Dependence of negative ion formation on inhomogeneous electric field strength in atmospheric pressure negative corona discharge

The dependence of negative ion formation on the inhomogeneous electric field strength in atmospheric pressure negative corona discharge with point-to-plane electrodes has been described. The distribution of negative ions HO^-, NO_x ^- and CO_x ^- and their abundances on the plane electrode was obtained with a mass spectrometer. The ion distribution on the plane was divided into two regions, the center region on the needle axis and peripheral region occurring the dominant NO_x ^- and CO_x ^- ions and HO^- ion, respectively. The calculated electric field strength in inhomogeneous electric field established on the needle tip surface suggested that the abundant formation of NO_x ^- and CO_x ^- ions and HO^- ion is attributed to the high field strength at the tip apex region over 10⁸ Vm^-1 and the low field strength at the tip peripheral region of the order of 10⁷ Vm^-1, respectively. The formation of HO^-, NO_x ^- and CO_x ^- has been discussed from the standpoint of negative ion evolution based on the thermochemical reaction and the kinetic energy of electron emitted from the needle tip.     

Spectral-luminescent properties of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> and malate dehydrogenase complexes

Spectral confirmation of the formation of stable equilibrium complexes (association constant K _as = 210⁶ M^–1) of the Krebs cycle enzyme — malate dehydrogenase (MDH) — and one of the promising photodynamic sensitizers — chlorin e ₆ — have been obtained. It is shown that the incorporation of dye molecules into the protein globule of dimeric MDH (each subunit of which contains 4 tryptophan amino acid residues, each binding one molecule of chlorin e ₆) is accompanied by quenching of the tryptophan fluorescence of the enzyme. However, despite the overlapping of the fluorescence spectra of tryptophanyls of MDH and the absorption spectrum of chlorin e ₆, the fluorescence quenching observed is not caused by singlet-singlet inductive-resonant transfer of energy from the donor to the acceptor. The conclusion has been drawn that the reason for the absence of energy transfer from tryptophanyls to the dye is the more effective intertryptophan migration of energy to one of the most longwave amino acid residues, the quenching of the luminescence of which occurs due to the reversible photoinduced transfer of an electron to chlorin e ₆ (formation of a complex with charge transfer). The formation of a complex with charge transfer between chlorin e ₆ (when it is excited) and one of the amino acid residues of the enzyme that contact with the dye at its binding site on the protein molecule is also the most noncontradictory explanation of the observed (when bound with MDH) decrease in the quantum yield of fluorescence of chlorin e ₆ upon increase in the duration of its quenching. The question of the ability of MDH to act as one of the most sensitive targets responsible for the disturbance of mitochondrial functions and initiation of the apoptosis of tumor cells in the process of photodynamic therapy is discussed.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 749–758, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Electron-Rich Diruthenium Complexes with π-Extended Alkenyl Ligands and Their F4TCNQ Charge-Transfer Salts**

The synthesis of dinuclear ruthenium alkenyl complexes with {Ru(CO)(PⁱPr₃)₂(L)} entities (L=Cl⁻ in complexes Ru₂-3 and Ru₂-7 ; L=acetylacetonate (acac⁻) in complexes Ru₂-4 and Ru₂-8 ) and with π-conjugated 2,7-divinylphenanthrenediyl ( Ru₂-3 , Ru₂-4 ) or 5,8-divinylquinoxalinediyl ( Ru₂-7 , Ru₂-8 ) as bridging ligands are reported. The bridging ligands are laterally π-extended by anellating a pyrene ( Ru₂-7 , Ru₂-8 ) or a 6,7-benzoquinoxaline ( Ru₂-3 , Ru₂-4 ) π-perimeter. This was done with the hope that the open π-faces of the electron-rich complexes will foster association with planar electron acceptors via π-stacking. The dinuclear complexes were subjected to cyclic and square-wave voltammetry and were characterized in all accessible redox states by IR, UV/Vis/NIR and, where applicable, by EPR spectroscopy. These studies signified the one-electron oxidized forms of divinylphenylene-bridged complexes Ru₂-7 , Ru₂-8 as intrinsically delocalized mixed-valent species, and those of complexes Ru₂-3 and Ru₂-4 with the longer divinylphenanthrenediyl linker as partially localized on the IR, yet delocalized on the EPR timescale. The more electron-rich acac⁻ congeners formed non-conductive 1 : 1 charge-transfer (CT) salts on treatment with the F₄TCNQ electron acceptor. All spectroscopic techniques confirmed the presence of pairs of complex radical cations and F₄TCNQ^.− radical anions in these CT salts, but produced no firm evidence for the relevance of π-stacking to their formation and properties.     

Recent Progress in Polycyclic Aromatic Hydrocarbon‐Based Organic Co‐Crystals

Recently, the development of polycyclic aromatic hydrocarbon ( PAH )‐based organic co‐crystals has attracted increasing interest due to their unique packing modes, optic‐electronic properties and various potential applications in electronic, optic‐electronic and magnetic devices. In this account, we mainly discuss the definition, classification, packing patterns, preparation methods, and applications of PAH‐based co‐crystals. Specifically, the main categories of PAH‐based organic co‐crystals, the frequent methods to prepare them, three main packing patterns, their optical and electrical properties, and their potential applications will be presented. Finally, an outlook of this field is provided.     

Perturbing the O–H…O Hydrogen Bond in 1-oxo-3-hydroxy-2-propene

Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to identify and characterize equilibrium structures and transition structures on the 1-oxo-3-hydroxy-2-propene: Lewis acid potential energy surfaces, with the acids LiH, LiF, BeH₂, and BeF₂. Two equilibrium structures, one with the acid interacting with the C=O group and the other with the interaction occurring at the O–H group, exist on all surfaces. These structures are separated by transition structures that present the barriers to the interconversion of the two equilibrium structures. The structures with the acid interacting at the C=O group have the greater binding energies. Since the barriers to convert the structures with interaction occurring at the O–H group are small, only the isomers with interaction occurring at the C=O group could be experimentally observed, even at low temperatures. Charge-transfer energies were computed for equilibrium structures, and EOM-CCSD spin–spin coupling constants ^2hJ(O–O), ^1hJ(H–O), and ¹J(O–H) were computed for equilibrium and transition structures. These coupling constants exhibit a second-order dependence on the corresponding distances, with very high correlation coefficients.     

2,3-二氮杂二环-[2,2,2]-辛-2-烯与卤素分子间电荷转移相互作用的量子化学研究

对2,3-二氮杂二环-[2,2,2]-辛-2-烯 (DBO) 与Cl2、Br2和I2 3种卤素分子形成的s型电荷转移复合物进行了不同方法的理论计算。结果表明, MP2方法结合LanL2DZ*基组可以很好地描述DBO与卤素分子间的相互作用。其中, DBO与I2的结合能为33.6 kJ/mol, 与DBO…Br2的结合能接近, 明显大于DBO…Cl2相应的值。几何结构变化以及布居分析均与这一结果吻合。针对DBO的结构, 对DBO与I2间 形成p型电荷转移复合物以及DBO…(I2)2的可能性进行了理论分析和预测。     

含Dawson结构杂多钨磷(砷)酸电荷转移配合物的合成、结构与性质

近年来,有机多金属氧酸盐电荷转移配合物由于有特殊的光、电、磁性质在催化、功能材料及药物化学等领域受到研究者的广泛关注［１］。自从１９８８年法国的Ｌ．Ｏｕａｈａｂ［２］首次报道（ＴＴＦ）６ＰＷ１２Ｏ４０（Ｅｔ４Ｎ）２的合成以来,已见报道的多金属氧酸盐仅限于ＡｎｄｅｒｓｏｎＥｖａｎｓｅ、ｌｉｎｄｑｕｉｓｔ和Ｋｅｇｇｉｎ结构的多阴离子,对它们功能性质的系统研究也未见文献报道。为了研究阴离子的大小和形状对标题化合物功能性质的影响,作者在以前工作的基础上［３,４］,首次以Ｄａｗｓｏｎ结构杂多钨磷（砷）…     

~(19)F NMR Study on the Charge-Transfer Process between Ground-State Acceptor Fluoranil (or Pentafluorophenyl Carboxylate) andSome N-Alkylphenothiazine Donors

Photoinitiatedelectron-transferprocessesareoffundamentalinterestinchemistry.Generallytherearetwokindsofstudy.1)Studiesinvolvingintermolecularelectrontransfersoftheexcitedchromophoreofanacceptor(ordonor)withthegroundstateofadonor(oracceptor).2)Studiesofintramolecularelectrontransfersbetweenlinkedacceptorsanddonors.Inpursuingourstudyonaggregationandself-coilingoforganicmoleculesbroughtaboutbyhydrophobic-lipophilicinteractions(HLI),wearenaturallyinterestedinstudyingwhetherHLIcanalsofacilitatet…     

Investigation on radical polymerization of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines

The reaction of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines with benzoyl peroxide (acceptor radical) and with N-ethylmaleimide (acceptor) was investigated. It was shown that benzoyl peroxide adds to monomers 1a and 1b , giving the corresponding linear diester amides 1a and 1b respectively. The oxazolidine 1c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group. Together with N-ethylmaleimide the oxazolidines 1a or 1b produce deep-colored charge transfer complexes, resulting in high molecular poly-N-ethylmaleimides probably via a radical mechanism. The 1,3-dioxolanes 2a and 2b were radically polymerized to produce polyacetals by vinyl polymerization. 2c was polymerized to produce randomly containing acetal units and ester units. The mechanism of polymerization of 2e is complex, affording polymers of nonuniform character. 2-Methylene-4-phenyl-1,3-dioxolane polymerization leads to polyester as the main structure, and to a lesser degree polyacetal structures. The chemical structures of the polymers were confirmed by NMR spectra and elemental analysis. © 1996 John Wiley & Sons, Inc.     

[(CH3)2NH2]3[NSiMo12O40]·2DMF·4H2O的合成和晶体结构

电荷转移盐;[(CH3)2NH2]3[NSiMo12O40]·2DMF·4H2O的合成和晶体结构