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 language | English |
|---|---|
| Pages (from-to) | 8649-8656 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry B |
| Volume | 106 |
| Issue number | 34 |
| DOIs | |
| State | Published - Aug 29 2002 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
Cite this
Dendrimers functionalized with a single pyrene label : Synthesis, photophysics, and fluorescence quenching. / Cardona, Claudia M.; Wilkes, Tom; Ong, Winston; Kaifer, Angel; McCarley, Tracy Donovan; Pandey, Siddarth; Baker, Gary A.; Kane, Maureen N.; Baker, Sheila N.; Bright, Frank V.
In: Journal of Physical Chemistry B, Vol. 106, No. 34, 29.08.2002, p. 8649-8656.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dendrimers functionalized with a single pyrene label
T2 - Synthesis, photophysics, and fluorescence quenching
AU - Cardona, Claudia M.
AU - Wilkes, Tom
AU - Ong, Winston
AU - Kaifer, Angel
AU - McCarley, Tracy Donovan
AU - Pandey, Siddarth
AU - Baker, Gary A.
AU - Kane, Maureen N.
AU - Baker, Sheila N.
AU - Bright, Frank V.
PY - 2002/8/29
Y1 - 2002/8/29
N2 - 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.
AB - 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.
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U2 - 10.1021/jp020862h
DO - 10.1021/jp020862h
M3 - Article
AN - SCOPUS:0037194926
VL - 106
SP - 8649
EP - 8656
JO - Journal of Physical Chemistry B Materials
JF - Journal of Physical Chemistry B Materials
SN - 1520-6106
IS - 34
ER -