Azo Linkage Research Articles

Synthesis, Antimicrobial and Antioxidant Activity of Some New Pyrazolines Containing Azo Linkages.

Pyrazolines and azo-pyrazolines are influential groups of heterocyclic compounds with two nitrogen atoms inside the five-membered ring. They play an important role in a wide range of biological processes, such as antifungal, antioxidant, antimalarial and other antimicrobial activities. The main objective of this study is to synthesize some new heterocyclic compounds with antioxidant and antimicrobial activity Methods: One-pot three components and traditional synthesis of new azo-pyrazoline compounds were achieved in this work. The preparation process has been started by diazotizing 4-(6-methylbenzothiazol-2-yl) benzamine and its coupling reaction with 4-hydroxy acetophenone producing azo-acetophenone, followed by benzylation with benzyl chloride to form the starting material, azo-benzyloxy acetophenone. A series of substituted benzaldehydes were reacted with the latter compound via one pot and classical methods, forming new chalcones containing azo linkages and benzyloxy moieties, which were then converted into new target azo-pyrazoline derivatives. The structures of the synthesized compounds were confirmed by spectroscopic techniques using FT-IR, 1H-NMR, 13C-NMR, and 13C- DEPT- 135 spectra. Finally, the synthesized compounds were screened for their antioxidant and antimicrobial activities against Staphylococcus aureus and Escherichia coli. Overall, the one-pot three-component synthesis of pyrazoline compounds generally provides advantages in terms of efficiency, simplicity, and time-consumption compared to classical synthesis methods. Hence, the study advocates the one-pot method because it eliminates the tedious process of making chalcones, which takes time, materials, and unnecessary effort. Therefore, this is the most convenient and effective approach to green chemistry.

Manipulation of Supramolecular Chirality in Bicontinuous Networks of Bent-Shaped Polycatenar Dimers.

Bicontinuous cubic liquid crystalline (LC) phases are of particular interest due their possible applications in electronic devices and special supramolecular chirality. Herein, we report the design and synthesis of first examples of achiral bent-shaped polycatenar dimers, capable of displaying mirror symmetry breaking in their cubic and isotropic liquid phases. The molecules have a taper-shaped 3,4,5-trialkoxybenzoate segment connected to rod-like building unit terminated with one terminal flexible chain. The two segments were connected using an aliphatic spacer with seven methylene units to induce bending of the whole structure. Investigated by the small-angle X-ray scattering (SAXS), a double network achiral cubic phase Cub/Ia3 d, which is a meso-structure, and a chiral triple network cubic phase Cub/I23[*] are formed. The molecules self-assemble into molecular helices and progress along the networks. Interestingly, different linking groups such as ester or azo linkages and core fluorination lead to distinct local helicity, resulting in an alkyl chain volume dependent phase transition sequence Ia3d(L)-I23*-Ia3d(S). The re-entry of Iad phase and loss of supramolecular chirality is attributed to the delicate influence of steric effect at the mono-substitute end and interhelix interaction. Besides, aromatic core fluorination was proved to be a successful tool stabilizing the cubic phases in these dimers.

Potential MRSA inhibitory activity of some new benzofuran-pyrazolo[1,5-a]pyrimidine hybrids attached to arene units via methylene or azo linkage

MRSA, a resistant bacteria causing severe infections, is targeted by researchers developing new anti-resistance compounds. The study aimed to investigate the MRSA inhibitory activity of two series of benzofuran-pyrazolo[1,5-a]pyrimidines 1 and 2, attached to arene units via methylene or azo linkage, respectively. The desired products were prepared, in 82–92% yields, by reacting benzofuran-based enaminone 4 with the appropriate 1H-pyrazole-3,5-diamines 5 in pyridine at reflux for 5–6 h. The new hybrids showed a wide spectrum of antibacterial activity against different ATCC strains. Products with azo linkage and para-substituted arene units with electron-releasing groups demonstrated higher antibacterial activity. 3-((4-Methoxyphenyl)diazenyl)-linked pyrazolo[1,5-a]pyrimidine 2e demonstrates activity that exceeded the reference ciprofloxacin with MIC/MBC values of 1.8/3.6 µM against S. aureus and E. coli strains. Also, it demonstrated more effective MRSA inhibitory activity than the reference linezolid, with MIC/MBC values of 3.6/14.4 and 1.8/7.2 µM against MRSA ATCC:33591 and ATCC:43300 strains, respectively.

Selective adsorption and removal of Congo red dye from waste water using catechol-stabilized reusable palladium nanoparticles

Several industries including textile, dye manufacturing industries, paper and pulp industries discharge colored wastewater. The majority of synthetic dyes is composed of toxic azo compounds. Eradication of toxic azo dyes, organic pollutants, radioactive materials from the global ecosystem has received remarkable attention due to their detrimental effects on human health and ecosystem. Nanotechnology-based applications on catalytic degradation of contaminants from aqueous ecosystem have evolved as a major topic of research in the scientific community, to develop a cost-effective and energy-effective strategy. In this context, nanomaterials have gained much attention because of its unique physico-chemical properties. Herein, catechol-generated palladium nanoparticles (PdNPs) have been utilized for the selective removal of congo red dye from wastewater. In this study, Palladium nanocatalyst (4 μg/ml) developed earlier by our group, was screened for degradation of dyes of different nature. The newly developed nanocatalyst was found to be effective against anionic dyes. Among the anaionic dyes, congo red was selected for degdradation study in detail. Complete degradation of congo red dye (CR) (150 μM) is found to happen within 10 min. Besides catalytic degradation, the efficiency of the recycled catalyst was evaluated, which exhibits 60 % efficiency even after the 3rd cycle. Gas chromatography-mass spectrometry (GC–MS) characterization of the degraded products reveals the formation of benzidine, indicating the reductive cleavage of azo linkage of the dye.In summary, the results highlight the potential development of a nanocatalyst for the selective and efficient removal of congo red, suggesting a simple,cost-effective, and reusable approach to prevent industrial pollutant in aqueous ecosystem.

Cleavable azobenzene linkers for the design of stimuli-responsive materials.

The azo linkage (NN) is one of the very few functional groups in organic chemistry that exhibits sensitivity towards thermal, chemical, photochemical, and biological stimuli. Consequently, this property has given rise to a distinct class of responsive materials. For example, thermal sensitivity has led to generation of free radical initiators useful in curing and polymerization applications. Chemically-induced cleavage has aided the development of self-immolative polymers and reactive scaffolds for proteomics applications. Photo-isomerization capability has given rise to photo-responsive systems. Azobenzene cleavage in biologically reducing environments, such as that of the colon, and under tumor hypoxia conditions has led to diagnostic, therapeutic, and delivery materials. Such conditions have also allowed for control over formation (assembly) and disruption (disassembly) of micellar nanoparticles. The aim of this review article is to look beyond the prevalent photosensitivity aspect of the aromatic azo compounds and draw attention to the azo scission reaction as a trigger of the change in the structure and properties of organic materials. Thus, the main discussion begins with the mechanism of the reductive cleavage. Then, its application in the design of molecules that can be activated as drugs and fluorescent sensors, (nano)materials with potential to release active substances, and polymers with side-chain and main-chain self-immolative capacity is discussed. Finally, the status and future challenges in this field are discussed.

Synthesis and liquid crystalline properties of novel series containing 5H-thiazolo[3,4-b][1, 3, 4]thiadiazole unit with schiff base and azo linkage

Two series were synthesized containing a 5H-thiazolo[3,4-b][1, 3, 4]thiadiazole unit with a Schiff base and an azo linkage. Polarized optical microscope (POM) and differential scanning calorimetry (DSC) were used to examine the mesomorphic behavior. Enantiotropic nematic phases were present in compounds with alkoxy terminal groups of n = 1–4 methylene units for both series. While enantiotropic smectic A (SmA) is also present in molecules with n = 6–8 carbon atoms in addition to nematic phases for a series of azo linkage. The molecules in the Schiff base linkage series with n = 6–8 exhibited pure smectogenic liquid crystalline behavior.

Biodecolorization and biodegradation of Reactive Green 12 textile industry dye and their post-degradation phytotoxicity-genotoxicity assessments.

The employment of versatile bacterial strains for the efficient degradation of carcinogenic textile dyes is a sustainable technology of bioremediation for a neat, clean, and evergreen globe. The present study has explored the eco-friendly degradation of complex Reactive Green 12 azo dye to its non-toxic metabolites for safe disposal in an open environment. The bacterial degradation was performed with the variable concentrations (50, 100, 200, 400, and 500mg/L) of Reactive Green 12 dye. The degradation and toxicity of the dye were validated by high-performance liquid chromatography, Fourier infrared spectroscopy analysis, and phytotoxicity and genotoxicity assay, respectively. The highest 97.8% decolorization was achieved within 12h. Alternations in the peaks and retentions, thus, along with modifications in the functional groups and chemical bonds, confirmed the degradation of Reactive Green 12. The disappearance of a major peak at 1450cm-1 corresponding to the -N=N- azo link validated the breaking of azo bonds and degradation of the parent dye. The 100% germination of Triticum aestivum seed and healthy growth of plants verified the lost toxicity of degraded dye. Moreover, the chromosomal aberration of Allium cepa root cell treatment also validated the removal of toxicity through bacterial degradation. Thereafter, for efficient degradation of textile dye, the bacterium is recommended for adaptation to the sustainable degradation of dye and wastewater for further application of degraded metabolites in crop irrigation for sustainable agriculture.

Symmetrical liquid crystalline dimers containing azo and azomethine linkages: synthesis, characterisation, mesomorphic study and DFT studies

ABSTRACT In the current study, one new series of symmetrical liquid crystalline homologous series of dimers with a rigid aromatic core with azo and azomethine group were synthesized using an ether-linking group. Several spectroscopic methods, including FT-IR, 1H-NMR, 13C-NMR and elemental analysis, were used to describe the synthesised dimers. The differential scanning calorimetry (DSC) and polarised optical microscopy (POM) were used to assess their mesomorphic properties. The results showed that the number of methylene spacers significantly affected the thermal properties of the synthesized dimers. To ascertain photophysical behaviour, UV-visible spectroscopy was employed. All the dimers of the present series show excellent enantiotropic nematic mesophase. The relationships between structure and its mesogenic property, the effects of various flexible spacers, the mesophase ranges, and the photo-isomerization of liquid crystalline dimers were all investigated. DFT study was carried out to gain a better understanding of structural features.

Traditional, one-pot three-component synthesis and anti-bacterial evaluations of some new pyrimidine derivatives

In this study, a novel series of pyrimidine compounds featuring azo linkages was synthesized via a sequence of stepwise and one-pot three-component reactions. The synthetic process commenced with the diazotization of 3-chloro-4-methyl aniline, followed bycoupling reaction with 4-hydroxy acetophenone, yielding the azo molecule denoted as 1-(3-((3-chloro-4-methylphenyl)diazenyl)-4-hydroxyphenyl)ethan-1-one. Subsequently, this compound underwent benzylation with benzyl bromide by Williamson ether synthesis, leading to the formation of 1-(4-(benzyloxy)-3-((3-chloro-4-methylphenyl)diazenyl)phenyl)ethan-1-one. The resultant azo-benzyloxy compound was then subjected to both classical and one-pot methodologies to synthesize pyrimidine derivatives, from results obtained from one pot reaction were in good yield. Structural elucidation of the newly synthesized compounds was characterized by spectral analysis, including FT-IR, 1H NMR, 13C NMR, and 13C-DEPT-135-NMR. The spectroscopic data confirmed the integrity of the molecular structures. Lastly, certain pyrimidine derivatives were evaluated for their antimicrobial activity against two strains of bacteria, namely Staphylococcus aureus and Escherichia coli. The results revealed that as the increasing of concentration, the sensitivity increased as reached 800 µg /mL no growth of bacterial was seen, It is also notable that the synthesized compounds have antimicrobial efficacy against both bacterial types.

Cover Feature: Reactivity of [Sm(DippForm)2(thf)2] with Substrates Containing Azo Linkages (Eur. J. Inorg. Chem. 1/2024)

Cover Feature: Reactivity of [Sm(DippForm)₂(thf)₂] with Substrates Containing Azo Linkages (Eur. J. Inorg. Chem. 1/2024)

Reactivity of [Sm(DippForm)2(thf)2] with Substrates Containing Azo Linkages

AbstractThis paper explores the interaction of divalent [Sm(DippForm)2(thf)2] with substrates containing azo linkages. Treatment of [Sm(DippForm)2(thf)2] with trans‐azobenzene results in formation of mononuclear [Smlll(DippForm)2(Ph2N2)(thf)] ⋅ 3THF (1) or dinuclear [Smlll(DippForm)(Ph2N2)(thf)]2 ⋅ 4THF (2) and [Sm(DippForm)3] depending on the reaction stoichiometry, where azobenzene has undergone either a one or two electron reduction. These reactions parallel the corresponding reactions of [Sm(C5Me5)2(thf)2], but the coordination of [N2Ph2]− in 1 differs significantly from that of {Sm(C5Me5)2(Ph2N2)(thf)}. On the other hand, the structure of 2 is similar to that of the pentamethylcyclopentadienyl analogue. The reaction of [Sm(DippForm)2(thf)2] with 1H‐1,2,3‐benzotriazole also yielded a trivalent samarium complex containing benzotriazolate (btz), [Smlll(DippForm)2(btz)(thf)] ⋅ THF (3), and suggests more utilization of 1H‐1,2,3‐benzotriazole in divalent lanthanoid reduction chemistry is possible.

Prodrug Rewards in Medicinal Chemistry: An Advance and Challenges Approach for Drug Designing.

This article emphasizes the importance of prodrugs and their diverse spectrum of effects in the field of developing novel drugs for a variety of biological applications. For the purpose of illustrating the usefulness of the prodrug approach, this review covers examples of prodrugs that have been made available or are now undergoing human trials. Additionally, it included lists of the most common functional groups, carrier linkage, and reactive chemicals that can be used to create prodrugs.The primary chemical carriers employed in the creation of prodrugs, such as esters, amides, imides, NH-acidic carriers, amines, alcohols, carbonyl, carboxylic, and azo linkage, are also discussed. This review also discusses glycosidic and triglyceride mutually activated prodrugs, which aim to deliver the drugs after bioconversion at the intended site of action. The article also discusses the extensive chemistry and wide variety of applications of recently approved prodrugs, such as antibacterial, anti-inflammatory, cardiovascular, antiplatelet, antihypertensive, atherosclerotic, and antiviral, etc. In order to illustrate the prodrug and mutual drugs concept's various applications and highlight its many triumphs in overcoming the formulation and delivery of problematic pharmaceuticals, this work represents a thorough guide that includes the synthetic moiety to the reader.

Film-shaped reusable smart polymer to produce lactose-free milk by simple immersion

In this study, we report the synthesis and characterization of a highly manageable polyacrylic film material for enzyme immobilization, using β-galactosidase (β-gal) as a model enzyme. The material is based on commercially available monomers and achieves efficient immobilization of β-gal through the formation of azo linkages between amino styrene groups in the polyacrylic material and the enzyme. The immobilized enzyme demonstrates superior performance compared to free enzyme in lactose hydrolysis of UHT milk, achieving lactose concentrations below 0.1% (<1 mg/mL), indicating its potential for lactose hydrolysis in dairy products. The film-shaped material is designed for easy submersion and removal, similar to a smart card, and offers reusability, with the ability to be reused at least 10 times without loss of enzymatic activity. Characterization of the immobilized enzyme on the polymeric material was performed using various techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. Protein release studies confirmed the stability of the immobilized enzyme during prolonged incubation in aqueous solution without significant enzyme leakage. Overall, the polyacrylic film material demonstrates promise as a simple and efficient approach for enzyme immobilization, with potential applications in various industries, including the food industry.

Exceptional Lithium‐Ion Storage Performance on an Azo‐Bridged Covalent Heptazine Framework

AbstractGraphitic carbon nitride (g‐C3N4) possesses rich pyridine nitrogens, which is helpful for facilitating electrochemical capability in Li+ storage; however, its poor conductivity is still the main challenge. Based on the knowledge of its intrinsic merits and defects, here, it is proposed to integrate active heptazine (HEP) species with functional linkers into orderly molecular structures for improved performance. As the first proof‐of‐concept, a unique azo‐linked covalent heptazine framework (Azo‐CHF) where two HEP units are bridged with azo linkages, is ingeniously designed and prepared to enhance the inherent charge conductivity for Li+ storage. Attributing to the deeply extended conjugation along overlapping azo nitrogens and the aromatic π system of HEP cores, Azo‐CHF with the lowest bandgap (2.58 eV) exhibits enhanced Li+/e− transport than g‐C3N4 through density functional theory calculations. Therefore, the Azo‐CHF anode exhibits an unprecedented performance with a large reversible capacity (1723.0 mAh g−1 at 0.1 A g−1), superior rate capability (824.0 mAh g−1 at 10 A g−1), and impressive cyclability (756.5 mAh g−1 undergoing 1000 cycles at 10 A g−1). This study not only demonstrates the great application prospect of Azo‐CHF for Li+ storage, but also opens a fantastic window to further explore high‐performance electrodes by integrating HEP with other active motifs.

Liquid crystalline naphthyl derivatives with bromoalkoxy tail: Photophysical behavior and DFT studies

One new homologous series of mesogenic bromoalkoxy terminated naphthyl derivatives containing flexible spacers as well as azo and ether linkages was synthesized by the etherification of an azo dye (E)-4-(naphthalen-2-yldiazenyl) phenol with various α, ω-dibromo-alkanes, respectively. Compounds in the present work were convinced with respective right structures confirmed with various spectroscopic techniques. Thermotropic properties of the compounds were investigated. Among all the compounds, compounds with flexible spacer (n = 4, 5, 6) exhibited excellent liquid crystalline nature. Structure–property relationships, the influence of different flexible spacers, the mesophase ranges and the photo-isomerization of liquid crystalline compounds were studied. The photophysical behavior was gained by UV–visible spectroscopy and optical properties were determined with a spectroscopic ellipsometer. Computational studies of all molecular structures were performed with satisfactory explanation to attribute mesogenic and optical properties. It's worth noting that synthesized mesogenic materials are excellent dielectrics making them suitable for electronic and industrial applications, as well as having a suitable refractive index making them suitable for light-guiding phenomena.

Reductive Oligomerization of Nitroaniline Catalyzed by Fe3O4 Spheres Decorated with Group 11 Metal Nanoparticles.

The present work demonstrates a simple and sustainable method for forming azo oligomers from low-value compounds such as nitroaniline. The reductive oligomerization of 4-nitroaniline was achieved via azo bonding using nanometric Fe3O4 spheres doped with metallic nanoparticles (Cu NPs, Ag NPs, and Au NPs), which were characterized by different analytical methods. The magnetic saturation (M s) of the samples showed that they are magnetically recoverable from aqueous environments. The effective reduction of nitroaniline followed pseudo-first-order kinetics, reaching a maximum conversion of about 97%. Fe3O4-Au is the best catalyst, its a reaction rate (k Fe3O4-Au = 0.416 mM L-1 min-1) is about 20 times higher than that of bare Fe3O4 (k Fe3O4 = 0.018 mM L-1 min-1). The formation of the two main products was determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS), evidencing the effective oligomerization of NA through N = N azo linkage. It is consistent with the total carbon balance and the structural analysis by density functional theory (DFT)-based total energy. The first product, a six-unit azo oligomer, was formed at the beginning of the reaction through a shorter, two-unit molecule. The nitroaniline reduction is controllable and thermodynamically viable, as shown in the computational studies.

Isolation and characterization of textile dye degrading Microbes from Ganga (Ganges) water

Among the most concerned environmental pollutions that are threatening our biodiversity, water pollution is a major one where effluents from dye-based industries. Textile industries consume a huge volume of azo dyes while up to 50% of dyes find its ultimate way in the water as effluent. In India, after many festivals like Durga Puja, idols are immersed in water. The dyes by which idols are painted affect aquatic livings. The structures of azo dyes consists coupling of diazotized amine with either an amine or a phenol and also contain azo linkage. Most of these dyes are potentially toxic to aquatic life and some are even carcinogenic and mutagenic to humans. Furthermore, colour of the dyestuff interrupts the aquatic environment by reducing light penetration, gas solubility and interference of phytoplankton’s photosynthesis. Unfortunately, most azo dyes are recalcitrant to aerobic degradation by bacterial cells. However, there are microorganisms that have the ability to reductively cleave azo bonds under aerobic conditions. So our goal is to isolate and identify some potential dye degrading bacteria from polluted Ganga water and characterize them biochemically.

Production, partial purification and characterization of intracellular Azoreductase from bacterial isolates during biodecolorization of textile dye Acid Maroon V

Azoreductase is an important enzyme for the reduction of the azo linkage of dye during the biodecolorization process. In the present study, the production of intracellular azoreductase from bacterial cultures Enterobacter dissolvens AGYP1 (ED) and Pseudomonas aeruginosa AGYP2 (PA) was achieved during biodecolorization of synthetic textile dye Acid Maroon V. When compared with PA, the enzyme activity of ED was 2.31 times greater. The partial purification of azoreductase revealed specific activity of the dialyzed enzyme 51.72 U mg-1 protein (ED) and 33.06 U mg1 protein (PA). Methyl Red served as the best substrate for the azoreductase enzyme with superior activity at optimal pH 7 and temperature 30 °C. 75-80% of azoreductase enzyme activity was maintained when Mg+2 and Ca+2 were present. The azoreductase activity was considerably increased with NADH as the most suitable electron donor. The kinetic study showed consequent Michaelis-Menten constant (Km) and maximal velocity (Vmax) values of 50 μM and 2222 U ml-1 (ED) and 250 μM and 1000 U ml-1 (PA), respectively

Foliar application of growth regulators and nutrients for enhanced yield attributes of guava cv Lalit

Azoreductase is an important enzyme for the reduction of the azo linkage of dye during the biodecolorization process. In the present study, the production of intracellular azoreductase from bacterial cultures Enterobacter dissolvens AGYP1 (ED) and Pseudomonas aeruginosa AGYP2 (PA) was achieved during biodecolorization of synthetic textile dye Acid Maroon V. When compared with PA, the enzyme activity of ED was 2.31 times greater. The partial purification of azoreductase revealed specific activity of the dialyzed enzyme 51.72 U mg-1 protein (ED) and 33.06 U mg1 protein (PA). Methyl Red served as the best substrate for the azoreductase enzyme with superior activity at optimal pH 7 and temperature 30 °C. 75-80% of azoreductase enzyme activity was maintained when Mg+2 and Ca+2 were present. The azoreductase activity was considerably increased with NADH as the most suitable electron donor. The kinetic study showed consequent Michaelis-Menten constant (Km) and maximal velocity (Vmax) values of 50 μM and 2222 U ml-1 (ED) and 250 μM and 1000 U ml-1 (PA), respectively

π-Conjugated Hexaazatrinaphthylene-Based Azo Polymer Cathode Material Synthesized by a Reductive Homocoupling Reaction for Organic Lithium-Ion Batteries.

A novel hexaazatrinaphthylene-based (HATN) azo polymer (PAH) was synthesized from a newly designed tri-nitro compound trinitrodiquinoxalino[2,3-a:2',3'-c]phenazine (HATNTN) through a Zn-induced reductive homocoupling reaction and used as a cathode material for lithium-ion batteries (LIBs). The integration of redox-active HATN units and azo linkages can improve the specific capacity, rate performance, and cycling stability of the PAH cathode. The control LIBs were assembled from HATNTN, in which HATNTN can be electrochemically reduced to an HATN-based azo polymer. Compared with the HATNTN cathode, the PAH cathode delivers higher specific capacities with much-improved cycling stability (97 mA h g-1 capacity retention after 1500 cycles at 500 mA g-1, which is around 28 times that of the HATNTN cathode) and considerably better rate performance (118 mA h g-1 at 2000 mA g-1, which is around 90 times that of the HATNTN cathode), simultaneously. This work provides a chemical polymerization strategy to construct extended π-conjugated azo polymers with multiple redox centers from nitro compounds for developing high-performance LIBs.