Toward the Rational Design of Superoxide Dismutase Mimics: Mechanistic Studies for the Elucidation of Substituent Effects on the Catalytic Activity of Macrocyclic Manganese(II) Complexes
| Autor: | Randy H. Weiss, Patrick J. Lennon, and William L. Neumann, Dennis P. Riley |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
biology
Stereochemistry Substituent chemistry.chemical_element General Chemistry Crystal structure Manganese Triclinic crystal system Biochemistry Catalysis Superoxide dismutase chemistry.chemical_compound Colloid and Surface Chemistry Pentagonal bipyramidal molecular geometry chemistry biology.protein Macrocyclic ligand |
| Zdroj: | Journal of the American Chemical Society. 119:6522-6528 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja964271e |
| Popis: | Two new isomeric bis(trans-fused cyclohexano) substituted 1,4,7,10,13-pentaazacyclopentadecane ligands and their Mn(II) complexes, 3 and 4, have been synthesized, and their activity as superoxide dismutase (SOD) catalysts has been studied. Complex 3 is an excellent SOD catalyst with a second-order rate constant at pH = 7.4 of 1.2 × 10+8 M-1 s-1. In contrast, the isomeric complex 4 has virtually no detectable catalytic SOD activity, implying the need to understand the effect that the position, number, and stereochemistry of substituents exert on the catalytic rate. The crystal structure of the complex 4 was determined and reveals that the Mn(II) ion is coordinated in a pentagonal bipyramid array of the five nitrogens of the macrocyclic ligand and capped by two trans-chloro ligands. Crystal data for MnC18H37Cl2N5 are as follows: triclinic at 20 °C, space group P1--Ci2 (no. 2); a = 9.746(3) A, b = 12.631(6) A, c = 11.311(5) A; α = 73.14(4)°, β = 76.39(3)°, γ = 79.98(3)°, V = 1287(1) A3, and Z = 2 (ρcalc = 1.... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|