Abstract:We synthesized nine quaternary ammonium compounds (QUATs) starting from phenylalanine, N-alkyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromides, which were prepared as optically pure substances. Five compounds were prepared as S-enantiomers and four compounds as R-enantiomers. These compounds were evaluated by their activities against bacteria and fungi. Three microbial strains were used in the study: the gram-negative bacteria Escherichia coli, the gram-positive bacteria Staphylococcus aureus and the fungi Candida albicans. The activities were expressed as minimum bactericidal or fungicidal concentrations (MBC). The most active compounds were (2S)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide and (2R)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide, with MBC values exceeding those of commercial benzalkoniumbromide (BAB) used as standard. The relationships between structure and biological activity of the tested QUATs were quantified by the bilinear model (QSAR) and are discussed.

Herein we report the synthesis and characterization of a linear, two-coordinate Pt(II) ketimide complex, Pt(N=C t Bu2)2 (1), formed via reaction of PtCl2(1,5-COD) with 2 equiv of Li(N=C t Bu2). Also generated in the reaction is the bimetallic complex, [(t Bu2C=N)Pt(µ-N,C-N=C(t Bu)C(Me)2CH2)Pt(N=C t Bu2)] (2). Both complexes 1 and 2 have been characterized by NMR spectroscopy and X-ray crystallography. Notably, complex 1 exhibits short Pt-N distances (av. Pt-N = 1.817 Å) and an unusually deshielded 195 Pt chemical shift (δPt =-629 ppm) with a large 1 J(195 Pt, 14 N) coupling constant (537 Hz). These data, in combination with a detailed DFT electronic structure analysis, reveal the presence of highly covalent Pt=N multiple bonds formed by a combination of σ-donation, π-donation, and π-backdonation.

A series of novel phospholium amphiphilic compounds with straight alkyl chains with different numbers of carbon atoms (12,14,15,16,17,18) were synthesized. The quaternary phosphorus, phosphonium cation, is incorporated into a five-membered heterocyclic ring. Their physicochemical properties were investigated by measurements of surface tension, conductivity and dynamic light scattering. The critical micelle concentration (c M ), the surface tension value at the c M (c cmc ), the surface area at the surface saturation per head group (A cmc ), the ionization degree of micelle (a), the free energy of micellization (DG°m ic ), and hydrodynamic diameter (d h ) were determined. Antimicrobial activity was tested against bacteria and yeast. The structure-activity relationship was determined. 3 J CP = 17.3 Hz, = C-CH 3 ) 22.5 (d, 1 J CP = 46.2 Hz, a CH 2 of alkyl chain), 22.6 (d, 2 J CP = 4.1 Hz, b CH 2 of alkyl chain), 22.7 (x CH 2 of alkyl chain), 29.1, 29.3, 29.4, 29.5, 29.6(0), 29.6(4), 29.7 (d-x-2 CH 2 of alkyl chain), 30.5 (d, 3 J CP = 15.6 Hz, c CH 2 of alkyl chain), 31.9 (x-1 CH 2 of alkyl chain), 113.6 (d, 1 J CP = 80.0 Hz, = CHP), 115.9 (d, 1 J CP = 83.9 Hz, Ph C 1 ), 130.0 (d, 3 J CP = 12.9 Hz, Ph C meta ), 133.6 (d, 2 J CP = 10.7 Hz, Ph C ortho ), 134.6 (d, 4 J CP = 3.0 Hz, Ph C para ), 163.2 (d, 2 J CP = 16.4 Hz, = C-CH 3 ); 31 P NMR (CDCl 3 , H 3 PO 4 ) d: 38.5; IR t max /cm -H NMR (CDCl 3 , TMS) d: 0.88 (t, 3 J H,H = 6.7 Hz, 3H, CH 3 of alkyl chain), 1.13-1.38 (m, 22H, 11 9 CH 2 of alkyl chain), 1.38-1.62 (m, 4H, b, c CH 2 of alkyl chain) 2.29 (s, 6H, 2 9 = C-CH 3 ), 3.08-3.22 (m, 2H, a CH 2 of alkyl chain), 7.08 (d, 2 J HP = 30.9 Hz, 2H, = CHP), 7.54-7.61 (m, 2H, Ph H meta ), 7.61-7.75 (m, 1H, Ph H para ), 8.15-8.23 (m, 2H, Ph H ortho ); 13 C NMR (CDCl 3 , TMS) d: 14.1 (CH 3 of alkyl chain), 18.5 (d, 3 J CP = 17.3 Hz, = C-CH 3 ) 22.5 (d, 1 J CP = 46.1 Hz, a CH 2 of alkyl chain), 22.6 (d, 2 J CP = 4.1 Hz, b CH 2 of alkyl chain), 22.7 (x CH 2 of alkyl chain), 29.1, 29.3, 29.4, 29.5, 29.6, 29.7 (d-x-2 CH 2 of alkyl chain), 30.5 (d, 3 J CP = 15.4 Hz, c CH 2 of alkyl chain), 31.9 (x-1 CH 2 of alkyl chain), 113.6 (d, 1 J CP = 80.0 Hz, = CHP), 115.8 (d, 1 J CP = 83.8 Hz, Ph C 1 ), 130.0 (d, 3 J CP = 12.9 Hz, Ph C meta ), 133.5 (d, 2 J CP = 10.4 Hz, Ph C ortho ), 134.7 (d, 4 J CP = 3.0 Hz, Ph C para ), 163.2 (d, 2 J CP = 16.5 Hz, = C-CH 3 ); 31 P NMR (CDCl 3 , H 3 PO 4 ) d: 38.5; IR t max /cm -

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