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Dendritic Chelating Agents. 1. Cu(II) Binding to Ethylene Diamine Core Poly(amidoamine) Dendrimers in Aqueous Solutions

Diallo, Mamadou S. and Christie, Simone and Swaminathan, Pirabalini and Balogh, Lajos and Shi, Xiangyang and Um, Wooyong and Papelis, Charalambos and Goddard, William A., III and Johnson, James H., Jr. (2004) Dendritic Chelating Agents. 1. Cu(II) Binding to Ethylene Diamine Core Poly(amidoamine) Dendrimers in Aqueous Solutions. Langmuir, 20 (7). pp. 2640-2651. ISSN 0743-7463. doi:10.1021/la036108k. https://resolver.caltech.edu/CaltechAUTHORS:20170510-065746632

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Abstract

This paper describes an investigation of the uptake of Cu(II) by poly(amidoamine) (PAMAM) dendrimers with an ethylenediamine (EDA) core in aqueous solutions. We use bench scale measurements of proton and metal ion binding to assess the effects of (i) metal ion−dendrimer loading, (ii) dendrimer generation/terminal group chemistry, and (iii) solution pH on the extent of binding of Cu(II) in aqueous solutions of EDA core PAMAM dendrimers with primary amine, succinamic acid, glycidol, and acetamide terminal groups. We employ extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the structures of Cu(II) complexes with Gx-NH_2 EDA core PAMAM dendrimers in aqueous solutions at pH 7.0. The overall results of the proton and metal ion binding measurements suggest that the uptake of Cu(II) by EDA core PAMAM dendrimers involves both the dendrimer tertiary amine and terminal groups. However, the extents of protonation of these groups control the ability of the dendrimers to bind Cu(II). Analysis of the EXAFS spectra suggests that Cu(II) forms octahedral complexes involving the tertiary amine groups of Gx-NH_2 EDA core PAMAM dendrimers at pH 7.0. The central Cu(II) metal ion of each of these complexes appears to be coordinated to 2−4 dendrimer tertiary amine groups located in the equatorial plane and 2 axial water molecules. Finally, we combine the results of our experiments with literature data to formulate and evaluate a phenomenological model of Cu(II) uptake by Gx-NH_2 PAMAM dendrimers in aqueous solutions. At low metal ion−dendrimer loadings, the model provides a good fit of the measured extent of binding of Cu(II) in aqueous solutions of G4-NH_2 and G5-NH_2 PAMAM dendrimers at pH 7.0.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/la036108kDOIArticle
http://pubs.acs.org/doi/abs/10.1021/la036108kPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/la036108kPublisherSupporting Information
ORCID:
AuthorORCID
Diallo, Mamadou S.0000-0002-2571-1568
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2004 American Chemical Society. Received 9 November 2003. Published online 5 March 2004. Published in print 1 March 2004. We thank Ms. Sa'Nia Carasquero (Graduate Student in Chemical Engineering) and Mr. Kwesi Falconer (Graduate Student in Environmental Engineering) of Howard University School of Engineering for their assistance with the proton and metal ion binding experiments. We also thank Dr. Prabal Maiti of the Materials and Process Simulation Center of the Beckman Institute at the California Institute of Technology for providing prior to publication data on the extent of binding of water molecules to EDA core PAMAM dendrimers. Funding for this work was provided by the National Science Foundation (NSF Grant CTS-0086727) and the U.S. Environmental Protection Agency (NCER STAR Grant R829626). Partial funding for this research was also provided by the Department of Energy (Cooperative Agreement EW15254). The EXAFS spectroscopic investigations were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.
Funders:
Funding AgencyGrant Number
NSFCTS-0086727
Environmental Protection Agency (EPA)R829626
Department of Energy (DOE)EW15254
Issue or Number:7
DOI:10.1021/la036108k
Record Number:CaltechAUTHORS:20170510-065746632
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170510-065746632
Official Citation:Dendritic Chelating Agents. 1. Cu(II) Binding to Ethylene Diamine Core Poly(amidoamine) Dendrimers in Aqueous Solutions Mamadou S. Diallo, Simone Christie, Pirabalini Swaminathan, Lajos Balogh, Xiangyang Shi, Wooyong Um, Charalambos Papelis, William A. Goddard III, and James H. Johnson, Jr. Langmuir 2004 20 (7), 2640-2651 DOI: 10.1021/la036108k
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77323
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 May 2017 20:54
Last Modified:15 Nov 2021 17:30

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