Two bromide-bearing, fluorene-based, conjugated polymers with oligo(ethylene glycol)- and poly(ethylene glycol)-tethered spacers have been prepared by the Suzuki coupling polymerization of bromide-bearing, fluorene monomers. beta-Glucose and alpha-mannose residues have been covalently attached to the conjugated polymers by post-polymerization functionalization of the precursor polymers with thiol-functionalized carbohydrates under basic conditions through thioether linkage. A glucose-bearing glycopolymer with oligo(ethylene glycol)-tethered spacers (polymer A) displays poor water solubility. However, glycopolymers with poly(ethylene glycol)-tethered spacers (polymers B and C) are highly water-soluble due to their long, flexible, hydrophilic spacers. Incubation of the ORN178 strain of Escherichia coli (E. coli) with alpha-mannose-bearing glycopolymer (polymer C) results in the formation of fluorescent cell clusters, causing significant red shifts in UV/Vis absorption and fluorescent spectra of the polymer through multivalent cooperative interactions of the polymeric carbohydrates with the bacterial pili. In contrast, polymer C displays no interactions with a mutant ORN208 strain of E. coli.
Three fluorescent conjugated copolymers, comprised of alternating fluorene and BODIPY units in the main chain, have been prepared by palladium-catalyzed Suzuki polymerization of 9,9-dihexylfluorene-2,7-diboronic acid with each of three different 2,6-diiodo-substituted BODIPY monomers. The copolymers were characterized using FT-IR spectroscopy, UV-vis spectroscopy, photoluminescence (PL), and molecular weight studies. Low-band gap BODIPY comonomers are effective in expanding the emission wavelength to the orange region because of significant extension of π-conjugation and have significantly enhanced fluorescent intensity with fluorescent quantum yield of up to 85% in methylene chloride solution. The copolymers show absorption maxima between 547 and 557 nm and emission maxima between 585 and 588 nm in methylene chloride solutions. The copolymers possess high molecular weight, good solubility and readily dissolve in common organic solvents such as THF, CH 2 Cl 2 , CHCl 3 , and toluene. The copolymers display sensitive fluorescent responses to fluoride and cyanide anions through their multivalent interactions while they do not respond to chloride, bromide, and iodide anions.
Highly diastereoselective metalloamination/cyclization reactions of zinc(II) hydrazides obtained through reaction of diethylzinc with N,N-dimethylhydrazinoalkenes are described. The resulting organozinc intermediates undergo facile allylation and acylation, in situ, to provide the corresponding functionalized piperidines and pyrrolidines.
The title compound, C16H22O3, is bent with a dihedral angle of 75.3 (1)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, the molecules are linked into infinite chains held together by weak C—H⋯O hydrogen-bonded interactions between an H atom on the benzene ring of one molecule and an O atom on the ketone functionality of an adjacent molecule. The chains are arranged with neighbouring tert-butyl and dimethyl groups on adjacent chains exhibiting hydrophobic stacking, with short C—H⋯H—C contacts (2.37 Å) between adjacent chains
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