STUDIES ON SEPARATION AND DETERMINATION OF THE COUMARINS IN MURRAYA PANICULATA（L）JACK BY RP－HPLC

ＳＴＵＤＩＥＳ　ＯＮ　ＳＥＰＡＲＡＴＩＯＮ　ＡＮＤ　ＤＥＴＥＲＭＩＮＡＴＩＯＮ　ＯＦ　ＴＨＥ　ＣＯＵＭＡＲＩＮＳ　ＩＮ　ＭＵＲＲＡＹＡ　ＰＡＮＩＣＵＬＡＴＡ（Ｌ）ＪＡＣＫ　ＢＹ　ＲＰ－ＨＰＬＣＳＴＵＤＩＥＳＯＮＳＥＰＡＲＡＴＩＯＮＡＮＤＤＥＴＥＲＭＩ...     

PARAMAGNETIC AND DIAMAGNETIC DICOPPER（Ⅱ） COMPLEXES WITH DI－SCHIFF BASE DERIVED FROM 2－HYDROXY－1－NAPHTHALDEHYDE AND1，3－DIANINO－2－PROPANOL

ＰＡＲＡＭＡＧＮＥＴＩＣＡＮＤＤＩＡＭＡＧＮＥＴＩＣＤＩＣＯＰＰＥＲ（Ⅱ）ＣＯＭＰＬＥＸＥＳＷＩＴＨＤＩ－ＳＣＨＩＦＦＢＡＳＥＤＥＲＩＶＥＤＦＲＯＭ２－ＨＹＤＲＯＸＹ－１－ＮＡＰＨＴＨＡＬＤＥＨＹＤＥＡＮＤ１，３－ＤＩＡＮＩＮＯ－２－ＰＲＯＰＡＮＯＬ...     

PREPARATION， ELECTRICAL PROPERTIES AND CRYSTAL STRUCTURE OF TWO NEW CHARGE－TRANSFER SALTS （BEDT－TTF）＿3Cu＿2Brx AND （TTM－TTF） （Cu＿2Bry） （y～4．72）

ＰＲＥＰＡＲＡＴＩＯＮ，　ＥＬＥＣＴＲＩＣＡＬ　ＰＲＯＰＥＲＴＩＥＳ　ＡＮＤ　ＣＲＹＳＴＡＬ　ＳＴＲＵＣＴＵＲＥ　ＯＦ　ＴＷＯ　ＮＥＷ　ＣＨＡＲＧＥ－ＴＲＡＮＳＦＥＲ　ＳＡＬＴＳ　（ＢＥＤＴ－ＴＴＦ）＿３Ｃｕ＿２Ｂｒｘ　ＡＮＤ　（ＴＴＭ－ＴＴＦ）　（...     

REACTIVE POLY（ARYLENEETHERSULPHONE） ：MALEIMIDE－TERMINATED POLY（ARYLENEETHERSULPHONE） OLIGOMERS USING N－（4－HYDROXYPHENYL） MALEIMIDE AS AN ENDBLOCKING MONOMER

ＲＥＡＣＴＩＶＥ　ＰＯＬＹ（ＡＲＹＬＥＮＥＥＴＨＥＲＳＵＬＰＨＯＮＥ）　：ＭＡＬＥＩＭＩＤＥ－ＴＥＲＭＩＮＡＴＥＤ　ＰＯＬＹ（ＡＲＹＬＥＮＥＥＴＨＥＲＳＵＬＰＨＯＮＥ）　ＯＬＩＧＯＭＥＲＳ　ＵＳＩＮＧ　Ｎ－（４－ＨＹＤＲＯＸＹＰＨＥＮＹＬ）　ＭＡＬＥ...     

SYNTHESIS AND PROPERTIES OF THERMOTROPIC LIQUID CRYSTALLINE COPOLYESTERS CONTAINING BIS（4－HYDROXYPHENYL）METHANONE（Ⅵ）

ＳＹＮＴＨＥＳＩＳＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦＴＨＥＲＭＯＴＲＯＰＩＣＬＩＱＵＩＤＣＲＹＳＴＡＬＬＩＮＥＣＯＰＯＬＹＥＳＴＥＲＳＣＯＮＴＡＩＮＩＮＧＢＩＳ（４－ＨＹＤＲＯＸＹＰＨＥＮＹＬ）ＭＥＴＨＡＮＯＮＥ（Ⅵ）ＳＹＮＴＨＥＳＩＳＡＮＤＰＲＯＰＥＲ...     

SYNTHESIS AND ~（183）W NMR CHARACTERIZATION OF P_4W_（30）Al_4（H_2O）_2O_（112）~（20－） HETEROPOLYANION

ＳＹＮＴＨＥＳＩＳ　ＡＮＤ　~（１８３）Ｗ　ＮＭＲ　ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮ　ＯＦ　Ｐ_４Ｗ_（３０）Ａｌ_４（Ｈ_２Ｏ）_２Ｏ_（１１２）~（２０－）　ＨＥＴＥＲＯＰＯＬＹＡＮＩＯＮＳＹＮＴＨＥＳＩＳＡＮＤ~（１８３）ＷＮＭＲＣＨＡＲＡＣＴＥＲＩＺ?..     

DIRECT ELECTROCHEMICAL SYNTHESIS AND CHARACTERIZATION OF SAMARIUM （Ⅲ） COMPLEX WITH 2－HYDROXY－2， 4， 6－CYCLOHEPTATRIENONE （TROPOLONE）

ＤＩＲＥＣＴ ＥＬＥＣＴＲＯＣＨＥＭＩＣＡＬ ＳＹＮＴＨＥＳＩＳ ＡＮＤ ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮ ＯＦ ＳＡＭＡＲＩＵＭ （Ⅲ） ＣＯＭＰＬＥＸ ＷＩＴＨ ２－ＨＹＤＲＯＸＹ－２，４，６－ＣＹＣＬＯＨＥＰＴＡＴＲＩＥＮＯＮＥ （ＴＲＯＰＯＬ...     

APPLICATIONS OF ULTRASONICALLY DISPERSED POTASSIUM（UDP）PART 4：REDUCTIVE COUPLING OF CHALCONES IN THE PRESENCE OF UDP，COMMENTS ON THE MECHANISM OF ALKALIMETAL REDUCTION OF α，β－UNSATURATED ENONES

ＡＰＰＬＩＣＡＴＩＯＮＳＯＦＵＬＴＲＡＳＯＮＩＣＡＬＬＹＤＩＳＰＥＲＳＥＤＰＯＴＡＳＳＩＵＭ（ＵＤＰ）ＰＡＲＴ４：ＲＥＤＵＣＴＩＶＥＣＯＵＰＬＩＮＧＯＦＣＨＡＬＣＯＮＥＳＩＮＴＨＥＰＲＥＳＥＮＣＥＯＦＵＤＰ，ＣＯＭＭＥＮＴＳＯＮＴＨＥＭＥＣＨＡＮＩＳ...     

RUTHENIUM COORDINATION COMPOUNDS WITH POLYPYRIDYL：Ⅰ SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM（Ⅱ） MIXED LIGAND COORDINATON COMPOUNDS CONTAINING PYRIDO［3，2－f］［1，7］PHENANTHROLINE

ＲＵＴＨＥＮＩＵＭＣＯＯＲＤＩＮＡＴＩＯＮＣＯＭＰＯＵＮＤＳＷＩＴＨＰＯＬＹＰＹＲＩＤＹＬ：ⅠＳＹＮＴＨＥＳＩＳＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＲＵＴＨＥＮＩＵＭ（Ⅱ）ＭＩＸＥＤＬＩＧＡＮＤＣＯＯＲＤＩＮＡＴＯＮＣＯＭＰＯＵＮＤＳＣＯＮＴＡ...     

THE CHIRAL SELECTIVITY IN ACROSS－MEMBRANE TRANSPORT OF 1，2－DIAMINOCYCLOHEXANE PLATINUM（II）COMPLEXES AND THE CONTRIBUTION OF LEAVING GROUPS

ＴＨＥＣＨＩＲＡＬＳＥＬＥＣＴＩＶＩＴＹＩＮＡＣＲＯＳＳ－ＭＥＭＢＲＡＮＥＴＲＡＮＳＰＯＲＴＯＦ１，２－ＤＩＡＭＩＮＯＣＹＣＬＯＨＥＸＡＮＥＰＬＡＴＩＮＵＭ（ＩＩ）ＣＯＭＰＬＥＸＥＳＡＮＤＴＨＥＣＯＮＴＲＩＢＵＴＩＯＮＯＦＬＥＡＶＩＮＧＧＲＯＵＰＳ￥...     

A new polyphenylene derivative bearing two stable radicals

Hydroxylization of poly(N,N-dimethylaniline) (PDMA) by using H₂O₂ in base medium gives rise to a new polyphenylene derivative containing a high concentration of stable phenoxy radicals in the solid state. In solution, hydroxylated PDMA can have two forms of stable radicals, phenoxy radical and radical cation, and these two forms can be converted reversibly into each other by adjusting the pH value of the solution.     

Electron transfer between two stable radicals

Electron spin resonance (ESR) is a sensitive tool to detect the electron-transfer processes in some specified systems from the change of the ESR signals. In this paper, the interaction between poly(N,N-dimethylaniline) (PDMA) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) was investigated by ESR spectra based on the stability of their radicals in ethanol. It is shown that an electron-transfer process occurs from nitrogen atoms of PDMA molecules to those of DPPH molecules which makes PDMA form more stable radical cations and eliminates the radicals on DPPH.     

Cyclopolymerization. II. Mechanism of the free-radical polymerization of N-n-propyldimethacrylamide

The mechanism of cyclopolymerization was investigated by using N-n-propyldimethacrylamide (PDMA). Completely cyclized polymers were formed on polymerization of PDMA by a radical initiator. Moreover, those copolymers of PDMA and various monomers, such as styrene, methyl methacrylate, and vinyl acetate, obtained did not contain any detectable pendent double bonds. The kinetic investigation showed that the termination reaction proceeded between the cyclized radicals. The attempted polymerization of N-n-propyl-N-isobutyrylmethacrylamide, the monofunctional counterpart of PDMA, was failed. These results appear to confirm that cyclopolymerization of PDMA proceeds through a concerted mechanism which has been proposed for the mechanism of the cyclopolymerization of various difunctional monomers. Measurement of the ESR spectra of propagating radical has, however, revealed that the rate-determining step of the cyclopolymerization of PDMA is not intermolecular propagation but intramolecular cyclization, which indicates that the cyclization reaction proceeds in a stepwise way. This apparent contradiction was explained based upon thermodynamic considerations.     

金属氧化物/聚(N,N-二甲基苯胺)界面相互作用的ESR研究

共轭聚合物在电、光、磁等方面有很大的应用价值［１～３］,利用其研制各种实用性电子器件时,往往会涉及到它与其它材料尤其是无机半导体材料的界面复合问题［４～７］．在这些界面间,除形成一定的化学键外［８］,更多的则是伴随着电子的转移和电荷的重新分配［９,１...     

聚硝基苯的合成,表征及反应机理的研究

在共轭高分子材料的研究中，聚苯一直是人们关注的热点之一［1～4]，但聚苯的不溶和不熔性大大限制了其应用前景，因而可溶性聚苯的开发研究成为目前的一种趋势．合成测基带有烷基和烷氧基的聚苯已有报道［5，6］，我们曾会成了侧基带有强推电子基团的可溶性聚苯——聚（N...     

Charge delocalization in self-assembled mixed-valence aromatic cation radicals

The spontaneous assembly of aromatic cation radicals (D(+?)) with their neutral counterpart (D) affords dimer cation radicals (D(2)(+?)). The intermolecular dimeric cation radicals are readily characterized by the appearance of an intervalence charge-resonance transition in the NIR region of their electronic spectra and by ESR spectroscopy. The X-ray crystal structure analysis and DFT calculations of a representative dimer cation radical (i.e., the octamethylbiphenylene dimer cation radical) have established that a hole (or single positive charge) is completely delocalized over both aromatic moieties. The energetics and the geometrical considerations for the formation of dimer cation radicals is deliberated with the aid of a series of cyclophane-like bichromophoric donors with drastically varied interplanar angles between the cofacially arranged aryl moieties. X-ray crystallography of a number of mixed-valence cation radicals derived from monochromophoric benzenoid donors established that they generally assemble in 1D stacks in the solid state. However, the use of polychromophoric intervalence cation radicals, where a single charge is effectively delocalized among all of the chromophores, can lead to higher-order assemblies with potential applications in long-range charge transport. As a proof of concept, we show that a single charge in the cation radical of a triptycene derivative is evenly distributed on all three benzenoid rings and this triptycene cation radical forms a 2D electronically coupled assembly, as established by X-ray crystallography.     

Esr and structure of sulfur-centered radicals and radical ions. γ-Irradiated dimethyl disulfide and methane thiol single crystals at 77°k

Single crystals of dimethyl disulfide and methane thiol were irradiated at 77°K. CH₃S radicals were produced in both compounds and measurement of the isotropic coupling constant from the methyl protons gave a value of 7.6 G. In the dimethyl disulfide crystal both the anion, CH₃SSCH₃, and the cation, CH₃SSCH⁺₃, radicals were observed. The disulfide anion radical exhibited an isotropic septet of lines with a = 5.0 G. Comparison with measurements on a polycrystalline sample gave g⊥ = 2.020 and g6 = 2.000 for this radical. The disulfide cation radical exhibited an evenly spaced septet of lines with a = 9.1 G and a maximum value for the g factor of 2.032.On illumination with IR radiation (λ > 590 mm) the disulfide cation radicals were easily bleached together with about 50% of the disulfide anion radicals suggesting a photoinduced neutralization process. The presence of weak ³³S satellite lines in the anion radical spectrum indicates that 12% of the unpaired spin is localized to the two sulfur 3s orbitals. The structure of the disulfide cation radical is discussed in relation to earlier studies and a dihedral angle of 180° is proposed. The mechanisms for radical formation and decay in dimethyl disulfide and methane thiol are also discussed.     

Sulfur radical cation-peptide bond complex in the one-electron oxidation of S-methylglutathione

Neighboring group participation was investigated in the *OH-induced oxidation of S-methylglutathione in aqueous solutions. Nanosecond pulse radiolysis was used to obtain the spectra of the reaction intermediates and their kinetics. Depending on the pH, and the concentration of S-methylglutathione, pulse irradiation leads to different transients. The transients observed were an intramolecularly bonded [>S thereforeNH2]+ intermediate, intermolecularly S thereforeS-bonded radical cation, alpha-(alkylthio)alkyl radicals, alpha-amino-alkyl-type radical, and an intramolecularly (S thereforeO)+-bonded intermediate. The latter radical is of particular note in that it supports recent observations of sulfur radical cations complexed with the oxygen atoms of peptide bonds and thus has biological and medical implications. This (S thereforeO)+-bonded intermediate had an absorption maximum at 390 nm, and we estimated its formation rate to be >or=6x10(7) s(-1). It is in equilibrium with the intermolecularly S thereforeS-bonded radical cation, and they decay together on the time scale of a few hundred microseconds. The S thereforeS-bonded radical cation is formed from the monomeric sulfur radical cation (>S*+) and an unoxidized S-methylglutathione molecule with the rate constant of 1.0x10(9) M(-1) s(-1). The short-lived [>S thereforeNH2]+ intermediate is a precursor of decarboxylation, absorbs at approximately 390 nm, and decays on the time scale of hundreds of nanoseconds. Additional insight into the details of the association of sulfur radical cations with the oxygen atoms of the peptide bonds was gained by comparing the behavior of the S-methylglutathione (S thereforeO+-bonded five-membered ring) with the peptide gamma-Glu-Met-Gly (S thereforeO+-bonded six-membered ring). Conclusions from experimental observations were supported by molecular modeling calculations.     

Effect of pH on one-electron oxidation chemistry of organoselenium compounds in aqueous solutions

Pulse radiolysis coupled with absorption detection has been employed to study one-electron oxidation of selenomethionine (SeM), selenocystine (SeCys), methyl selenocysteine (MeSeCys), and selenourea (SeU) in aqueous solutions. Hydroxyl radicals (*OH) in the pH range from 1 to 7 and specific one-electron oxidants Cl2*- (pH 1) and Br2*- (pH 7) have been used to carry out the oxidation reactions. The bimolecular rate constants for these reactions were reported to be in the range of 2 x 10(9) to 10 x 10(9) M(-1) s(-1). Reactions of oxidizing radicals with all these compounds produced selenium-centered radical cations. The structure and stability of the radical cation were found to depend mainly on the substituent and pH. SeM, at pH 7, produced a monomer radical cation (lambdamax approximately 380 nm), while at pH 1, a dimer radical cation was formed by the interaction between oxidized and parent SeM (lambdamax approximately 480 nm). Similarly, SeCys, at pH 7, on one-electron oxidation, produced a monomer radical cation (lambdamax approximately 460 nm), while at pH 1, the reaction produced a transient species with (lambdamax approximately 560 nm), which is also a monomer radical cation. MeSeCys on one-electron oxidation in the pH range from 1 to 7 produced monomer radical cations (lambdamax approximately 350 nm), while at pH < 0, the reaction produced dimer radical cations (lambdamax approximately 460 nm). SeU at all the pH ranges produced dimer radical cations (lambdamax approximately 410 nm). The association constants of the dimer radical cations of SeM, MeSeCys, and SeU were determined by following absorption changes at lambdamax as a function of concentration. From these studies it is concluded that formation of monomer and dimer radical cations mainly depends on the substitution, pH, and the heteroatoms like N and O. The availability of a lone pair on an N or O atom at the beta or gamma position results in monomer radical cations having intramolecular stabilization. When such a lone pair is not available, the monomer radical cation is converted into a dimer radical cation which acquires intermolecular stabilization by the other selenium atom. The pH dependency confirms the role of protonation on stabilization. The oxidation chemistry of these selenium compounds is compared with that of their sulfur analogues.     

Elementary radical formation and conversion processes in γ-irradiated polyvinylchloride

Elementary processes of γ-irradiated polyvinylchloride (PVC) have been investigated by both electron spin resonance (ESR) and optical absorption measurements. On irradiating PVC film with γ rays at ?196°C, alkyl-type radicals are produced. When the PVC film is warmed to room temperature, the radicals convert to polyenyl type. γ Irradiation of PVC film containing biphenyl (Ph₂) or pyrene (Py) at ?196°C yields the corresponding radical cation. The relative ESR peak heights of the radicals decrease and the G values for the formation of cation radicals increase with increasing additive concentrations. These facts indicate that energy is transferred from the precursor of the radicals to the additive. In the case of PVC film containing Py, the Py cation radical decreases and the cyclohexadienyl-type radical from Py is produced by thermal annealing. A possible mechanism for radical formation and conversion is proposed.