Construction of Monomeric and Polymeric Porphyrin Compartments by a Pd(II)—Pyridine Interaction and Their Chiral Twisting by a BINAP Ligand.

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 1H 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 β-pyrrole protons in the 1H 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. Th...