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 (C97H106Cl4N8O5), monoclinic, space group P2(1)/c, a = 28.8353(12) Angstrom, b = 17.1139(7) Angstrom, c = 17.5978(7) Angstrom, beta = 98.826(1)degrees, Z = 4; 8 (C101H123Cl2N8O11.5Zn2), monoclinic, space group P2(1)/n, a = 14.5517(6) Angstrom, b = 22,9226(10) Angstrom, c = 28.5155(13) Angstrom, beta = 90.312(14)degrees, Z = 4; 12 (C99H102Cl14N8O5Mn2), monoclinic, space group P2/c, a = 19.5891(3) Angstrom, b = 15.0741(2) Angstrom, c = 33.2019(6) Angstrom, beta = 91.947(10)degrees, 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.