Preparation and crystallographic studies of a new mercuric salicylaldimine complex for fabrication of microscaled and nanoscaled mercuric sulfide as antimicrobial agents against human pathogenic yeasts and filamentous fungi

摘要

The new mercuric complex [Hg(HL)(2)Cl-2] incorporating salicylaldimine ligand (HL = 2-((pyridin-3-ylimino)methyl)phenol) was fabricated where the ligand molecules behaved in a monodentate manner via their pyridine nitrogen atoms. In addition to elemental characterization, X-ray crystallographic studies of the complex revealed its packing in a monoclinic crystal system (space group: I2/a, a = 13.4276(2) angstrom, b = 6.20950(10) angstrom, c = 27.7530 (4) angstrom, alpha = gamma = 90 degrees, and beta = 98.1610(10)degrees). Hydrothermal treatment of [Hg(HL)(2)Cl-2] with thioacetamide afforded HgS microparticles (HgS mu Ps; Brunauer-Emmett-Teller [BET] surface area = 6.205 m(2)/g, diameter = 196.53-259.13 nm, and average size = 213.27 nm), whereas these microparticles were transformed to nanoscaled HgS particles (HgS NPs; BET surface area = 14.380 m(2)/g, diameter = 58.87-90.56 nm, and average size = 72.78 nm) by the action of ultrasonication. The as-prepared HgS, HgS NPs in particular, afforded remarkable microbicidal activity against eight strains of filamentous and unicellular human pathogenic fungi and yeasts in comparison with cycloheximide. Remarkably, Aspergillus terreus grew up to 34.7 +/- 1.88 mm in the absence of any fungicide, but HgS mu Ps, HgS NPs, and cycloheximide limited the fungal growth to 26 +/- 0.94, 12.33 +/- 1.6, and 28.3 +/- 1.7 mm after incubation for 6 days. Besides, inhibition of Rhodotorula glutinis was of 7.6 +/- 0.01 x 10(7) CFU/ml in control sample, but experiments included HgS mu Ps, HgS NPs, and cycloheximide limited the colony-forming units of R. glutinis to 4.2 +/- 0.01 x 10(7), 3.5 +/- 0.02 x 10(7), and 5.9 +/- 0.05 x 10(7) CFU/ml.