Construction of monomeric and polymeric porphyrin compartments by a Pd(II)-pyridine interaction and their chiral twisting by a BINAP ligand

Masatsugu Ayabe; Kousei Yamashita; Kazuki Sada; Seiji Shinkai; Atsushi Ikeda; Shigeru Sakamoto; Kentaro Yamaguchi

doi:10.1021/jo020575+

Construction of monomeric and polymeric porphyrin compartments by a Pd(II)-pyridine interaction and their chiral twisting by a BINAP ligand

J Org Chem. 2003 Feb 7;68(3):1059-66. doi: 10.1021/jo020575+.

Authors

Masatsugu Ayabe¹, Kousei Yamashita, Kazuki Sada, Seiji Shinkai, Atsushi Ikeda, Shigeru Sakamoto, Kentaro Yamaguchi

Affiliation

¹ Department of Chemistry & Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.

PMID: 12558435
DOI: 10.1021/jo020575+

Abstract

The construction of chirally twisted porphyrin-based molecular capsule 6 and polymeric capsule 8 was investigated by means of scanning electron microscopy (SEM) and (1)H NMR, UV-visible, and CD spectroscopic observations. Molecular capsule 6 and polymeric capsule 8 were constructed by the reaction of chiral cis-Pd(II) complex 4 bearing a (R)-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) ligand with porphyrin 1 bearing four pyridyl groups and porphyrin 2 bearing eight pyridyl groups, respectively. The peak-splitting pattern of the beta-pyrrole protons in the (1)H NMR spectrum and the specific CD spectral pattern bearing an exciton coupling band indicate that both molecular capsule 6 and polymeric capsule 8 are chirally twisted. Moreover, it was found that the CD intensity of the polymeric capsule plotted against [4]/([4] + [3]) shows a sigmoidal curvature, reflecting a unique cooperativity among the ligand groups; that is, the ligand existing in excess over the other dominates the twisting direction. These results consistently demonstrate that "chirality" in these molecular assembly systems is conveniently controlled by the use of chiral ligands.