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Title: Computational Design of Metal Ion Sequestering Agents

Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort. This project seeks to enhance and strengthen the traditional approach through computer-aided design of new and improved host molecules. Accurate electronic structure calculations are coupled with experimental data to provide fundamental information about ligand structure and the nature of metal-donor group interactions (design criteria). This fundamental information then is used in a molecular mechanics model (MM) that helps us rapidly screen proposed ligand architectures and select the best membersmore » from a set of potential candidates. By using combinatorial methods, molecule building software has been developed that generates large numbers of candidate architectures for a given set of donor groups. The specific goals of this project are: further understand the structural and energetic aspects of individual donor group- metal ion interactions and incorporate this information within the MM framework; further develop and evaluate approaches for correlating ligand structure with reactivity toward metal ions, in other words, screening capability; use molecule structure building software to generate large numbers of candidate ligand architectures for given sets of donor groups; and screen candidates and identify ligand architectures that will exhibit enhanced metal ion recognition. These new capabilities are being applied to ligand systems identified under other DOE-sponsored projects where studies have suggested that modifying existing architectures will lead to dramatic enhancements in metal ion binding affinity and selectivity. With this in mind, we are collaborating with Professors R. T. Paine (University of New Mexico), K. N. Raymond (University of California, Berkeley), and J. E. Hutchison (University of Oregon), and Dr. B. A. Moyer (Oak Ridge National Laboratory) to obtain experimental validation of the predicted new ligand structures. Successful completion of this study will yield molecular-level insight into the role that ligand architecture plays in controlling metal ion complexation and will provide a computational approach to ligand design.« less
Authors:
;
Publication Date:
OSTI Identifier:
838770
Report Number(s):
EMSP-73759--2004
R&D Project: EMSP 73759; TRN: US200508%%490
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 15 Jun 2004
Research Org:
Pacific Northwest National Lab., Richland, WA (US)
Sponsoring Org:
USDOE Office of Science (SC) (US)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; ACTINIDES; AFFINITY; ARCHITECTURE; CATIONS; COMPUTER-AIDED DESIGN; DESIGN; ELECTRONIC STRUCTURE; RADIOISOTOPES; RARE EARTHS; SCREENS; SEPARATION PROCESSES; SYNTHESIS; TARGETS; TESTING; VALIDATION