184 research outputs found

    エポキシキノンルイ ノ コウカガク ハンノウ ニ カンスル ケンキュウ

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    京都大学0048新制・論文博士理学博士乙第4729号論理博第789号新制||理||413(附属図書館)UT51-57-L388(主査)教授 丸山 和博, 教授 加治 有恒, 教授 岡 信三郎学位規則第5条第2項該当Kyoto UniversityDFA

    Synthesis, properties and reactivity of an ortho-phenylene-cyclopentene-bridged tetrapyrrole

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    Increasing the number of meso-methine carbons of porphyrin has led to a creation of a series of vinylogous expanded porphyrins, while the introduction of an ortho-phenylene-unit as a pyrrole-connecting two-carbon bridge usually leads to prevention of effective macrocyclic conjugation. Cyclopentene can serve as a conjugative bridge to increase the macrocyclic conjugation owing to its cis-geometry. In this work, ortho-phenylene-cyclopentene-bridged tetrapyrrole 5 was prepared on the basis of a coupling strategy. The tetrapyrrole 5 exhibited slightly more conjugative features as compared to ortho-phenylene-bridged tetrapyrrole 4. Oxidation of 5 with [bis(trifluoroacetoxy)iodo]benzene (PIFA) at low temperature afforded a partly fused tetrapyrrolic compound 9 having a spiro-connected pyrrolo[2, 1-a]isoindole moiety

    A doubly 2,6-pyridylene-bridged porphyrin-perylene-porphyrin triad.

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    A doubly 2, 6-pyridylene-bridged porphyrin-perylene-porphyrin triad was synthesized via Suzuki-Miyaura cross coupling reaction, which captures a tetrakis(3-pyridyl)porphyrin guest in a 2 : 1 manner to form a supramolecular complex that undergoes photo-induced electron transfer

    Diazadimethano[8]circulene: Synthesis, structure, properties, and isolation of stable radical cation

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    Hetero[8]circulenes have emerged as novel heteroatom-doped polycyclic aromatic hydrocarbons whose properties depend on the constituent aromatic units. Herein we report a C-doped variant, diazadimethano[8]circulene 3, in which two diphenylcyclopentadiene units are installed into the core of [8]circulene that may prevent effective conjugation. The structure of 3 has been revealed to have two longer C–C bonds in the central eight-membered ring, while the absorption and emission profiles are quite similar to those of tetraaza[8]circulene. Stable radical cation 3⁺ was easily obtained by facile oxidation of 3. X-ray diffraction analysis of 3⁺ showed a slipped dimer arrangement with negligible intermolecular interaction. Interestingly, the lowest-energy absorption of 3⁺ reaches around 2500 nm, while that of 3 is 447 nm

    Synthesis and catalytic activities of porphyrin-based PCP pincer complexes.

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    2, 18-Bis(diphenylphosphino)porphyrins undergo peripheral cyclometalation with group 10 transition-metal salts to afford the corresponding porphyrin-based PCP pincer complexes. The porphyrinic plane and the PCP-pincer unit are apparently coplanar, with small strain. The catalytic activities of the porphyrin-based pincer complexes at the periphery were investigated in the allylation of benzaldehyde with allylstannane and in the 1, 4-reduction of chalcone to discover the electronic interplay between the inner metal and the outer metal in catalysis

    Palladium-catalyzed amination of aryl sulfides with anilines.

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    A combination of a palladium-NHC catalyst and potassium hexamethyldisilazide enables the amination of aryl sulfides with anilines to afford a wide variety of diarylamines. The reaction conditions are versatile enough for the reaction of even bulky ortho-substituted aryl sulfides. This amination can be applied to the modular synthesis of N-aryl carbazoles from the corresponding ortho-bromothioanisoles. As aryl sulfoxides undergo extended Pummerer reactions to afford ortho-substituted aryl sulfides, the Pummerer products are thus useful substrates for the amination to culminate in efficient syntheses of a 2-anilinobenzothiophene and an indole as proof-of-principle of the utility of the extended Pummerer reaction/amination cascade

    Boron Arylations of Subporphyrins with Aryl Zinc Reagents

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    Boron arylations of B‐(methoxo)triphenylsubporphyrin have been developed with a combined use of ArZnI⋅LiCl and trimethylsilyl chloride. Aryl zinc reagents bearing bromo, cyano, amide, and ester groups can be employed for the B‐arylation reaction to provide the corresponding B‐arylated subporphyrins in moderate yields. Postmodifications of B‐arylated subporphyrins have been demonstrated without loss of the B−C bond. These modifications include conversion of the cyano group into a benzoyl group with PhMgBr, hydrolysis of the ester group to give B‐(4‐carboxyphenyl)subporphyrin, and Pd‐catalyzed Suzuki–Miyaura coupling of the 4‐bromophenyl group to give a 1,4‐phenylene‐bridged subporphyrin–ZnII porphyrin hybrid that displays intramolecular excitation energy transfer from the subporphyrin to the porphyrin. The newly synthesized B‐arylated subporphyrins have been fully characterized by NMR, UV/Vis absorption and fluorescence spectroscopies, mass spectrometry, electrochemical measurements, and X‐ray diffraction analysis.Bonding B to C: Boron arylations of B‐(methoxo)triphenylsubporphyrin have been developed with a combined use of ArZnI⋅LiCl and trimethylsilyl chloride (TMSCl; see scheme), which allow the synthesis of B‐aryl subporphyrins bearing bromo, cyano, amide, and ester groups. Postmodifications of the B‐aryl subporphyrins have been demonstrated without loss of the B−C bond. Newly synthesized B‐arylated subporphyrins have been fully characterized.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137618/1/chem201504719.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137618/2/chem201504719-sup-0001-misc_information.pd

    Facile synthesis of fluorescent hetero[8]circulene analogues with tunable solubilities and optical properties

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    Hetero[8]circulenes are an interesting class of polycyclic heteroaromatic molecules having rigid and planar structures, which are promising in light of their potential applications for OLEDs, OFETs and so forth. Although their synthetic methods have been developed in some specific cases, a facile synthetic protocol of novel hetero[8]circulenes with tunable properties is highly desirable. We herein report the unexpected formation of methoxy-substituted quasi-aza[8]circulene and its conversion into unprecedented triazaoxa[8]circulene. The structures and optical properties were comparatively studied. Remarkably, triazaoxa[8]circulene is highly soluble in THF, acetone and DMSO mainly because of effective hydrogen-bonding of the NH moieties to these solvents. Their highly soluble nature in various solvents enabled us to study the solvent effects of these molecules. In particular, triazaoxa[8]circulene displays a high fluorescence quantum yield of 0.72 in DMSO. Furthermore, enantiomeric separation of highly distorted quasi-aza[8]circulene was successfully achieved by chiral HPLC. Thus, these novel hetero[8]circulene derivatives are practically useful fluorescent nanographene-like molecules with intriguing optical properties

    Nickel–NHC-Catalyzed Cross-Coupling of 2-Methylsulfanylbenzofurans with Alkyl Grignard Reagents

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    NiCl2(PPh3)(IPr) catalyzes cross-coupling reactions of 2-methylsulfanylbenzofurans with alkyl Grignard reagents. Other nickel complexes such as NiCl2(dppe) failed to catalyze the same reaction. The alkylation is applicable to the synthesis of a couple of protein tyrosine phosphatase inhibitors, 3-(4-biphenylyl)-2-alkylbenzofurans

    Electron transfer reactions in sub-porphyrin-naphthyldiimide dyads

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    A series of donor-acceptor compounds based on a sub-porphyrin (SubP) as an electron donor and naphthyldiimide (NDI) as an acceptor has been designed, synthesized and investigated by time-resolved emission and transient absorption measurements. The donor and acceptor are separated by a single phenyl spacer substituted by methyl groups in order to systematically vary the electronic coupling. The electron transfer reactions in toluene are found to be quite fast; charge separation is quantitative and occurs within 5-10 ps and charge recombination occurs in 1-10 ns, depending on the substitution pattern. As expected, when steric bulk is introduced on the adjoining phenyl group, electron transfer rates slow down because of smaller electronic coupling. Quantum mechanical modelling of the potential energy for twisting the dihedral angles combined with a simplified model of the electronic coupling semi-quantitatively explains the observed variation of the electron transfer rates. Investigating the temperature variation of the charge separation in 2-methyltetrahydrofuran (2-MTHF) and analyzing using the Marcus model allow experimental estimation of the electronic coupling and reorganization energies. At low temperature, relatively strong phosphorescence is observed from the donor-acceptor compounds with onset at 660 nm signaling that charge recombination occurs, at least partially, through the sub-porphyrin localized triplet excited state. Finally, it is noted that charge separation in all SubP-NDI dyads is efficient even at cryogenic temperatures (85 K) in 2-MTHF glass
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