregates and excimers, while for 1, in which a dimer is an elementary structural fragment, only the excimer luminescence is registered. A delayed excimer fluorescence of the P-type was observed for crystals of 1 and 2 at room temperature. The intensity of the delayed fluorescence of 1 is 300-fold higher than that of 2. Graphical AbstractLuminescence of J-aggregates and the formation of excimers in crystals of 1 and 2

Nitrogen-containing analogues of boron difluoride benzoylacetonate: synthesis, structure, luminescence, and quantum chemical modeling

Nitrogen-containing analogues of boron difluoride benzoylacetonate (1), i.e., boron difluoride ketoiminates (boron difluoride 3-amino-1-phenyl-2-buten-1-onate (2) and 3-methylamino-1-phenyl-2-buten-1-onate (3)), were taken as examples to study the influence of a substituent (H, Me) at the nitrogen atom on structure and spectral-luminescent properties. The replacement of the oxygen atom with the nitrogen atom in compound 1 led to a bathochromic shift of the monomeric luminescence maximum. Quantum chemical modeling of absorption spectra for compound 2 was carried out. In contrast to compounds 1 and 3, crystals of compound 2 are characterized by the formation of J-aggregates and excimers on their basis, which leads to a bathochromic shift of the luminescence spectrum and an increase in the luminescence intensity.

Photoinduced excimer formation of boron difluoride β-diketonates in poly(methyl methacrylate)

The photochemical behavior of β-diketonates of boron difluoride in poly(methyl methacrylate) was studied. Excimers of boron chelates are formed in the course of UV irradiation of polymer compositions accompanied by a bathochromic shift of the luminescence spectrum. The intensification (quenching) of luminescence of the polymer compositions during irradiation depends on the ratio of the quantum yields of the monomer and excimer luminescence of boron difluoride β-diketonates.