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Control of Face ‐ to ‐ face and Extended Aggregations of Crown Ether‐Appended Metalloporphyrins
Author(s) -
Shinmori Hideyuki,
Yasuda Yuzo,
Osuka Atsuhiro
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200204)2002:7<1197::aid-ejoc1197>3.0.co;2-j
Subject(s) - chemistry , porphyrin , crown ether , steric effects , dimer , aryl , ether , monomer , medicinal chemistry , proton nmr , stereochemistry , polymer chemistry , photochemistry , organic chemistry , polymer , ion , alkyl
Metalloporphyrins bearing two crown ether moieties (benzo‐15‐crown‐5) at the 5‐ and 15‐postions have been prepared by condensation of 4′‐formyl‐benzo‐15‐crown‐5 with either unsubstituted or meso ‐aryl‐substituted dipyrromethanes, followed by oxidation and metallation. The meso ‐ meso ‐coupled Zn II diporphyrin Zn4 was prepared by the oxidative coupling of Zn1 with AgPF 6 . UV/vis, fluorescence, and 1 H NMR spectroscopic studies revealed that addition of K + and Rb + to solutions of monomeric porphyrin derivatives M1 (M = 2 H, Zn, Co, Ni, Pd, Cu) in CHCl 3 :MeCN (2:1 v/v) induced face ‐ to ‐ face dimerization with high stability constants (ca. 10 15 −10 19 M −3 ). 1 H NMR analysis showed that the two Zn1 molecules in the face ‐ to ‐ face dimer were packed more closely than in TPP‐type Zn II porphyrin bearing four crown ethers (Krishnan et al, J. Am. Chem. Soc. 1982, 104 , 3643), but such dimerization was hardly detected for 10,20‐diphenylated Zn II porphyrin Zn2 , probably due to steric hindrance exerted by the meso phenyl groups. meso ‐Monoarylated Zn II porphyrin Zn3 exhibited a comparably large stability constant for formation of the face ‐ to ‐ face dimer with the meso ‐aryl substituents pointing outward. Coordination of 4‐dimethylaminopyridine to Co II porphyrin was shown to be stronger than the interaction of K + with the crown ether, thereby dissociating the face ‐ to ‐ face dimer (Co1 ) 2 into six‐coordinated monomeric Co II porphyrin 5 . The diporphyrin Zn4 formed extended linear aggregates upon addition of K + and Rb + , owing to the divergent disposition of the crown ether substituents. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)