All-aza smaragdyrin, a historic but elusive pentapyrrolic macrocycle, was successfully synthesized and characterized for the first time. [22]­Smaragdyrin BF2-complex 3 was smoothly synthesized by 2-fold SNAr reaction of 1,9-dibromo-5-mesityldipyrrin with 5,10-dimesityltripyrrane. Treatment of 3 with methanesulfonic acid gave [20]­smaragdyrin 5 as a stable antiaromatic compound. Reduction of 5 with NaBH4 under inert conditions gave [22]­smaragdyrin 6 as an aromatic congener, which was easily oxidized back to 5 in the air. Complex 3 was interconvertible with its 20π-congener 4 via oxidation with MnO2 and reduction with NaBH4. Treatment of 3 or 4 with CuCl2 in the presence of NaOAc gave hetero bimetal complex 8.

β,β-tripyrrin-bridged earring porphyrins were synthesized through Suzuki-Miyaura cross coupling reactions. These porphyrinoids have multiple cavities and can accommodate two or three metal ions per molecule. The structures of the porphyrins have been elucidated by x-ray diffraction analysis, and feature curved π planes. The electronic spectra of the porphyrins exhibit near-infrared (NIR) absorptions and metal insertion leads to red-shifted and intensified absorption features. Electrochemical analysis and transient absorption measurements indicated that the porphyrins exhibit effective electronic communication between their central and peripheral moieties.

Ar eaction sequence of regioselective peripheral bromination, Suzuki-Miyaura coupling with 2-borylated thiophene or pyrrole,and oxidative ring-closure with FeCl 3 allowed the synthesis of heterole-fused earring porphyrins 4Pd and 9Pd from the parent earring porphyrin 1.Differently pyrrole-fused porphyrins 5H and 6H and their Pd II complexes 5Pd and 6Pd were also synthesized.T he structures of 4Pd, 5H, 6Pd,a nd 8Pd have been revealed by X-rayanalysis to be slightly twisted owingtoconstraints imposed by heterole-fused structures. 5Pd exhibits an intensified band at 1505 nm, while 4Pd and 9Pd displays mall but remarkably red-shifted absorption bands reaching around 2200 nm.

Smaragdyrin had been an important but elusive expanded porphyrin until our recent first synthesis (Xie et al., J. Am. Chem. Soc. 2018, 140, 16553). In this paper, we report the synthesis of singly and doubly neo-confused [22]­smaragdyrin BF2-complexes 13 and 15 both as stable smaragdyrin mutants by nucleophilic substitution reactions of 1,9-dibromo-5-mesityldipyrrin 1 with singly and doubly N-confused tripyrranes, 10 and 11, respectively. Demetalation of 13 and 15 with methanesulfonic acid furnished singly and doubly neo-confused [22]­smaragdyrin free bases 16 and 18, respectively, both as air-sensitive porphyrinoids. These neo-confused [22]­smaragdyrin free bases display characteristic properties such as decreased diatropic ring current, regioselective diprotonation at the inner α-carbon of the neo-confused pyrrole to give 16H 2 2+ and 18H 2 2+ , and smooth oxygenation at the inner α-position of the neo-confused pyrroles, giving neo-confused [22]­oxosmaragdyrin 17 and doubly neo-confused [24]­dioxosmaragdyrin Cu­(II) complex 19Cu via metalation of 18 with CuCl2 in the presence of NaOAc. Finally, demetalation of 19Cu with methanesulfonic acid gave the corresponding doubly neo-confused [24]­dioxosmaragdyrin 19.

Direct β-to-β linked branched and cyclic porphyrin trimers and pentamers have been synthesized by the Suzuki-Miyaura coupling of β-borylporphyrins and β-bromoporphyrins. The cyclic porphyrin trimer, the smallest directly linked cyclic porphyrin wheel to date, and its twined pentamer, exhibit small electrochemical HOMO-LUMO gaps, broad nonsplit Soret bands, and red-shifted Q-bands, thus indicating large electronic interactions between the constituent porphyrin units.

Herein, a host-guest interaction-controlled photoproduct created by using cucurbit[7]uril (Q[7])-based pseudorotaxane structures is reported. The assembly exhibited controlled behavior towards the reduction of the ethylene (C=C) bond in the tetrakis(pyridin-4-yl)ethylene (TPyE) guest molecule under UV light irradiation. This can be attributed to the Q[7] encapsulation masking the four pyridinium arms of the guest, which inhibits planarization of the TPyE core to form the cyclization product. In particular, the strong affinity of Q[7] for the butyl-substituted guest (TPyE-4C) led to an unusual radical fluorescence emission of the photoirradiationtriggered intermediate of the guest molecule being observed in aqueous solution. This work provides a valuable paradigm and new insight for macrocycle-based host À guest interactions in supramolecular catalysis and luminescent radical materials.

The one‐pot self‐coupling reaction of 3‐amino‐5‐bromo‐BODIPY 9 under Buchwald–Hartwig amination conditions gave nitrogen‐bridged cyclic BODIPY tetramer 10, pentamer 11, and hexamer 12. Oxidation of 10, 11, and 12 in the presence of alkali metal ions provided 13, 15, and 16, respectively, as the first examples of expanded azaporphyrins possessing more than six pyrrole rings. Curiously, the oxidation even in the absence of alkali metal ions gave the same complexes as a result of spontaneous complexation. 10–12 showed large association constants (104–106 M−1) with K+ and Na+, but the spontaneous complexations were not observed, indicating the extremely high affinities of 13–16 toward alkali metal ions, which can be ascribed to the multiple and effective ion–dipole interaction of the alkali metal ion with the negatively polarized F atoms of the BF2 walls surrounding the cavity. Importantly, 13, 14, and 15 show diatropic ring currents as a result of global aromaticity.

The oxidation of Ni II −porphyrin dimer 10 with PbO 2 or MnO 2 resulted in the simultaneous implementation of an Nheterocycle-fused bridge and a modified pyrrole to give three unprecedented porphyrin dimers 11, 12, and 13. The reduction of 12 smoothly afforded 14. The structures of these dimers were all unambiguously confirmed by X-ray crystallographic analysis. These dimers show significantly red-shifted absorption bands and perturbed electrochemical properties with a decreasing HOMO−LUMO gap in the order of 14 > 13 > 11 > 12.