Photoswitchable Flexible and Shape-Persistent Dendrimers: Comparison of the Interplay between a Photochromic Azobenzene Core and Dendrimer Structure

Li Xin Liao, Francesco Stellacci, Dominic V. McGrath

Research output: Contribution to journalArticle

Abstract

Two analogous classes of dendrimers with a single azobenzene moiety at the core have been prepared. Flexible benzyl aryl ether dendrimers 1a-e were obtained in good yields by direct alkylation of diphenolic azobenzene 3 with benzyl aryl ether dendrons [G-n]-Br (n = 0-4). In rigid dendrimers 2a-e, the azobenzene configurational switch was linked to phenylacetylene dendrons through acetylenic linkages to maintain the shape-persistent nature of these dendrimers. A comparison of these two different classes of dendrimers with azobenzene cores reveals a difference in the properties of the photochromic moiety upon dendritic incorporation as well as a significant difference in the photomodulation of dendrimer properties. The E → Z photoisomerization quantum yield decreased markedly with increasing generation for dendrimers 1a-e but only slightly for dendrimers 2a-e. However, increasing generation did not significantly alter thermal isomerization kinetics or activation barriers. The hydrodynamic volumes of azobenzene-containing dendrimers 2b-e were significantly modulated when the azobenzene unit is subjected to irradiation, while those of dendrimers 1b-e were only slightly affected.

Original languageEnglish
Pages (from-to)2181-2185
Number of pages5
JournalJournal of the American Chemical Society
Volume126
Issue number7
DOIs
Publication statusPublished - Feb 25 2004

ASJC Scopus subject areas

  • Chemistry(all)

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