New crown ether ligands of Schiff base type (4-11) have been synthesised by the reaction of two equivalents, of benzaldehyde, 2-hydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 5-methoxy-2-hydroxybenzaldehyde, 5-bromo-2-hydroxybenzaldehyde, 5-nitro-2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde or 2-hydroxy-l-naphthaldehyde with 2,3,5,6-di[4-aminobenzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-dien (3). The ligand 2,3,5,6 -di[4-N-(salicylidene)benzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-dien (5) (5) reacts with Mn-II, Fe-II, Co-II, Ni-II, Cu-II and Zn-II to yield 1 : 1 metal-ligand complexes. The structures of ligands and complexes have been investigated by elemental analysis, IR, UV-visible, (1)(H) NMR and C-13 NMR data. The tetradentate nature of the ligands is inferred from IR spectra. The UV-visible spectral data suggest octahedral geometry for metal complexes. The antimicrobial activities and yeast cultures of the ligands and metal complexes have been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538 P, Bacillus cereus ATCC 7064, Proteus vulgaris ATCC 8427, Salmonella typhimurium DSM 554, Corynebacterium xerosis ATCC 373 and Hanseniaspora guilliermondii DSM 3432, Rhodotorula rubra DSM 70403 and Kluyveromyces fragilis ATCC 8608. The metal complexes are more fungitoxic than the free ligand.