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Although aromatic compounds occupy a central position in organic chemistry, antiaromatic compounds have demonstrated little practical utility. Herein we report the application of an antiaromatic compound as an electrode-active material in rechargeable batteries. The performance of dimesityl-substituted norcorrole nickel(II) complex (NiNC) as a cathode-active material was examined with a Li metal anode. A maximum discharge capacity of about 207 mAhg(-1) was maintained after 100 charge/discharge cycles. Moreover, the bipolar redox property of NiNC enables the construction of a Li metal free rechargeable battery. The high performance of NiNC batteries demonstrates a prospective feature of stable antiaromatic compounds as electrode-active materials.

N-fused pentaphyrins (NFP5), stable forms of meso-aryl pentaphyrins, are interesting platforms to realize Hückel aromaticity, nonaromaticity, and Möbius aromaticity depending upon the number of π-electrons, meso-substituent, and metalation. Remarkably, Rh(I) complex of pentakis(pentafluorophenyl) substituted [24]NFP5 has been characterized as a Möbius aromatic macrocycle by the crystal structure, 1H NMR spectrum, NICS calculation, and two-photon absorption (TPA) cross section. This system is, to the best of our knowledge, the smallest Möbius aromatic molecule with a distinct diatropic ring current characterized so far. This work demonstrates the great potential of our synthetic strategy toward Möbius aromatic molecules as well as the possible use of TPA value as a quantitative measure of aromaticity.

Aromaticity is a fundamental concept in chemistry. It is described by Hückel’s rule that states that a cyclic planar π-system is aromatic when it shares 4n+2 π-electrons and antiaromatic when it possesses 4n π-electrons. Antiaromatic compounds are predicted to exhibit remarkable charge transport properties and high redox activities. However, it has so far only been possible to measure compounds with reduced aromaticity but not antiaromatic species due to their energetic instability. Here, we address these issues by investigating the single-molecule charge transport properties of a genuinely antiaromatic compound, showing that antiaromaticity results in an order of magnitude increase in conductance compared with the aromatic counterpart. Single-molecule current–voltage measurements and ab initio transport calculations reveal that this results from a reduced energy gap and a frontier molecular resonance closer to the Fermi level in the antiaromatic species. The conductance of the antiaromatic complex is further modulated electrochemically, demonstrating its potential as a high-conductance transistor.

From the acid‐catalyzed condensation of aryl aldehyde and pyrrole a new type of fused expanded porphyrins, N‐fused pentaphyrins NFP5‐Y (24 π, yellow) and NFP5‐R (22 π, red) were obtained in total yields of 2–19 %. The two normal‐type porphyrins are quantitatively interchanged through a redox reaction (see scheme). DDQ=2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone.

Quercetin, one of the most abundant flavonoids in human diet has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the protective effect of quercetin on hepatic injury induced by dimethylnitrosamine (DMN) in rats. Treatment with DMN caused a significant decrease in body and liver weight. Oral administration of quercetin (10 mg kg(-1) daily for 4 weeks) remarkably prevented this DMN-induced loss in body and liver weight and inhibited the elevation of serum alanine transaminase, aspartate transaminase and bilirubin levels. Quercetin also increased serum albumin and hepatic glutathione levels and reduced the hepatic level of malondialdehyde. Furthermore, DMN-induced elevation of hydroxyproline content was reduced in the quercetin treated rats, the result of which was consistent with a reduction in type I collagen mRNA production and histological analysis of liver tissue stained with Sirius red. A reduction in hepatic stellate cell activation, as assessed by alpha-smooth muscle actin staining, was associated with quercetin treatment as well as a reduction in transforming growth factor-beta1 expression. In conclusion, these results demonstrate that quercetin exhibited in-vivo hepatoprotective and anti-fibrogenic effects against DMN-induced liver injury and suggest that quercetin may be useful in the preventing the development of hepatic fibrosis.

meso-Aryl-substituted pentaphyrins were isolated in the modified Rothemund-Lindsey porphyrin synthesis as a 22-pi-electron N-fused pentaphyrin ([22]NFP5) and a 24-pi-electron N-fused pentaphyrin ([24]NFP5), which were reversibly interconvertible by means of two-electron reduction with NaBH4 or two-electron oxidation with dichlorodicyanobenzoquinone (DDQ). Judging from 1H NMR data, [22]NFP5 is aromatic and possesses a diatropic ring current, while [24]NFP5 exhibits partial anti-aromatic character. Metalation of [22]NFP5 1 with a rhodium(I) salt led to isolation of rhodium complexes 9 and 10, whose structures were unambiguously characterized by X-ray diffraction analyses and were assigned as conjugated 24-pi and 22-pi electronic systems, respectively. In the rhodium(I) metalation of 1, the complex 9 was a major product at 20 degrees C, but the complex 10 became preferential at 55 degrees C. Upon treatment with DDQ, compound 9 was converted to 10 with an unprecedented rearrangement of the rhodium atom.

In recent years there has been a considerable upsurge in the development of expanded porphyrins with five or more conjugated pyrrolic rings, because of their ability to exhibit a variety of interesting optical, electrochemical, stereochemical, and coordination properties. [1, 2] Among such macrocyclic systems, there are only scattered reports on meso-arylsubstituted expanded porphyrins that are structurally homologous to tetrakis-meso-aryl porphyrin in respect of the alternate conjugative arrangement of pyrrole and methine carbon atoms. Recently, we reported that simple modified Rothemund±Lindsey reaction of pentafluorobenzaldehyde and pyrrole unexpectedly allowed the formation of a series of meso-aryl-substituted expanded porphyrins ranging from pentaphyrin to dodecaphyrin. [3] meso-Aryl-substituted expanded porphyrins thus formed have received particular attention as a result of their ability to chelate multimetal ions as well as the multitude of oxidation states. In addition, meso-aryl-substituted expanded porphyrins can be structurally diverse, depending on the ring size, the metalation, and the degree of protonation. [3,4] For example, in the solid states, [26]hexaphyrin takes a flat rectangular conformation with two inverted pyrrole rings, [4] [36]octaphyrin exhibits a figureof-eight conformation, [3] and the [42]nonaphyrin-trifluoroacetic acid (TFA) complex shows a butterfly conformation with a central cleft in which TFA is bound by two inverted pyrrole rings. [3] Finally, these meso-aryl-substituted expanded porphyrins and other related large macrocycles offer a good opportunity to study the interplay between the aromaticity/ non-aromaticity that may be brought about by the twoelectron oxidation/reduction of the macrocycle.Provided that the successful formation of meso-arylsubstituted expanded porphyrins is mainly a consequence of the steric congestion around the formyl group and the electron-deficient property of the aryl aldehyde, the similar reaction of pentafluorobenzaldehyde and 3,4-difluoropyrrole [5,6] may be facilitated by the additional steric crowding as well as by the electron-deficient nature of the fluorine substituents in the pyrrole ring. Furthermore, perfluorinated meso-aryl-substituted expanded porphyrins may be interesting as robust oxidation catalysts and functional dyes. [7] Here we report the synthesis of a series of perfluorinated expanded porphyrins that possess fluorine substituents at both the meso-aryl and b-pyrrole positions. In a typical synthesis, a solution of 3,4-difluoropyrrole and pentafluorobenzaldehyde (66.7 mm each) in CH 2 Cl 2 was stirred for 8 h with BF 3 ¥OEt 2 . After oxidation with DDQ for 10 h, chromatographic separation on silica gel gave porphyrin 1 (6±9 %), [7] pentaphyrin 2 (about 1 %), [8] hexaphyrin 3 (2±5 %), heptaphyrin 4 (4±6 %), octaphyrin 5 (4±7 %), nonaphyrin 6 (~2 %), and decaphyrin 7 (about 2 %; Scheme 1). The X-ray crystal structures of the hexaphyrin and octaphyrin were found to be particularly interesting, in that both these structures are quite...