Amine oxides—XIII

Polycentric binding in complexes of trimethylamine-N-oxide with dihalogens

Dihalogens readily interact with trimethylamine-N-oxide under ambient conditions. Accordingly, herein, stable 1 : 1 adducts were obtained in the case of iodine chloride and iodine bromide. The crystal and molecular structure of the trimethylamine-N-oxide-iodine chloride adduct was solved. Furthermore, the geometry and electronic structure of the trimethylamine-N-oxide-dihalogen complexes were studied computationally. Only molecular ensembles were found in the global minimum for the 1 : 1 stoichiometry. The O⋯X-Y halogen bond is the main factor for the thermodynamic stability of these complexes. Arguments for electrostatic interactions as the driving force for this noncovalent interaction were discussed. Also, the equilibrium structures are additionally stabilised by weak C-H⋯X hydrogen bonds. Consequently, formally monodentate ligands are bound in a polycentric manner.

Pyrolysis gas-liquid chromatography of N,N-dimethylalkylamine N-oxides and their mixtures

A rapid quantitative and small scale method based on direct injection pyrolysis gas-liquid chromatography is described for the determination of N,N-dimethylalkylamine N-oxides. The method is suitable for determination of individual N-oxides as well as of their homologous compositions with or without the presence of parent tertiary amines in water or methanol solutions. The sensitivity of the method is 10-15 nmol of compounds injected. The unsymmetrical (1-methyldodecyl)dimethylamine N-oxide forms two isomeric alkenes 1-tridecene and trans-2-tridecene in a ratio of 1.68, in agreement with the predicted value.

Interaction of amine oxides and quaternary ammonium salts with membrane and membrane-associated processes in E. coli cells: mode of action

The antimicrobials (1-methyldodecyl)dimethylamine oxide and (1-methyldodecyl)trimethylammonium bromide affect the cytoplasmic membrane of E. coli. The interaction results in release of intracellular material (K+, 260nm-absorbing material), an effect on dehydrogenase enzyme activity and inhibition of respiration. The final effect of both substances is the same; they differ only in their dynamics. The effect of the membrane was correlated with parameters characterizing these surfactants i.e. critical micelle concentration (c.m.c.) minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) over the concentration range of 10(-4) to 10(-1) mmol/dm3 of active substance. The three stage mode of action model can be summarized as follows: 1-polar (coulombic) interactions, 2-polar and hydrophobic interactions, 3-hydrophobic interactions (extraction and solubilization). The polar and hydrophobic interactions (1st and 2nd stage) are discussed also in relation to model membranes.

Microsomal N-oxidation of long chain N,N-dimethylalkylamines: quantitative structure-activity relationships

N,N-Dimethylalkylamines CmH2m+1N(CH3)2 (m = 4 to 18) undergo in vitro N-oxidation to the corresponding amine oxides by mouse liver microsomes. The relative oxidisability of these compounds is parabolically dependent on structural and physico-chemical characteristics (with a maximum at m 12) and is controlled by at least three factors: lipophilicity, stereochemistry and the nucleophilicity of the compounds under evaluation. The results from the QSAR study support this multifactorial view.