Nishida Jun'ichi

N-di(isopropyl)phenyl-2-azaphenalenyl radical cations were obtained as a dark brown air-sensitive crystalline compound. The high HOMA values and the ACID calculation indicate relatively high aromatic character of a 5,8-di-tert-butyl derivative, and...

Abstract Despite having an asymmetric structure, 2‐(thiopyran‐4‐ylidene)‐1,3‐benzodithiole (TP‐BT) is a good p‐type semiconductor containing isotropic three‐dimensional (3D) intermolecular interactions. Moreover, its π‐extended analogs can potentially work as organic electronic materials. Herein, a fused‐type π‐extended analog containing an extra benzene ring on the benzodithiole unit, i. e., 2‐(thiopyran‐4‐ylidene)‐1,3‐naphtho[2,3‐d]dithiole (TP‐NT), and three σ‐bonded‐type π‐extended analogs, i. e., phenyl‐, naphthyl‐, and anthryl‐substituted analogs (Ph‐TP‐BT, Nap‐TP‐BT, and Ant‐TP‐BT, respectively), were prepared and their molecular arrangements and organic field‐effect transistor (OFET) properties were investigated. TP‐NT formed a herringbone arrangement with 3D intermolecular interactions similar to that of the parent TP‐BT. Meanwhile, Ant‐TP‐BT formed a bilayer‐type layered herringbone arrangement. Since the highest occupied molecular orbital and the lowest unoccupied molecular orbital are located on the TP‐BT and anthracene units, respectively, a unique donor–acceptor separated network was formed. In OFETs prepared via a vapor deposition method using the σ‐bonded‐type analogs, slightly lower mobilities (0.1 to 8×10⁻³ cm²/Vs) than that of TP‐NT (0.1 cm²/Vs) were observed. Upon photo‐irradiation, the OFET of Ant‐TP‐BT exhibited a larger threshold voltage shift and an increase in the off current compared with TP‐NT. The σ‐bonded‐type analogs showed a larger photo‐response effect than TP‐NT derived from the donor–acceptor molecular structure.

We report the synthesis of aryl-substituted TP-BT derivatives and their OFET properties. 4-Pyridyl substituted TP-BT shows switching characteristics by photo-irradiation.

In this study, we describe the synthesis of a cholesterol-linked cyanostilobazole salt dye and the tuning of its luminescence by physical stimuli such as electricity and grinding. The dyes exhibited liquid-crystalline properties at temperatures above 170 °C. Some of the solutions were transformed into orange luminescent gels upon the addition of poor solvents. When the solvent was evaporated, the resulting solid xerogel exhibited mechanochromism, its color changed, and its luminescent color changed from orange to red. Furthermore, we investigated the construction of functional gels (mechanochromic gels) that can respond to two stimuli, damage detection by abrasive responsiveness, and electrical response using ionic liquid complexes of polymers as dispersing media. This study provides a new strategy for tuning and switching luminescence using non-chemical stimuli in a single-component system using aggregation.

Abstract 2‐Aryl‐5,8‐di‐tert‐butyl‐1H‐benz[de]isoquinolinium tetrafluoroborates were synthesized and crystalized to form yellow to orange crystals. Absorption and fluorescence maxima (λ_ABS and λ_FL‐SL) of the compounds in CH₂Cl₂ depend on the electronic and steric properties of the aryl ring substituents and closely match those arising from theoretical calculations. λ_ABS and λ_FL‐SL values of the compound possessing bulky 2,6‐diisopropylphenyl substituents are the shortest among the substances because of sterically promoted retardation of conjugation between the isoquinolinium and aryl ring planes. In contrast, solid‐state fluorescence maxima (λ_FL‐SD) of the compounds are not closely correlated with the electronic properties of the aryl substituents. Furthermore, one crystalline form of both the 4‐trifluoromethylphenyl and 4‐nitrophenyl derivatives exhibit mechanochromic and crystallochromic behavior reflected in absorption and fluorescence color changes. X‐ray diffraction and crystallographic analysis reveal that the solid state photophysical properties of these substances are related to different molecular stacking interactions occurring in different crystalline forms.

We report the synthesis of P-BT and TP-BT and their OTFT properties based on electronic dimensionality and access resistance (R_acc). TP-BT can suppress R_acc due to its 3D electronic structure.

Abstract Highly strained cyclic xanthene dimers, which serve as models for reduced graphene oxide (RGO), were synthesized by Ni(0) mediated homo-coupling reactions. The dimers are obtained as highly stable colorless solids. X-ray crystallographic analysis of a tetra-tert-butyl derivative demonstrates that it possesses a highly strained structure with an extremely short non-bonded O⋯O distance (2.5662(44) Å). The results of variable temperature NMR experiments show that no signal broadening occurs even at 398 K, indicating that conformational flipping requires considerably high energy.

A novel alkyltolane-terminated cyanostilbene is synthesized. The photoluminescence colour changed depending on the precipitation method, with either a red shift or blue shift in the photoluminescence spectra observed upon mechanical grinding.

In the molecule of the title compound, C₅₀H₄₉NO₂, the acenaphtho[1,2-j]fluoranthene-4,5-dicarboximide framework has an approximately planar structure [maximum deviation = 0.124 (3) Å] and subtends a dihedral angle of 62.94 (8)° with the pendant phenyl group. Two of thetert-butyl groups are disordered over two sets of sites, with occupancy ratios of 0.506 (8):0.494 (8) and 0.669 (17):0.331 (17). An intermolecular short contact between a methyl group and the aromatic ring occurs in the crystal structure.