Nanometer-Scale Ion Aggregates in Aqueous Electrolyte Solutions:  Guanidinium Carbonate

Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations have been used to characterize the structure of aqueous guanidinium carbonate (Gdm2CO3) solutions. The MD simulations found very strong hetero-ion pairing in Gdm2CO3 solution and were used to de...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2006-07, Vol.110 (27), p.13477-13483
Main Authors: Mason, P. E, Neilson, G. W, Kline, Steve R, Dempsey, C. E, Brady, J. W
Format: Article
Language:English
Subjects:
Electrolytes - chemistry
Guanidine - chemistry
Models, Molecular
Nanotechnology
Solutions
Water - chemistry
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Summary:Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations have been used to characterize the structure of aqueous guanidinium carbonate (Gdm2CO3) solutions. The MD simulations found very strong hetero-ion pairing in Gdm2CO3 solution and were used to determine the best structural experiment to demonstrate this ion pairing. The NDIS experiments confirm the most significant feature of the MD simulation, which is the existence of strong hetero-ion pairing between the Gdm+ and CO3 2- ions. The neutron structural data also support the most interesting feature of the MD simulation, that the hetero-ion pairing is sufficiently strong as to lead to nanometer-scale aggregation of the ions. The presence of such clustering on the nanometer length scale was then confirmed using small-angle neutron scattering experiments. Taken together, the experiment and simulation suggest a molecular-level explanation for the contrasting denaturant properties of guanidinium salts in solution.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp0572028