Effect of C7-Substituent on Self-Assembly of Chlorosomal Chlorophylls

Publisher Website
Google Scholar
Abstract
Bacteriochlorophyll d analogues that possessed a series of bulky substituents of OMe, OCOMe, and OCO t Bu at the C71-position were synthesized (Zn-complexes of methyl 71-substituted-3-(1-hydroxy-methyl)pyropheophorbide a). Aggregation behavior of these pigments was examined in comparison with a natural-type compound (C71-H) to elucidate the effects of size of the C71-moiety on self-assembly of the chlorins. These C71-substituted Zn-chlorins formed self-aggregates in 1% THF/hexane. The aggregates gave almost the same visible absorption bands, especially a ca. 2000-cm−1 red-shifted Qy peak; the spectra were essentially similar to those of the natural-type Zn-chlorin (C71-H). All the aggregates of the C71-substituted compounds showed similar exciton-type CD couplets in the red-shifted Qy region, which were different from the feature of the couplet of the C71-H Zn-chlorin aggregate. These spectral data suggested that the C71-moiety did not interrupt the intermolecular linkages between chlorin molecules but altered the supramolecular structure which influences the long-range chirality.

This publication has 30 references indexed in Scilit: