Synthesis of Fluorescent, Dumbbell-Shaped Polyurethane Homo- and Heterodendrimers and Their Photophysical Properties.

Fluorescent dendrimers have wide applications in biomedical and materials science. Here, we report the synthesis of fluorescent polyurethane homodendrimers and Janus dendrimers, which often pose challenges due to the inherent reactivity of isocyanates. Polyurethane dendrons (G1-G3) were synthesized via a convergent method using a one-pot multicomponent Curtius reaction as a crucial step to establish urethane linkages.

Low-generation fluorescent polyurethane dendrimers late-stage modification using azide-alkyne click chemistry.

Protecting group free one-pot multicomponent Curtius reaction afforded a versatile MN type dendron, ensuring late-stage modification of both dendron and dendrimer to afford highly fluorescent symmetrical and unsymmetrical (Janus) polyurethane dendrimers. Fluorescence study of these dendrimers exhibited the Förster resonance energy transfer (FRET) between blue and mint green fluorophores.

A Model for Late-Stage Modification of Polyurethane Dendrimers Using Thiol-Ene Click Chemistry.

Dendritic materials possessing urethane linkage are surprisingly more stable than similar structures having functional groups such as ether, ester, amide, or carbosilane. This generates profound interest in dendritic polyurethanes. Construction of a well-defined polyurethane dendrimer is, however, challenging because of isocyanates' high reactivity.

Capillary electrophoresis of heparin and other glycosaminoglycans using a polyamine running electrolyte.

This study involves the use of polyamines as potential resolving agents for the capillary electrophoresis (CE) of glycosaminoglycans (GAGs), specifically heparin, dermatan sulfate, chondroitin sulfate, over-sulfated chondroitin sulfate (OSCS), and hyaluronan. All of the compounds can be separated from each other with the exception of chondroitin sulfate and hyaluronan. Using optimization software, the final run conditions are found to be 200 mM ethylenediamine and 45.

Detection of ozone gas using gold nanoislands and surface plasmon resonance.

Gold nanoislands interact with gaseous ozone to produce a surface plasmon resonance shift, similarly to the interaction of ozone and gold nanoparticles in water. Gold nanoislands are produced by sputtering, which significantly simplifies the synthesis and produces controlled size for the gold nanoislands. The shift of surface plasmon resonance peak was monitored while gold nanoislands were exposed to variable concentration of gaseous ozone.

Removal of transition metals from motor oil using ion exchange resins.

A variety of polystyrene-divinylbenzene resins functionalized with such groups as SOH, N(CHCOOH), and SH were tested in the slurry batch mode for the removal of transition metals from used motor oil. Naturally occurring materials such as coal and clay were also tested. The N(CHCOOH) resin (Chelex 100) and the SH resin (Duolite GT-73) were found effective removing on the average 70 and 78% of metals such as Fe, Pb, Zn, Cu, Ni, and Mn, respectively.