Theoretical study of ion/macrocycle interactions using both hybrid quantum mechanical-molecular mechanical and ab initio methods
- Pacific Northwest Lab., Richland, WA (United States)
Crown-ethers and related macrocycles show a remarkable range of specificity for a variety of cations and are thus of particular interest to environmental remediation of radioactive nuclides such as {sup 90}Sr{sup ++} and {sup 137}Cs{sup +}. Understanding the fundamental interactions that control the selectivity and affinity of ion/macrocycle interactions is central to our the oretical effort. We present the first results of a hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) Molecular Dynamics study of 18-crown-6 (18c6) interacting with K{sup +} in H{sub 2}O. Our simulation results demonstrate the importance of CM polarization in describing ion-macrocycle interactions. QM/MM free energy calculations of cation binding will also be presented. We also present results of an ab initio and density functional study of Li & Still`s new {open_quotes}s18c6{close_quotes} macrocycle which exhibits a reversal in K{sup +}/Na{sup +} selectivity relative to 18c6. To date, no firm explanation exists for the unusual selectivity of this crown-ether. The key role of two {open_quotes}capping{close_quotes} waters is assessed in this study.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 214637
- Report Number(s):
- CONF-950801--
- Country of Publication:
- United States
- Language:
- English
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