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Construction of Giant Porphyrin Macrorings Self‐Assembled from Thiophenylene‐Linked Bisporphyrins for Light‐Harvesting Antennae
Author(s) -
Fujisawa Kaori,
Satake Akiharu,
Hirota Shun,
Kobuke Yoshiaki
Publication year - 2008
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.200801466
Subject(s) - porphyrin , chemistry , fluorescence , crystallography , ring size , photochemistry , spectral line , ring (chemistry) , physics , organic chemistry , optics , astronomy
As a model of bacterial photosynthetic light‐harvesting antenna, a large number of porphyrin units were organized into barrel‐shaped macrorings. Two imidazolylporphyrinatozinc(II) molecules were linked through either unsubstituted thiophenes or 3,4‐dioctylthiophenes 1 a and 1 b , respectively. These structures were spontaneously organized by complementary coordination of the imidazolyl to zinc and produced a series of self‐assembled fluorescent polygonal macrorings under high dilution conditions. The ring size increased compared with previous m ‐phenylene examples. The size distribution was also controlled by the presence of octyl substituents. A wide distribution of macrorings from 7‐ to >15‐mer was obtained from 1 a , whereas macrorings ranging from 7‐ to 11‐mer with a maximum population focused at the 8‐mer were formed with 1 b . The size distribution was governed by competition between entropy‐favored, smaller‐ring formation and the enthalpy‐favored, less‐strained larger macroring. The UV/Vis spectra showed a gradual redshift for the larger rings reflecting an increase in the transition dipole interactions.