Dimeric assemblies from 1 2,3-triazole-appended Zn(II) porphyrins with control of NH-tautomerism in 1 2,3-triazole

Cu(I)-catalyzed 1,3-dipolar cycloaddition of meso-ethynyl Zn(II) porphyrin with benzyl azide efficiently provides meso-1-benzyl-1H-1,2,3-triazolyl Zn(II) porphyrin, which assembles to form a slipped cofacial dimer by the complementary coordination of the triazole nitrogen atom at the 3-position to the zinc center of a second porphyrin moiety both in the solid and solution states. Removal of the benzyl protection and introduction of a 2-ethoxycarbonylphenyl moiety greatly stabilize the dimeric assembly through an additional hydrogen bonding interaction between the NH proton of 2H-1,2,3-triazole and the carbonyl oxygen.