A new luminescent Mnii complex based on 1-benzyl-3,4-bis(diphenylphosphoryl)pyrrolidine ligand has been synthesized and fully characterized. This complex exhibits intense luminescence in the solid state (lem = 585 nm) with a high quantum yield (60%) as well as luminescence lifetime of 17 ms.

Polymer films doped by Eu(III) complexes are promising candidates for the development of luminescent chemosensors. Here, luminescent properties of Eu(III) carboxylate dibenzoylmethanates in interaction with ammonia and amine vapors have been studied. Quantitative measurements of the optical response showed that with an increase of the analyte concentration in the range of 3-330 ppm, an increase in the luminescence intensity of europium(III) is observed. The reversibility of the luminescent response is established. Quantum chemical calculations showed that ammonia and amine molecules enter not in the Eu(III) coordination sphere, but forms hydrogen bonds between analyte molecules and carbonyl groups of the dibenzoylmethanate ion. Moreover, analyte changes ligand coordination mode: there occur the transformation from tridentate-bridgingcyclic coordination of carboxyl groups to bidentate-bridging which leads to decreasing in the efficiency of crossrelaxation of lanthanide ions. The obtained "turn-on" chemosensory polymer materials are promising for environmental monitoring and food safety testing.

A series of methoxylated bis(pentafluorophenyl)boron-beta-diketonates (dkB(C6F5)(2)) with intense emission has been synthesized and characterized by a variety of physicochemical methods. The photophysical properties of the synthesized compounds were thoroughly investigated by electronic absorption, steady-state, and time-resolved fluorescence spectroscopy in both solution and solid state. The studied compounds exhibit solvatochromic behavior attributed to the intramolecular charge transfer (ICT) nature of the first excited state. The formation of exciplexes between DBMB(C6F5)(2) and benzene derivatives was also studied. Notably, the studied compounds display a complex luminescence profile in the solid state, featuring fluorescence, delayed fluorescence and phosphorescence emission. Furthermore, the hydrolytical stability of the complexes was assessed, demonstrating excellent resistance to hydrolysis. Estimated rate constants, determined at 60 degrees C, are significantly lower (90-2000 times) than those observed for the well-studied dibenzoylmethanatoboron difluoride (DBMBF2). The incorporation of pentafluorophenyl substituents at the boron atom enables the synthesis of highly fluorescent and hydrolytically stable boron chelate complexes, suitable for sensing and bioimaging applications in water-containing environments.

Nowadays, the synthesis and investigation of the properties of new fluorescent polymers based on polysiloxanes and organic fluorophores is an actual topic of research. These polymers find application in various fields of science and technology, in particular, as sensors, fluorescent covers, and optical materials. This work describes the method for obtaining new naphthalene end-capped and side-chain modified polydimethylsiloxanes. The physicochemical, optical, and thermal properties of the resulting polymers are thoroughly studied.

The complexation of dibenzoylmethanatoboron difluoride (DBMBF2) 2 ) with (3- cyclodextrin ( (3- CD) was studied in a water/acetone (99:1, v/v) mixture using electronic absorption, steady-state and time-resolved fluorescence spectroscopy as well as the time-resolved fluorescence anisotropy method. The introduction of (3- CD to the water/acetone mixture enhanced the solubility of DBMBF2, 2 , indicating the formation of a DBMBF2/(3-CD 2 / (3- CD complex. Analysis of the fluorescence intensity of DBMBF2 2 solutions as a function of (3- CD concentration revealed a 1:1 binding stoichiometry with a binding constant of 275 M-1.-1 . The interaction of DBMBF2 2 with (3- CD results in a reduced fluorescence quantum yield, a shorter fluorescent lifetime, and an increased rotational correlation time. Upon evaporation of the solvent from the solution containing the DBMBF2/(3-CD 2 / (3- CD complex, a transparent film is formed, exhibiting a fluorescence spectrum similar to DBMBF2 2 solutions. The complexation reduced the stability of DBMBF2 2 to hydrolysis. DFT-based quantum-chemical calculations were used to model the structure of the supramolecular DBMBF2/(3-CD 2 / (3- CD complexes.

Crosslinked polysiloxanes with boron bis(dibenzoylmethanate) complexes used as crosslink junctions of polymer networks are first synthesized, and their physicochemical, mechanical, thermal, and fluorescent properties are studied. It is shown that the polymers under study feature the elastic behavior, possess high thermal and thermo-oxidative stability, and exhibit intense fluorescence in a wide wavelength range (400‒700 nm).

Fluorescent dyes which exhibit emission/excitation in the second near-infrared (NIR-II, 1000-1350 nm) region are currently attracting significant attention in bioimaging and diagnostics applications. Furthermore, dyes with high two-photon absorption cross-section (TPA), such as BODIPY derivatives, are of a particular interest due to deeper signal penetration into biological tissues, better image contrast, reduced phototoxicity and photobleaching. Herein we report the synthesis and properties of new monomeric and dimeric di-styryl-BODIPY dyes, which have absorption maxima near 625 nm and emission in the range of 600-800 nm (NIR-I, 650-950 nm). For the first time, we used a femtosecond Cr:Forsterite laser with a wavelength of 1250 nm (NIR-II) for the excitation of NIR-I di-styryl-BODIPY dyes by TPA. A cooperative effect was observed for TPA for the dimeric di-styryl-BODIPY dyes. The results obtained may be of great interest due to their potential applications in bioimaging and photodynamic therapy.

A seriesof new tetrachromophoric systems based on stereoregulartetracyclosiloxanes and dibenzoylmethanatoboron difluoride derivativeshave been synthesized and characterized by a complex of physicochemicalmethods. The photophysical properties of the synthesized compoundsare studied by electronic absorption, steady-state, and time-resolvedfluorescence spectroscopy. In the synthesized compounds, four dibenzoylmethanatoborondifluoride (DBMBF2)-based fluorophores are in an all-cisarrangement with respect to a cyclotetrasiloxane scaffold. DFT calculationspredict that they can form H-type dimers, trimers, or tetramers withan antiparallel orientation of their ground-state dipole moments.Under UV excitation, solutions of these compounds in polar and nonpolarsolvents exhibit complex fluorescence consisting of monomer- and excimer-likeemissions with different lifetimes. Global fitting analysis revealsthe presence of at least four kinetically distinguishable speciesin the excited state. The studied compounds in solutions have CIEchromaticity coordinates very close to the white color point and arepromising objects for the development of next-generation single-emissionmaterials for white illumination.

Long-lived delayed fluorescence of dispersions of microcrystals of naphthalene–β-cyclodextrin–cyclohexane ternary complexes has been studied. It has been established that the delayed fluorescence is due to the T–T annihilation process. The kinetics of delayed fluorescence has a nonexponential character; the average lifetime is 0.68 s. The shape of the decay rate curves of delayed fluorescence does not depend on the intensity of excitation light. The nonexponential nature of the delayed fluorescence is presumably associated with the presence in the crystals of paired naphthalene molecules with different mutual positions and pair formation energies.

In the present work, a method for the preparation of the new luminescent polymer compositions was described. A series of polymer films based on organosilicon dimethylsiloxane-phenylsilsesquioxane block-copolymer con-taining flexible linear dimethylsiloxane and rigid polycyclic phenylsilsesquioxane blocks in the structure of the macromolecule and polyfunctional phenyleuropiumethoxysiloxane [C6H5Si(OC2H5)2O]3Eu, as a molecular luminescent filler, was prepared and fully characterized. Physicochemical, mechanical, optical, and thermal properties all the polymer films were investigated. The polymer films form stable 3D networks and demonstrate a high thermal and thermo-oxidative stability. The study of mechanical properties showed that the tensile strength is in the range of 14-19 MPa, elongation at break is in the range of 5-8% and the Young's modulus is in the range of 380-560 MPa for the investigated polymers. The optical properties of the polymers were studied in the solid state at room temperature. It was shown, that upon excitation with 310 nm UV light the emission spectra of all samples show the five emission peaks that are characteristic for the Eu3+ ion arising from the 5D0 -> 7FJ (J = 0-4) transitions.

The photophysical properties of functional distyryl derivatives of dipyrrometheneboron difluoride (BODIPY) in various solvents have been studied. It was shown that in all solvents, the studied compounds have similar absorption and fluorescence spectra, which are characteristic of the distyryl derivatives of BODIPY. Small bathochromic shifts of the spectra with increasing solvent polarity, as well as insignificant changes in the rate constants of radiative and nonradiative processes, provide evidence that the S1 states are of the (π,π*) type. These dyes can be used to visualize processes in living systems.

A series of new dibenzoylmethanatoboron difluoride (DBMBF2) and methoxy-substituted DBMBF2 dyads linked via flexible diphenylsiloxane linkers of various length have been synthesized and characterized. The structure and optical properties of these compounds were studied by X-ray single-crystal measurements, electron absorption, and steady-state and time-resolved fluorescence spectroscopy. In the dyads under study, which are in an equilibrium between the open and folded conformations, the formation of intramolecular H-dimers in the ground state are observed. For the dyads in dilute solutions in various solvents, both monomer and excimer (through intramolecular excimer formation) emissions are observed at room temperature. The effect of solvent polarity and linker length on the formation of intramolecular excimers has been studied. The contribution of excimers into the total fluorescence spectrum decreases with increasing the solvent polarity, and the length of the siloxane linker. The studied dyads in hexane and cyclohexane solutions have CIE chromaticity coordinates very close to the white color point. The mechanofluorochromic properties of the synthesized dyads were studied.

Novel BODIPY and DBMBF2dyads connectedviaa flexible trisiloxane linker were synthesized and their photophysical properties were investigated.

Photoprocesses in 1,4-diazadistyrylbenzene (1) and 1,3-diazadistyrylbenzene derivative (2) diperchlorates in MeCN were studied by absorption, luminescence, and kinetic laser spectroscopies. For compound 1, trans-cis-photoisomerization and intersystem crossing to a triplet state are observed. For compound 2, photoelectrocyclization is suggested. Quantum chemical calculations of diazadistyrylbenzene structures in the ground and excited states were carried out. The schemes for photoreactions were proposed.

Compounds sensitive to reactive oxygen species are widely used in the study of processes in living cells and in the development of therapeutic agents for photodynamic therapy. In the present work, we have synthesized a dyad in which the BODIPY dye is chemically bound to 9,10-diphenylanthracene (DPA). Here, DPA acts as a specific sensor of singlet oxygen and BODIPY as a reference dye. We studied the photophysical properties of the BODIPY-DPA dyad and showed that energy transfer occurs between the chromophores. As a result, the compound has excitation maxima in the absorption region of both DPA and BODIPY, but the fluorescence emission occurs mainly from BODIPY. In the presence of singlet oxygen, the excitation maximum of DPA decreases, while the intensity of the excitation maximum of BODIPY remains almost unchanged. This allows the BODIPY-DPA dyad to be used as a ratiometric sensor of singlet oxygen.

Nowadays, luminescent materials attract wide attention due to their valuable characteristics and broad area of potential application. Luminescent silicone-based polymers possess unique properties, such as flexibility, hydrophobicity, thermal and chemical stabilities, etc., which allow them to be utilized in various fields, such as optoelectronics, solid-state lasers, luminescent solar concentrators, sensors, and others. In the present work, a metal-ligand interaction approach was applied to obtain new cross-linked luminescent polymers based on multiligand polysiloxanes with grafted β-diketone fragments and organoeuropiumsiloxanes containing various organic substituents. Organoeuropiumsiloxanes were utilized as a source of Eu3+ ions due to their compatibility with the silicon matrix. All synthesized polymers were fully characterized and their physicochemical, mechanical, self-healing, optical, and thermal properties were studied.

This review considers the main stages in the development of fluorescent chemosensor materials performed at the Photochemistry Center of the Russian Academy of Sciences over the past 15 years. Systems based on original acridine dyes synthesized at the Photochemistry Center and well-known fluorescent dyes and fluorophores of the family of boron difluoride diketonates are described. Polymer films and microparticles and silica micro- and nanoparticles have been studied as solid-state matrices for chemosensors.

A series of multifluorophore compounds with two, four, six and eight BODIPY residues linked to a siloxane core via a flexible spacer was synthesized. An increasing number of BODIPY units caused an enhanced propensity to chromophore aggregation with characteristic photophysical effects evoked by the aggregation. The increase in the number of fluorophores additionally resulted in considerable increase in molar extinction coefficient. Meanwhile, a slight drop of the extinction coefficient as calculated per a single chromophore was detected. Multifluorophore conjugates showed a significant broadening of fluorescence emission bands in polar solvents and a substantial decrease in the fluorescence quantum yield due to the aggregation-caused quenching. Time resolved fluorescence measurements of multifluorophore compounds in different solvents showed that the fluorescence decays have a multiexponential character and strongly depend on the number of fluorophores in the conjugate, polarity/viscosity of the solvent and the detection wavelength.

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.