Formation of a copillar[5]arene-based supramolecular polymer in solution and in the solid state.

A linear supramolecular polymer based on the self-assembly of an easily available copillar[5]arene monomer is efficiently prepared, which is evidenced by the NMR spectroscopy, viscosity measurement, and DOSY experiment. The single-crystal X-ray analysis reveals that the polymerization of the AB-type monomer is driven by the quadruple CH•••π interactions and one CH•••O interaction.

Synthesis and antibacterial activities of 4-hydroxy-o-phenylphenol and 3,6-diallyl-4-hydroxy-o-phenylphenol against a cariogenic bacterium Streptococcus mutans OMZ 176.

For the purpose of survey of the antibacterial activity against a cariogenic bacterium Streptococcus mutans OMZ 176 with the introduction of hydroxyl and allyl groups to o-phenylphenol (Fig. 2, 1), 4-hydroxy-o-phenylphenol (2), and 3,6-diallyl-4-hydroxy-o-phenylphenol (4) were synthesized, successively. The synthesized compounds, 2 and 4 showed more potent antibacterial activity than the starting material, 1. The hydroxyl group was supposed to the essential element for the antibacterial activity and the introduction of allyl group to phenolic ring to be another element to increase the activity.

Hydroquinone modified chitosan/carbon film electrode for the selective detection of ascorbic acid.

A redox active polymer, hydroquinone modified chitosan (Q-chitosan) was synthesized and characterized by IR and (1)H NMR spectroscopy. The nanocomposite of Q-chitosan with carbon was prepared and used to construct a stable conductive film on the electrode surface. The SEM studies confirms that the Q-chitosan/C composite covers the electrode surface with polymer embedded 50 nm size carbon particles. The formal redox potential, E(0) of the Q-chitosan/C composite modified electrode is evaluated to be 0.09 V vs. Ag/AgCl at pH 7 and the composite electrode shows an excellent electrocatalytic activity toward the ascorbic acid (AA) at 0.0 V vs. Ag/AgCl. It is more negative potential than the similar AA biosensors and the lower potential oxidation of AA enabled the selective detection of AA over major interferences such as dopamine and uric acid. Using amperometric method, the linear range for ascorbic acid is estimated to be 10 µM to 5 mM with the detection limit of 3 µM and the sensitivity is 0.07 6µA µM(-1)cm(-2).

Reaction pathways of glucose during esterification: effects of reaction parameters on the formation of humin type polymers.

The formation of humin-type polymers and other products during exposure of glucose to methanol/water mixtures with methanol/water mass ratios from 10 to 0.22 in the presence of the acid catalyst Amberlyst 70 was investigated. In water-rich medium (methanol/water mass ratio: 0.22), dehydration of glucose produced 5-(hydroxymethyl)furfural (HMF), furfural, and substantial amounts of polymer. In methanol-rich medium (methanol/water mass ratio: 10), the hydroxyl and carbonyl groups of glucose, HMF or furfural were protected via etherification and acetalisation. These protections stabilized these reactive compounds and significantly lowered the polymer formation (1.43% of the glucose loaded). The polymerization of glucose and HMF was also favored at high temperatures and long residence times. Conversely, high catalyst dosage mainly accelerated the conversion of glucose to methyl levulinate. Thus, the polymerization of glucose and HMF can be suppressed in methanol/water mixtures with high methanol ratios, at low temperatures and short residence times.

Synthesis of sugar-substituted poly(phenylenevinylene)s.

Sugar-containing PPVs, poly{2-[O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)]-5-methoxy-p-phenylenevinylene-alt-p-phenylenevinylene} (PPV-GlcNAc) and poly{2,5-bis-[O-(beta-d-glucopyranosyl)]-p-phenylenevinylene-alt-p-phenylenevinylene} (PPV-Glc(2)), were synthesized via Heck reaction of p-divinylbenzene (DVB) with O-glycosylated hydroquinones, 2,5-dibromo-4-methoxyphenyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranoside (3) and 1,4-bis(O-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2,5-dibromobenzene (6), respectively. Acetyl protecting groups of the PPVs are completely removable under mild conditions (yield 69-87%). The structures were confirmed using (1)H NMR and IR spectra. Size exclusion chromatography (SEC) (eluent: DMF, polystyrene standards) measurements indicated that respective M(n) and M(w)/M(n) values of the obtained polymers are 4.49 x 10(3) and 2.3(5) (PPV-GlcNAc) and 3.86 x 10(3) and 1.3(9) (PPV-Glc(2)). These sugar-containing PPVs are soluble in water/DMF (8/2, v/v) and are recognized by Concanavalin A (Con A), D-glucose-binding protein. Blue shift of lambda(max) of the conjugated polymer backbone was confirmed when the glucose-substituted PPV interacts with Con A. Based on those binding properties, these results revealed that the obtained PPVs with pendant sugars have capabilities for detection of biological stimuli.

Blocking nitrosamine formation with polymers.

A set of polymers have been synthesized in order to determine whether polymers containing nitrosation-reactive functional groups could effectively block nitrosamine formation. Polymers containing both hydrophobic backbones [poly[(chloromethyl)styrene], poly(ethylene oxide-co-epichlorohydrin), chloromethylated cross-linked polystyrene] and hydrophilic backbones [poly(ethylenimine) and poly(acryloyl chloride)] have been derivatized with pyrrole, 2,5-dimethylpyrrole, 2-[(methylamino)methyl]pyrrole, or hydroquinone. All of these polymers, as well as PEI itself, are effective at blocking the nitrosation of morpholine by nitrous acid. The hydrophilic polymers are much better able to compete for the available nitrosating agent in aqueous solution than are the hydrophobic polymers. Nevertheless, all of the polymers were highly effective in scavenging nitrous acid from aqueous solution prior to addition of the amine. The reaction products derived from the reactive, polymer-attached functional groups are retained on the polymer and are easily removed from mixtures of chemicals by physical means. Since nitrosamines and other N-nitroso compounds are known to be potent animal carcinogens, this work is of significance in the area of preventive chemical toxicology.