Strain-promoted alkyne azide cycloaddition for the functionalization of poly(amide)-based dendrons and dendrimers

Cátia Ornelas, Johannes Broichhagen, Marcus Weck

Research output: Contribution to journalArticlepeer-review

Abstract

Functionalization of a poly(amido)-based dendron with ethylene glycol chains (PEG) using coppercatalyzed alkyne azide cycloaddition (CuAAC) afforded dendrons with significant levels of copper contaminations, preventing the use of such materials for biological applications. We suggest that the presence of amide, PEG, and triazole functional groups allows for copper complexation, thereby preventing the separation of the copper catalyst from the final dendron. To minimize this problem, synthetic variations on CuAAC including the addition of "click" additives for copper sequestering as well as the use of copper wire as the copper source were investigated. None of these strategies, however, resulted in copper-free products. In contrast, we developed a copper-free strain-promoted alkyne azide cycloaddition (SPAAC) strategy that functionalized poly(amide)-based dendrons and dendrimers with PEG chains quantitatively under mild reaction conditions without any metal contamination. The SPAAC products were characterized by 1H and 13C NMR, 2D HSQC and COSY NMR, mass spectrometry, and elemental analysis. This is the first report on the use of SPAAC for dendrimer functionalization, and the results obtained here show that SPAAC is an important tool to the dendrimer and more general biomaterials community for the functionalization of macromolecular structures due to the mild and metal-free reaction conditions, no side products, tolerance toward functional groups, and high yields.

Original languageEnglish (US)
Pages (from-to)3923-3931
Number of pages9
JournalJournal of the American Chemical Society
Volume132
Issue number11
DOIs
StatePublished - Mar 24 2010

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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