Analog inverting active

Depending on the chemical modification of the conjugated core, either n- or p-type behavior is observed, while the fluorine-free acyl analogs behave as either ambipolar or p-type semiconductor. Insertion of the dioxolane group into the thiophene core inverts the majority charge carrier type from electrons (371) to holes (372) in a very similar fashion to 369. The 373 data reveal that n-type activity is recovered with mobility and on-off ratio 0.07 cm2 V 1 s-1 and 106. 

Due to its ability to form inverted hexagonal phase, DOPE is believed to impart fusogenicity to lipoplexes, thus facilitating fusion followed by destabilization of the endosomal membrane, lipoplex escape from the endosomes, and eventually the DNA release. Indeed, inclusion of DOPE into lipoplexes was shown to enhance considerably the transfection activity of some of the cationic lipid carriers [35,120, 121]. For example, formulations of oxypropyl quaternary ammonium cationic lipids with 50 mol% DOPE have been reported to exhibit 2-5 times higher transfection activity in COS7 cells than formulations with pure cationic lipid (Fig. 29) [35]. Recently, a triple-bond dialkynoyl analog of DOPE has been... 

As in the MBH reactions, / -ICD (44) is also an efficient and remarkably general catalyst in aza-MBH reactions [94, 95]. This catalyst promotes the addition a variety of electron-deficient olefins such as acrylates, enones, and enals with activated aromatic aldimines. Of note, the absolute stereochemistry of the product is generally opposite compared to the analogous MBH reaction with / -ICD catalyst imines gives rise to (S)-enriched adducts, in contrast to aldehydes which afford ( -products [94]. Substitution patterns of the olefin may alter or even invert this trend, however. 

A remarkable recent example of the influence of electropolymerization temperature on the properties of PAn products is observed in the potentiostatic polymerization of aniline in the presence of chiral (+)-HCSA to give optically active PAn/(+)-HCSA films. The CD spectra of the polymers electrodeposited at < 25°C were inverted compared to the spectra of analogous emeraldine salts deposited at > 40°C, indicating an inversion of the preferred helical hand for PAn chains.38 The observations may be rationalized in terms of a temperature-induced interconversion between two initially (kinetically) formed diastereomeric PAn products. 

In the second type of mechanism, analogous to that used by the aspartyl and metalloproteases, an activated water molecule attacks the phosphorus atom directly. In this mechanism, a single displacement reaction takes place at the phosphorus atom. Hence, the stereochemical configuration of the tetrahedral phosphorus atom is inverted each time a displacement reaction takes place. Monitoring the stereochemical changes of the phosphorus could be one approach to determining the mechanism of restriction endonuclease action. 

A series of valinomycin analogs in which the ring size was enlarged or in which a single asymmetric center was inverted were found to be much less active than the parent valinomycin This information together with the extremely low concentrations of valinomycin required ( 10 M), was interpreted as suggesting that valinomycin activated a specific mitochondrial K" transport receptor. 

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