Photophysical and antimicrobial properties of new double-armed benzo-15-crown-5 ligands and complexes

Abstract

New double-armed crown ether ligands linked to pyridine derivatives have been synthesized and characterized. These macrocyclic ligands (1-5) have been synthesized by the reactions of 4,5-bis(bromomethyl)benzo-15-crown-5 with 3-hydroxy pyridine derivatives. A series of Na+, K+ and Ag+ complexes (1a-5a, 1b-5b and 1c-5c) of the macrocyclic ligands have been prepared from sodium perchlorate, sodium picrate, potassium iodide, potassium picrate and silver nitrate salts, respectively. The most suitable cation Na+ is bound to the 15-crown-5 cavity and 1:1 filling complexes are formed (1a-5a) while the K+ cation interacts with the crown ether cavity and forms sandwich-type complexes (1b-5b). The Ag+ complexes (1c-5c) have been obtained with a pyridine moiety of the new crown ethers. New ligands undergo photophysical changes when bonding the cation. The influence of metal cations such as Na+, Li+, K+, Fe3+, Cu2+, Ca2+, Ba2+ and Al3+ on the spectroscopic properties of the pyridine linked to the double-armed crown ether moiety was investigated in EtOH solution by means of absorption and emission spectrometry. The prepared compounds (1-5, 1a-5a, 1b-5b and 1c-5c) were evaluated for antibacterial and antifungal activities against pathogenic microorganisms. The results show that the antimicrobial activity of the synthesized compounds varying a degree of inhibitory effects on the growth of different tested pathogenic strains.