Investigation of the azo-hydrazone tautomeric equilibrium in an azo dye involving the naphthalene moiety by UV–vis spectroscopy and quantum chemistry

In the present study, a new compound was used for decontaminating water polluted by Congo Red dye. Phosphono-aminoacid-Cd(II) pendant groups grafted on a polymeric support was prepared using impregnation of a polymer support functionalized with phosphono-aminoacid groups with an aqueous solution of Cd(NO3)2x4H2O. The catalyst was characterized by Fourier transform infrared ray, scanning electron microscope, termogravimetric analysis UV-Vis spectroscopy. The results suggest that the studied material could efficiently be used as photocatalyst in the degradation process of waters containing organic dyes under UV-Vis light irradiation.

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Tautomerism and Self-Association in the Solution of New Pinene-Bipyridine and Pinene-Phenanthroline Derivatives

Molecules ◽

10.3390/molecules25020298 ◽

2020 ◽

Vol 25 (2) ◽

pp. 298

Author(s):

Atena B. Solea ◽

Ivan Cornu ◽

Vera Deneva ◽

Aurelien Crochet ◽

Katharina M. Fromm ◽

...

Keyword(s):

Solid State ◽

Dft Calculations ◽

Structure Determination ◽

Tautomeric Equilibrium ◽

Dft Studies ◽

X Ray ◽

Vis Spectroscopy ◽

Self Association

Two novel pinene-type ligands have been synthesized and their tautomeric and self-associating behavior studied in solution and in the solid state. The first ligand, an acetylated derivative of 5,6-pinene-bipyridine, displays keto-enol tautomerism in solution. This tautomeric equilibrium was studied by NMR and UV-Vis spectroscopy in various solvents, and the results were compared with the ones obtained through DFT calculations. The second ligand was obtained by an unusual oxidation of the phenanthroline unit of a pinene-phenanthroline derivative. This compound exists as a single tautomer in solution and aggregates both in solution (as observed by NMR) and in the solid state through H-bonding as observed by X-ray structure determination and confirmed by DFT studies.

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Colorimetric Detection of Hydrogen Sulfide in Ambient Air

Proceedings ◽

10.3390/proceedings2130804 ◽

2018 ◽

Vol 2 (13) ◽

pp. 804

Author(s):

Laura Engel ◽

Karina R. Tarantik ◽

Carolin Pannek ◽

Jürgen Wöllenstein

Keyword(s):

Hydrogen Sulfide ◽

Azo Dye ◽

Screen Printing ◽

Color Change ◽

Colorimetric Detection ◽

Ambient Air ◽

Fast Method ◽

Vis Spectroscopy

We present a fast method to monitor hydrogen sulfide (H2S) in ambient air based on a visible color change. Therefore, an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in a matrix for screen printing. Different materials, reaching from opaque paper to transparent foils served as substrate. The reaction of the copper(II) complex (Cu-PAN) to the target gas H2S was measured in reflection via UV/VIS spectroscopy.

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Molecular Structures of N,N′-Dimethylbenzimidazoline-2-germylene and -stannylene in Solution and in Solid State by Means of Optical (Raman and UV–vis) Spectroscopy and Quantum Chemistry Methods

Inorganic Chemistry ◽

10.1021/acs.inorgchem.6b00572 ◽

2016 ◽

Vol 55 (10) ◽

pp. 4698-4700 ◽

Cited By ~ 16

Author(s):

R. R. Aysin ◽

L. A. Leites ◽

S. S. Bukalov ◽

A. V. Zabula ◽

R. West

Keyword(s):

Solid State ◽

Quantum Chemistry ◽

Molecular Structures ◽

Vis Spectroscopy

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Green Synthesized of Ag/Ag2O Nanoparticles Using Aqueous Leaves Extracts of Phoenix dactylifera L. and Their Azo Dye Photodegradation

Membranes ◽

10.3390/membranes11070468 ◽

2021 ◽

Vol 11 (7) ◽

pp. 468

Author(s):

Salah Eddine Laouini ◽

Abderrhmane Bouafia ◽

Alexander V. Soldatov ◽

Hamed Algarni ◽

Mohammed Laid Tedjani ◽

...

Keyword(s):

Azo Dye ◽

Dye Degradation ◽

Volume Ratio ◽

Spherical Shape ◽

Cost Effective ◽

Phoenix Dactylifera ◽

Infrared Analysis ◽

Phoenix Dactylifera L ◽

Vis Spectroscopy ◽

Silver Silver

In this study, silver/silver oxide nanoparticles (Ag/Ag2O NPs) were successfully biosynthesized using Phoenix dactylifera L. aqueous leaves extract. The effect of different plant extract/precursor contractions (volume ratio, v/v%) on Ag/Ag2O NP formation, their optical properties, and photocatalytic activity towards azo dye degradation, i.e., Congo red (CR) and methylene blue (MB), were investigated. X-ray diffraction confirmed the crystalline nature of Ag/Ag2O NPs with a crystallite size range from 28 to 39 nm. Scanning electron microscope images showed that the Ag/Ag2O NPs have an oval and spherical shape. UV–vis spectroscopy showed that Ag/Ag2O NPs have a direct bandgap of 2.07–2.86 eV and an indirect bandgap of 1.60–1.76 eV. Fourier transform infrared analysis suggests that the synthesized Ag/Ag2O NPs might be stabilized through the interactions of -OH and C=O groups in the carbohydrates, flavonoids, tannins, and phenolic acids present in Phoenix dactylifera L. Interestingly, the prepared Ag/Ag2O NPs showed high catalytic degradation activity for CR dye. The photocatalytic degradation of the azo dye was monitored spectrophotometrically in a wavelength range of 250–900 nm, and a high decolorization efficiency (84.50%) was obtained after 50 min of reaction. As a result, the use of Phoenix dactylifera L. aqueous leaves extract offers a cost-effective and eco-friendly method.

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Kinematics of Photoisomerization Processes of PMMA-BDK-MR Polymer Composite Thin Films

Polymers ◽

10.3390/polym12061275 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1275 ◽

Cited By ~ 1

Author(s):

Qais M. Al-Bataineh ◽

A. A. Ahmad ◽

A. M. Alsaad ◽

I. A. Qattan ◽

Areen A. Bani-Salameh ◽

...

Keyword(s):

Thin Films ◽

Polymer Composite ◽

Data Storage ◽

Azo Dye ◽

Uv Light ◽

Optical Data Storage ◽

Optical Data ◽

Hysteresis Cycle ◽

Composite Thin Films ◽

Vis Spectroscopy

We investigate and report on the kinematics of photoisomerization processes of polymer composite thin films based on azo dye methyl red (MR) hosted in polymethylmethacrylate (PMMA) incorporated with Benzyl dimethyl ketal (BDK) as a photo-initiator. Understanding photoisomerization mechanisms is crucial for several optical applications such as Read/Write/Erase (WRE) optical data storage media, UV light Read/Write heads, and UV light sensors. The as-prepared polymer composite thin films are characterized using UV–Vis spectroscopy. Furthermore, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) are employed to investigate the optical, chemical, and morphological properties of trans- and cis-states of PMMA-BDK-MR polymer composite thin films. The presence of the azo dye MR in the composite is essential for the efficient performance of the cis ↔ trans cycles through illumination ↔ thermal relaxation for Write/Read/Erase optical data storage and UV-light sensors. Moreover, UV–Vis and FTIR results confirm the hysteresis cycle of trans- and cis-states and that PMMA-BDK-MR thin films may be regarded as potential candidates for successful Write/Read/Erase optical data storage and UV-light sensors. In addition, the morphology of the thin film surface is investigated by SEM technique. The SEM images indicate that uncured surfaces of PMMA-BDK-MR thin films are inhomogeneous compared with the corresponding surfaces after curing. The transformation from inhomogeneous surfaces to homogeneous surfaces is attributed to the polymerization of thin films by UV curing.

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Thione–thiol tautomerism and stability of 2- and 4-mercaptopyridines and 2-mercaptopyrimidines

Canadian Journal of Chemistry ◽

10.1139/v90-227 ◽

1990 ◽

Vol 68 (9) ◽

pp. 1482-1489 ◽

Cited By ~ 91

Author(s):

Stefan Stoyanov ◽

Ivan Petkov ◽

Liudmil Antonov ◽

Tatyana Stoyanova ◽

Petros Karagiannidis ◽

...

Keyword(s):

Absorption Spectra ◽

Time Course ◽

Tautomeric Equilibrium ◽

Polar Solvents ◽

Nonpolar Solvents ◽

Vis Spectroscopy ◽

Thiol Form ◽

Self Association ◽

Symmetrical Disulfides ◽

Symmetrical Disulfide

The possible thione–thiol tautomerism of 2- and 4-mercaptopyridines, 2-mercaptopyrimidine, and 4,6-dimethyl-2-mercaptopyrimidine in solution is studied by means of absorption (UV–VIS) spectroscopy. In accordance with earlier observations, polar solvents and self-association shift the apparent tautomeric equilibrium significantly towards the thione form. In dilute solutions of nonpolar solvents the thiol form predominates. On standing, significant changes are observed in the absorption spectra of these tautomeric compounds in ethanol, dioxane, and water. The time course of the tautomerization, followed spectrophotometrically, reveals quantitative transformation of the thiol form to the corresponding symmetrical disulfides. The influence of concentration, temperature, and irradiation with indirect sunlight are discussed. This thione–disulfide process is reversible in water, starting either from the tautomeric thione or from its symmetrical disulfide, implying a possible importance in biological systems. Keywords: thione–thiol tautomerism, absorption spectra, thiol–disulfide oxidation, mercaptopyridines and pyrimidines.

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Photocatalytic Activity of Magnetic Nano-β-FeOOH/Fe3O4/Biochar Composites for the Enhanced Degradation of Methyl Orange Under Visible Light

Nanomaterials ◽

10.3390/nano11020526 ◽

2021 ◽

Vol 11 (2) ◽

pp. 526

Author(s):

Zheng Zhang ◽

Guanghua Wang ◽

Wenbing Li ◽

Lidong Zhang ◽

Benwei Guo ◽

...

Keyword(s):

Electron Microscopy ◽

Catalytic Activity ◽

Methyl Orange ◽

Visible Light ◽

Photoelectron Spectroscopy ◽

Azo Dye ◽

Photocatalytic Performance ◽

Active Species ◽

Step Method ◽

Vis Spectroscopy

A novel nano-β-FeOOH/Fe3O4/biochar composite with enhanced photocatalytic performance and superparamagnetism was successfully fabricated via an environmentally friendly one-step method. The structural properties of the prepared composite were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and a vibrating sample magnetometer. The XPS spectrum of the as-prepared composites confirmed the presence of Fe-O-C bonds between β-FeOOH and biochar, which could be conducive to transfer photo-generated electrons. UV-vis spectroscopy confirmed the existence of an electron–hole connection between β-FeOOH and biochar, which promoted the rapid interface transfer of photogenerated electrons from β-FeOOH to biochar. These novel structures could enhance the response of biochar to accelerate the photoelectrons under visible light for more free radicals. Electron spin resonance analysis and free radical quenching experiments showed that •OH was the primary active species in the photodegradation process of methyl orange by nano-β-FeOOH/Fe3O4/biochar. In the synergistic photocatalytic system, β-FeOOH/Fe3O4/biochar exhibited excellent catalytic activity for the degradation of azo dye (methyl orange), which is 2.03 times higher than that of the original biochar, while the surface area decreased from 1424.82 to 790.66 m2·g−1. Furthermore, β-FeOOH/Fe3O4/biochar maintained a stable structure and at least 98% catalytic activity after reuse, and it was easy to separate due to its superparamagnetism. This work highlights the enhanced photocatalytic performance of β-FeOOH/Fe3O4/biochar material, which can be used in azo dye wastewater treatment.

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Spectroscopic studies of keto–enol tautomeric equilibrium of azo dyes

RSC Advances ◽

10.1039/c4ra16184j ◽

2015 ◽

Vol 5 (23) ◽

pp. 18097-18110 ◽

Cited By ~ 56

Author(s):

M. A. Rauf ◽

S. Hisaindee ◽

N. Saleh

Keyword(s):

Azo Dyes ◽

Azo Dye ◽

Solvent Polarity ◽

Spectroscopic Studies ◽

Tautomeric Equilibrium ◽

Keto Form

Keto–enol tautomeric equilibrium of an azo dye is shifted to the keto form as the solvent polarity is increased.

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Efficiency of Differently Processed Membranes Based on Cellulose as Cationic Dye Adsorbents

Nanomaterials ◽

10.3390/nano10040642 ◽

2020 ◽

Vol 10 (4) ◽

pp. 642 ◽

Cited By ~ 2

Author(s):

Laura Maleš ◽

Darinka Fakin ◽

Matej Bračič ◽

Selestina Gorgieva

Keyword(s):

Textile Industry ◽

Azo Dye ◽

Fluorescent Microscopy ◽

Cellulose Nanofibrils ◽

Dye Adsorption ◽

Coupling Reaction ◽

Casting Process ◽

Anthraquinone Dye ◽

Effective Manner ◽

Vis Spectroscopy

In order to minimize the pollution caused by the reuse of textile dyes, technologies and materials have been developed that purify waste water in an efficient and cost-effective manner before it is discharged into a water body. In this context, the presented research investigates the potential of two types of fully cellulose-based membranes as adsorbents for cationic dyes used in the textile industry. The first type combines cellulose nanofibrils (CNFs) and carboxymethylated cellulose (CMC) using the solvent casting process and an esterification coupling reaction, while the second type uses commercial bacterial cellulose (BC) in a native and sodium periodate-treated form (BCox). The corresponding membranes were comprehensively evaluated by means of Fourier Transform Infrared (FTIR) Spectroscopy. Results confirm the esterification process within the CNF/CMC membranes, as well as BC oxidation after periodate treatment, as shown by bands at 1726.2 cm−1 and 895 cm−1, respectively. The Potentiometric Titration shows the highest total negative charge of 1.07 mmol/g for 4CNF/4CMC, which is assigned to the presence of COO− within CMC polymers, and lowest (0.21 mmol/g) for BCox. The Contact Angle Goniometry data confirm the hydrophilicity of all membranes, and the angle increased from 0 ° (in pure BC) to 34.5 ° in CMC-rich and to 31.4 ° in BCox membranes due to the presence of CH2COO− and CHO groups, respectively. Confocal Fluorescent Microscopy (CFM) demonstrated the highest µ-roughness in 4CNF/4CMC, while Scanning Electron Microscopy (SEM) depicted diverse morphological features between the membranes, from ultrafine nanofiber networks (in BC and BCox) to larger fiber bundles connected within the polymer phase in CNF/CMC membranes. The adsorption experiment followed by UV–VIS spectroscopy, showed ~100% dye removal efficiency in both CNF/CMC-based membranes, while BC and BCox adsorbed only 24.3% and 23.6%, respectively, when anthraquinone dye was used. Azo dye was only adsorbed with an efficiency of 7–9% on CMC/CNF-based membranes, compared with 5.57% on BC and 7.33% on BCox membranes. The adsorption efficiency at equilibrium was highest for BC (1228 mg/g) and lowest for 7CNF/1CMC (419.24 mg/g) during anthraquinone dye adsorption. In the case of azo dye, the BCox was most effective, with 445.7 mg/g. Applicability of a pseudo second-order model was confirmed for both dyes and all membranes, except for BCox in combination with azo dye, showing the fastest adsorption rate in the case of the 7CNF/1CMC membrane.

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