A Triply Linked Copper(III) Dicarbacorrole Dimer.

A triply linked dicarbacorrole dimer (7) was synthesized from a new meso-meso singly linked dicarbacorrole dimer precursor (6) via an oxidative fusion reaction by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in the presence of trifluoromethanesulfonic acid (TfOH). Single crystal X-ray structure of 7 adopts a flat conformation with a length as ca. 15.946 Šand a width as 6.903 Å, which can be regarded as a short carbaporphyrinoid tape. Two coordinated Cu ions keeps the +3 oxidation state in 7, as confirmed by NMR spectroscopy, single crystal X-ray diffraction and X-ray photoelectron spectroscopy (XPS). This is in sharp contrast to the Osuka's triply linked tetrapyrrolic corrole dimers, where the inner 3NH form is not stable and thus can only act as a divalent ligand. Due to the non-aromatic nature of dicarbacorrole macrocycle, the largely decreased HOMO-LUMO gap and red-shifted absorption of 7 are best ascribed to the strong electronic interaction between two dipyrromethene-type chromophores. To our knowledge, this is the first fully fused carbaporphyrinoid dimer with ß-ß, meso-meso, ß-ß triply linkages prepared to date.

A Fully Conjugated Porphyrin-[36]Octaphyrin-Porphyrin Hybrid Tape Exhibiting Möbius Aromaticity.

Directly meso-meso linked porphyrin-tetrabromo[36]octaphyrin-porphyrin hybrid trimer 10 was successfully synthesized via acid-catalyzed condensation reaction and subsequent oxidation. ZnII -metalation of 10 induced transannular meso-meso bond formation to give Möbius aromatic bis-ZnII octaphyrin 11, which was oxidized by DDQ/Sc(OTf)3 to provide fully conjugated porphyrin-[36]octaphyrin-porphyrin hybrid tape 12 as the first example of porphyrin tape exhibiting Möbius aromaticity. Hybrid tape 12 displays significantly red-shifted absorption and small electrochemical HOMO-LUMO gap, indicating the effective conjugation through the whole chromophores.

Synthesis of Di-peri-dinaphthoporphyrins by PtCl2 -Mediated Cyclization of Quinodimethane-type Porphyrins.

Di-peri-dinaphthoporphyrins can be regarded as a key and common substructure of fused porphyrinoids. PtCl2 -mediated cycloisomerization reaction of quinodimethane-type porphyrins provided these doubly fused porphyrins, which exhibit characteristic paratropic ring currents that presumably arise from 24π antiaromatic circuit as a dominant resonance contributor. UV/Vis absorption spectra, cyclic voltammetry, and excited-state dynamics as well as theoretical calculation support this conclusion.