Copper(I)-catalyzed 1,3-dipolar cycloaddition reaction of nonfluorescent 3-azidocoumarins and terminal alkynes afforded intense fluorescent 1,2,3-triazole products. The mild condition of this reaction allowed us to construct a large library of pure fluorescent coumarin dyes. Since both azide and alkyne are quite inert to biological systems, this reaction has potential in bioconjugation and bioimaging applications. [reaction: see text]

Acetylenes. -9 Azidocoumarins and 24 acetylenes, both inert to biological systems, are used for the construction of a large library consisting of fluorescent 1,2,3-triazole dyes. This "click and probing" ligation protocol may have a high potential in functionalizing bionanoparticles. -(SIVAKUMAR, K.; XIE, F.; CASH, B. M.; LONG, S.; BARNHILL, H. N.; WANG*, Q.; Org. Lett. 6 (2004) 24, 4603-4606; Dep. Chem. Biochem., Univ. S. C., Columbia, SC 29208, USA; Eng.) -Lindner 13-138

We report a simple and low-cost strategy to enhance the dielectric permittivity of polystyrene by up to an order of magnitude via incorporating an oligoaniline trimer moiety at the end of the polymer chains. The oligoaniline-capped polystyrene was prepared by a copper-catalyzed click reaction between azide-capped polystyrene and an alkyne-containing aniline trimer, which was doped by different acids. By controlling molecular weight of polystyrene, the end-capped polymers can be induced to form nanoscale oligoaniline-rich domains embedded in an insulating matrix. Under an external electric field, this led to an increase in dielectric polarizability while maintaining a low dielectric loss. At frequencies as high as 0.1 MHz, the dielectric permittivity and dielectric loss (tan δ) were ∼22.8 and ∼0.02, respectively. This strategy may open a new avenue to increasing the dielectric permittivity of many other commodity polymers while maintaining relatively low dielectric loss.

Horse spleen apoferritin, the hollow protein shell derived from ferritin, a special biological nanoparticle, can be chemoselectively modified at the lysine residues, which affords a robust scaffold for further chemical reactions including Cu(i)-catalyzed azide-alkyne cycloaddition reaction and atom transfer radical polymerization reaction.

The preparation of carboxylic acid‐coated silica nanoparticles was investigated. A monolayer of carboxylic acid residues with controllable graft density was anchored to the nanoparticle by a ring‐opening reaction with succinic anhydride. Poly(methacrylic acid) [poly(MAA)] grafted nanoparticles were prepared via a polymerization–deprotection strategy. Tert‐butyl methacrylate was polymerized from the surface of silica nanoparticles in a predictable manner and with excellent control over the molecular weight distribution. Subsequent removal of the tert‐butyl group resulted in poly (MAA) grafted nanoparticles. The polymer nanoparticles were also functionalized with dyes, which may be useful in tracking the particles in biological systems. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012