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3-D Structural Modeling of Humic Acids through Experimental Characterization, Computer Assisted Structure Elucidation and Atomistic Simulations. 1. Chelsea Soil Humic Acid

Diallo, Mamadou S. and Simpson, Andre and Gassman, Paul and Faulon, Jean Loup and Johnson, James H., Jr. and Goddard, William A., III and Hatcher, Patrick G. (2003) 3-D Structural Modeling of Humic Acids through Experimental Characterization, Computer Assisted Structure Elucidation and Atomistic Simulations. 1. Chelsea Soil Humic Acid. Environmental Science and Technology, 37 (9). pp. 1783-1793. ISSN 0013-936X. doi:10.1021/es0259638. https://resolver.caltech.edu/CaltechAUTHORS:20170426-072506824

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Abstract

This paper describes an integrated experimental and computational framework for developing 3-D structural models for humic acids (HAs). This approach combines experimental characterization, computer assisted structure elucidation (CASE), and atomistic simulations to generate all 3-D structural models or a representative sample of these models consistent with the analytical data and bulk thermodynamic/structural properties of HAs. To illustrate this methodology, structural data derived from elemental analysis, diffuse reflectance FT-IR spectroscopy, 1-D/2-D ^1H and ^(13)C solution NMR spectroscopy, and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI QqTOF MS) are employed as input to the CASE program SIGNATURE to generate all 3-D structural models for Chelsea soil humic acid (HA). These models are subsequently used as starting 3-D structures to carry out constant temperature-constant pressure molecular dynamics simulations to estimate their bulk densities and Hildebrand solubility parameters. Surprisingly, only a few model isomers are found to exhibit molecular compositions and bulk thermodynamic properties consistent with the experimental data. The simulated ^(13)C NMR spectrum of an equimolar mixture of these model isomers compares favorably with the measured spectrum of Chelsea soil HA.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/es0259638DOIArticle
http://pubs.acs.org/doi/abs/10.1021/es0259638PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/es0259638PublisherSupporting Information
ORCID:
AuthorORCID
Diallo, Mamadou S.0000-0002-2571-1568
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2003 American Chemical Society. Received 11 July 2002. Date accepted 9 February 2003. Published online 4 April 2003. Published in print 1 May 2003. M.S.D. dedicates this paper to his wife Laura for encouraging him to tackle difficult problems in environmental science. We thank Prof. Weilin Huang of Drexel University (Philadelphia, PA) for providing the Chelsea soil humic acid samples. The theoretical component of this work (computer assisted structure elucidation and atomistic simulations) was conducted in the Department of Civil Engineering and the Institute of Multimedia Applications at Howard University and at the Materials and Process Simulation of the Beckman Institute at the California Institute of Technology. Funding for this work was provided to Howard University by the Great Lakes and Mid-Atlantic Hazardous Substance Research Center under Grant R-825540 from the USEPA Office of Research and Development. Partial funding for this research was also provided to Howard University and Caltech by the US Department of Commerce under Cooperative Agreement 7NANB8HO102. The 1-D and 2-D 1H/13C solution NMR and ESI Q-ToF MS experiments were carried out in the Department of Chemistry at The Ohio State University (OSU). Funding was provided by the National Science Foundation to the OSU Environmental Molecular Science Institute (CHE- 0089147) and Collaborative Research Agreement In Environmental Molecular Science (CHE-0089173). The DRIFT spectroscopic investigations were carried out at the W. R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy's Office of Biological and Environmental Research and located at the Pacific Northwest National Laboratory (PNNL). PNNL is operated for the Department of Energy by Battelle.
Funders:
Funding AgencyGrant Number
Environmental Protection Agency (EPA)R-825540
Department of Commerce7NANB8HO102
NSFCHE- 0089147
NSFCHE-0089173
Issue or Number:9
DOI:10.1021/es0259638
Record Number:CaltechAUTHORS:20170426-072506824
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170426-072506824
Official Citation:3-D Structural Modeling of Humic Acids through Experimental Characterization, Computer Assisted Structure Elucidation and Atomistic Simulations. 1. Chelsea Soil Humic Acid Mamadou S. Diallo, Andre Simpson, Paul Gassman, Jean Loup Faulon, James H. Johnson, Jr., William A. Goddard III, and Patrick G. Hatcher Environmental Science & Technology 2003 37 (9), 1783-1793 DOI: 10.1021/es0259638
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76935
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:26 Apr 2017 16:04
Last Modified:15 Nov 2021 17:03

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