排序方式: 共有27条查询结果,搜索用时 31 毫秒
11.
Yusaku Ogura Masahiro Nakano Hajime Maeda Masahito Segi Taniyuki Furuyama 《Molecules (Basel, Switzerland)》2022,27(9)
Herein, we report the synthesis of sulfur-substituted boron(III) subphthalocyanines (SubPcs) with cationic axial ligands. Subphthalocyanines were synthesized by a condensation reaction using the corresponding phthalonitriles and boron trichloride as a template. An aminoalkyl group was introduced on the central boron atom; this process was followed by N-methylation to introduce a cationic axial ligand. The peripheral sulfur groups shifted the Q band of SubPcs to a longer wavelength. The cationic axial ligands increased the polarity and enhanced the hydrophilicity of SubPcs. The effect of axial ligands on absorption and fluorescence properties is generally small. However, a further red shift was observed by introducing cationic axial ligands into the sulfur-substituted SubPcs. This change is similar to that in sulfur-substituted silicon(IV) phthalocyanines. The unique effect of the cationic axial ligand was extensively investigated by theoretical calculations and electrochemistry. In particular, the precise oxidation potential was determined using ionization potential measurements. Thus, the results of the present study provide a novel strategy for developing functional dyes and pigments based on SubPcs. 相似文献
12.
Synthesis, UV–vis absorption, and fluorescence spectroscopic properties of 1,3,6,8-tetrakis(silylethynyl)pyrenes 2–10 were studied. Absorption maxima of CH2Cl2 solutions of these compounds appeared at 437–445?nm, and molar absorption coefficients (ε) of most of these compounds exceeded 105?L?mol?1?cm?1. Fluorescence emissions measured in dilute CH2Cl2 solutions are observed in visible region, and their intensities remarkably increased compared with that of pyrene. Fluorescence spectra obtained from concentrated CH2Cl2 solutions exhibited broad excimer emissions when steric bulk of substituents on silicon atoms is sufficiently low. Molecular orbital calculations indicated that HOMO-LUMO energy gap decreased with increasing the number of phenyl groups on silicon atoms, and that the silyl groups act as electron-donating groups to tetraethynylpyrene core. Resonances in 29Si NMR spectra shifts to upfield with increasing the number of phenyl groups on silicon atoms due to the shielding effect of phenyl groups. 相似文献
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14.
Mohd.Rafi Segi Rahmat 《模糊系统与数学》2008,22(3)
In this paper, we obtain some new fixed point theorems in fuzzy-Banach spaces by considering the t-norms of h-type and a linear mapping of weakly demicompact. 相似文献
15.
Masahito Segi Mamoru Takahashi Tadashi Nakajima Sohei Suga Noboru Sonoda 《合成通讯》2013,43(13-14):2431-2439
Intramolecular Diels-Alder reaction of thioaldehydes which were generated from bis(trimethylsilyl) sulfide and dienals gave the corresponding bicyclic adducts. 相似文献
16.
Selenoaldehydes, regenerated by thermal retro Diels-Alder reaction of anthracene cycloadducts under neutral conditions, reacted with 2-methoxyfuran to give methyl penta-2,4-dienoates along with the deposition of elemental selenium. In a similar reaction with 2-methoxyfuran using thioaldehyde, thiirane compound was isolated. This suggests the formation of selenirane intermediates in the above reaction. 相似文献
17.
Masahito Segi Mamoru Takahashi Tadashi Nakajima Sohei Suga
Shinji Murai
Noboru Sonoda 《Tetrahedron letters》1988,29(52):6965-6968Intramolecular Dieis-Alder reaction of selenoaldehydes which were generated from bis(trimethylsilyl) selenide and dienals gave the corresponding bicyclic adducts. 相似文献
18.
Mitsunori Honda Sho Sasaki Tsuyoshi Nishimoto Hiromoto Koshiro Ko-Ki Kunimoto Masahito Segi 《Tetrahedron letters》2018,59(42):3777-3781
The synthesis of cyclopropyl silyl ketones possessing a hydrocarbon group at 1-position of three-membered ring was investigated. The reaction of sulfoxonium ylide with α,β-unsaturated acylsilanes derived from α,β-unsaturated aldehydes did not afford the desired acylsilane derivatives. Instead, the corresponding silyl enol ethers were yielded exclusively. On the other hand, the Corey-Chaykovsky cyclopropanation of α-substituted α,β-unsaturated aldehydes proceeded well to give 1-substituted cyclopropyl aldehydes. The silyl substitution of formyl proton in the obtained aldehydes via umpolung of carbonyl group afforded the target acylsilanes. 相似文献
19.
Mitsunori Honda Takahito Mita Toshiaki Nishizawa Toru Sano Masahito Segi Tadashi Nakajima 《Tetrahedron letters》2006,47(32):5751-5754
Treatment of 1-silylcyclopropylmethanols with TsOH in methanol gives different homoallyl ethers depending upon the configuration of substituents on cyclopropane ring and the kinds of substituents on carbinyl carbon. Especially, the reaction of cyclopropylmethanols having no substituents on the same side with silyl group on cyclopropane ring proceeds to give the corresponding E-homoallyl ethers with high stereoselectivity. The following protiodesilylation of resulting homoallyl ethers proceeds with retention of configuration. 相似文献
20.
Taniyuki Furuyama Junichi Shinozaki Thiago Teixeira Tasso Hajime Maeda Masahito Segi Nagao Kobayashi 《Tetrahedron letters》2017,58(45):4243-4247
D-A-D (Donor-Acceptor-Donor) type dinitriles linked by a styryl or phenylethynyl group have been prepared. These groups were introduced to increase the flexibility and the size of the π-conjugation in the chromophores. Both compounds showed strong emission in the solid state, AIE (aggregation-induced emission) behavior, and mechanochromism. The fluorescence color of ground powder changed by organic solvent vapor (vapochromism). Especially, the emission color of the styryl dinitrile after exposures depends on the solvent, while that of the phenylethynyl dinitrile is the same after exposure to different solvents. These results were explained by single crystal and powder XRD measurements, which revealed that the flexible styryl linker leads to a loose crystal packing, resulting in a dinitrile with multi-state microcrystalline structures. This methodology based on the flexible linker allows for the detection of small organic molecules without transition metals. 相似文献