Selective Conversion of Planar <i>trans</i>-Chlorins into Highly Twisted Doubly Fused Porphyrins or Chlorins via Oxidative Fusion

β-to-<i>o</i>-phenyl doubly fused porphyrins (DFPs) or chlorins (DFCs) were selectively synthesized by facile oxidative fusion of <i>trans</i>-chlorins using 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) in good-to-excellent yields (70–92%) under mild reaction conditions with high atom economy. The selectivity in product formation (difused porphyrin or chlorin) was controlled by the presence or absence of a Ni­(II) ion in the macrocyclic core. Notably, nickel­(II) <i>trans</i>-chlorins selectively yielded DFPs, whereas free-base <i>trans</i>-chlorins afforded only DFCs. The synthesized fused porphyrinoids exhibited significantly red-shifted electronic spectral features (Δλ_max = 16–53 nm) of the Soret band due to the extended π conjugation and highly twisted macrocyclic conformation (twist angle ∼20–34°). Inner-core NHs of fused chlorins exhibited a tremendous downfield shift (Δδ = 1.71–2.02 ppm) compared to their precursors. The overall protonation constants for indanedione-substituted free-base-difused chlorins (<b>4</b>–<b>6</b>) were profoundly higher (∼20–50-fold) compared to dicyanomethyl-appended free-base-difused chlorins (<b>10</b>–<b>12</b>) because of the combined effect of the electronic nature of the β-substituents and nonplanarity of the macrocyclic core. The first oxidation potential of H₂DFC­(MN)₂Ph₂ (<b>12</b>) was 0.54 V cathodically shifted with respect to H₂DFC­(MN)₂ (<b>10</b>) because of the electron-donating nature of the β-phenyl groups, which resulted in extensive destabilization of the highest occupied molecular orbital