Novel bis-crown ethers and their sodium complexes as antimicrobial agent: synthesis and spectroscopic characterizations

A series of new compounds containing formyl and imine group were synthesized. New formyl-substituted compounds were prepared by the reaction of 1,2-bis(bromomethyl)benzene with benzaldehyde derivatives in the presence of NaOH. New bis-crown ether imine compounds were prepared by the condensation of corresponding aldehydes with 4′-aminobenzo-15-crown-5. Sodium complexes of the bis-crown ethers form crystalline 2:1 (Na⁺:ligand) stoichiometries were also been synthesized. The prepared compounds were structurally confirmed by analytical and spectral data and evaluated for their antibacterial and antifungal activities. The results show that the antibacterial activity of compounds including o-methoxy group was significantly higher against S. epidermis compared to the other studied antimicrobial group.