Synthesis and characterization of a novel proton salt of 2-amino-6-nitrobenzothiazole with 2,6-pyridinedicarboxylic acid and its metal complexes and their antimicrobial and antifungal activity studies

•Four air stable proton transfer complexes have been synthesized.•They were characterized by spectral and single crystal X-ray diffraction studies.•Their antimicrobial and antifungal activities were studied.

A novel proton transfer compound, (O2NHABT)+(HDPC)−.0.4EtOH (1), obtained from 2-amino-6-nitrobenzothiazole (O2NABT) and 2,6-pyridinedicarboxylic acid (H2DPC), and its Fe(III), Co(II), Ni(II) and Cu(II) complexes (2–5) have been prepared and characterized by spectroscopic techniques. Additionally, single crystal X-ray diffraction techniques were applied to complexes 3–5. While complexes 3 and 4 have distorted octahedral conformations, complex 5 exhibits a distorted square pyramidal structure. The structure of 2 might be proposed as octahedral according to spectral and analytical results. Furthermore, parent compounds, O2NABT and H2DPC, simple metal complexes of H2DPC, and the synthesised compounds (1–5) were screened for their antibacterial and antifungal activities against Staphylococcus aureus (ATCC 29213) (Gram positive), Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 29212) (Gram negative) and Candida krusei (ATCC 6258), Candida parapisilosis(ATCC 22019) (yeast). The results were compared with the control compounds, Vancomycin, Cefepime, Levofloxasin as antibacterial, and Flucanozole as antifungal agents.

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