New low-temperature oil-in-water (O/W) type microemulsions that resist freezing and phase separation
at −18 °C have been developed. These systems were shown to simultaneously destroy, via oxidative and
hydrolytic mechanisms, simulants of three chemical warfare agents. Reactions, monitored at 25 °C by
gradient elution high-performance liquid chromatography, took place instantly or over many minutes,
depending upon the particular simulant. Neglecting reaction products, the low-temperature microemulsions
contained 11 components: propylene glycol, water, base, oxidant/nucleophile, surfactant, cosurfactant, oil,
stabilizer, two nerve agent simulants, and a mustard simulant. Only by virtue of self-aggregation does
this extraordinarily complex chemical system adopt a useful molecular organization and, in this limited
sense, the microemulsion chemistry resembles what happens in a living cell. Substantial practical issues
remain: rates for a recalcitrant VX simulant should be increased and overoxidation of the mustard simulant
to a sulfone retarded. Nonetheless, the new system demonstrates once again the potential of microemulsions
in carrying out useful organic reactions at realistic substrate concentrations in aqueous solvents.
Two mutual prodrugs, in which two different anti-cancer drugs are attached to the same molecule via labile linkages, are synthesized and examined kinetically. One of the mutual prodrugs loses a drug component under physiological conditions within an hour, but the other mutual prodrug (having a longer spacer between the two drugs) is stable to chemical degradation even at higher pH values. Thus, enzymatic hydrolysis alone will release the two anti-cancer drugs. The potential value of anti-cancer mutual prodrugs is discussed.
The design and utility of a family of isocyanate functionalized branched monomers, as well as others, are described. Use of these monomers in logical combinations for the construction of branched architectures leads to the formation of unique, asymmetric dendritic species possessing multiple functionalities. Ramifications of this combinatorial-based, macromolecular construction technique are discussed with respect to functional group positioning and the potential to create dynamic heterogenous surfaces resembling a molecular "Rubik's sphere."
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