Grafting behavior of copolymers of styrene and ortho-vinylbenzaldehyde

Statistical copolymers of styrene and ortho-vinylbenzaldehyde (o-VBA) have been prepared by free radical solution polymerization using azodiisobutyronitrile initiator. Subsequent “grafting from” reactions could be induced through photolytic excitation of the pendant aldehyde carbonyl functionality in the presence of methyl methacrylate monomer; however, actual grafting of polymethylmethacrylate (PMMA) to the copolymer backbone was shown to be quite low (< 6% graft-on). Another more promising route involved abstraction of labile benzylic hydrogens of the copolymer by chemical methods [e.g., dibenzoyl peroxide or α,α′-di-(t-butylperoxy)diisopropylbenzene] to produce potential graft sites. Graft copolymers prepared by this procedure had PMMA content ranging up to about 30% (by weight), depending upon polymerization conditions. Higher grafting levels were generally observed with increasing reaction temperature and prolonged reaction times. While some grafting evidently originated from the copolymer backbone, the presence of the o-VBA moiety significantly enhanced the ultimate percent grafting. The resulting multicomponent polymer systems displayed substantial miscibility as evidenced by the transparency of their cast films as well as by their glass transition behavior.     

Hydrogen-bonded cubanes and ladder fragments by analogy with the inorganic solid state

By application of an analogy with the structures of alkali-metal phosphinimides, two hydrogen-bonded cubanes, [Ph(3)CNH(3)(+)X(-)](4) (X = Cl, Br), and one unprecedented four-rung ladder fragment, [Ph(3)CNH(3)(+)I(-)](4), have been prepared in the organic solid state.     

IRREVERSIBLE BINDING OF NITROFURANTOIN TO SKIN AND TO PLASMA PROTEINS OF UV-A EXPOSED RATS

Abstract— Allergic reactions to the widely applied urinary tract disinfectant nitrofurantoin (NFT) often concern the skin. They are probably mediated by a NFT-protein adduct. which has been suggested to result from incomplete nitro-reduction during metabolism. In this study it was investigated whether photoactivation of NFT in rats, upon exposure to UV-A, leads to formation of adducts between the drug and biomacromolecules. Rats were given p.o. doses of [¹⁴C]-NFT, and some were exposed to UV-A. More irreversible binding was found in skin of the back (both in dermis and in epidermis). tail, ears, eyes, plasma proteins, and spleen of light-exposed rats compared to those kept in the dark. This photobinding increased (up to ∼0.6 nmol/mg protein =∼25 nmol/g tissue) with dose and light-intensity. When rats were kept at 32°C, instead of 22°C during NFT/UV-A treatment, even more irreversible binding was observed; this is probably caused by an increased dermal blood flow. Under these conditions, irreversibly bound radioactivity was even found in kidney, lung and liver. Irreversible binding in these inner organs is explained by systemic distribution of radioactivity, photobound to plasma proteins. Photodecomposition of NFT in the skin, followed by reaction of photoproducts with (cellular) biomacromolecules may explain some of the skin rashes and other (allergic) reactions reported for this drug.