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1.
Double Ring Expansion from an Aromatic [18]Porphyrin(1.1.1.1) to an Antiaromatic [20]Porphyrin(2.1.2.1) 下载免费PDF全文
Masataka Umetani Dr. Takayuki Tanaka Taeyeon Kim Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2016,55(28):8095-8099
Double ring expansion from a 5,15‐diarylporphyrin to a 5,16‐diaryl‐10,11,21,22‐tetradehydro[20]porphyrin(2.1.2.1) occurred through a reaction sequence consisting of oxidation with PbO2 to 5,15‐dioxoporphodimethene, a Corey–Fuchs reaction with tetrabromomethane in the presence of triphenylphosphine, and Fritsch–Buttenberg–Wiechell rearrangement triggered by tert‐butyllithium. The obtained tetradehydro[20]porphyrin(2.1.2.1) and its mono‐ and dihydrogenated congeners exhibited 20 π antiaromatic character, whereas overhydrogenated congeners bearing a saturated bridge were nonaromatic owing to disrupted π conjugation. 相似文献
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卟啉化学是有机化学研究中不可或缺的一个方向。由于卟啉在结构上具有一个大的共轭体系,从而具有典型的芳香性。其具有优异的光电性能、独特的光动力治疗作用、高效的催化活性,并且广泛存在于血红素、叶绿素、维生素B_(12)、过氧化氢酶等有机生物分子中,所有这一切都吸引着科学家们进行深入研究。本文从取代卟啉、缩合卟啉以及扩环卟啉三个方面分别讨论了卟啉的研究进展,通过列举一系列经典的反应以及卟啉衍生物,总结了卟啉衍生物的合成方法及其发展方向。另外,文中还对于卟啉的一些特殊物理、化学和光电性质,做了重点介绍。本文旨在为卟啉的研究者们提供参考。 相似文献
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Lincoln Lucilio Romualdo André Luis Bogado Eliana M.A. Valle Icaro S. Moreira Javier Ellena Eduardo E. Castellano Márcio P. de Araujo Alzir A. Batista 《Polyhedron》2008
New tetraruthenated manganese (III) porphyrins were synthesized and characterized (31P NMR, cyclic voltammetry, UV–Vis). This new system presents four units of cationic “[RuCl(dppb)(X-bipy)]+”. The electrochemical and catalytic properties of the central manganese (III) show dependence on the characteristics of the peripheral ruthenium complexes as evidenced by the Mn(III)/Mn(II) reduction potential. 相似文献
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Osvaldo A. Serra Cláudio R. Neri Yassuko Iamamoto Eduardo J. Nassar Paulo S. Calefi Simone A. Cicillini Cynthia M. C. P. Manso 《Journal of inclusion phenomena and macrocyclic chemistry》1999,35(1-2):271-280
A topic of constant investigation in recent decades has been the study of electron and/or energy transfer reactions in supramolecular systems. The energy transfer between donor-acceptor depends on the influence of the substituent in the intersystem crossing. The competition between the radiative and non-radiative processes also depends on other factors such as temperature, solvent and energy gap. In this work, we have studied the suppression of the emission of monocarboxyphenyl porphyrins after addition of rare earth ions (RE(III)). The porphyrin emission decreases with the addition of RE(III), no matter which ion is present. When Eu(III) was used, the emission of this ion was not observed either. This suppression happens due to the effect of the heavy atom and not due to the energy transfer through electronic levels between the porphyrin and the RE(III). After the addition of RE(III), the lifetime for MCTPPH2 started to decay biexponentially, indicating the formation of a new species (MCTPPH2-RE(III)) of a shorter lifetime. The presence of NO2 groups in the ortho mesoaryl positions of MCTNPPH2 and the presence of Zn(II) in Zn(MCTPP) decreased both the porphyrin lifetime and emission due to an increase in the spin-orbit coupling. 相似文献
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Neeraj Agarwal 《Tetrahedron》2004,60(21):4739-4747
A series of β-pyrrole and β-thiophene substituted porphyrins with N2S2 and N3S porphyrin cores were synthesized and characterized. The introduction of substituents at β-pyrrole and β-thiophene carbons resulted in significant shifts in 1H NMR, absorption and fluorescence maxima. These effects were attributed to alteration of the porphyrin ring current caused by substituents at β-positions. 相似文献
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S. K. Pushpan S. Venkatraman V. G. Anand J. Sankar H. Rath T. K. Chandrashekar 《Journal of Chemical Sciences》2002,114(4):311-338
Porphyrins and metallopophyrins have attracted the attention of chemists for the past 100 years or more owing to their widespread
involvement in biology. More recently, synthetic porphyrins and porphyrin-like macrocycles have attracted the attention of
researchers due to their diverse applications as sensitizers for photodynamic therapy, MRI contrasting agents, and complexing
agents for larger metal ions and also for their anion binding abilities. The number of π-electrons in the porphyrin ring can
be increased either by increasing the numberof conjugated double bonds between the pyrrole rings or by increasing the number
of heterocyclic rings. Thus, 22π sapphyrins, 26π rubyrins, 30π heptaphyrins, 34π octaphyrins and higher cyclic polypyrrole
analogues containing 40π, 48π, 64π, 80π and 96π systems have recently been reported in the literature. These macrocycles show
rich structural diversity where normal and different kinds of inverted structures have been identified. In this review, an
attempt has been made to collect the literature of the inverted porphyrins and expanded porphyrins reported until December
2001. Since themeso aryl expanded porphyrins have tendency to form both inverted and non-inverted structures more emphasis has been given tomeso aryl expanded porphyrins. 相似文献
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M. Ravi T. K. Chandrashekar 《Journal of inclusion phenomena and macrocyclic chemistry》1999,35(4):553-582
Studies on the design and synthesis of receptor molecules capable of selectively binding and transporting substrates (neutral, anionic and cationic) is currently being pursued to develop artificial membranes permeable to the bound species. Expanded porphyrin systems by virtue of increased cavity size and aromatic nature are capable of binding a variety of substrates depending on the nature of the porphyrin and the cavity size. Recently there are a number of reports on the use of expanded porphyrins as molecular receptors for various substrates. Specifically, expanded porphyrins such as sapphyrins and rubyrins in their protonated form bind a variety of anionic and neutral substrates and it has been shown that they act as carriers for transporting different ionic and neutral species. Additionally, expanded porphyrins find their application as MRI contrasting agents and as sensitizers for photodynamic therapy. In this review, an attempt has been made to discuss molecular receptor properties in the solid and solution phases of two expanded porphyrins, sapphyrin and rubyrin which are 22 and 26 electron systems respectively. Furthermore, the synthesis, binding and transport properties of core modified expanded porphyrin systems are also highlighted. 相似文献
10.
Schiff-base (SB) derivatives of Ni(II) and Cu(II) porphyrins endowed with various amine functions (R−NH2),n-butylamine,p-anisidine andm-nitroaniline have been prepared from corresponding formyl porphyrins. Protonation studies of these SB derivatives reveal
a marked red shift of the optical absorption bands in the visible region relative to the unprotonated imines. The magnitude
of the observed red shifts in the protonated derivatives, (SBH+) are found to depend on the electron-withdrawing or electron-donating nature of the R group of the amines. The results of
the optical absorption,1H NMR, EPR, and cyclicovoltammetric studies are illustrative of the fact that protonation of the SB derivatives results in
a localized positive charge,
in the periphery of the porphyrin (p) system. The dibenzo-18-crown-6 interspersedbisporphyrin schiff bases have been prepared fromtrans 4,4′-diamino dibenzo-18-crown-6 and formyl porphyrins. The protonation of these SB derivatives is found to proceed in a concerted
fashion. The cation complexation studies by the crown ether entity in thebisporphyrin systems have been investigated using optical absorption, magnetic resonance and electrochemical methods. The redox
characteristics of the protonated dimeric SB porphyrins reveal that the first oxidation step involves a two-electron transfer
reaction. This is important in view of their possible usage in multielectron transfer reactions of biological and catalytic
interest. 相似文献
11.
Claudia Fabbri Claudia Aurisicchio Osvaldo Lanzalunga 《Central European Journal of Chemistry》2008,6(2):145-153
The mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO5 as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant
have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which
is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation
of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane,
two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species
iron-oxo porphyrin radical cation and the substrate.
相似文献
12.
Łukasz Orzeł Justyna Polaczek Magdalena Procner 《Journal of Coordination Chemistry》2015,68(17-18):2971-2989
Cobalt and manganese porphyrins are known for their ability to activate small molecules. This is particularly important in the case of nitric oxide, whose role and mechanism of action in the redox biological systems have not yet been fully recognized. The goal of this article is to draw attention to some of the current trends of research in this area. The interactions involving NO itself and the primary products of its oxidation (nitrite) and reduction (nitroxyl) have been distinguished and separately discussed. The diversity of undertaken issues sheds light on both the expected behavior in biologically relevant systems as well as potential practical applications. 相似文献
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S. A. Syrbu T. V. Lyubimova A. S. Semeikin 《Chemistry of Heterocyclic Compounds》2004,40(10):1262-1270
A method was developed for the synthesis of a series of meso-phenyl-substituted octaalkylporphyrins with various numbers of phenyl groups at various positions. Some of their properties were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1464–1472, October, 2004. 相似文献
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Hiroyuki Furuta Prof. Dr. Hideki Nanami Tatsuki Morimoto Dr. Takuji Ogawa Prof. Dr. Vladimir Král Dr. Jonathan L. Sessler Prof. Dr. Vincent Lynch Dr. 《化学:亚洲杂志》2008,3(3):592-599
The new N‐confused porphyrin (NCP) derivatives, meso‐unsubstituted β‐alkyl‐3‐oxo N‐confused porphyrin (3‐oxo‐NCP) and related macrocycles, were synthesized from appropriate pyrrolic precursors by a [3+1]‐type condensation reaction. 3‐Oxo‐NCP forms a self‐assembled dimer in dichloromethane that is stabilized by complementary hydrogen‐bonding interactions arising from the peripheral amide‐like moieties. The protonated form of 3‐oxo‐NCP was observed to bind halide anions (F?, Cl?) through the outer NH and the inner pyrrolic NH groups, thus affording a dimer in dichloromethane. The structure of the chloride‐bridged dimer in the solid state was determined by X‐ray diffraction analysis. 相似文献
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Licheng Wu Feilong Li Yutao Rao Bin Wen Ling Xu Mingbo Zhou Takayuki Tanaka Atsuhiro Osuka Jianxin Song 《Angewandte Chemie (International ed. in English)》2019,58(24):8124-8128
A reaction sequence of regioselective peripheral bromination, Suzuki–Miyaura coupling with 2‐borylated thiophene or pyrrole, and oxidative ring‐closure with FeCl3 allowed the synthesis of heterole‐fused earring porphyrins 4Pd and 9Pd from the parent earring porphyrin 1 . Differently pyrrole‐fused porphyrins 5H and 6H and their PdII complexes 5Pd and 6Pd were also synthesized. The structures of 4Pd , 5H, 6Pd , and 8Pd have been revealed by X‐ray analysis to be slightly twisted owing to constraints imposed by heterole‐fused structures. 5Pd exhibits an intensified band at 1505 nm, while 4Pd and 9Pd display small but remarkably red‐shifted absorption bands reaching around 2200 nm. 相似文献
18.
Sangita SantraDuraisamy Kumaresan Neeraj AgarwalMangalampalli Ravikanth 《Tetrahedron》2003,59(13):2353-2362
Synthesis of a series of 21-thia and 21-oxoporphyrin building blocks containing two pyridyl functional groups at the meso positions in a cis fashion is reported. The building blocks were used to synthesize a series of cationic water-soluble 21-thia and 21-oxoporphyrins. An unsymmetrical non-covalent trimer containing two dissimilar porphyrin cores such as one N3S and two N4 porphyrins cores was also constructed using the pyridyl porphyrin building blocks reported here. 相似文献
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Tavarekere K. Chandrashekar Sundararaman Venkatraman Viswanathan Prabhuraja Rajneesh Misra Viswanathan Baskar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):845-872
Abstract Various supramolecular assemblies based on expanded porphyrins building blocks containing sulfur and/or selenium in the core, formed through multiple non-covalent hydrogen bonding interactions are highlighted. Specifically, modified expanded porphyrins such as 22 π sapphyrins, 26 π rubyrins, and 34 π octaphyrins self assemble in solid state through C–H…O, C–H…N, C–H…S, C–H…Se, C–H…π, and C–H…Cl interactions to form dimeric, oligomeric, and three dimensional networks. Furthermore, the supramolecular networks promoted by trapped solvent molecules such as nitrobenzene and bound anions such as chloride or trifluoroacetate through noncovalent interactions will be discussed. 相似文献
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《Tetrahedron》2003,59(14):2409-2415
We investigated the formation of host-guest complexes between zinc porphyrins covalently attached to calixarenes via amidic bonds and a small bidentate ligand bearing two nitrogen atoms. Depending upon the calixarene structure (S vs CH2 bridges), the ligand 1,4-diazabicyclo[2.2.2]octane (DABCO) is complexed by metalloporphyrin units by two different ways. While the thiacalix[4]arene prefers an intramolecularly closed cavity with a binding constant of (1.0±0.1)×107 M−1 in CHCl3 at 294 K (stoichiometry 1:1), the classical calix[4]arene forms a complex by ligation of both porphyrin units separately (stoichiometry 2:1). The differences observed can be rationalized in terms of cavity size and the preorganization due to intramolecular hydrogen bonding of the calixarene lower rim. 相似文献