Dendrimers functionalized with a single pyrene label: Synthesis, photophysics, and fluorescence quenching

Claudia M. Cardona, Tom Wilkes, Winston Ong, Angel E. Kaifer, Tracy Donovan McCarley, Siddarth Pandey, Gary A. Baker, Maureen N. Kane, Sheila N. Baker, Frank V. Bright

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

We have used a wide variety of molecular (i.e., nitromethane, acrylamide, N,N'-dimethylaniline, and methyl iodide) and ionic (iodide and cupric ions) quenchers to assess the relative structural permeabilities of a single, pyrenyl residue attached to the tertiary amine within a series of asymmetric poly(amido) dendrimers possessing carboxylate moieties at their periphery. From these quenching experiments, chain segmental densities and pyrene accessibility are probed as a function of dendrimer generation number (Pn, n = 1, 2, or 3), providing insight into the roles of size and electrostatics in this process. With the exception of dendrimer quenching by Cu2+, we observe classic Stern-Volmer behavior for Pn fluorescence quenching by all quenching agents. The recovered Stern-Volmer quenching constants (Ksv) and bimolecular quenching rates (kq) generally decrease as n increases. This result is explained by a blocking of the pyrenyl residue by the growing dendrimer network. The decrease is particularly dramatic for the anionic heavy atom quencher I-. This observation is rationalized in terms of pronounced electrostatic repulsion between the I- quencher and the terminal COO- residues of the dendrimer combined with an increase in the molecular network density surrounding the pyrenyl moiety as n increases. The Cu2+ quenching of the dendrimers is inconsistent with a diffusion-controlled reaction. Binding between the dendrimer and the Cu2+ is demonstrated.

Original languageEnglish (US)
Pages (from-to)8649-8656
Number of pages8
JournalJournal of Physical Chemistry B
Volume106
Issue number34
DOIs
StatePublished - Aug 29 2002

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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    Cardona, C. M., Wilkes, T., Ong, W., Kaifer, A. E., McCarley, T. D., Pandey, S., Baker, G. A., Kane, M. N., Baker, S. N., & Bright, F. V. (2002). Dendrimers functionalized with a single pyrene label: Synthesis, photophysics, and fluorescence quenching. Journal of Physical Chemistry B, 106(34), 8649-8656. https://doi.org/10.1021/jp020862h