Photophysics and Photochemistry of Naphthoxazinone Derivatives (original) (raw)
Related papers
Journal of Photochemistry and Photobiology A-chemistry, 2009
The synthesis, the structural characterization and electrochemical and photophysical properties of new linear (OFn) and macrocyclic (MFn) bichromophoric systems containing one flavin and one naphthalene moiety, separated by (CH2)n alkyl chains (n = 4 or 6), are reported. The electrochemical properties of OF4, OF6, MF4, MF6 were investigated by cyclic voltammetry (CV) in ultra-dry THF and compared with the model compounds containing either the flavin unit (FL6) or the monomethoxy- (mona) and dimethoxy naphthalene (dmona) derivatives, respectively. While only minor ground-state interactions were evidenced between the chromophores in the voltammetric curves and absorption spectra of bichromophores, luminescence data evidenced intramolecular photoinduced electron transfer processes as main deactivation routes of flavin-centered excited states. The rates of the intramolecular photoinduced electron transfer, involving the oxynaphthalene moieties as electron donors, were finally determined.
Fluorescence Characteristics of Some Hydroxyl-Substituted Naphthalenes
The fluorescence characteristics of some hydroxyl substituted naphthalenes and their radical cations have been studied in a rigid matrix, Radical cations have been produced by photo -oxidation in boric acid glass at room temperature The observed longest absorption band maxima for these molecules and their radical cations has been compared with the calculated value obtained by using closed shell and open shell SCF-MO methods with limited configuration interaction. In the case of 1,2-dihydroxY-naphthalene, the appearance of an additional weaker band in fluorescence spectra on the longer wavelength side has been interpreted as due to intramolecular hydrogen bonding. Further, an approximate analysis of the vibronic structures of the fluorescence band has been reported. .
Isoxazolyl-Derived 1,4-Dihydroazolo[5,1-c][1,2,4]Triazines: Synthesis and Photochemical Properties
Molecules
New fluorescent dyes containing an assembled 1,4-dihydroazolo[5,1-c][1,2,4]triazine (DAT) core and an isoxazole ring were synthesized through a reaction between diazopyrazole or diazoimidazoles and isoxazolyl-derived enamines in mild conditions. The photophysical characteristics (maxima absorption and emission, Stokes shifts, fluorescent quantum yields, and fluorescence lifetimes) of the new fluorophores were obtained. The prepared DATs demonstrated emission maxima ranging within 433–487 nm, quantum yields within 6.1–33.3%, and a large Stokes shift. The photophysical characteristics of representative DAT examples were studied in ten different solvents. Specific (hydrogen bonds) and non-specific (dipole–dipole) intermolecular and intramolecular interactions were analyzed using XRD data and spectral experiments. Solvatochromism was analyzed using Lippert–Mataga and Dimroth–Reichardt plots, revealing the relationship between the DAT structure and the nature of solute–solvent interactio...
Journal of Physical Organic Chemistry, 1997
Electronic absorption and steady-state fluorescence emission of seven 3,4-dihydro-1-(2-p-substituted benzylidene)naphthalenones (1-7) show sizable solvent dependence. The charge-transfer (CT) absorption maxima of these compounds in various solvents show a red shift for the electron-donating substituted compounds (1-5), whereas a blue shift is observed for compounds possessing electron-withdrawing substituents (6, 7). Excitation into the lowest energy absorption gives emission from the locally excited state, which relaxes to the emitting intramolecular charge-transfer state for compounds with strong electron-donating substituents (1-3) in hydroxylic solvents. However, in moderately polar solvents, dual emissions are observed for these compounds. No CT emission is observed for the compounds with moderate electron-donating substituents (3 and 4) or those with electron-withdrawing substituents (6 and 7). Compound 1 with an -N(CH 3 ) 2 substituent shows an excited-state dipole moment of 17 D.
Journal of Photochemistry, 1985
Orbital correspondence analysis in maximum symmetry of the photoisomerization of naphthvalene to naphthalene, with predominant formation of its lowest triplet, is inconsistent with the assignment of the first excited singlet of naphthvalene to the highest occupied molecular orbitallowest unoccupied molecular orbital (HOMO-LUMO) st&e 'B,, suggesting instead that it is the totally symmetric open-shell singlet 'Al'. Computations with modified neglect of diatomic overlap and the correlated version of modified neglect of diatomic overlap confirm that the HOMO and LUMO indeed have bz and a2 symmetry respectively, but that the first-order configuration interaction stabilizes lA1' sufficiently to bring it below 'B1. These results illustrate the value of orbital symmetry analysis of photochemical reactions as an aid in the characterization of the relevant excited states and the necessity, in the present instance, of including c&figuration interaction, even for the purposes of qualitative discussion.
Optical Materials, 2015
Cyanine dyes of zero/bis-zero methine incorporating imidazo(1,2-a)Pyridine (quinoline) or pyrazino(1,2-a)pyridine (quinoline) with stable C-N bond were synthesized using keto-oxime methylene Clink heterocyclic quaternary salts [1-phenyl-3-methyl-pyrazolino-4-keto-oxime-α-methylene-bis-pyridin-(quin oin)-1(4)-di-ium-iodide(ethiodide) salts and 1-phenyl-3-methyl-pyrazolino-4-ketooxime-α-methylene-N-2-methyl-bis pyridin (quinoin)-1(4)-di-iumiodide(ethiodide) salts]. Such heterocyclic precursors and related dyes were identified by elemental and spectral analyses. The absorption spectra properties of such dyes were investigated in 95% Ethanol to attempt and throw some light on the influence of such new heterocyclic nuclei and to compare or evaluate spectral behaviors. The absorption spectra of dyes in different pure solvents were examined in the visible region showing solvatochromism and the colour changes of dyes with solvents having different polarities. This permits a selection of the optimal solvent (fractional solvent) when such dyes are applied as photosensitizers. The spectral behavior of some selected newly synthesized cyanine dyes is observed in mixed solvents of different polarities and progressively increasing quantities of one solvent over the other were studied and showed an increase in the absorbance of CT band with increasing proportion of that solvent. Evidence for hydrogen bond formation between the solute molecules and solvent molecules allows measurement of certain energies such as hydrogen bonding, orientation, and free energies.
Naphthotriazole derivatives: Synthesis and fluorescence properties
Dyes and Pigments, 2010
Eight fluorescent compounds containing a naphthotriazole moiety substituted at position 2 by a (vinylsulfonyl)aryl group or its precursors, containing either a hydroxyl or sulphonic acid groups or N-methylglycine, were prepared and characterized. The products were recovered in moderate yield after column chromatography or recrystallization and identified using 1 H and 13 C NMR; double resonance, heteronuclear multiple quantum coherence and heteronuclear multiple bond correlation experiments were carried out for complete assignment of proton and carbon signals. Absorption and emission spectra were obtained, in acetonitrile and fluorescence quantum yield determined. All compounds offer promise as fluorescent probes owing to their high fluorescence quantum yield.
Azacrown Ethers with Naphthyl Branches. Fluorescence Properties, Protonation and Metal Coordination
Journal of Inorganic and Organometallic Polymers and Materials, 2007
Starting from 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, we have prepared two compounds by replacing the amine hydrogens with naphthyl or 3,5-bis (2 0 -oxymethylnaphthyl)benzyl units. The absorption and emission spectra of compounds 2 (N,N 0 -bis(2-naphthylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) and 3 (N,N 0 -bis[3,5-bis(2 0 -oxymethylnaphthyl)benzyl]-1,4,10, 13-tetraoxa-7,16-diazacyclooctadecane) have been studied in CH 3 CN:CH 2 Cl 2 1:1 (v/v) solution. For comparison purposes, the spectroscopic properties of N-methyl(2methylnaphthalene)ethylamine (1) have also been investigated. For each compound, the absorption spectra are qualitatively very similar to that of naphthalene, with molar absorption coefficients as expected for the presence of one (1), two (2), and four (3) naphthyl chromophoric groups. The fluorescence spectra, however, are quite different from that of naphthalene. The naphthalene-type fluorescence (k max = 337 nm) is strongly quenched, particularly for compounds 1 and 2 which also exhibit a broad emission band in the visible region (k max & 480 nm) assigned to a low lying charge-transfer excited state. In the case of compound 3, a quenched naphthalene-type band is accompanied by weak exciplex and excimer emissions. Upon titration with CF 3 SO 3 H, the charge transfer bands of 1 and 2 and the exciplex emission of 3 disappear and the naphthalene-type bands regain intensity. Titration plots show that in compounds 2 and 3 the protonation of the two nitrogens occurs stoichiometrically in two distinct steps. Titration with Zn 2+ gives rise to 2.Zn 2+ and 3.Zn 2+ complexes.
Chemical Physics, 2003
A new class of nonproteinogenic aromatic amino acids, benzoxazol-5-yl-alanine derivatives, possessing an aromatic hydrocarbon substituent in position 2 is described. They characterize by long-wavelength absorption and emission bands, high molar absorption coefficient, high fluorescence quantum yield and short, compared to the parent methyl-substituted hydrocarbon, fluorescence lifetime. The MOPAC 2002 package with COSMO model of the solvent was used to calculate the structure of compounds studied in the ground and excited states in methanol, acetonitrile and methylcyclohexane. The position of the vertical absorption and emission transitions were calculated using a INDO/S method within a SCRF approximation for the solvent. The calculated absorption transitions agreed with the corresponding experimental values when all possible singly excited configuration were considered, while the emission-transition wavelengths were overestimated regardless the size of the active space.