Solvent and Media Effects on the Photophysics of Naphthoxazole Derivatives (original) (raw)
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Tetrahedron, 2013
ESIPT inspired fluorescent 2-(4-benzo[d]oxazol-2-yl)naphtho[1,2-d]oxazol-2-yl)phenol was synthesized from 1-amino-3-(1,3-benzoxazol-2-yl)naphthalen-2-ol. Photophysical behavior of the synthesized compound was studied using UVevisible and fluorescence spectroscopy in polar and non-polar solvents. The synthesized naphthoxazolyl benzoxazole is fluorescent and very sensitive to the micro-environment. It shows a single absorption and dual emission in non-polar solvents with large Stokes shift originating from Excited State Intramolecular Proton Transfer while in polar solvents only a single short wavelength emission is observed. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. The largest wavelength difference between the experimental and computed absorption maxima was 16 nm (acetonitrile) and 7 nm (ethyl acetate, THF, and 1,4-dioxane) in the short and long wavelength regions, respectively. A largest difference of 25 nm was observed for the short wavelength emission in DMF and 22 nm for the longer wavelength emission in chloroform.
Journal of Molecular Liquids, 2020
The solvatochromic behavior of four 1-phenyl-3-naphthyl-5-(4-ethylbenzoate)-2-pyrazoline with various electron donating and withdrawing substituents on N1-phenyl group were investigated in nonpolar, polar aprotic and protic solvents experimentally and theoretically. The photophysical behavior of pyrazoline in solvents was attributed to the intramolecular charge transfer (ICT) of the compound along with the specific and nonspecific interactions with the solvent molecules. On view of the effect of different types of interactions on the optical properties, the Stokes shift of each compound in various solvents was correlated to various parameters such as orientation polarity parameter (Δƒ), microscopic solvent polarity parameter (E T 30), and linear solvation regression of the absorption and emission with specific and non-specific types of interaction. The dipole moments of these compounds in the ground and excited state were also explored and compared using different methods, and the results showed greater stabilization of the studied pyrazoline molecules in the excited state. The DFT and TDDFT calculations supported and explained the experimental data, by obtaining the absorption and emission energies, HOMO/LUMO energies and the dipole moments for each compound in various solvents. Analysis of electron-hole distribution suggests that the intense fluorescent of these molecules originates from a hybrid local excitation charge-transfer state (HLCT).
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.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2006
The spectroscopic properties and photoreactivity of 2-(4-dimethylaminostryl)benzoxazole and its butadienyl analogue (abbreviated as DMASBO and BODB, respectively) were investigated in thin films of PS, PMMA and PVA polymer matrices as well as immobilized on silica surface. The experimental results showed that the investigated benzoxazole derivatives are sensitive to the polarity of its microenvironment even in the glassy matrices and in the solid state. The micropolarity of PVA and silica surface is greater than that of PMMA and PS. The combined results of fluorescence quantum yield and photoisomerization indicated that the size of the free volume within the polymer matrix influence strongly the photochemical reactivity of the used dyes. In PVA, which offers the smaller free volume, the photoreaction is totally blocked while the fluorescence yield is extremely enhanced relative to those in solutions and other polymer matrices. This is associated with an emission of green laser from DMASBO-PVA doped film when pumped by nitrogen laser (337 nm). The results showed that the present dyes are excellent probes for nonfluorescent systems presenting constrained geometry. The spectra of amorphous solid thin films of both dyes were also measured and show large red shifts relative to those in solutions indicating symmetric aggregation of molecules in the solid crystals.
Solvent effect on the phosphorescence of 2,5-diphenyloxazole at 77 K
Chemical Physics Letters, 1978
The lummesccnce properties of the ZJdlphenyloxazole (PPO) at 77 K are very sensitrve to complex formation with hydrouyl-cont~inin~ so!vcnts. At the triplet level complex formation affects the Internal conversion tti the ground state as shown by adding laqc salt concentration in ethanol solutions_ Salt addition induces an increase in the phosphorescence quantum efficiency and a b!ue-shift of this emission_
Solvent influence on the photophysical properties of 4-methoxy-N-methyl-1,8-naphthalimide
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2006
4-Methoxy-N-methyl-1,8-naphthalimide (1) exhibits considerable solvatochromism and its UV-vis spectral properties have been studied in several polar/non-polar and protic/aprotic solvents, as well as in ethanol-water mixtures. The results reveal a strong influence of the solvent's polarity and its hydrogen-bond donor (HBD) capability on the photophysical properties of 1. For binary ethnaol/water mixtures, preferential solvation models describe the band shifts in the probe's visible absorption spectrum well, but they fail to describe the correponding shifts of the emission maxima. Pseudolinear approximations between solvent composition and molecule's transition energies, E T , can be used to study the composition of ethanol-water mixtures, simplifying the mathematical treatment for eventual analytical applications.
Photophysics and Photochemistry of Naphthoxazinone Derivatives
The Journal of Organic Chemistry, 2008
The photophysics and photochemistry of a series of naphthoxazinones have been studied using a combination of methods ranging from steady-state and time-resolved spectroscopic techniques to product analysis. The photophysics of naphthoxazinone derivatives is very dependent on the structure: phenanthrene-like compounds exhibit higher fluorescence quantum yield than the less aromatic anthracenelike homologous. The latter, exhibit a substantial degree of charge transfer in the excited singlet state. These compounds are fairly photostable in the absence of additives, yielding a single photoproduct arising from the triplet state. The presence of electron donors such as amines increases the photoconsumption quantum yield and changes the product distribution, the primary photoproduct being a dihydronaphthoxazinone that photoreacts further yielding ultimately an oxazoline derivative.
Journal of Photochemistry and Photobiology A: Chemistry, 2012
Ground and excited state dipole moment Empirical polarity parameters Protic solvent sensitivity Laser flash photolysis Photoinduced electron transfer a b s t r a c t Photophysical properties of a fluorophore 1-keto-6,7-dimethoxy-1,2,3,4-tetrahydrocarbazole (KTHC-67) have been studied in a number of organic solvents. The profile of the fluorescence spectrum and the wavelength at which fluorescence intensity maximizes are found to vary with the nature of the solvent. The photophysics of KTHC-67 is much more influenced by the hydrogen bond donor and acceptor abilities of the solvents rather than their polarity of the solvent. Excited state interactions of KTHC-67 with N,Ndimethylaniline (DMA) have also been investigated in three homogeneous solvents, acetonitrile (ACN), dimethyl sulphoxide (DMSO) and ethanol (EtOH). Photoinduced electron transfer from DMA to KTHC-67 is evident from the subsequent changes in the fluorescence intensity, fluorescence lifetime and transient absorbance of KTHC-67 in presence of DMA.