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We prepared a free-base 10,20-diphenyl-5,15-diazaporphyrin and its Ni(II), Cu(II), Pd(II), and Pt(II) complexes. These molecules uniformly form an infinite one-dimensional [Formula: see text]-stacking array in the solid state. The four-fold intermolecular hydrogen bonding interactions between the meso-nitrogen atom of the diazaporphyrin core and the ortho-hydrogen atom of the phenyl substituent dominate the crystal packing arrangement. The present study revealed that the meso-nitrogen atom of diazaporphyrins would be used as an inherent hydrogen bonding acceptor to construct supramolecular assemblies.

We report the synthesis and properties of a dinaphthooxepine bisimide (DNOBI), a nonplanar perylene bisimide (PBI) analogue with an inserted oxygen atom. A DNOBI underwent an oxygen-extrusion reaction smoothly upon electron injection at room temperature, affording PBI in good yield. Studies on the reaction mechanism suggest that the injection of two electrons triggers the isomerization of DNOBI to dinaphthooxanorcaradiene bisimide, which is a key step in inducing the oxygen-extrusion reaction.

The development of highly electron-accepting π-systems is a fundamentally challenging issue despite their potential applications as various functional materials.

Recently, norcorrole Ni(II) complexes have received much attention because they exhibit peculiar solid-state structures and fascinating electronic properties originating from their distinct antiaromatic character. In this work, we have prepared a norcorrole Ni(II) complex with 5-hexylthien-2-yl substituents at the meso-positions, of which the antiaromatic nature was evaluated by 1H NMR analysis as well as NICS and ACID calculations. The X-ray diffraction analysis elucidated its molecular structure and crystal packing arrangement. Crystal packing structures of Ni(II) meso-di(5-methylthien-2-yl)norcorrole and Ni(II) meso-di(5-hexylthien-2-yl)norcorrole were markedly different. The latter provided a polar crystal because of the unidirectional alignment of 5-hexylthien-2-yl groups in the solid state.

Stacked-ring aromaticity arising from the close stacking of antiaromatic π-systems has recently received considerable attention. Here, we realize stacked-ring aromaticity via a rational supramolecular approach. A nanocapsule composed of bent polyaromatic amphiphiles was employed to encapsulate several antiaromatic norcorrole Ni(II) complexes (NCs) in water. The resulting micellar capsules display high stability toward heating and concentration change. The encapsulation resulted in the appearance of a broad absorption band in the near-infrared region, which is characteristic of norcorroles with close face-to-face stacking. Importantly, a

The elegant architectures of nonplanar π-systems, such as fullerene and corannulene, exhibit distinctive functionalities that have played a significant role in advancing science and technology. The current approach to synthesizing nonplanar π-systems heavily relies on the stepwise formation of bonds between their constituent fragments, which is known as the bottom-up approach. The limited number of synthetic pathways to nonplanar π-systems inevitably results in impractical molecular frameworks. Herein, we demonstrate that a constructive destruction approach, based on the oxidative cleavage of internal double bonds of dibenzo[g,p]chrysene that immediately produces eightphenone: the first readily available figure-eight molecule. Eightphenone adopts a D2-symmetric structure with excellent configurational stability and is a highly efficient emitter of circularly polarized phosphorescence. The oxidative cleavage of internal double bonds is also applicable to larger nanographene molecules, resulting in unprecedented structures with multiple figure-eight units. This study introduces the concept of constructive destruction as an alternative to conventional bottom-up approaches, paving the way for the design of new materials.

The beautiful structures of conjugated -systems with three-dimensional shapes have stimulated the curiosity of scientists and contributed to the evolution of science and technology. However, the construction of such distorted structures by multistep transformations often accompanies with undesirable side reactions. Consequently, the mass production of nonplanar-systems has still been challenging despite its utility for accelerating interdisciplinary research. In this article, we demonstrate that the inner double bond cleavage of nanographenes is a rational strategy for creating figure-eight molecules. Treatment of dibenzo[g,p]chrysene (DBC) with sodium dichromate dihydrate selectively cleaves the inner double bond to afford cyclobisbiphenylenecarbonyl (CBBC), which adopts a figure-eight structure. This transformation is scalable up to 23 g. This protocol is also applicable to brominated DBC derivatives. The Suzuki-Miyaura cross-coupling reactions of thus obtained brominated CBBCs afforded the corresponding p-tolyl derivatives, which emit circularly polarized luminescence (CPL) with high g values of more than 0.01. CBBC exhibits various intriguing properties: (1) the spontaneous resolution to afford a conglomerate, (2) configurational stability at room temperature, (3) the formation of a triplet excitation state upon photo-irradiation, and (4) the transformations of carbonyl groups. We also examined the oxidative inner bond cleavage of larger nanographenes, which furnished three non-planar -systems consisting of two figure-eight subunits. These highly distorted structures are difficult to construct by the conventional bottom-up approach, thus highlighting the power of the oxidative inner bond cleavage strategy.

Mimicking the interconvertible carbon allotropes of 2-dimensional (2D) graphene and 1-dimensional (1D) carbon nanotubes, herein we report the in-situ transformation of 2D conjugated covalent organic frameworks (COFs) sheet into 1D nanotubular structures via self-assembly the sheets at solvent interfaces. The facile “roll-the sheets” self-assembly resulted in coaxial nanotubes with uniform cross-sectional diameter, which was realized for aza-pyrene based COF instead of pyrene COF, although both possess very similar chemical structure. Upon replacing the carbon atoms at 2,7-positions of pyrene with nitrogen, contrasting optical and electronic properties was realized reflecting the rolled structure of the conjugated 2D sheets. The nanotubes exhibited semiconducting nature with stable conducting pathways at ambient conditions. The aza centers act as the point for charge carrier doping as evident from the photoconductivity and electrical conductivity results.

s-Indacene is a classical non-alternant hydrocarbon that contains 12 π-electrons in a cyclic π-conjugation system. Herein, we report its nitrogen-doped analogue, 1,5-diaza-s-indacene. 1,5-Diaza-s-indacenes were readily prepared from commercially available 2,5-dichlorobenzene-1,4-diamine through a two-step transformation consisting of a palladium-catalyzed Larock cyclization with diaryl acetylenes followed by hydrogen abstraction. The thus obtained 1,5-diaza-s-indacenes exhibited distinct antiaromaticity, as manifested in clear bond-length alternation, a forbidden HOMO-LUMO transition, and a paratropic ring current. As compared to the parent s-indacene, the 1,5-diaza-s-indacenes showed higher electron-accepting ability owing to the presence of imine-type nitrogen atoms. The 1,5-diaza-s-indacene core is effectively conjugated with the peripheral aryl groups, which enables fine-tuning of the absorption spectra and redox properties. The two possible localized forms of 1,5-diaza-s-indacene were compared in terms of their energetic aspects.

Fluorination of sp3 C–H bonds has attracted considerable attention as a promising method for the synthesis of organofluorine compounds. Manganese porphyrins have been extensively investigated as catalysts in the fluorination of saturated sp3 C–H bonds. Recently, we have found that iron(III) 5,15-diazaporphyrins, which are porphyrin analogues with imine-type sp2-hybridized nitrogen atoms at the meso-positions, showed high catalytic performance in the oxidation of sp3 C–H bonds. Here we disclose the synthesis, structure, and electronic properties of manganese(III) 5,15-diazaporphyrins. We also demonstrate the catalysis of chloromanganese(III) 5,15-diazaporphyrins for benzylic fluorination.

5,15-Diazaporphyrin appended with d-mannose moieties was prepared through Suzuki–Miyaura cross-coupling reaction and SN2 alkylation.

The synthesis and properties of dinaphthotropone bisimide (DNTrBI) and dinaphthocycloheptatriene bisimide (DNCHepBI) are described. Their molecular design is conceptually based on the insertion of a carbon atom into a perylene bisimide (PBI) core. These molecules adopt non-planar structures due to the presence of a seven-membered ring. The PBI derivative into which a carbonyl group was inserted (DNTrBI) immediately underwent nonradiative decay and/or intersystem crossing in its excited state. The PBI derivative into which a methylene group was inserted (DNCHepBI) was susceptible to deprotonation on account of the two electron-withdrawing naphthalene monoimide units. Subsequent aerobic oxidation resulted in the formation of a C−C bond at the central methylene unit, thus affording a σ-dimer. The formation of this C−C bond is dynamically redox-active, i.e., electron injection into the σ-dimer almost quantitatively regenerated the deprotonated DNCHepBI.

A series of nickel(II) pyridinophane complexes were synthesized and characterized by X-ray crystallographic analysis. Their IR spectra supported the existence of mononuclear nickel(II) complexes in...

[16]Norcorrole is an antiaromatic ring-contracted porphyrinoid. Here, we show that the phosphorus insertion of the free-base [16]norcorrole switches its antiaromaticity to aromaticity. The treatment of a free-base meso-dimesityl[16]norcorrole with phosphorus tribromide in pyridine afforded an [18]norcorrole P(V) complex, which exhibited porphyrin-like absorption and fluorescence spectra. The phosphorus center adopted a distorted tetragonal pyramidal coordination geometry. The distinct aromatic nature of the [18]norcorrole P(V) complex was corroborated both experimentally and theoretically.

We have succeeded in the synthesis of various tetrasilatetrathia[8]circulenes with alkyl and aryl groups on the silicon atoms. We also disclosed the effect of phosphine ligands on palladium-catalyzed silylation of tetraiodotetrathienylene and rhodium-catalyzed intramolecular silylation of tetrasilyltetrathienylenes. Experimental and theoretical analysis revealed the effect of the substituents on the silicon atoms on their electronic property.

Self-assembly of π-conjugated molecules in solution generally occurs owing to either an enthalpic or an entropic gain; however, designing π-conjugated systems that simultaneously exhibit enthalpically and entropically favorable self-assembly behavior is challenging. Herein, the self-assembly behavior of tetraazatetrathia[8]circulenes is disclosed, which is driven by both enthalpy and entropy. Single-crystal X-ray diffraction analysis demonstrated that molecules of these tetraazatetrathia[8]circulenes form face-to-face stacked dimers with a 1D columnar structure owing to the circularly arranged dipole moments. Importantly, concentration- and temperature-dependent 1 H NMR spectra revealed that the formation of self-assemblies of tetraazatetrathia[8]circulenes in chloroform and methanol is favored by both enthalpic and entropic factors. The unique association behavior is due to the presence of sp2 -hybridized nitrogen atoms, which weakly coordinate to the hydrogen atoms of these solvents and reduce the π-electron density of the circulene cores.

Iron hexamesityl-5,15-diazaporphyrin was synthesized through the cross-coupling reaction of tetrabromodiazaporphyrin. The use of chloroiron(III) hexamesityl-5,15-diazaporphyrin as a catalyst for oxidation of cyclooctane showed high performance with a total TON up to 731. The introduction of bulky mesityl groups at β-positions prevented the catalyst deactivation via formation of a μ-oxo dimer.

Complexation of 1,3,6,8-tetra(2-hydroxyphenyl)-2,7-diazapyrene with boron precursors provided the tetracoordinate diazapyrene boron complexes as separable anti- and syn-isomers. The structural difference of these isomers induces unique properties such as self-association behaviour of the syn-isomer and isomerisation of the anti-isomer in the solution and solid states.

The photophysical properties of 4-aminonaphthalene-1,8-imide-based derivatives, bis-ANI, consisting of two naphthalimide (NI) units linked by a butylamine bridge and its monomer ANI have been intensively investigated by steady-state and transient spectroscopy combined with quantum chemical calculations. The excited state relaxation dynamics of the two molecules are studied in three solvents of varying polarity - from hexane to tetrahydrofuran to acetone. A strong reduction in the fluorescence quantum yields and larger red shifts of the emission spectra are observed when going from the monomer ANI to dimer bis-ANI with increasing solvent polarity. It is found that the presence of the central amino linker in bis-ANI facilitates the formation of an asymmetric CS state between the ANI and NI moieties in bis-ANI, where NI˙

Post-functionalization of porphyrinoid catalysts provides a powerful tool for fine-tuning their electronic structure. We have succeeded in the stepwise methylation of the peripheral nitrogen atoms in ruthenium and cobalt 5,15-diazaporphyrins. The axial coordination of an anion to the metal center accelerates the second methylation through charge neutralization. N-Methylation of the diazaporphyrin complexes effectively controls their electron deficiency, Lewis acidity, and catalytic activity.

The switching of cyclic π-conjugation pathways using external stimuli is an attractive research topic in the field of organic chemistry. Here, we synthesized C

We synthesised thionium-ion embedded aromatic porphyrinoids: a free-base 5-thiaporphyrinium cation and its zinc complex. The sulphur atom effectively participates in the macrocyclic π-conjugation. Fluorescence quantum yields of thiaporphyrinium cations were lower than 1% unlike oxaporphyrinium cations. Detailed photophysical analysis and DFT calculations clarified the vibrational mode regarding the out-of-plane motion of the sulphur atom induced ultrafast quenching of the excited state in comparison to the corresponding oxaporphyrinium cations.

5,15-Diazaporphyrins are porphyrin analogues with imine-type sp2-hybridized nitrogen atoms at the meso-positions. Even though these compounds are more electron-deficient than regular porphyrins, the use of iron diazaporphyrins as catalysts has not been reported. Herein, we disclose the synthesis, structure, and electronic properties of iron(III) 5,15-diazaporphyrins. We evaluate their structures and electronic natures by X-ray analysis and electrochemical analyses. We also demonstrate that chloroiron(III) 5,15-diazaporphyrins exhibit high catalytic activity in the direct oxidation of alkanes due to their intrinsic electron-deficient nature. On the basis of stoichiometric reactions of iron(III) diazaporphyrin with iodosylbenzene as an oxidant, it was possible to demonstrate the existence of an iodosylbenzene-iron diazaporphyrin adduct reaction intermediate that serves as a reservoir to generate oxo-iron species.

Carbon and hydrogen are fundamental components of organic molecules and a fascinating plethora of functions can be generated using these two elements. Yet, realizing attractive electronic structures only by using carbon and hydrogen remains challenging. Herein, we report the synthesis and properties of the C70 fragment as-indaceno[3,2,1,8,7,6-ghijklm]terrylene, which exhibits near-infrared (NIR) absorption (up to ca. 1300 nm), even though this molecule consists of only 34 carbon and 14 hydrogen atoms. A remarkably small highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap is confirmed by electrochemical measurement and theoretical calculations. Furthermore, as-indacenoterrylene is stable despite the absence of peripheral substituents, which contrasts with the cases of other NIR-absorbing hydrocarbons such as diradicaloids and antiaromatic molecules. The results of this study thus offer fundamental insights into the design of hydrocarbons with a small band gap. The synthesis of hydrocarbons with attractive electronic structures remains challenging. Here, the authors describe the synthesis and properties of the C70 fragment as-indaceno[3,2,1,8,7,6-ghijklm]terrylene, which exhibits near-infrared (NIR) absorption.

The synthesis and properties of dinaphtho[1,8-bc:1′,8′-ef]thiepine bisimide (DNTBI) and its oxides are described. Their molecular design is conceptually based on the insertion of a sulfur atom into the perylene bisimide (PBI) core. These sulfur-inserted PBI derivatives adopt nonplanar structures, which significantly increases their solubility in common organic solvents. Upon electron injection, light irradiation, or heating, DNTBI and its sulfoxides undergo sulfur extrusion reactions to furnish PBI. The photoinduced and thermal sulfur extrusion reactions proceed almost quantitatively. This unique reactivity enabled the fabrication of a high-performance solution-processed n-type organic field-effect transistor with an electron mobility of up to 0.41 cm2 V^–1 s^–1., ファイル公開：2021-07-08

We have developed the synthesis of 1,3,6,8-tetramethoxy-2,7-diazapyrene through reductive aromatization of naphthalene diimide. The methoxy groups were readily converted to a variety of alkyl group...

N‐Alkylation significantly changes the electronic and optical properties, as well as the reactivity of nitrogen‐containing π‐conjugated molecules. In this study, it is found that treating 5,15‐diazaporphyrins with methyl triflate selectively affords the corresponding N ‐methyl‐5,15‐diazaporphyrinium cations in good yield. N‐Methylation substantially alters the electronic properties and reactivity of diazaporphyrins. The electron‐accepting properties of the N ‐methyl‐5,15‐diazaporphyrinium cations are enhanced due to their lowered LUMO level. Stabilization of the LUMO energy enables regio‐ and stereoselective Diels–Alder reactions of the cationic diazaporphyrin with cyclopentadiene. N‐Methylation also enhances the acidity of the inner NH protons, and thus, allows facile deprotonation to provide nitrogen‐substituted isoporphyrin analogues with only one NH group in the central cavity., ファイル公開：2021-02-26

In this Feature Article, we summarize the synthetic progress of hetero[8]circulenes, focusing on their structures and intrinsic properties. Various hetero[8]circulenes have been synthesized to date, of which structural features are categorized on the basis of the numbers of annulated pentagons. From the viewpoint of key steps, the synthetic routes are classified into two methodologies, the annulative construction of the central eight-membered ring and the ring fusion of eight-membered ring precursors. Electronic and photophysical properties based on the structural features and the introduced heteroatoms of hetero[8]circulenes are also described.

We have developed site-selective bromination on the mesityl substituents of 10,20-dimesityl-5,15-diazaporphyrins. Treatment of 10,20-dimesityl-5,15-diazaporphyrin and its nickel(ii) complex with a combination of AuBr3/AgOTf induced selective bromination on the mesityl groups. These brominated products can be employed for late-stage modification of the aryl substituents.

We have successfully prepared 5-aza-15-thiaporphyrin through nucleophilic sulfination of nitrogen-bridged dibromobisdipyrrin with sodium sulfide. X-ray diffraction analysis elucidated its structure in the solid state: two dipyrrin subunits were roughly coplanar around the sp^2-hybridized meso-nitrogen. In contrast, they adopted a folded conformation around the meso-sulfur atom. Due to its relatively distorted structure, 5-aza-15-thiaporphyrin shows weak antiaromaticity in the magnetic criteria. The sulfur atom was oxidized with m-chloroperbenzoic acid to provide 5-aza-15-thiaporphyrin S-dioxide in good yield. While 5-aza-15-thiaporphyrin was non-emissive, its S-dioxide exhibited fluorescence in solution., ファイル公開：2021/03/01

meso-Dimethylnorcorrole NiII complex exhibited enough stability under ambient conditions despite the distinct antiaromaticity. The small methyl substituents realized a dense and long-range π-stacking in its solid state, which resulted in the superior electron-transporting ability to previously reported NiII norcorroles.

For the creation of next-generation organic electronic materials, the integration of π-systems has recently become a central theme. Such functional materials can be assembled by supramolecular polymerization when aromatic π-systems are used as monomers, and the properties of the resulting supramolecular polymer strongly depend on the electronic structure of the monomers. Here, we demonstrate the construction of a supramolecular polymer consisting of an antiaromatic π-system as the monomer. An amide-functionalized Ni(II) norcorrole derivative formed a one-dimensional supramolecular polymer through π-π stacking and hydrogen-bonding interactions, ensuring the persistency of the conducting pathway against thermal perturbation, which results in higher charge mobility along the tightly bound linear aggregates than that of the aromatic analogue composed of Zn(II) porphyrins.