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Title: Influence of Functionalized Pyridine Ligands on the Radio/Chemical Behavior of [MI(CO)3]+ (M = Re and 99mTc) 2 + 1 Complexes

Author
item HAYES, THOMAS - Washington State University
item LYON, PATRICE - Washington State University
item BARNES, CHARLES - Washington State University
item Trabue, Steven - Steve
item BENNY, PAUL - Washington State University

Submitted to: Inorganic Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2014
Publication Date: 2/26/2015
Publication URL: https://handle.nal.usda.gov/10113/6551238
Citation: Hayes, T.R., Lyon, P., Barnes, C., Trabue, S.L., Benny, P. 2015. Influence of functionalized pyridine ligands on the radio/chemical behavior of [MI(CO)3]+ (M = Re and 99mTc) 2 + 1 complexes. Inorganic Chemistry. 54:1528-1534.

Interpretive Summary: Metals form complexes with organic compounds and these metal complexes are key components in imaging technology. Imaging technology allows for viewing objects that normally cannot be viewed or measured using the properties of the metal organic compound complexes for viewing the obscured object. Organic compounds forming the metal complexes have different stabilities depending on the organic molecules. This study looked at the complexion and stability effect of different organic molecules. Information from this study could be used to create and design more stable metal organic compound complexes for improved imaging of objects. Information in this report will be of value to scientists and medical researchers designing metal organic compound complexes used in imaging technology.

Technical Abstract: While a number of chelate strategies have been developed for the organometallic precursor fac-[M (OH2)3(CO)3]+ (M = Re, 99mTc), a unique challenge has been to improve the overall function and performance of these complexes for in vivo and in vitro applications. Since its synthesis, the fac-[M (CO)3]+ core has served as an essential scaffold for development of new targeted 99mTc based radiopharmaceuticals due to its readily substitutable aquo ligands. Unfortunately, the lipophilic nature of the fac-[MI(CO)3]+ core can negatively affect the pharmacokinetics and in vivo clearance of the radiopharmaceuticals. In an effort to direct future research, mono-substituted pyridine ligands were used to assess the effect of donor nitrogen basicity on binding strength and stability of fac-[M (CO)3]+ in a 2+1 labeling strategy. Using picolinic acid as a bidentate ligand, 4-substituted pyridines were compared to determine their effect on complexation efficiency and stability to transchelation in comparison to pyridine. Labeling studies showed that pyridine basicity was directly correlated to yield and stability.