共查询到20条相似文献,搜索用时 15 毫秒
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《Chemical physics letters》1985,119(1):17-21
Several Sn(n,π*) and Tn(n,π*) states of glyoxal vapor with n ⩾ 2 were observed for the first time by two-color fluorescence dip and phosphorescence dip spectroscopies. 相似文献
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《Journal of Photochemistry》1981,15(3):229-240
Efficiencies of excitation—resonance energy transfer in n-hexane from 3(n,π*) and 3(π,π*) states of seven aromatic ketones to cis-1,3-pentadiene (c-P) and 3α,24-dimethoxy-Δ7,9-choladiene (D) were measured. The sterically hindered diene D is approximately 6 times less efficient as an acceptor than is c-P, regardless of the configuration of the sensitizer triplet state. A treatment of the energy transfer efficiencies which assumes no difference between n,π* and π,π* states and which includes only gross aspects of individual sensitizer—acceptor orientations accounts for c-P being no more than 4 times as efficient an acceptor as D. It is concluded that excitation energy migration within the benzoyl sensitizer is sufficiently rapid to make state differences of little importance during excitation—resonance energy transfer. 相似文献
4.
Chromones are introduced into a double-tandem [4(π)+2(π)]·[2(π)+2(π)]·[4(π)+2(π)]·[2(π)+2(π)] synthetic sequence, culminating in photoprotolytic oxametathesis, which leads to an expeditious growth of molecular complexity over a few experimentally simple steps. The overall reaction can potentially be utilized in diversity-oriented synthesis, as it allows for three or more diversity inputs furnishing novel unique polycyclic scaffolds decorated with a variety of functionalities and aromatic/heterocyclic pendants. The polycyclic alkenes, resulting from the oxametathesis step, were found to undergo efficient and clean photoinduced epoxidation when irradiated in the presence of molecular oxygen. 相似文献
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《Journal of organometallic chemistry》1986,302(1):19-21
The results of a VT 13C NMR study of alkoxy and alkylthio derivatives of 2- and 3-methylpiperidinophenylboranes demonstrate that the pπ-pπ bonding between boron and oxygen is some 3 kcal mol−1 stronger than that between sulphur and boron. 相似文献
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Akella Sivaramakrishna Hadley S. Clayton Mokgolela M. Mogorosi John R. Moss 《Coordination chemistry reviews》2010,254(23-24):2904-2932
With the exception of metallocenes, transition metal complexes with hydrocarbon ligands only are rare. However, complexes of this type containing Group 10 metals are known and have been shown to be quite stable. These complexes are versatile precursors for many organometallic compounds. In addition, such compounds can play an important role in many reactions including C–H or C–C activation reactions and have useful applications in the thermal and photochemical production of metal films by chemical vapour deposition (CVD). The present review summarizes the synthesis, properties and chemistry of hydrocarbon complexes of Group 10 metals of the type LnM or LnMR1R2 (where Ln = σ- or π-hydrocarbon ligands; M = Ni, Pd and Pt; R1, R2 = σ-hydrocarbon ligands) without the involvement of any hetero donor ligands such as N, P, O and S in the metal coordination spheres. 相似文献
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Yulan Zhu Libin Tian Kuirong Ma Yuhe Kan Xueling Tang Huayou Hu 《Solid State Sciences》2010,12(3):391-396
Two novel conjugated imino-π-extended tetrathiafulvalenes with p-iminobenzene, N,N′-bis(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)benzene-1,4-diamine (1) and N,N′-bis(4,5-bis(ethylenedithio)-1,3-dithiolo-2-ylidene)benzene-1,4-diamine (2), have been synthesized and characterized by NMR, IR, MS and X-ray single-crystal diffraction. Both the two targets adopt chair-like conformation, and the central rings of p-iminobenzene moieties of the two molecules are severely twisted from the planarity of two dithiole rings, respectively. The UV–vis spectra of 1 and 2 show the lowest-energy absorption bands caused by the HOMO–LUMO one-electron promotion. Cyclic voltammetry (CV) measurements show only one, two-electron irreversible oxidation picks. These experimentally estimated energy levels of the frontier orbital of 1 and 2 (EHOMO 1: = ?5.45, 2: ?5.47 eV) are in good agreement with those obtained from DFT calculations (EHOMO 1: = ?5.5, 2: = ?5.3 eV). The high HOMO–LUMO gaps of 1 (4.05 eV) and 2 (4.00 eV) indicate high kinetic stability of the title compounds. 相似文献
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Rui Yuan Longyan Zhang Lichuan Chen Haoli Zhang Pengfei Dou Xuanxuan Ren Wen Chen Hang Zhou Yu Wan Hui Wu 《Tetrahedron letters》2019,60(27):1803-1807
Available online A series of diphenylamine (DPA)-containing triarylamine-based D-D-π-A organic fluorescence dyes were designed under the guidance of theoretical calculations and then synthesized (cyanoacrylic acid, methylene malononitrile or isophorone served as the electron acceptor while ethylene served as the π-bridge). The results of theoretical calculations, electrochemical properties and optical properties tests indicated that the new dyes possessed high thermal stability, desirable HOMO levels and intramolecular charge transfer property. Some of them possessed high fluorescence quantum yields and performed very well as luminescent material as expected.. 相似文献
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Škorić I Pavošević F Vazdar M Marinić Ž Šindler-Kulyk M Eckert-Maksić M Margetić D 《Organic & biomolecular chemistry》2011,9(19):6771-6778
The first example of thermal (8π,6π)-electrocyclisation of 1,3,5,7-octatetraene with one double bond embedded in an aromatic moiety is described. By this process, [3,4]-benzo-8-substituted octatetraene derivatives, the cis,trans-1-(o-vinylphenyl)-4-(R = Me, Ph, 2-furyl)buta-1,3-dienes were transformed to a new endo-7-(R = Me, Ph, 2-furyl) and exo-7-(R = Me)-2,3-benzobicyclo[4.2.0]octa-2,4-dienes. Mechanism of reaction was also studied by DFT quantum-chemical calculations. The M06/6-311+G(d,p)//M06/6-31+G(d,p) calculations indicate that formation of the single endo-isomer in the case of phenyl and 2-furyl substituents is determined by higher activation barriers for exo-6π-electrocyclisation than for 8π-cycloreversion. 相似文献
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DINGAi-Xiang JIAWen-Bin ZHANGGao-Bin PANJian-Ting ZHANGYu-Yang YANGJia-Xiang 《结构化学》2014,(8):1239-1244
Researches on a-cyanostilbene derivatives demonstrated them to be promising AIE or AIEE structural molecules and potential photoelectric materials. One novel a-cyanostilbene derivative, namely (E)-2-(4-butoxyphenyl)-3-(4-(diethylamino)phenyl)acrylonitrile (BPDPA), has been designed, synthesized and characterized. The crystalline structure of BPDPA has been studied in detail. The single-crystal X-ray diffraction revealed BPDPA crystallizes in triclinic space group Pi, with a = 12.860(5), b = 13.327(5), c = 15.016(5)А, a = 72.650(5), β = 66.969(5), Y = 62.897(5)°, Mr = 696.95, V= 2085.6(13) A3, Z = 2, Dc = 1.110 g/cm-3, p = 0.068 mm1, F(000) = 752, Rint = 0.0264, R(I〉 2σ(/)) = 0.0649, wR(l〉 2σ(/) = 0.1724, R(all data) = 0.1321, wR (all data) = 0.2158, completeness to theta = 25.00 is 99.4% and GOF = 1.067. Like most reported a-cyanostilbene derivatives, BPDPA possesses a somewhat twisted molecular structure. UV-Vis and FL measurements showed an obviously bathochromic effect of BPDPA with increasing the polarity of the solvents. 相似文献
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For the first time monocluster -arene derivatives of biphenyl Ph2Co4(CO)9 and Ph2Ru6C(CO)14, the shared mononuclear monocluster complex Ph2Cr(CO)3Co4(CO)9, and the bicluster derivative of cobalt Ph2[Co4(CO)9]2 have been synthesized. IR and H1 NMR spectra of the compounds have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1978–1980, November, 1993. 相似文献
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Morpholine adducts of nickel(II), cobalt(II), and manganese(II) benzoylacetonates, as well as a morpholine solvate of manganese(II)
benzoylacetonate, were prepared and characterized by X-ray diffraction and thermal analysis. All four compounds crystallize
in the P21/c space group with two complex molecules per unit cell. The morpholine solvate, along with the two adduct molecules, also contains
four solvent morpholine molecules in the unit cell. The non-solvate compounds are isostructural, with crystal structures comprising
2D networks formed by C–H···O hydrogen bonding between phenyl rings and morpholine oxygen atoms. The topology of these networks
can be described as intersecting C22(24) chains forming R44(48) rings. Networks with the same topology are also present in the solvate, but they are heavily distorted due to the presence
of solvent morpholine molecules. Thermogravimetric analysis shows similar behavior of the non-solvate compounds upon thermal
decomposition, with three degradation steps which can be related to gradual loss of morpholine molecules and subsequent overall
decomposition. Decomposition of the solvate also proceeds in several steps, the first of which can be related to loss of solvent
morpholine molecules and the further steps are analogous to those in the non-solvate compounds. 相似文献
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Qingzhong Li Xiulin An Feng Luan Wenzou Li Baoan Gong Jianbo Cheng Jiazhong Sun 《International journal of quantum chemistry》2008,108(3):558-566
The effect of the methyl group on the cooperativity between three types of hydrogen bond (O H···O, C H···O, and O H···π) in cyclic complex involving an acetylene and two waters has been studied on the basis of high-level ab initio calculations. The total interaction energy of three hydrogen bonds increases as the number of methyl group in the complex increases. The binding distances of O H···π and O H···O hydrogen bonds shorten, while that of C H···O hydrogen bond elongates with increasing methyl group. This indicates that addition of methyl group leads to enhancement of O H···π and O H···O hydrogen bonds, and weakening of C H···O hydrogen bond, as also shown in frequency shift, chemical shifts, charge populations, and stabilization energies of orbital interactions. Although the presence of methyl group has a complicated effect on different type of hydrogen bond, the cooperativity of three hydrogen bonds increases in general with the addition of methyl group. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
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The binding energies of thirty-six hydrogen-bonded peptide-base complexes, including the peptide backbone-ase complexes and amino acid side chain-base complexes, are evaluated using the analytic potential energy function established in our lab recently and compared with those obtained from MP2, AMBER99, OPLSAA/L, and CHARMM27 calculations. The comparison indicates that the analytic potential energy function yields the binding energies for these complexes as reasonable as MP2 does, much better than the force fields do. The individual N H…O=C, N H…N, C H…O=C, and C H…N attractive interaction energies and C=O…O=C, N H…H N, C H…H N, and C H…H C repulsive interaction energies, which cannot be easily obtained from ab initio calculations, are calculated using the dipole-dipole interaction term of the analytic potential energy function. The individual N H…O=C, C H…O=C, C H…N attractive interactions are about 5.3±1.8, 1.2±0.4, and 0.8 kcal/mol, respectively, the individual N H … N could be as strong as about 8.1 kcal/mol or as weak as 1.0 kcal/mol, while the individual C=O…O=C, N H…H N, C H…H N, and C H…H C repulsive interactions are about 1.8±1.1, 1.7±0.6, 0.6±0.3, and 0.35±0.15 kcal/mol. These data are helpful for the rational design of new strategies for molecular recognition or supramolecular assemblies. 相似文献
16.
Rojas RS Cabrera AR Peoples BC Spannhoff K Valderrama M Fröhlich R Kehr G Erker G 《Dalton transactions (Cambridge, England : 2003)》2012,41(4):1243-1251
In this contribution the synthesis and characterization of two distinct, yet similar, zirconium complexes, [(π-P-nacnac-CN)Cp] and [(π-nacnac-CN)Cp] zirconium dichloride were discussed. In addition to the complexes, Lewis acid adducts [B(C(6)F(5))(3)] of the complexes were isolated and characterized as well. It was found that while structurally similar, the complexes behave distinctly upon adduct formation and in their ethylene polymerizations. 相似文献
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Jiucheng Nie Daliao Tao Prof. Xiaoyu Huang Guolin Lu Prof. Chun Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8479-8483
In this work, it is demonstrated for the first time that heterojunction nanowires, consisting of a gradient and segmented-like heterogeneous π-conjugated core with controllable length, composition and morphology, can be generated by co-self-seeding of oligo(p-phenylene vinylene) (OPV)- and oligo(p-phenylene ethynylene) (OPE)-containing block copolymers in spite of different chain lengths and molecular conformation for OPE and OPV. More importantly, based on the understanding of the formation of heterogeneous core by the co-self-seeding approach, a “heating/cooling” seeded growth route was developed, by which linear and branched heterojunction nanowires containing a segmented heterogeneous π-conjugated core of controlled length, composition and morphology can be obtained. This work provides a versatile platform to generate heterojunction nanowires with excellent controllability in length, composition, and morphology. 相似文献
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A series of 4,4'-π-conjugated-2,2'-bipyridine chromophores (MS 1-8) were synthesized, and their photophysical and thermal properties were investigated. The title "push-pull' chromophores", except MS 1, were integrated with both alkoxy and alkylamino donor functionalities that differ in their donation capabilities. The oligophenylenevinylene (OPV) chromophores MS 4-8 are associated with a π-extended backbone in which the position and the number of alkoxy donors were systematically varied. All of the studied systems possess a D-π-A-A-π-D dyad archetype in which the A-A is the central 2,2'-bipyridine acceptor core that is electronically attached with the donor termini through π-linkers. The fluorescence quantum yields of the synthesized chromophores are found to be sensitive to the molecular archetype and the solvent medium. Out of the eight fluorescent compounds reported in this article, the compound MS 5 exhibits fluorescence in the solid state also. The modulating effect of the nature, position, and number of donor functionalities on the optical properties of these classes of compounds has further been comprehended on the basis of DFT and TD-DFT computation in a solvent reaction field. 相似文献
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Tanika Khanasa Narid Prachumrak Palita Kochapradist Supawadee Namuangruk Tinnagon Keawin Siriporn Jungsuttiwong Taweesak Sudyoadsuk Vinich Promarak 《Tetrahedron letters》2014
New D-π-A-π-A type organic dyes were synthesized and characterized as sensitizers for dye-sensitized solar cells (DSSCs). These dyes showed wide absorption spectra (300–625 nm) and high molar extinction coefficients (ε467 nm = 60,911 M−1 cm−1). As dye sensitizers in DSSC, the D-π-A-π-A dye having a cyanoacrylic acid as an acceptor gave the best cell performance with a short-circuit photocurrent density (Jsc) of 7.14 mA/cm2, an open-circuit voltage (Voc) of 0.62 V, and a fill factor (FF) of 0.72, corresponding to an overall conversion efficiency η of 3.19%. 相似文献