Spectroscopic, spectrophotometric and thermal characterization of synthesized nitrobenzyl-pyridyl ether compounds and Ag (I) complexes, evaluation of their antibacterial activities against plant-borne and food-borne pathogens

New nitrobenzyl-pyridyl ether ligands were synthesized by reacting nitrobenzyl bromide (2-, 3- and 4-nitro) and halogen-substituted hydroxy pyridine (2-chloro-3-hydroxy-pyridine, 2-bromo-3-hydroxy-pyridine) compounds in DMF. By interacting the obtained ligands (L1, L3, L4 and L6) with silver (I) nitrate, transition metal complexes were prepared (AgL1, AgL3, AgL4 and AgL6). The structures of the synthesized ligands and complexes were characterized using FTIR, HRMS, ¹H-NMR and ¹³C-NMR spectroscopic techniques. In addition, fluorescence spectra of the ligands (L1-L6) were detected in the presence of different metal cations (Li⁺, Na⁺, Mg²⁺, Al³⁺, K⁺, Ca²⁺, Cr³⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Ag⁺). In addition, the thermal behavior of all compounds were examined by TGA-DTA methods and the data of silver complexes and ligands were compared. Within the scope of the study, the antibacterial activities of all compounds were investigated against 4 pathogens, 2 of which were plant-borne (Xanthomonas vesicotoria, Clavibacter michiganensis subsp. Michiganensis) and 2 were food-borne (Escherichia coli, Listeria monocytogenes).

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