Polyviologen dendrimers as hosts and charge-storing devices

Célia M. Ronconi, J. Fraser Stoddart, Vincenzo Balzani, Massimo Baroncini, Paola Ceroni, Carlo Giansante, Margherita Venturi

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Two dendrimers were designed and synthesized that contain a 1,3,5-trisubstituted benzenoid core and incorporate 9 and 21 viologen (4,4′-bipyridinium) units in their branches in addition to hydrophilic (aryloxy) terminal groups. For comparison purposes, model compounds containing one and two viologen units were also studied. These polycationic dendrimers form strong host-guest complexes with the dianionic form of the red dye eosin in dilute CH2Cl2 solutions. Titration experiments, based on fluorescence measurements, showed that each viologen unit in the dendritic structures becomes associated with an eosin dianion. Electrochemical (in MeCN) and photosensitization (in CH2Cl2) experiments revealed that only a fraction of the viologen units present in the dendritic structures can be reduced. This fraction corresponds to the number of viologen units present in the outer shells of the dendrimers. The reasons for incomplete charge pooling are discussed. Comparison with the behavior of polyviologen dendrimers that are terminated with bulky tetraarylmethane groups and were studied previously enabled the role played by the terminal groups in the redox and hosting properties to be elucidated.

Original languageEnglish (US)
Pages (from-to)8365-8373
Number of pages9
JournalChemistry - A European Journal
Volume14
Issue number27
DOIs
StatePublished - Sep 19 2008

Keywords

  • Dendrimers
  • Electrochemistry
  • Host-guest systems
  • Photosensitization
  • Viologens

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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