ABSTRACT
The copper(I), silver(I), and gold(I) metals bind π-ligands by σ-bonding and π-back bonding interactions. These interactions were investigated using bidentate ancillary ligands with electron donating and withdrawing substituents. The π-ligands span from ethylene to larger terminal and internal alkenes and alkynes. Results of X-ray crystallography, NMR, and IR spectroscopy and gas phase experiments show that the binding energies increase in the order AgSubject(s)
Copper
, Silver
, Copper/chemistry
, Crystallography, X-Ray
, Gold/chemistry
, Ligands
, Silver/chemistry
ABSTRACT
Highly fluorinated tris(pyrazolyl)borates were tested for their antimicrobial activity against various bacterial species. Both the silver(I) tris(pyrazolyl)borate [HB(3,5-(CF(3))(2)Pz)(3)]Ag(THF) (THF=tetrahydrofuran) and the sodium analog [HB(3,5-(CF(3))(2)Pz)(3)]Na(THF) appeared highly effective at inhibiting the growth of two different species of Gram-positive bacteria (i.e. being 12 and 21 fold more effective, respectively, (on a molar basis, based on the minimum inhibitory concentrations) against Staphylococcus aureus than silver sulfadiazine, a currently used silver antimicrobial). This suggests that the ligand portion of these molecules is responsible for the observed high effectiveness against the Gram-positive species. Furthermore, it appeared that the fluorinated substituents on the tris(pyrazolyl)borate were important for this high level of growth inhibition. Against two species of Gram-negative bacteria, including Pseudomonas aeruginosa, the fluorinated silver(I) tris(pyrazolyl)borate exhibited a moderate level of growth inhibition (similar to that of silver sulfadiazine), while the sodium analog showed very little ability to inhibit growth, indicating that for the Gram-negative species, the apparent responsible antimicrobial portion is the silver ion.
Subject(s)
Anti-Infective Agents/chemistry , Borates/chemistry , Pyrazoles/chemistry , Anti-Infective Agents/metabolism , Anti-Infective Agents/pharmacology , Bacillus subtilis/drug effects , Bacillus subtilis/growth & development , Borates/metabolism , Borates/pharmacology , Fluorine/chemistry , Ligands , Microbial Sensitivity Tests , Pyrazoles/metabolism , Pyrazoles/pharmacology , Silver Sulfadiazine/pharmacology , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & developmentABSTRACT
Tetrahydrobenzimidazoles, on treatment with dimethyldioxirane, rearrange to provide 5-imidazolones exclusively. These rearrangements proceed with a broad range of substrates and with good to excellent levels of diastereoselectivity. [reaction: see text]
