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Quantitative Analysis of the Self‐Assembly Process of Hexagonal Pt II Macrocyclic Complexes: Effect of the Solvent and the Components
Author(s) -
Baba Ayako,
Kojima Tatsuo,
Hiraoka Shuichi
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702955
Subject(s) - chemistry , self assembly , polar , cooperativity , steric effects , supramolecular chemistry , crystallography , ligand (biochemistry) , solvent , hexagonal crystal system , stereochemistry , solvent polarity , polymer chemistry , organic chemistry , crystal structure , receptor , biochemistry , physics , astronomy
The self‐assembly process of three Pt II ‐linked hexagonal macrocycles consisting of dinuclear Pt II complexes and organic ditopic ligands was investigated in polar and less polar solvents by a recently developed approach: quantitative analysis of the self‐assembly process (QASAP). In polar CD 3 NO 2 , for all the three macrocycles, an ML 2 complex was the dominant intermediate during self‐assembly, as a result of high positive allosteric cooperativity for the ligand exchange on the Pt II centers of the dinuclear Pt II complexes. On the other hand, in less polar CD 2 Cl 2 , the self‐assembly process was affected by the components. For two of the three macrocycles, the chainlike oligomers that contain fewer metals and ligands than the corresponding macrocycles grew with time and the type of the chainlike intermediates formed correlated with the allostericity of the two binding sites in the organic ditopic ligands. In every case, no long oligomers containing more components than the macrocycles themselves were produced during the self‐assembly even though free rotation around single bonds in the chainlike oligomers allows them to adopt various conformations that do not facilitate the cyclization. This result suggests that electrostatic and/or steric factors besides rigidity of the components make the cyclization advantageous not only thermodynamically but also kinetically.