Benzenehexapyrrole-α,ω-dialdehyde, composed of a pair of formyltripyrrole units with a 1,3-phenylene linker, was metallated to give dinuclear single-stranded helicates. X-ray studies of the bis-nickel(II) complex showed a helical C₂ form with a pair of helical–metal coordination planes of a 3N+O donor set. The terminal aldehyde was readily converted into the imine by optically active amines, whereby helix-sense bias was induced. Bis-nickel(II) and bis-palladium(II) complexes of the benzenehexapyrrole-α,ω-diimines were studied to show that an enantiomer pair of the helical C₂ form are interchanged by slow flipping of each coordination plane and fast rotation around the C(benzene)C(pyrrole) bond. The helical screw in the bis-nickel(II) complexes was biased to one side in more than 95 % diastereoselectivity, which was achieved by using a variety of optically active amines, such as (R)-1-cyclohexylethylamine, (S)-1- phenylethylamine, L-Phe(OEt) (Phe=phenylalanine), and (R)-valinol. The nickel complexes showed much better diastereoselectivity than the corresponding palladium complexes.

1,3-Bis(2-pyrryl)benzene was used to prepare dibenziamethyrin, in which two pyrrole units of [24]amethyrin(1.0.0.1.0.0) are replaced by benzene. 1,4-Bis(2-pyrryl)benzene, 2,5-bis(2-pyrryl)thiophene, and 4,4′-bis(2-pyrryl)biphenyl were also used in place of 2,2′-bipyrrole to give expanded analogues of [24]rosarin(1.0.1.0.1.0) and [32]octaphyrin(1.0.1.0.1.0.1.0). These large porphyrinoids can incorporate multiple metal units of Rh(CO)₂ and Pd(π-allyl) with considerable deviation of the metal atoms from the dipyrrin planes, evidenced by X-ray crystallography. The coordinated Rh(CO)₂ group shuttled between both sides of the macrocycle; the rate was dependent on the spacer, ring size, and number of metal atoms. Variable temperature ¹H NMR spectroscopy showed that the tris-rhodium complexes of the expanded rosarins with 1,4-phenylene or 2,5-thienylene spacers adopt a C_3v-symmetric form and a C_s-symmetric form as a result of the Rh(CO)₂ groups hopping through the macrocycle cavity. The C_3v-symmetric form has a greater dipole moment and, therefore, is favored in solvents of greater polarity. The Rh(CO)₂ groups in the tris-rhodium complex of the expanded rosarin with 4,4′-biphenylene spacers hop so fast that an averaged spectral pattern (D_3h) was seen in the ¹H NMR spectrum, even at −60 °C. Expanded octaphyrins with 1,4-phenylene and 2,5-thienylene spacers bind four Rh(CO)₂ groups outside the macrocycle cavity to form a D_2d-symmetric saddle-shaped structure that did not show any dynamic behavior on the NMR timescale, even at 80 °C. This tetranuclear complex is one of the largest porphyrinoid metal complexes characterized by X-ray crystallography to date.