Some heterocyclic azo dyes derived from thiazolyl derivatives; synthesis; substituent effects and solvatochromic studies

Nonlinear optical properties of azo sulfonamide derivatives

CONTEXT

The present work deals with the linear and nonlinear optical properties such as the dipole moment, polarizability, total hyperpolarizability, electric field-induced second harmonic generation, and hyper-Rayleigh scattering first hyperpolarizability of four heterocyclic azo compounds containing the sulfonamide group considered promise in nonlinear optic. The obtained polarizability and hyperpolarizability were supported by the frontier molecular orbital analysis. The properties have been effectively estimated and thoroughly examined to shed light on the nonlinear optical activity based on the density functional theory. The observed results show a high total first hyperpolarizability β tot up to 2503 a.u. and a low energy gap E g less than 1.41 eV. An inverse relationship has been obtained between the β tot and E g . The calculated E g values confirm that charge occurs within the azo sulfonamides. The new study provides a promising avenue for the development of these azo sulfonamides as novel NLO materials.

METHODS

The molecular modeling and the theoretical studies were performed with Gaussian software packages. The B3LYP/6-311 + G** level was used for optimization. All the linear and nonlinear optical properties reported here are obtained using the DFT. The optimized structures and their frontier molecular orbitals were plotted using the GaussView 5.1 program.

Design and Synthesis of Novel Fluorescent 2-(aryloxy)-3-(4,5-diaryl)-1H-imidazol-2-yl)quinolines: Solvatochromic, DFT, TD-DFT Studies, COX-1 and COX-2 Inhibition and Antioxidant Properties

The present work focuses on the synthesis of novel heterocycles 2-(aryloxy)-3-(4,5-diaryl-1H-imidazol-2-yl)quinolines (6k-v) by an effective condensation reaction. These molecules exhibited fluorescent properties and hence for the proper understanding of their optical behavior and quantum yields, solvatochromic studies have been carried out. Further, frontier molecular orbitals, molecular electrostatic potential (MEP), and geometrical structure optimization have been investigated using the B3LYP/6-311G ++ (d, p) method. The energy gap between the HOMO, LUMO of the optical and energy band gap is determined by DFT and UV-visible spectra for TD-DFT studies are done. The screening of these compounds for in vitro COX-1 and COX-2 inhibition and DPPH free radical scavenging ability assays produced promising results. The binding interactions of these molecules against the COX-2 enzyme (PDB: 5IKR) were validated by docking studies.

o-Azophenylboronic Acid-Based Colorimetric Sensors for d-Fructose: o-Azophenylboronic Acids with Inserted Protic Solvent Are the Key Species for a Large Color Change

Many boronic acid-based chemosensors for saccharides have been developed; however, their detection mechanisms have seldom been studied. In this study, we synthesized 10 o-azophenylboronic acid derivatives (azoBs) and conducted a fundamental study on the reactivity and the sensing mechanism of azoBs, which undergoes a large color change, e.g., from red to yellow, upon a reaction with saccharides. Their pH-independent formation constants were determined by spectrophotometric titration and then converted to the conditional formation constant K' at pH 7.4. A linear free energy relationship was established between log K' and the pK_a of azoB. ¹¹B NMR measurements indicate that in aprotic solvents, azoB forms a trigonal planar structure, while in protic solvents, it forms a quasi-tetrahedral structure (azoB-ROH) with a protic solvent molecule (ROH) inserted between the boronic acid moiety and the azo group. In addition, UV-vis spectroscopic studies showed that the color change during the reaction between azoB and d-fructose in ROH was caused by the release of the ROH from azoB-ROH by d-fructose. Based on the findings in this study, we proposed a guideline for designing an azoB-based chemosensor that exhibits high reactivity toward saccharides and a sufficient color change to allow for the visual detection of saccharides.

An inexpensive and environmentally friendly staining method for semi-permanent slides from plant material probed using anatomical and computational chemistry analyses

Abstract One of the main methods for plant anatomy study is the analysis of thin, transparent, and stained tissue sections. Synthetic dyes traditionally used in anatomical studies might be expensive and produced by specific companies. In contrast, the use of alternative industrial dyes can both represent an inexpensive substitute as well as an environmentally friendly option for conducting plant anatomy studies. In this study, a set of 22 textile dyes was evaluated. Transversal-, longitudinal, and paradermal sections of plant organs obtained using the freehand cutting technique were stained using hydroalcoholic solution (0 to 100%) of textile dyes purchased from a local market. Dyes mixed with 50% hydroalcoholic solution showed higher efficiency in tissue contrast, allowing greater solubility of dye powder and better solution interaction with the plant tissues. Most of the tested dyes showed satisfactory staining results. Cell wall, especially lignified one, showed higher staining efficiency. Computational docking analysis and molecular models of cellulose and lignin showed the probable association mechanisms and dye selectivity to cell wall constituents. Our findings suggest that the developed method can be useful in mixed practical classes of plant anatomy, chemistry, and/or biochemistry, both at high school as well as undergraduate levels.

The Solvatochromic Materials: A Progress Review

Solvatochromic compounds attracted more and more attentions in the application of fluorescent probe, indicator, chromogenic reagent, molecular recognition field and so on. Although sovatochromic effects have been discovered for more than a century, they are still difficult to understand and even more difficult to predict. This review introduced organometallic complexes and organic compounds of solvatochromic materials and highlight the latest progress in recent years, and the molecular structure design and solvatochromic properties are discussed.

Synthesis, spectral features and biological activity of some novel hetarylazo dyes derived from 8-chloro-4-hydroxyl-2-quinolone

In this study, 8-chloro-4-hydroxyl-2-quinolone was synthesized from cyclocondensation of corresponding dianilide and subsequently used as a potent coupling component with some diazotized heterocyclic amines. These compounds were characterized by UV-vis, FT-IR, (1)H NMR spectroscopic techniques and elemental analysis. Absorption spectra of these dyes were measured in six polar solvents and discussed with respect to the nature of solvents and substituted groups. The effects of acid, base, temperature and concentration on the visible absorption spectra of the dyes were reported. In addition, the antimicrobial activity of the dyes was explored in detail.

Phenylazoindole dyes--part I: the syntheses, characterizations, crystal structures, quantum chemical calculations and antimicrobial properties

In this study, the synthesis of four new phenylazo indole dyes (dye 1-4) were carried out by diazotization of 4-aminoacetophenone and coupling with various 2- and 1,2-disubstituted indole derivatives. The dyes were characterized by UV-vis, FT-IR, (1)H NMR, HRMS and X-ray single crystal diffraction methods. Azo-hydrazone tautomeric bahavior of the dyes in different solvents (DMSO, methanol, acetic acid and chloroform) was investigated by using (1)H NMR and UV-vis results. The experimental results were compared with the corresponding calculated values. The results of experimental data and theoretical calculations showed that the azo tautomer is more stable than hydrazone tautomer. In addition to this, the antimicrobial activity of the dyes was also evaluated.

Synthesis, crystal structure and thin-film-optical properties of 3-amino-2-(2-nitrophenyl)diazinyl-3-(morpholin-1-yl)acrylonitrile

3-Amino-2-(2-nitrophenyl)diazinyl-3-(morpholin-1-yl)acrylonitrile (ANMA) has been successfully synthesized via conventional solvent method, and its molecular structure has been identified by using various techniques including FTIR, (1)H NMR, MS and elemental analysis. The crystal structure of ANMA is characterized by single crystal X-ray crystallography. Crystallographic data revealed that the spatial structure of ANMA belongs to monoclinic, P21 a space group. ANMA thin films were deposited onto optical flat quartz substrates by using thermal evaporation under vacuum pressure of 2×10(-4) Pa. The optical properties of the films are studied in terms of the measurements of transmittance and reflectance determined at the normal incident of light over the spectral range 200-2400 nm. The absorption coefficient of the films is computed and the optical band gap of the films is estimated. In addition, the complex refractive index for the films has been calculated and described. Single oscillator model is found to be applicable for the films in which the dispersion parameters namely; single oscillator energy, dispersion energy, dielectric constant at high frequency, lattice dielectric constant and the ratio of carrier concentration to the effective mass are estimated.

Synthesis and evaluation of changes induced by solvent and substituent in electronic absorption spectra of some azo disperse dyes

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 1H 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 (ɛ), refractive index (n) and Kamlet-Taft polarity parameters (hydrogen bond donating ability (α), hydrogen bond accepting ability (β) and dipolarity/polarizability polarity scale (π*)). Acceptable agreement was found between the maximum absorption band of dyes and solvent polarity parameters especially with π*. 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.