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The basic photophysical characteristics and the hydrolytic stability and photostability of dibenzoylmethanatoboron complexes containing various substituents at the boron atom have been studied. It has been found that the hydrolytic stability of these complexes increases in the order DBMBO < DBMBF2 < DBMB(C6F5)2. The rate constants of the hydrolysis reaction and the energy (EA), enthalpy (ΔH≠), and entropy (ΔS≠) of activation have been calculated from the data obtained. The study of the photostability of boron complexes of dibenzoylmethane showed that the photodegradation of these compounds in acetonitrile increases in the order DBMBF2 < DBMBO < DBMB(C6F5)2 and correlates with the change in ΔH≠ of hydrolysis.

Preparation and properties of photoactive polymeric materials based on mesoporous matrices of high-density polyethylene and Butyl Rhodamine B are described. The above materials are characterized by well-pronounced fluorescence response, and its intensity is controlled by pore dimensions of the mesoporous matrix and by the presence of highly viscous inert additive (dioctyl phthalate) at fixed porosity and dye concentration. Upon interaction with heavy anions (iodine), fluorescence quenching of the sensing additive takes place.

Four tetrahedral silicon-centered derivatives of dibenzoylmethanatoboron difluoride (DBMBF2 ) were synthesized and characterized. Their structural and optical features both in solution and the solid state were investigated by using X-ray crystallography, steady-state and time-dependent spectroscopy, and DFT-based calculations. In dilute solutions, the molar absorption coefficient increases from 40500 to 175200 M-1 cm-1 as the number of DBMBF2 fragments in a molecule increases from one to four, while, in contrast, the nonradiative rate constant of fluorescence decay decreases from 0.49 to 0.34. In the solid state, absorption and emission spectra depend on the degree of crystallinity and microcrystal size. The tris-DBMBF2 derivative forms fully overlapping dimeric structures that exhibit excimer-like fluorescence, which is accurately predicted by the quantum-chemical calculations. The mono-DBMBF2 derivative exhibits fully reverse mechanofluorochromic behavior.

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. The structure and optical properties of the DBMBF2 derivative with one pentafluorinated phenyl group were studied by X-ray single-crystal measurements, steady-state UV-visible spectroscopy and computational modeling. 5F-DBMBF2 is non-planar in the ground state, the fluorinated phenyl ring and dioxaborine heterocycle are inclined at an angle of 30° relative to each other. 5F-DBMBF2 shows no detectable fluorescence in non-aromatic solvents, but exhibits exciplex emission in the presence of benzene, chlorobenzene, toluene, o- and m-xylenes with considerable red-shifted maxima as compared with corresponding exciplexes of the parent unsubstituted DBMBF2. DFT calculations predict that the geometric rearrangements during the exciplex formation from a van der Waals complex of 5F-DBMBF2 with benzene in the ground state involve rotating the perfluorinated phenyl ring by about 10°, shortening of the C–C bond between the phenyl and dioxaborine rings, and a decrease in the average interplanar distance between 5F-DBMBF2 and benzene molecules by about 0.7 A.

It has been shown that the introduction of electron-donating or electron-withdrawing groups in the para-position of dibenzoylmethanatoboron difluoride (DBMBF2) makes it possible to control the fluorescenсe characteristics of fluorophore exciplexes with methylbenzenes (MB). The fluorescent properties of DBMBF2/MB exciplexes at the gas–solid interface have been studied using the example of DBMBF2 adsorbed on the surface of trimethylsilylated aerosil.

New mono-, bis- and tetra-fluorophoric organosilicon naphthalene derivatives, that are able to form intramolecular excimers have been synthesized and characterized. The synthesized compounds show only monomeric fluorescence in dilute solutions of common organic solvents, but exhibit relatively strong excimer-like emission in DMSO-water and THF-water mixtures. In all cases, the intensity of excimer fluorescence increases with increasing water content and decreases with increasing temperature. Fully and partially overlapping excimer conformations have been modeled by DFT-based calculations. Properties of different intramolecular excimers in an ensemble of four naphthalene molecules linked to a cyclotetrasiloxane ring in an all-cis arrangement are considered.

Silica nanoparticles (SNPs) with a diameter of 100 nm and surface-modified by covalently linked dibenzoylmethanatoboron difluoride have been synthesized and characterized. Suspensions of SNPs in dichloroethane are used as ink suitable for the microvalve ink-jet printing of sensing layers. It is demonstrated that SNP-based thin films are sensitive for methylbenzene vapors and could be a good candidate as a printed sensor. Responses of sensing films to methylbenzene vapors are analyzed using multivariate nonlinear regression.

A series of (dibenzoylmethanato)boron difluoride (BF 2 DBM) derivatives with a halogen atom in one of the phenyl rings at the para -position were synthesized and used to elucidate the effects of changing the attached halogen atom on the photophysical properties of BF 2 DBM. The room-temperature absorption and fluorescence maxima of fluoro-, chloro-, bromo- and iodo-substituted derivatives of BF 2 DBM in THF are red-shifted by about 2–10 nm relative to the corresponding peaks of the parent BF 2 DBM. The fluorescence quantum yields of the halogenated BF 2 DBMs (except the iodinated derivative) are larger than that of the unsubstituted BF 2 DBM. All the synthesized compounds are able to form fluorescent exciplexes with benzene and toluene (emission maxima at λ em = 433 and 445 nm, respectively). The conformational structure and electronic spectral properties of halogenated BF 2 DBMs have been modeled by DFT/TDDFT calculations at the PBE0/SVP level of theory. The structure and fluorescence spectra of exciplexes were calculated using the CIS method with empirical dispersion correction.

Boron 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 Abstract Luminescence of J-aggregates and the formation of excimers in crystals of 1 and 2.

Samples of sensor layers containing a mixture of spherical silica gel microparticles and spherical macromolecular silica sol nanoparticles have been prepared by inkjet printing. The average diameter of microparticles is 5 μm; nanoparticles about 100 nm in diameter contain covalently anchored fluorophore, dibenzoylmethane boron difluoride (DBMBF2), on the surface. The microstructure of the layers is shown to considerably affect the availability of the fluorophore indicator for gas-phase analyte molecules of the methylbenzene group. The sensitivity of the sensor layers is shown to reach 0.5 ppm with a response time of about 100 s.

A simple fluorescent sensor utilizing a material based on dibenzoylmethanatoboron difluoride (DBMBF 2 ) fluorophore capable of forming exciplexes with benzene, toluene and xylenes (BTX) has been developed. A physicochemical model for the dependence of the sample emission spectra on exposure to vapors of aromatic compounds was used to formulate criteria which should be fulfilled to detect individual analytes in a multicomponent mixture. It is experimentally demonstrated that after calibration the sensor provides simultaneous quantification of benzene, toluene and p -xylene in three-component mixtures. The approach proposed can be applied to a wide range of fluorescent sensor materials based on donor-acceptor interactions in the excited states.

A series of novel dibenzoylmethanatoboron difluoride (DBMBF2) and methoxy-substituted DBMBF2 dyads linked via flexible dimethylsiloxane linkers of variable length were synthesized and characterized. Both monomer and excimer (trough intramolecular excimer formation) emissions are observed for the dyads in dilute dichloromethane solutions at room temperature. The excimers contribution into the total fluorescence spectrum decreases with increasing siloxane linker length. The parallel-sandwich conformation of intramolecular pre-excimers formed by two terminal DBMBF2 moieties is confirmed by DFT-based calculations.

A procedure for preparing transparent silica gels and xerogels has been developed and samples of these materials have been fabricated to investigate the effect of microenvironment on spectral and sensor properties of the Nile Red dye. Spectral properties of the dye in modified and unmodified gels and xerogels have been investigated using fluorescence spectroscopy. It has been found that these xerogels are permeable to volatile organic substances, and their potential use as fluorescent sensor material has been demonstrated.

Dibenzoylmethanatoboron difluoride (DBMBF2) is a fluorophore capable of forming exciplexes with benzene and its derivatives in solutions [1] or in the adsorbed state on the silica gel surface by reacting with vapor of these substances [2, 3], a property that may be used for the fabrication of highly selective and responsive sensor devices. In this study, the dependence of the fluorescence spectra of silica-supported DBMBF2 samples on the vapor concentration of the aromatic compounds benzene, toluene, and p-xylene has been examined. A model describing the observed spectral changes has been proposed. The data on the concentration dependence of the fluorescence spectra of silica gel microspheres bearing adsorbed DBMBF2 are in good agreement with the proposed model.

The nature of absorption bandshapes of dibenzoylmethanatoboron difluoride (DBMBF2) dye substituted in ortho-, meta-, and para-positions of the phenyl ring is investigated using DFT and TDDFT with the range-separated hybrid CAM-B3LYP functional and the 6-311G(d,p) basis set. The solvent effects are taken into account within the polarized continuum model. The vibronic bandshape is simulated using a time-dependent linear coupling model with a vertical gradient approach through an original code. For flexible chromophores, the spectra of individual conformers are summed up with Boltzmann factors. It is shown that the long-wavelength absorption bandshape of DBMBF2 derivatives is determined by three factors: the relative statistical weights of conformers with different electronic absorption patterns, the relative position and intensity of the second low-energy electronic transition, and the vibronic structure of individual electronic peaks. The latter is governed by the relationship between the hard vibrational modes, which contribute to vibronic progression, and soft modes, which provide broadening of the peaks. The simulated spectra of the dyes in the study are generally consistent with the available experimental data and explain the observed spectral features.

The applicabilities of various CIS- and TDDFT-based procedures to the calculation of the fluorescence spectra of DBMBF2 exciplexes with aromatic hydrocarbons are analyzed. It is shown that a reasonable agreement between the calculated and experimental fluorescence spectra is obtained when a combined procedure is used. In this combined procedure, the geometries of the exciplexes are optimized beforehand using the CIS method with an empirical dispersion correction, while the exciplex transition energies are calculated at the optimized geometries using the CIS(D) method or the TDDFT approach with double-hybrid B2PLYP and mPW2PLYP functionals.

Structures of the (dibenzoylmethanato)boron difluoride molecule (DBMBF2) and its complexes with a series of aromatic hydrocarbons (benzene; toluene; o-, m-, and p-xylenes, naphthalene; anthracene; and pyrene) in the ground and the first singlet excited states have been calculated. The calculations have been performed by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) for the ground and excited states, respectively, with the empirical dispersion correction. It has been shown that the complexes in the ground and excited states have similar stacking structures and are characterized by short contacts between the F atom of DBMBF2 and H atoms of the hydrocarbon molecule, which decrease on transition from the ground to the excited state. The calculated binding energies in the complexes in the excited state are two to three times higher than those in the ground state. The charge transfer in the ground state of the complexes is insignificant and directed from DBMBF2 to the ligand, while in the excited state it is 0.6–0.8 e and directed from the ligand to DBMBF2.

The synthesis of three 9-diarylamino-substituted acridines is reported. The compounds of the donor–acceptor type – N,N-diphenylacridin-9-amine (1), 2,7-dimethyl-N,N-bis(4-methylphenyl)acridin-9-amine (2), and 2,7-bis(1-methyl-1-phenylethyl)-N,N-bis[4-(1-methyl-1-phenylethyl)phenyl]acridin-9-amine (3) were characterized by IR, 1H and 13C NMR, mass-spectral and elemental analysis. The crystal structures of compounds 1–3 and their protonated forms were determined by X-ray diffraction analysis. The absorption and fluorescence spectra were measured in various solvents. Solvatochromic shifts and dependence of the fluorescence quantum yields on the solvent polarity and protonation suggest the use of these compounds as chemical sensors. An example of a sensor material based on compound 2 is presented. Density functional theory calculations of the structures and time-dependent density functional theory calculations of the gas-phase excitation and emission energies of 1 were performed at the PBE0/SVP level of theory.

The UV photostability of boron difluoride dibenzoylmethanate (DBMBF2) in the aprotic solvents acetonitrile, dimethylsulfoxide, acetone, methyl cyclohexane, dioxane, and tetrahydrofuran has been studied. The DBMBF2 half-life largely depends on the solvent and varies from 3 min in tetrahydrofuran to 9 h 40 min in acetonitrile. It has been found that the photodegradation of DBMBF2 involves the detachment of the BF2 molecule to yield dibenzoylmethane occurring in the ketone (absorption at 220–240 nm) and enol (absorption at 340–345 nm) forms. It has been shown that DBMBF2 can be stabilized by sterically hindered piperidines, thereby suggesting the participation of singlet oxygen in the photodegradation of DBMBF2.

Alkoxysilyl derivatives of dibenzoylmethanatoboron difluoride (DBMBF2) are synthesized by the hydrosilylation reaction of the corresponding O-allyl derivatives of DBMBF2 with triethoxysilane. The photophysical properties of the synthesized O-allyl and alkoxysilyl derivatives are investigated. It is found that the absorption and fluorescence spectra of the DBMBF2 derivatives essentially depend on the position of the O-allyl or O-propyl alkoxysilyl substituent. The highest fluorescence quantum yield is obtained for the para-position, whereas the substitution at the meta-position gives the largest bathochromic shift in the fluorescence spectrum. Density functional theory calculations of the structures and time-dependent density functional theory calculations of the gas-phase excitation and emission energies of alkoxysilyl derivatives are performed at the PBE0/SVP level of theory. Some spectral features of para-, ortho-, and meta-substituted derivatives can be adequately explained by the overlapping of two absorption bands.

The molecular imprinting technique is used for the synthesis of monodisperse polymer particles via the seed emulsion copolymerization of methyl methacrylate, ethylene glycol dimethacrylate, and comonomers based on Nile Red. The introduction of lower alcohol templates into the reaction mixture and their removal after the synthesis lead to the formation of molecular-recognition sites in the shell that contain luminophore groups and give an optical response to the presence of methanol and ethanol in the gas phase. The particles are investigated via electron microscopy and dynamic light scattering, and their specific surface area is determined through the BET method. The kinetics of a change in the luminescence of thin films based on the particles in vapors of lower alcohols is investigated.

The process of naphthalene adsorption from the gas phase by layers of core-shell polymer nanoparticles obtained with the use of molecular imprinting methods is studied by the fluorescent analysis method. Within the pseudo-second-order kinetic model of sorption, data on the rate constants of fluorescence change are obtained, primary regularities of the sorption process are determined, and the presence of selective recognition sites in the shells of nanoparticles is proven.

Silica core-shell nanoparticles with SiO2 cores and an alkoxysilyl derivative of dibenzoylmethanatoboron difluoride (A-DBMBF2) fluorophore covalently attached to the core surface have been synthesized. It is shown that these nanoparticles can be used as the basis of selective sensor materials capable of detecting benzene, toluene, and xylene vapors. As benzene or its methyl derivatives are adsorbed on the surface of nanoparticles, a quenching of A-DBMBF2 fluorescence occurs while an A-DBMBF2/analyte exciplex fluorescence buildup emerges. The position of isoemissive points in the fluorescence spectra is specific for each analyte and can be used for its identification.

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.

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 metaxylene. 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 metaxylene. Results of the quantumchemical calculations of the struc� ture of the (dbm)BF2 monomer complex with the matrix and toluene and (dbm)BF2 dimers with matrix are presented.

It has been shown that fluorescence quenching of 2,7-dimethyl-N,N-di-p-tolylacridine-9-amine (9-DTAA) solutions in hexane and acetone by tetrabromomethane (TBM) was dynamic in nature with the quenching rate constants of 1.5 × 1010 and 0.6 × 1010 M−1s−1, respectively. The difference in the constants was explained by the possibility of competition between the processes of the formation of solvation shell around the excited singlet 9-DTAA* molecule and the formation of the 9-DTAA*/TBM encounter complex.

The interaction of 9-diphenylaminoacridine dye (indicator) with several small analyte molecules (methanol, acetonitrile, acetone, tetrahydrofuran, benzene, ammonia, formaldehyde, and acetaldehyde) has been theoretically studied in relation to the problem of the development of optical chemosensors based on organic dyes. The structures of the resulting complexes and the absorption spectra of 9-diphenylaminoacridine and its complexes with analytes were calculated using density functional theory (DFT) with the PBE0 functional and the 6-31G(d,p) basis set. It was demonstrated that complexes of two types with different mutual arrangements of molecules corresponding to the lateral and stacking structures can be formed for each analyte. The calculated absorption spectrum only weakly changes upon complex formation, which is in agreement with experimental data on the absorption spectra of 2,7-dimethyl-9-ditolylaminoacridine in solutions of corresponding solvents. The method for the calculation of excited states that was used in this work can be applied to the calculation of the fluorescence spectra of 9-diphenylaminoacridine complexes.

The structures of complexes of some small molecules (formaldehyde, acetaldehyde, ammonia, methylamine, methanol, ethanol, acetone, benzene, acetonitrile, ethyl acetate, chloroform, and tetrahydrofuran, considered as possible analytes) with ethylbenzene and silanol (C(6)H(5)C(2)H(5) and SiH(3)OH, considered as models of polystyrene and silica gel substrates) and with acridine (C(13)H(9)N, considered as a model of an indicator dye molecule of the acridine series) and the corresponding interaction energies have been calculated using the DFT-D approximation. The PBE exchange-correlation potential was used in the calculations. The structures of complexes between the analyte and the substrate were determined by optimizing their ground-state geometry using the SVP split-valence double-zeta plus polarization basis set. The complex formation energies were refined by single-point calculations at the calculated equilibrium geometries using the sufficiently large triple-zeta TZVPP basis set. The calculated interaction energies are used to assess the possibility of using dyes of the acridine series adsorbed on a polystyrene or silica substrate for detecting the small molecules listed above.

The organic-inorganic materials with fluorescence properties are synthesized in the form of gels and xerogels from tetraethoxysilane and glycidoxypropyltrimethoxysilane by the sol-gel method. The concentration of the introduced Nile Red dye is 2.2 × 10−6 M. The fluorescence spectra of the prepared materials are measured and analyzed as a function of the ratio between the initial components forming the sol-gel epoxy siloxane matrices. The assumption regarding the structure of the synthesized hybrids is made invoking the data obtained by Fourier-transform IR spectroscopy and atomic-force microscopy.

Complex (experimental and quantum-chemical) investigation of the spectral and luminescent properties of acridine, 9-aminoacridine, 2,7-dimethyl-9-ditolylaminoacridine, and their protonated forms was performed. The electronic absorption and fluorescence spectra of the acridine dyes were studied at room temperature in ethanolic solutions at different pH values and in other solvents of different chemical nature and polarity. The energies of the excited states, the deactivation rate constants for the excited states, and the dipole moments are presented, which were obtained by calculations using the method of intermediate neglect of the differential overlap with special spectroscopic parameterization.

Poly(styrene-co-N-vinylformamide) (poly(St-co-VFA)) nanoparticles with the diameter from 55 to 200 nm were prepared by emulsion copolymerization and their self-assembling was studied. In the dispersions of these particles, the formation of iridescent periodic colloid structures is observed. The period of the structures is about 220 nm and shows no cymbate dependence on the nanoparticle size, indicating the possible variety of packing types occurring during the self-assembling of nanoparticles in dispersions. For 250–300 nm sized poly(styrene-co-methacrylic acid) (poly(St-co-MAA)) particles, it was shown that ionization of their surface carboxylic groups in alkaline media leads to the considerable improvement of the photonic crystal structures obtained from the dispersions of these nanoparticles. It was demonstrated that cationic chromophores can be adsorbed on their negatively charged surface. In this way, chromophore-modified polymer photonic crystal materials for applications as gas or liquid sensors could be prepared, as their measured fluorescence spectra show remarkable and reversible responses to the presence of polar organic solvent vapors, e.g. acetone. Copyright © 2009 John Wiley & Sons, Ltd.

The hybrid organic-inorganic materials with fluorescence properties are synthesized in the form of gels and xerogels from tetraethoxysilane and a mixture of epoxy resins by the sol-gel method. The concentration of the introduced Nile Red dye is 1.6 × 10−6M. The fluorescence spectra of the prepared materials are measured and analyzed as a function of the ratio between the initial components forming the sol-gel epoxy siloxane matrices. The assumption regarding the structure of the synthesized hybrids is made invoking the data obtained by Fourier-transform IR spectroscopy and atomic-force microscopy.

An experimental system for investigating the characteristics of optical sensor materials, in particular, materials based on modified fluorescent micro- and nanoparticles, is described. The system can be used to obtain multicomponent gas-vapor mixtures, measure fluorescence and reflection spectra, and record color images of sensor materials with a time resolution of a few milliseconds. Experimental data obtained when investigating the responses of sensor materials to analytes are presented.

A detailed account of quantum chemical procedures for estimating the rate constants of the photophysical processes at work in polyatomic organic molecules is given. The results obtained from combined experimental and theoretical research into the spectral-luminescent properties of acridine, 9-aminoacridine, 2,7-dimethyl-9-diphenylaminoacridine, and of their protonated forms are reported. The electronic absorption and fluorescence spectra of acridine have been investigated at room temperature in ethanol solution of varying pH and in other solvents of different chemical nature and polarity. The energy of excited states, the rate constants of the deactivation of the excited states, and the dipole moments obtained by quantum chemical methods for the examined compounds are presented. The findings of the investigations are discussed.

The hybrid organic-inorganic materials with optical properties are synthesized in the form of gels and thin-layer coatings by the sol-gel method. The fluorescence of the materials synthesized is investigated as a function of the Nile Red concentration and the composition of the precursors forming the hybrid sol-gel matrices. It is demonstrated that the materials synthesized hold much promise for use in the fabrication of optical gas sensors.

The effect of intermolecular interactions of different types (universal interactions, H-bonding, electronic donor-acceptor interactions, and interactions with proton transfer) on the absorption and luminescence spectra of organic molecules of different classes, which are or can be used as optical molecular sensors, was considered. The classification of the types of intermolecular interactions and corresponding spectroscopic effects is given, which can be used, particular, in the development of optical sensors for detection of organic molecules in liquid and gaseous media.

The values of steady-state solvatochromic Stokes shifts (SS) in absorption/emission electronic spectra of organic chromophores are studied theoretically in the framework of the Hush-Marcus model. Charge distributions for chromophore solutes in their S0 and S1 states are found by means of conventional quantum-chemical methods combined with the continuum PCM approach for treating solvation effects. The solvent reorganization energies, which are expected to correlate with the solvent-induced part of 1/2 SS, are found in a molecular dynamics (MD) simulation which invokes a novel method for separation of the inertial piece of the electrostatic response (Vener, et al. J. Phys. Chem. B 2006, 110, 14950). Computations, performed in two solvents (acetonitrile and benzene), consider three organic dyes: coumarin 153 as a benchmark system and two other chromophores, for which experimental spectra are also reported. The results are found to be in reasonable agreement with the experiment. A consistent treatment of nonlinear effect in the solvent response, promoted by the polarizability of solutes and contributing to the solvent reorganization energies (Ingrosso, et al. J. Phys. Chem. B 2005, 109, 3553), improves the results of computations.

Electronic absorption and fluorescence spectra of the acridine dye 2,7-dimethyl-9-(ditolylamino)acridine were studied at room temperature in solvents of different polarity (hexane, toluene, chloroform, tetrahydrofuran, acetonitrile, etc.). The obtained data on the shift of the fluorescence band maximum depending on the solvent polarity were used for the estimation of the dipole moment of 2,7-dimethyl-9-ditolylaminoacridine in the ground and the first excited state.

An approach is proposed for the quantum-chemical calculation of the structure and fluorescence spectra of exciplexes. The procedure involves the geometry optimization of exciplexes using the CIS method with empirical dispersion correction (CIS-D) and the subsequent single-point calculation of the transition energy using the CIS method with perturbative correction for double excitations (CIS(D)). Calculated fluorescence band positions for exciplexes of (dibenzoylmethanato)boron difluoride with substituted benzenes are in reasonable agreement with the experimental data.

(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

The fluorescent spectra in combination with gas response behavior of acrylic polymers doped with dibenzoyl(methanato)boron difluoride (DBMBF2) were studied by fluorescence spectroscopy and time-resolved fluorescence lifetime. The role of acrylic matrix polarity upon the fluorescence spectra and fluorescence lifetime was analyzed. Changes in emission of the dye doped polymers under exposure to toluene, n-hexane and ethanol were monitored. The fluorescence lifetimes were measured for the singlet excited state as well as the exciplex formed between DBMBF2 and toluene. A reduction of the transition energy to the first singlet-excited state in the four polymers was observed, compared to solution. Reversible exciplex formation, viz. a red shifted fluorescence emission was perceived when exposing the polymers to toluene, while for hexane and ethanol only reversible reduction of the fluorescence occurred. Longer singlet and shorter exciplex lifetimes were observed for non-polar matrixes. The latter mechanism is explained in function of the lower charge transfer character of the exciplex in non-polar matrixes. Additionally, the quantum yield of the dye in the polymer matrix increased almost seventh-fold compared to values for solution.

Alkoxysilyl derivatives of dibenzoylmethanatoboron difluoride (DBMBF2) are synthesized by the hydrosilylation reaction of the corresponding O-allyl derivatives of DBMBF2 with triethoxysilane. The photophysical properties of the synthesized O-allyl and alkoxysilyl derivatives are investigated. It is found that the absorption and fluorescence spectra of the DBMBF2 derivatives essentially depend on the position of the O-allyl or O-propyl alkoxysilyl substituent. The highest fluorescence quantum yield is obtained for the para-position, whereas the substitution at the meta-position gives the largest bathochromic shift in the fluorescence spectrum. Density functional theory calculations of the structures and time-dependent density functional theory calculations of the gas-phase excitation and emission energies of alkoxysilyl derivatives are performed at the PBE0/SVP level of theory. Some spectral features of para-, ortho-, and meta-substituted derivatives can be adequately explained by the overlapping of two absorption bands.

FABRICATI$N OF FLUORESCENT AMMONIA SENSOR USING POLYMER NANOAND MICROPARTICLES Khlebunov*, D. Ionov, V. Sazhnikov, A. Koshkin, A. Aristarkhov, A. Petrov, N. Shevchenko, T. Evseeva, A. Menshikova, A. Yakimanski, M. Alfimov 1 Photochemistry Center, Russian Academy of Sciences, ul. Novatorov 7a , Moscow, 119421 Russia 2 Institute of Macromolecular Compounds, Russian Academy of Sciences, Bol’shoi pr. 31, St. Petersburg, 199004 Russia * Corresponding author: Artem Khlebunov, phone: +7-495-9361754, e-mail: byzantium@list.ru

1. The relative contribution of the triple bond to conjugation in the tert-butyl derivtives of tolan, diphenylacetylene, 4-tert-butyl-4′-(phenylethynyl)biphenyl, and 1,4-bis(p-tert-butylphenylethynyl) benzene is comparable with the contribution from a double bond or a phenyl ring. 2. The introduction of a phenyl ring into compounds with triple bonds leads to an increase in the fluorescence. 3. The reduction in the phosphorescence lifetime resulting from the increase in the number of triple bonds in the molecule is the result of an increase in the constant for the radiationless triplet—singlet transition.

An in-plane flexible sensor platform for BTXs detection was developed using low-cost patterning techniques and foil-based optical components. The platform was produced by a combination of laser patterning, inkjet printing and capillary filling. Key optical components such as lightguides, optical cladding layers and metallic interconnections were realized on low cost substrates such as paper and PET. The sensing mechanism is based on the change in fluorescence spectra of a reporter dye, supported over a porous matrix. Detection limits down to 1 ppm for benzene, toluene and xylene have been measured. Response times down to a few seconds were observed for different gas concentrations.