Antiaromatic Sapphyrin Isomer: Transformation into Contracted Porphyrinoids with Variable Aromaticity

Abstract

Sapphyrin is a pentapyrrolic expanded porphyrin with a 22π aromatic character. Herein, we report the synthesis of a 20π antiaromatic sapphyrin isomer 1 by oxidative cyclization of a pentapyrrane precursor P5 with a terminal β‐linked pyrrole. The resulting isomer 1, containing a mis‐linked bipyrrole unit in the skeleton, exhibits a reactivity for further oxidation due to the distinct antiaromatic electronic structure, affording a fused macrocycle 2, possessing a spiro‐carbon‐containing [5.6.5.6]‐tetracyclic structure. Subsequent treatment with an acid afforded a weakly aromatic pyrrolone‐appended N‐confused corrole 3, and thermal fusion gave a [5.6.5.7]‐tetracyclic‐ring‐embedded 14π aromatic triphyrin(2.1.1) analog 4. The cyclization at the mis‐linked pyrrole moiety of P5 played a crucial role in synthesizing the antiaromatic porphyrinoid susceptible to facile transformation to novel porphyrinoids with variable aromaticity.

Panchromatic porphyrin-based dye-sensitized solar cells: from cosensitization to concerted companion dye approaches

“…A typical porphyrin dye has a Soret band within 400–450 nm with a high molar extinction coefficient and moderate Q bands within 500–700 nm. The excellent photoelectronic properties and rich structural diversities of porphyrins 30–34 enable fabrication of DSSCs with efficiencies of over 13%. 35,36 In brief, the absorption ability of the sensitizer is the most important factor for achieving high efficiencies.…”

Mono- and bis-Pd(ii) complexes of N-confused dithiahexaphyrin(1.1.1.1.1.0) with the absorption and aromaticity modulated by Pd(ii) coordination, macrocycle contraction and ancillary ligands

“…[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] In addition, the N-confused pyrrole unit may trigger interesting macrocycle transformations and thus further modulate the coordination behavior. [49][50][51][52][53][54][55] These metal complexes are promising for applications in various areas like catalytic, photoelectric and biomedical materials. [56][57][58][59][60][61][62][63][64][65][66][67] To further enrich the coordination chemistry of hexaphyrins and probe the underlying property-structural correlations for porphyrinoid complexes, herein we report N-confused dithiahexaphyrin 1, which has been synthesized by simultaneously incorporating an N-confused pyrrole unit and a bithiophene unit into a hexaphyrin framework (Fig.…”

“…31–48 In addition, the N-confused pyrrole unit may trigger interesting macrocycle transformations and thus further modulate the coordination behavior. 49–55 These metal complexes are promising for applications in various areas like catalytic, photoelectric and biomedical materials. 56–67…”

Conformation Governed Reactivity of Fused Thia-Sapphyrin Dimers Bearing Multiply Fused Heteroaromatic Rings

“…24,25 Because the regioselectivity of the oxidative coupling reactions strongly depends on the distinct electronic structure (i.e., electron density) and steric factors, the elaborately designed porphyrin analogs with mislinked pyrrole units (e.g., α-β, α-β′, or N-β modes) in the corresponding scaffolds show selective reactivity. [26][27][28][29][30][31][32] Thus, chemical oxidation of N-confused porphyrin, 33,34 N-fused porphyrin, [35][36][37][38] neo-confused corrole (norrole), [39][40][41][42] and neo-confused hexaphyrin, 43,44 afforded the three-dimensional dimeric structures [45][46][47][48][49][50] with high regioselectivity via dehydrogenative C-C bond formation (Figure 1b). In this regard, we have previously demonstrated that the cyclization of a pentapyrrane with two terminal β-pyrrolyl units (P 5 ) afforded a highly twisted dihydrosapphyrin possessing a meso-sp 3 -carbon atom, which exhibited an unusual skeletal transformation reaction (Figure 1c).…”