Synthesis of Silver (I) Coordination of Aspirinate Azo Ligands as Potential Antibacterial Agents

The rise of antimicrobial resistance for infectious bacteria has become an alarming issue to human health. New antimicrobial drugs are in dire need and pivotal to overcome this issue. In this study, aspirinate azo ligands bearing different halogens L1-5 has been prepared via diazo-coupling reaction. The ligands L1-5 were coordinated with silver, Ag (I) metal to produce Ag (I) aspirin-azo complexes C1-5. The antibacterial properties of L1-5 and C1-5 were evaluated against Staphylococcus aureus and Escherichia coli using turbidimetric kinetic method. The complexes C1-5 showed comparable growth inhibition activity towards E. coli (MIC 82-105 ppm) and S. aureus (MIC 80-105 ppm) compared to ligands L1-5 with E. coli (MIC 83-200 ppm), S. aureus (80-131 ppm) and ampicillin (MIC 93 and 124 ppm, respectively). The excellent bacterial resistance of both L1-5 and C1-5 indicates the potential of aspirinate azo and their complexes as new antibacterial agents, which significantly benefit to the pharmaceutical industries.

Speciation Study of Nitrite/Nitrate through Diazo-Coupling Reaction Using Silica-Perchloric Acid as a Novel Catalyst at Trace Level: Application to Environmental Samples

A simple, sensitive and rapid spectrophotometric method has been developed based on the diazo coupling reaction in the quantification of nitrite/nitrate at trace level using silica perchloric acid (SPCA) as an acid catalyst. 5-Amino-2-mercapto benzimidazole has been used as a novel amine and coupled with N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to produce an intense coloured azo dye. The proposed method showed wide linearity in the concentration range 0.1-1000 ppm of nitrite. The molar absorptivity and Sandell′s sensitivity were found to be 1.6 × 106 L mol–1 cm–1 and 0.0012 μg cm–2 respectively. Nitrate was measured after its reduction to nitrite using optimized copper-cadmium reductor column. The proposed method has been successfully applied to measure trace level nitrite/nitrate from a variety of sample matrices like water, soil, milk and radiator coolant.

Antiradical and Antioxidative Activity of Azocalix[4]arene Derivatives: Combined Experimental and Theoretical Study

Developing antioxidants with high efficiency is fundamentally important for the protection of living cells and engineering materials against oxidative damage. In this present study, two azocalix[4]arene derivatives were synthesized via a diazo coupling reaction between calix[4]arene and diazonium salts. Their antiradical and antioxidative performances were evaluated by hydroxyl radical scavenging and pyrogallol autoxidation inhibition experiments. Combined with theoretical studies, the antiradical and antioxidative mechanisms have been explored. The results demonstrated that these two azocalix[4]arene derivatives both exhibited remarkable antiradical and antioxidative activity. The macrocyclic framework of the calix[4]arene and para-azo substituent group at the upper rim of calix[4]arene contributed synergistically and importantly to its excellent antiradical and antioxidant activity.

The Spectroscopic and theoretical investigations of complex formation of (3E,3'E)-7,7'-(carbonylbis(azanediyl))bis(3-(2-(2-hydroxyphenyl)hydrazono)-4-oxo-3,4-dihydronaphthalene-2-sulfonic acid) with metal cations

A novel azo-dye was isolated by a diazo-coupling reaction and characterized by the elemental analysis, mass spectra, IR and UV-VIS spectroscopy. The processes of complex formation of H4L with some mono-, bis-, and trivalent metal cations were studied by spectrophotometric titration and theoretical modeling. The NBO effective charge calculations indicate a strong covalent character of the coordination bonds at complexation.

Green methods for the determination of nitrite in water samples based on a novel diazo coupling reaction

Green, sensitive and selective spectrophotometric methods were developed for the determination of nitrite in water samples. The methods (A, B and C) are based on the reduction of 5-nitroimidazoles; metronidazole (MTL), secnidazole (SCL) and tinidazole (TNL), respectively, followed by diazotization using nitrite in acidic medium, then coupling with pyrogallol (PG). The amount of nitrite was determined by measuring the absorbance of the colored product at 385 nm. The new methods were linear in the ranges of 2.5–30 μgml

Synthesis of Azo Polyurethane-Urea and Investigation of its Thermo-Optic Properties

An azo chromophore molecular S(-)-1,2-bis(4-azophenyl-4-nitro)-ethylenediamine (OABANEDA) was synthesized with 4-nitroaniline and S(-)-1,2-diphenyl ethylenediamine by diazo-coupling reaction. The azo polyurethane-urea (OAAPUU) was obtained from OABANEDA, polyether diol (NJ-210) and isophorone diisocyanate (IPDI). The structure of OAAPUU was characterized by the Fourier transform infrared and UV-visible spectroscopy. The physical and mechanical properties of OAAPUU were investigated. The refractive index (

A panchromatic modification of the light absorption spectra of metal–organic frameworks

Zr-based MOFs' light absorption spectra were shifted from UV to NIR via diazo coupling reaction. The photocatalytic performance of the solids was correlated with absorption edge.