Stability and structure of activated macrocyles. Ligand with biological applications

Journal Article · Wed Jun 19 04:00:00 EDT 1996 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic960067g· OSTI ID:274268

Motekaitis, R J; Martell, A E ^[1]

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1. Texas A&M Univ., College Station, TX (United States); and others

Single p-toluic acid pendant groups were attached to 1,4,7,10,13-pentaazacyclopentadecane (15aneN5) and 1,4,8,11-tetraazacyclotetradecane (cyclam) to prepare bifunctional reagents for radiolabeling monoclonal antibodies with {sup 64, 67}Cu. The ligands are 1,4,7,10,13-pentaazacyclopentadecane-1-({alpha}-1,4-toluic acid) (PCBA) and 1,4,8,11-tetraazacyclotetradecane-1-({alpha}-1,4-toluic acid) (CPTA). For the parent macrocycles and their pendant arm derivatives, the 1:1 Cu{sup 2+} complexes dissociate only below pH 2. At pH 0.0 and 25 {degrees}C the CPTA-Cu complex has a half-life toward complete dissociation of 24 days. A new approach was developed for the estimation of the Cu{sup 2+} stability constant for the kinetically robust CPTA. All other formation constants were determined at 25.0 {degrees}C with batch spectrophotometric techniques. Potentiometric titrations were used to determine the protonation constants of the macrocyclic ligands as well as of the metal chelates. The protonation constants, stability constants, and pM`s are discussed in terms of both molecular mechanics calculations and the ligands` potential applicability as copper(II) radiopharmaceuticals.

• DOE Contract Number: FG02-87ER60512
• OSTI ID: 274268
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 13 Vol. 35; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
55 BIOLOGY AND MEDICINE
BASIC STUDIES
CHEMICAL REACTIONS
COPPER COMPLEXES
LIGANDS
MATHEMATICAL MODELS
MOLECULAR STRUCTURE
POTENTIOMETRY
RADIOPHARMACEUTICALS
TITRATION