Fungicidal and spectral studies of some triphenyltin compounds

In the interest of developing a more effective fungicide to combat Dutch elm disease, our laboratories have synthesized several triphenyltin carboxylates and some 1:1 addition compounds of triphenyltin chloride using 2,3-disubstituted thiazolidin-4-ones as the ligand and screened them in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease, using a shake culture method. Elemental analyses and spectroscopic data indicate that the structures of the carboxy- lates in the solid state are monomeric with a tetrahedral tin atom with the exception of the furan-2-carboxylic acid derivative, which was found to be polymeric. The triphenyltin chloride adducts are trigonal-bipyramidal with the three phenyl groups in the equatorial plane. Far-infrared data indicate that the three phenyl groups are not co-planar. Screening results for both series of organotins indicate that these two classes of compounds are effective inhibitors of Ceratocystis ulmi, with the adducts having a higher activity. The furan-2-carboxylic acid derivative has a markedly decreased activity compared with the other carboxylates and this is attributed to its polymeric structure. © 1998 John Wiley & Sons, Ltd.     

Six-bar motion I. The Watt mechanism

Algebraic, geometric and kinematic properties are derived for the curves generated by points on the floating links of plane, six-link mechanisms with turning pairs. In part I the motion obtained from the Watt kinematic chain has been analyzed; parts II and III are concerned with the motions obtained from the Stephenson chain and extensions involving eight-bar and 2n-bar mechanisms.     

Six-bar motion III. Extension of the six-bar techniques to eight-bar and 2n-bar mechanisms

Using concepts developed in the course of the study of six-bar motion, we concern ourselves in this part with the derivation of certain extensions to mechanisms having eight and more links.     

Mononuclear Polypyridylruthenium(II) Complexes with High Membrane Permeability in Gram‐Negative Bacteria—in particular Pseudomonas aeruginosa

Ruthenium(II) complexes containing the tetradentate ligand bis[4(4′‐methyl‐2,2′‐bipyridyl)]‐1,n‐alkane (“bb_n”; n=10 and 12) have been synthesised and their geometric isomers separated. All [Ru(phen)(bb_n)]²⁺ (phen=1,10‐phenanthroline) complexes exhibited excellent activity against Gram‐positive bacteria, but only the cis‐α‐[Ru(phen)(bb₁₂)]²⁺ species showed good activity against Gram‐negative species. In particular, the cis‐α‐[Ru(phen)(bb₁₂)]²⁺ complex was two to four times more active than the cis‐β‐[Ru(phen)(bb₁₂)]²⁺ complex against the Gram‐negative strains. The cis‐α‐ and cis‐β‐[Ru(phen)(bb₁₂)]²⁺ complexes readily accumulated in the bacteria but, significantly, showed the highest level of uptake in Pseudomonas aeruginosa. Furthermore, the accumulation of the cis‐α‐ and cis‐β‐[Ru(phen)(bb₁₂)]²⁺ complexes in P. aeruginosa was considerably greater than in Escherichia coli. The uptake of the cis‐α‐[Ru(phen)(bb₁₂)]²⁺ complex into live P. aeruginosa was confirmed by using fluorescence microscopy. The water/octanol partition coefficients (log P) were determined to gain understanding of the relative cellular uptake. The cis‐α‐ and cis‐β‐[Ru(phen)(bb_n)]²⁺ complexes exhibited relatively strong binding to DNA (K_b≈10⁶ M ^?1), but no significant difference between the geometric isomers was observed.     

Characterization of water–ethanol electrosprays

The electrospray (ES) ionization method is widely used in the analysis of biological molecules. The stable cone regime spray is usually obtained by adding methanol or ethanol to the electrosprayed dipolar fluid, with the role of reducing fluid surface tension. We investigate the spray onset voltages of water–ethanol mixtures starting from distilled water to pure ethanol. Positive or negative DC is applied separately in our measurements. The experimental setup allows for the study of nozzle-counter electrode gaps of up to 50 cm. Significant variations in the spray onset are observed and analyzed. The onset voltage and the surface tension of water–ethanol binary mixtures appear to be in line with Smith’s formula. The largest variations of onset values are observed for surface tensions of 20 mN/m–40 mN/m in the mixtures. The results of the study may be instrumental to electrospray electrode design and spray control.     

Six-bar motion II. The Stephenson-1 and Stephenson-2 mechanisms

Algebraic, geometric and kinematic properties are derived for the curves generated by points on the floating links of the six-link mechanisms derived from the Stephenson kinematic chain.