Study of the spectroscopic properties and first hyperpolarizabilities of disperse azo dyes derived from 2-amino-5-nitrothiazole (original) (raw)
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
Five azo disperse dyes were prepared by diazotizing 4 ′ -aminoacetophenone and p-anisidine and coupling with varies N-alkylated aromatic amines. Characterization of the dyes was carried out by using UV-vis, FTIR and 1 H NMR spectroscopic techniques. The electronic absorption spectra of dyes are determined at room temperature in fifteen solvents with different polarities. The solvent dependent maximum absorption band shifts, were investigated using dielectric constant (ε), refractive index (n) and Kamlet-Taft polarity parameters (hydrogen bond donating ability (˛), hydrogen bond accepting ability (ˇ) and dipolarity/polarizability polarity scale (*)). Acceptable agreement was found between the maximum absorption band of dyes and solvent polarity parameters especially with *. The effect of substituents of coupler and/or diazo component on the color of dyes was investigated. The effects of acid and base on the visible absorption maxima of the dyes are also reported.
Changes induced by solvent polarity in electronic absorption spectra of some azo disperse dyes
Journal of Molecular Liquids, 2010
The electronic absorption spectra of some azo disperse dyes in various solvents of different polarities have been studied at room temperature. The solvent effects on the wavenumbers of the absorption band maxima (ṽ max) were discussed using the following solvent parameters, refractive index, n, dielectric constant, ε and empirical Kamlet-Taft solvent parameters, π* (dipolarity/polarizability), α (hydrogen bond donating capacity) and β (hydrogen bond accepting ability). The solute-solvent interactions were determined on the basis of multilinear solvation energy relationships concept. The fitting coefficients obtained from this analysis allowed us to estimate the contribution of each type of interactions to the total spectral shifts in solution. The established dependences between ṽ max and the solvent parameters emphasize that the visible band of the studied molecules is affected by both non-specific and specific solute-solvent interactions.
Studies on the electronic absorption spectra of some monoazo derivatives
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
The electronic absorption spectra of a series of azo dye compounds containing -Cl, -SO 3 H and -OH groups were recorded in twenty one solvents with different polarities. The solvents were selected to cover a wide range of parameters (refractive index, dielectric constant and hydrogen bonding ability). Solvent-induced effect on the maximum absorption band frequencies of azo dye compounds are described in terms of solute-solvent interactions. Multiple linear regression equation for max was performed using polarizability-polarity parameters and Kamlet-Taft solvatochromic parameters. The results help to assign the solvent-solute interactions and the solvatochromic potential of the investigated compounds. It is concluded that the electronic of the substituent and hydrogen bonding acceptor ability of the solvents are the major factors to the interaction in solutions.
Journal of Molecular Structure
The synthesis of the title compounds has been carried out by condensation via a Wittig-type reaction of a pyridinium hexafluorophosphate with a phosphonate ester to give the desired (4-nitrophenyl)tetrathiafulvalene the nitro group of which was reduced to an amino group. Reaction of the amine with chlorosulfonyl isocyanate and subsequently with tert-butyl alcohol gave the corresponding open-chain sulfamide. Cyclization under basic conditions and de-protection led to 2-[4-(4 0 ,5 0-dipropyltetrathiafulvalen-4-yl)]phenyl-1,2,6-thiadiazinane 1,1-dioxide. Finally, N-alkylated and N-acylated cyclic sulfamides linked to tetrathiafulvalene were obtained. Their electron donor ability was measured by cyclic voltammetry. A detailed DFT study based on B3LYP/6-31G (d,p) of electronic properties is also presented. The calculated molecular electrostatic potential shows that, the negative charge covers the nitro and sulfamide function, while positive charge is located at the hydrogen atoms of the amine and sulfamide rings. The calculated HOMO and LUMO energy reveals that charge transfer occurs within the molecule. The chemical reactivity parameters reveal that tetrathiafulvalene 1 is highly reactive, which facilitates the desired formation of the cyclic sulfamide. The first hyperpolarizability b tot shows that compounds 1 and 5 are good candidates as a NLO material.
Solvent Effects on the Electronic Spectra of Some Heterocyclic Azo Dyes
Bulletin of the Korean Chemical Society, 2014
The influence of solvent polarity on the absorption spectra of some synthesized azo dye with heterocyclic moieties and -naphthol (1-3) have been investigated using a UV-Visible spectrophotometer. The spectral characteristics of the azo dyes (1-3) in different solvents at room temperature were analyzed. The solvatochromic empirical variables like * , , and have been used to discuss the solvatochromic behaviour of the dyes and to evaluate their contributions to the solute-solvent interactions. A multi-parameter regression model for quantitative assessment of the solute/solvent interaction and the absorption has been used to explain the solvent effect on azo dyes (1-3).
Tetrahedron, 2011
Keywords: Heterocyclic azo dyes Thienylpyrrole Benzothiazole Nonlinear optical (NLO) materials Reverse polarity First hyperpolarizability (b) Thienylpyrroles as auxiliary donors Redox properties Density functional theory (DFT) Thermal stability a b s t r a c t Two series of related donoreacceptor conjugated heterocyclic azo dyes based on the thienylpyrrole system, functionalized with benzothiazol-2-yl (5e6) or benzothiazol-6-yl acceptor groups (7) through an N]N bridge, have been synthesized by azo coupling using 1-alkyl(aryl)thienylpyrroles (1) and benzothiazolyl diazonium salts (2e4) as coupling components. Their optical (linear and first hyperpolarizability), electrochemical, and thermal properties have been examined. Optimized ground-state molecular geometries and estimates of the lowest energy single electron vertical excitation energies in dioxane solutions were obtained using density functional theory (DFT) at the B3LYP/6-31þG(d,p) level. Hyper-Rayleigh scattering (HRS) in dioxane solutions using a fundamental wavelength of 1064 nm was employed to evaluate their second-order nonlinear optical properties. Of these systems, the benzothiazol-2-yl-diazenes 5e6 exhibit the largest first hyperpolarizabilities (b¼460e660Â10 À30 esu, T convention) compared to benzothiazol-6yl-diazenes 7 (b¼360e485Â10 À30 esu, T convention). Good to excellent thermal stabilities were also obtained for all azo dyes (235e317 C). This multidisciplinary study showed that modulation of the optical and electronic properties can be achieved by introduction of the benzothiazole acceptor group in the thienylpyrrole system through position 2 or 6 of the benzothiazole heterocycle.
Photochemical & Photobiological Sciences, 2013
Solvatochromic probes are often used in biophysical studies to obtain information about polarity of the microenvironment. As there is not much natural fluorophores with such properties, there is still need for new synthetic compounds such as 3-(2-benzoxazol-5-yl)alanine derivatives. Among this group of nonproteinogenic fluorescent amino acids especially interesting are 3-[2-(4-aminophenyl)benzoxazol-5-yl]alanine derivatives whose solvatochromism depends on the substituents on the nitrogen atom, as revealed by our recent studies. To expand them we synthesized two new derivatives with an N-phenylcarbazole moiety in position 2 of the benzoxazole ring and studied their photophysical properties in solvents of different polarity and ability to form hydrogen bonds using absorption and steady-state and time-resolved fluorescence spectroscopy. Applying single parameter and multi-linear correlations with different solvent parameters, the excited state dipole moments were determined as well as the influence of solvent parameters on each photophysical property was estimated. Moreover, the geometry of compounds and vertical absorption transition were theoretically calculated (DFT and TD DFT methods). It was found that the place of substitution of the N-phenylcarbazole part by the benzoxazole unit determines the character of the electron transition (π-π* or ICT) and thereby the spectral and photophysical properties of the compounds studied. † Electronic supplementary information (ESI) available: Emission spectra of exciplex of compound 2 in dimethoxyethane, results of the single-parameter linear correlations of photophysical parameters of 1 and 2 with E T N as well as their multi-parameter linear correlations with three-parameter Catalán and Kamlet-Taft solvent scales, theoretically calculated absorption wavelengths for both compounds studied, their HOMO and LUMO orbitals and orientation of the transition dipole moments as well as the results of fluorescence anisotropy measurements of stretched samples in PVA films. See
UV-spectral changes for some azo compounds in the presence of different solvents
Journal of Molecular Liquids, 2011
The electronic absorption spectra of four azo dyes with different substituents (such as Cl, I, OH) are determined at room temperature in twenty-one solvents with different polarities. The electronic transitions of azo dyes are interpreted. Linear solvation energy relationships have been investigated for solvatochromic behaviors and solute-solvent interactions of azo dyes. Linear solvation energy relationships were performed by multiple linear regression analysis using dielectric function, refractive index function and Kamlet-Taft parameters. We have observed that the hydrogen bonding acceptor ability and the induction-dispersive forces of solvent molecules have caused the bathochromic shift in absorption maxima of azo dyes.