A series of new thienylazothiophenes were prepared by coupling reactions of diazotized thienocoumarins with their corresponding free amines. The structures of the products 3–7 were assigned on the basis of their elemental and spectroscopic data. The HMBC and HSQC techniques were used in some cases to ascertain the structural assignments. The antimicrobial screenings of compounds 3–7 along with substituted 2-aminothiophenes 1a,b were performed against three bacteria and three fungal species and their activities compared to those of nystatin, gentamycin and ciprofloxacin used as reference drugs. It was found that the antimicrobial activities of the tested new hybrid compounds were in some cases equal or better than those of the reference drugs.

A new diazo derivative of a pyrrolidine-2,5-dione (8) fused at position-3,4 to a dibenzobarrelene backbone has been prepared by coupling the previously reportedN-arylsuccinimid (5) precursor with aryldiazonium ion of aniline. The initial step of the reaction involved the preparation of the intermediate 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic anhydride (3) through [4 + 2]-cycloaddition between anthracene and maleic anhydride in refluxing xylene which was then condensed with para-aminophenol to give compound5. Compounds5and8were characterized by their physical, elemental, and spectroscopic data. 2D-NMR (COSY, HSQC, and HMBC) techniques were used to confirm the structure of compound5. Compounds5(MIC = 32–128 μg/mL) and8(MIC = 16–256 μg/mL) along with the precursor3(MIC = 64–128 μg/mL) displayed moderate to low antimicrobial activities against selected bacterial and fungal species when compared with those of nystatin (MIC = 0.50–2 μg/mL) and ciprofloxacin (MIC = 0.50–16 μg/mL) used as reference drugs.Graphical Abstract

A new trisazo dye has been synthesized by coupling the diazonium ion of 3-amino-4H thieno[3,4-c][1]benzopyran-4-one with 2-tert-butyl-4-methoxyphenol. The newly prepared trisazo dye was characterized by its physical, elemental, and spectroscopic data. 2D-NMR (COSY, HSQC, and HMBC) techniques were used to secure the structural assignments. The new trisazo dye (compound 7) along with precursors 3, 4, and 6 was screened by microdilution susceptibility assay for antibacterial and antifungal activities towards eight bacterial strains and three yeasts selected on the basis of their relevance as human pathogens. The results showed that compound 7 (MIC = 2–128 μg/mL) was the most active as compared with its precursors. The most resistant microorganisms were V. cholerae NB2 and V. cholerae SG24, whereas the most sensitive microorganism was C. neoformans. The overall results of this study indicated that compound 7 had the greatest potential value against both yeasts and multidrug-resistant bacteria, so further investigation is warranted.

A series of recently reported phenolic azo dyes 7a–e were prepared by coupling the thienyl diazonium sulfate of 3-Amino-4H-benzo[f]thieno[3,4-c](2H)chromen-4-one with selected diversely substituted phenolic and naphtholic derivatives. These compounds were evaluated for their antibacterial and antifungal activities. Furthermore their voltammetric behavior was compared at a glassy carbon electrode. The voltammetric behavior of the five recently reported azo dyes has been compared at a glassy carbon electrode. It is shown that the azo dyes 7a–e with a hydroxyl group in the ortho position with respect to the azo bridge give rise to well defined, irreversible peaks for the oxidation and reduction process within a pH range of 2–7. The mechanisms of electrochemical oxidation of compound 7a–c and 7e are proposed. For the hydroxyl-substituted dyes, re-oxidation peaks were obtained in the subsequent scan. The antimicrobial activities of the reported compounds 7a–e along with the entire precursors 1–4 and 6a–e were performed against selected bacterial and fungal species and their activities compared to those of nystatin, griseofulvin and ciprofloxacin used as reference drugs. The present study showed significant antimicrobial activity of compounds 6d, 7a and 7c,e against the tested microorganisms; this result confirms the antimicrobial potency of azo compounds and some of their precursors.

Two new Cobalt(II) complexes 12 and 13 have been synthesized from 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid (11) as a novel ligand. These three new compounds were characterized on the basis of their powder X-Ray Diffraction, UV–Vis, IR, NMR, elemental analysis and MS spectral data. DFT/B3LYP mode of calculations were carried out to determine some theorical parameters of the molecular structure of the ligand. The purity of the azoic ligand and the metal complexes were ascertained by TLC and melting points. The analysis of the IR spectra of the polyfunctionalized azo compound 11 and its metal complexes 12 and 13, reveals that the coordination patterns of the ligand are hexadentate and tetradentate respectively. Based on the UV–Vis electronic spectral data and relevant literature reports, the ligand and derived complexes were assigned the E (trans) isomer form. Likewise, octahedral and square-planar geometries were respectively assigned to the cobalt(II) complexes. The broth microdilution method was used for antibacterial assays through the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The ligand 11 displayed moderate antibacterial activity (MIC = 32–128 μg/mL) against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa and Klebsiella pneumoniae 22. The octahedral cobalt(II) complex 12 showed moderate activity against Pseudomonas aeruginosa (MIC = 128 μg/mL) and Klebsiella pneumoniae 22 (MIC = 64 μg/mL) and none against Staphylococcus aureus ATCC25923 and Escherichia coli ATCC25922, whereas the square-planar complex 13 displayed moderate activity only on Klebsiella pneumoniae 22 (MIC = 64 μg/mL). Graphical abstract