A convergent synthetic approach using sterically demanding aryldipyrrylmethanes for tuning the pocket sizes of cofacial bisporphyrins

Meso substitution opposite to the spacer provides a convenient approach for tuning the pocket sizes of pillared cofacial bisporphyrins. The synthesis and coordination chemistry of xanthene and dibenzofuran anchored platforms structurally modified with 2,6-dimethoxyaryl groups are described. Comparative structural analysis of xanthene derivatives confirms the ability of the trans-aryl groups to adjust the vertical dimension of the cofacial cleft: 7 (C₉₇H₁₀₆Cl₈N₈O₅), monoclinic, space group P2₁/c, a = 28.8353(12) Å, b = 17.1139(7) Å, c = 17.5978(7) Å, β = 98.826(1)°, Z = 4; 8 (C₁₀₁H₁₂₃Cl₂N₈ O_11.5Zn₂), monoclinic, space group P2₁/n, a = 14.5517(6) Å, b = 22.9226(10) Å, c = 28.5155(13) Å, β = 90.312(14)°, Z = 4; 12 (C₉₉H₁₀₂Cl₁₄N₈ O₅Mn₂), monoclinic, space group P2/c, a = 19.5891(3) Å, b = 15.0741(2) Å, c = 33.2019(6) Å, β = 91.947(10)°, Z = 4. The convenience and versatility of this synthetic method offers intriguing opportunities to specifically tailor the binding pockets of cofacial bisporphyrins for the study of small-molecule activation within a proton-coupled electron transfer framework.