Reactions of indoles with nitrogen dioxide and nitrous acid in an aprotic solvent

The reaction of 2-phenyl- and 1-methyl-2-phenylindole with nitrogen dioxide or with nitrous acid (NaNO2-CH3COOH) in benzene leads mainly to the formation of the isonitroso and 3-nitroso indole derivatives, respectively. When reacted with nitrous acid, 1-methyl-2-phenylindole gives also the corresponding azo-bis-indole in good yields. The reaction of indole with nitrogen dioxide leads to 2-(indol-3-yl)-3H-indol-3-one as the main product together with small amounts of 2-(indol-3-yl)-3H-indol-3-oxime; whereas the major product obtained when the same indole is reacted with nitrous acid is represented by 2-(indol-3-yl)-3H-indol-3-oxime. The reaction of 3-alkyl substituted indoles with nitrogen dioxide is rather complex and results in the formation of different nitro indoles, whereas nitrosation is observed when nitrous acid is used. Crystal structures of 2-(indol-3-yl)-3H-indol-3-one and of 4-nitro-N-acetyltryptamine have been determined by X-ray analysis.     

负载型三氧化钼催化剂表面结构和表面酸位的激光Raman光谱研究

测定了MoO3/γ-Al2O3、MoO3/TiO2、MoO3/SiO2的激光Raman谱. 通过MoO3/γ-Al2O3、MoO3/TiO2在吡啶吸附前后、氨水提取前后的谱图对比说明, 单层分散的MoO3, 即特征峰为～950cm^-^1的"二维聚钼酸"中钼的配位状态不是单一的,其中一种表面含钼物种(Mo-1)不吸附吡啶, 不溶于氨水, 不显示较强的表面酸性; 另一种表面含钼物种(Mo-2)可吸附吡啶, 溶于氨水, 与催化剂的表面酸位密切相关. 我们认为Mo-1为四面体配位的钼; Mo-2为八面体配位的钼. MoO3/SiO2中的MoO3能100%被氨水溶去, 其酸位数与表面Mo^6^+数之比接近1, 是由其中Mo-2的比例较高, 载体与活性组分之间的相互作用较弱这两个因素所造成的。     

Reactions of the Dirhenium(II) Complexes Re(2)X(4)(&mgr;-dppm)(2) (X = Cl, Br; dppm = Ph(2)PCH(2)PPh(2)) with Isocyanides. 11.(1) A Triply Bonded Dirhenium Complex Containing a Labile Acetonitrile Ligand. Synthesis, Structural Characterization, and Reactivity of [(XylNC)(CH(3)CN)ClRe(&mgr;-dppm)(2)ReCl(2)(CO)]O(3)SCF(3)

The reaction of the open bioctahedral form of Re(2)Cl(4)(&mgr;-dppm)(2)(CO)(CNXyl) (1), where XylNC = 2,6-dimethylphenyl isocyanide, with TlO(3)SCF(3) in the presence of acetonitrile proceeds with retention of stereochemistry at the dirhenium unit to afford the complex [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)(NCCH(3))]O(3)SCF(3) (3). The single-crystal X-ray structure determination of 3 shows that a Re&tbd1;Re bond is retained (the Re-Re distance is 2.378(3) ?) and that it is the chloride ligand trans to the XylNC ligand of 1 which is labilized. Complex 1 reacts with TlO(3)SCF(3) in a noncoordinating solvent to produce the unsymmetrical complex [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)]O(3)SCF(3) (2), through loss of this same chloride ligand of 1 and CO transfer from the adjacent Re center. The acetonitrile ligand of 3 is very labile and is readily displaced by XylNC and t-BuNC, with retention of stereochemistry, to produce complexes of stoichiometry [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)(CNR)]O(3)SCF(3) (R = Xyl, 4a; R = t-Bu, 4b). In a noncoordinating solvent, the nitrile ligand of 3 is lost and 2 is formed following CO transfer; this conversion is reversed upon the reaction of 2 with acetonitrile. When 3 is treated with CO, the acetonitrile ligand is again displaced, but in this instance the reaction is accompanied by a structure change to produce an edge-sharing bioctahedral complex of the type [Re(2)(&mgr;-CO)(&mgr;-Cl)(&mgr;-dppm)(2)Cl(2)(CO)(CNXyl)]O(3)SCF(3) (5).     

四电极法测量Na_3AlF_6-Al_2O_3-RE_2O_3熔体的电导率

为了排除和减小电极与熔体接触面间的阻抗,电极与连接导线的电阻以及石英电导池腐蚀的影响,本文用交流四电极法测量了熔体Na_3Na_3AlF_6-Al_3O_3-RE_2O_3的电导率,其中RE指以Ce为主的混合稀土。 实验装置如图1所示,电极为φ0.8mm的Pt和Pt-Rh丝(其中二根Pt、二根Pt-Rh),中     

Tuning of optical band gaps: syntheses, structures, magnetic properties, and optical properties of CsLnZnSe(3) (Ln = Sm, Tb, Dy, Ho, Er, Tm, Yb, and Y)

Eight new quaternary selenides CsSmZnSe(3), CsTbZnSe(3), CsDyZnSe(3), CsHoZnSe(3,) CsErZnSe(3), CsTmZnSe(3), CsYbZnSe(3), and CsYZnSe(3) have been synthesized with the use of high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS(3), crystallizing with four formula units in the orthorhombic space group Cmcm. The structure of these CsLnZnSe(3) compounds is composed of [LnZnSe(3)(-)] layers separated by Cs atoms. The Ln atom is octahedrally coordinated by six Se atoms, the Zn atom is tetrahedrally coordinated by four Se atoms, and the Cs atom is coordinated by a bicapped trigonal prism of eight Se atoms. Because there are no Se-Se bonds in the structure, the oxidation state of Cs is 1+, that of Ln is 3+, and that of Zn is 2+. CsYbZnSe(3) exhibits an antiferromagnetic transition at 11 K, whereas CsSmZnSe(3) does not follow a Curie-Weiss law. The remaining rare-earth compounds are paramagnetic, and the calculated effective magnetic moments of the rare-earth ions agree well with their theoretical values. Optical absorption data on face-indexed single crystals of CsSmZnSe(3), CsErZnSe(3), CsYbZnSe(3), and CsYZnSe(3) demonstrate that the optical band gap changes by more than 0.75 eV with the composition and by as much as 0.20 eV with the crystal orientation. The optical band gaps range from 2.63 eV (CsSmZnSe(3), CsErZnSe(3)) to 1.93 eV (CsYbZnSe(3)) for the (010) crystal face and 2.56 eV (CsErZnSe(3)) to 1.88 eV (CsYbZnSe(3)) for the (001) crystal face. The difference in the optical band gap of the (010) face vs the (001) face varies from +0.05 eV (CsYbZnSe(3)) to +0.20 eV (CsSmZnSe(3)).     

蒽醌与稀土离子间的能量转移研究

分子间或分子内的电子激发态能量转移是重要的初级光化学过程，很多体系电子激发态能量转移过程已经报导[1-3]，对稀土离子和谈基化合物的研究发现，用光激发配体时，激发了的配体可将能量转移给稀土离子，使稀土离子激发到发光能级，可观察到稀土的特征荧光，若稀土离子和谈基     

熔盐中熟化处理提高BiFeO3的可见光催化活性

研究发现, 通过熔盐中熟化处理可以显著地提高BiFeO3的可见光催化活性.     

用EXAFS方法研究双功能催化剂NiO-MoO3/γ-A2O3的表面分散那

The surface dispersion of bifunctional NiO-MoO_3/γ-alumina catalysts prepared by different procedures was studied with Ni-K EXAFS spectroscopy. The contents of NiO(13.6%) and MoO_3(16.5%) were the same in the three samples, which were a little higher than the monolayer dispersion capacity of each component on γ-Al_2O_3. The dispersion temperature was 450 ℃. The sample impregnated with NiO first shows that the NiO is monolayer-dispersed on γ-Al_2O_3 surface and the outer layer is MoO_3. The sample impregnated with MoO_3 and the outer layer is NiO. There is strong interaction between MoO_3 and γ-Al_2O_3 which affects the dispersion of NiO on the surface. The sample impregnated with NiO and MoO_3 simultaneously shows that the Ni is not dispersed in the form of NiO but another compound on the surface.     

Structural stability and electronic state of transition metal trimers

Ground state geometries were searched for transition metal trimers Sc3, Y3, La3, Lu3, Ti3, Zr3, and Hf3 by density functional methods. For all the studied trimers, our calculation indicates that the ground state geometries are either equilateral triangle (Zr3 and Hf3) or near equilateral triangle (Ti3, Sc3, Y3, La3, and Lu3). For rare earth trimers Sc3, Y3, La3, and Lu3, isosceles triangle (near equilateral triangle) at quartet state is the ground state. Isosceles triangle at doublet state is the competitive candidate for the ground state. For Zr3 and Hf3, equilateral triangle at singlet state is the most stable. For Ti3, isosceles triangle (near equilateral triangle) at quintet state gives the ground state. For Sc3, Zr3, and Hf3, where experimental results are available, the predicted geometries are in agreement with experiment in which the ground state is equilateral triangle (Zr3) or fluxional (Sc3 and Hf3). For Y3, the calculated geometry is in agreement with experimental observation and previous theoretical study that Y3 is a bent molecule for the ground state. For La3, our calculation is in excellent agreement with previous theoretical study based on density functional methods.     

A New High Efficiency Green Luminescent Material──the System Al_2O_3-B_2O_3 Containing Ce~(3 ) and Tb~(3 ) Ions

IntroductionThelundnescenceofrare-earth-dopedcompoundshasbeenstudiedextensivelyduringthelastdecade,especiallyontrivalentceriumandterbiumandontheenergytransferbetweentheseionsl'2'3.Thegreen-emittingphosphorousarecerium-sensitizedterbiummaterials,themostwidelyusedoneisCe,.,,Tb,,,MgAl,,O,,'.However,thealuminiumfamilyrequireshightemperaturesfortheirsynthesis.Investigationswere,therefore,focusedonloweringthepreparativetemperatures.Thephosphatefamily,forexample,(La,Ce,Tb)PO"",needsalowerprepara…     

Second hyperpolarizability of phenalenyl radical system involving acetylene π-conjugated bridge

The static second hyperpolarizability (γ) of a singlet diradical system involving phenalenyl radicals linked with acetylene π-conjugated bridge, BPLE, is investigated as well as reference closed-shell systems, BPRY1 and BPRY2, by the hybrid density functional theory method. The γ value of BPLE with intermediate diradical character is shown to be about four times as large as that of BPRY1 with similar π-conjugation length and to be about twice as large as that of BPRY2 with longer π-conjugation length. This feature is in agreement with our prediction that the molecules with intermediate diradical characters enhance γ values compared to the closed-shell molecules.     

Reactions of diborane with ammonia and ammonia borane: catalytic effects for multiple pathways for hydrogen release

High-level electronic structure calculations have been used to construct portions of the potential energy surfaces related to the reaction of diborane with ammonia and ammonia borane (B2H6 + NH3 and B2H6 + BH3NH3)to probe the molecular mechanism of H2 release. Geometries of stationary points were optimized at the MP2/aug-cc-pVTZ level. Total energies were computed at the coupled-cluster CCSD(T) theory level with the correlation-consistent basis sets. The results show a wide range of reaction pathways for H2 elimination. The initial interaction of B2H6 + NH3 leads to a weak preassociation complex, from which a B-H-B bridge bond is broken giving rise to a more stable H3BHBH2NH3 adduct. This intermediate, which is also formed from BH3NH3 + BH3, is connected with at least six transition states for H2 release with energies 18-93 kal/mol above the separated reactants. The lowest-lying transition state is a six-member cycle, in which BH3exerts a bifunctional catalytic effect accelerating H2 generation within a B-H-H-N framework. Diborane also induces a catalytic effect for H2 elimination from BH3NH3 via a three-step pathway with cyclic transition states. Following conformational changes, the rate-determining transition state for H2 release is approximately 27 kcal/mol above the B2H6 + BH3NH3 reactants, as compared with an energy barrier of approximately 37 kcal/mol for H2 release from BH3NH3. The behavior of two separated BH3 molecules is more complex and involves multiple reaction pathways. Channels from diborane or borane initially converge to a complex comprising the H3BHBH2NH3adduct plus BH3. The interaction of free BH3 with the BH3 moiety of BH3NH3 via a six-member transition state with diborane type of bonding leads to a lower-energy transition state. The corresponding energy barrier is approximately 8 kcal/mol, relative to the reference point H3BHBH2NH3 adduct + BH3. These transition states are 27-36 kcal/mol above BH3NH3 + B2H6, but 1-9 kcal/mol below the separated reactants BH3NH3 + 2 BH3. Upon chemical activation of B2H6 by forming 2 BH3, there should be sufficient internal energy to undergo spontaneous H2 release. Proceeding in the opposite direction, the H2 regeneration of the products of the B2H6 + BH3NH3reaction should be a feasible process under mild thermal conditions.     

Some reactions of 3-hydroxythietane

3-Hydroxythietane is readily oxidized by hydrogen peroxide in acetone or acetic acid solution at 0°C to give 3-hydroxythietane-1-oxide. 3-Thietyl acetate is oxidized similarly. 3-Hydroxythietane-1-oxide reacts vigorously with SOCl₂ in benzene, with the formation of bis-2, 3-dichloropropyl disulfide. 3-Hydroxythietane-1,1-dioxide reacts with phosgene to give 3-thietyl-1, 1-dioxide chloroformate, which gives with diethylamine 3-thietyl-1, 1-dioxide N, N-dimethylcarbamate. Sodium peroxide and barium perbenzoate with the chloroformate give the corresponding di-(3-thietyl-1, 1-dioxide) peroxydicarbonate and 3-thietyl-1, 1-dioxide perbenzoate.     

Structure, reactivity and solution behaviour of [Re(ser)(7-MeG)(CO)(3)] and [Re(ser)(3-pic)(CO)(3)]: "nucleoside-mimicking" complexes based on the fac-[Re(CO)(3)](+) moiety

The fac-[Re(CO)(3)](+) moiety was reacted with the amino acid serine (D- and L-ser) and with 7-methylguanine (7-MeG), 3-methylpyridine (3-pic) or adenine (ade) to yield novel complexes intended as nucleoside-mimicking compounds. Reaction of [Re(H(2)O)(3)(CO)(3)](+)(1) with L-ser yields the complex [Re(L-ser)(2)(CO)(3)](L-2). X-Ray structure analysis of L-2 reveals that one of the two amino acids is bound to the metal centre in a bidentate fashion while the other amino acid is bound as a zwitterion via the carboxylate oxygen only. Reaction of L-2 and of [Re(D-ser)(2)(CO)(3)](D-2) with 7-MeG yields complexes [Re(L-ser)(7-MeG)(CO)(3)](L-3) and [Re(D-ser)(7-MeG)(CO)(3)](D-3) respectively. Complexes L-3 and D-3 are received as a mixture of diastereomers. If 3-pic is used instead of 7-MeG complex [Re(L-ser)(3-pic)(CO)(3)](L-4) is obtained in good yield, while interaction of L-2 with ade gives a mixture of five distinct species. Crystallization gave one single diastereomer for L-3 and D-3 and the two forms for 4 respectively. X-Ray structure analyses reveal that in all cases the amino acid is bound in a chelate fashion with the base occupying the sixth co-ordination site. When crystals of either 2 or 3 are dissolved in a CD(3)OD/D(2)O mixture (1:1, 293 K) rapid transformation to the diastereomeric mixture is observed. While for L-2 this reorganisation is fast on the NMR time scale even at 193 K, the rate constant for the rearrangement of L-3 and D-3 is 1.36 +/- 0.24 x 10(-2) s(-1) at 293 K.     

An experimental and computational study on the effect of Al(OiPr)3 on atom-transfer radical polymerization and on the catalyst-dormant-chain halogen exchange

Compound Al(OiPr)3 is shown to catalyze the halide-exchange process leading from [Mo(Cp)Cl2(iPrN=CH-CH=NiPr)] and CH3CH(X)COOEt (X=Br, I) to the mixed-halide complexes [Mo(Cp)ClX(iPrN=CH-CH=NiPr)]. On the other hand, no significant acceleration is observed for the related exchange between [MoX3(PMe3)3] (X=Cl, I) and PhCH(Br)CH3, by analogy to a previous report dealing with the Ru(II) complex [RuCl2(PPh3)3]. A DFT computation study, carried out on the model complexes [Mo(Cp)Cl2(PH3)2], [MoCl3(PH3)3], and [RuCl2(PH3)3], and on the model initiators CH3CH(Cl)COOCH3, CH3Cl, and CH3Br, reveals that the 16-electron Ru(II) complex is able to coordinate the organic halide RX in a slightly exothermic process to yield saturated, diamagnetic [RuCl2(PH3)3(RX)] adducts. The 15-electron [MoCl3(PH3)3] complex is equally capable of forming an adduct, that is, the 17-electron [MoCl3(PH3)3(CH3Cl)] complex with a spin doublet configuration, although the process is endothermic, because it requires an energetically costly electron-pairing process. The interaction between the 17-electron [Mo(Cp)Cl2(PH3)2] complex and CH3Cl, on the other hand, is repulsive and does not lead to a stable 19-electron adduct. The [RuCl2(PH3)3(CH3X)] system leads to an isomeric complex [RuClX(PH3)3(CH3Cl)] by internal nucleophilic substitution at the carbon atom. The transition state of this process for X=Cl (degenerate exchange) is located at lower energy than the transition state required for halogen-atom transfer leading to [RuCl3(PH3)3] and the free radical CH3. On the basis of these results, the uncatalyzed halide exchange is interpreted as the result of a competitive S(N)i process, whose feasibility depends on the electronic configuration of the transition-metal complex. The catalytic action of Al(OiPr)3 on atom-transfer radical polymerization (and on halide exchange for the 17-electron half-sandwich Mo(III) complex) results from a more favorable Lewis acid-base interaction with the oxidized metal complex, in which the transferred halogen atom is bound to a more electropositive element. This conclusion derives from DFT studies of the model [Al(OCH3)3]n (n=1,2,3,4) compounds, and on the interaction of Al(OCH3)3 with CH3Cl and with the [Mo(Cp)Cl3(PH3)2] and [RuCl3(PH3)3] complexes.     

原位固相接枝改性碳酸钙/聚丙烯复合材料的制备

用马来酸酐（MAH）在碳酸钙（CaCO3）表面引入双键,通过原位固相接枝法将聚丙烯蜡（PPW）化学键合在CaCO3表面,制得3种接枝率的CaCO3-MAH-PPW。 将这3种改性CaCO3填充聚丙烯（PP）制备复合材料,研究了PP/CaCO3界面作用对复合材料强度的影响。 结果表明,CaCO3表面经PPW接枝改性后在PP中的分散性提高,与PP相容性变好;随着改性CaCO3表面PPW接枝率的提高,CaCO3与PP之间界面作用逐渐增强。 当PPW接枝率为4.48 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用最强,复合材料拉伸强度下降最小,杨氏模量提升最大,当m(PP)∶m(CaCO3)=100∶50时,杨氏模量达0.86 GPa,是纯PP的1.63倍;而PPW化学接枝率为2.49 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用适中,复合材料缺口冲击强度提升最大,且当m(PP)∶m(CaCO3)=100∶10时,缺口冲击强度达3.91 kJ/m2,是纯PP的1.35倍。     

New layered materials: syntheses, structures, and optical and magnetic properties of CsGdZnSe3, CsZrCuSe3, CsUCuSe3, and BaGdCuSe3

Four new quaternary selenides CsGdZnSe3, CsZrCuSe3, CsUCuSe3, and BaGdCuSe3 have been synthesized with the use of traditional high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS3, crystallizing with four formula units in the orthorhombic space group Cmcm. Cell constants (A) at 153 K are CsGdZnSe3 4.1684(7), 15.765(3), 11.0089(18); CsZrCuSe3 3.903(2), 15.841(10), 10.215(6); CsUCuSe3 4.1443(7), 15.786(3), 10.7188(18); and BaGdCuSe3 4.1839(6), 13.8935(19), 10.6692(15). The structure of these ALnMSe3 compounds (A = Cs, Ba; Ln = Zr, Gd, U; M = Cu, Zn) is composed of 2 to infinity [LnMSe3(n-)] (n = 1, 2) layers separated by A atoms. The Ln atom is octahedrally coordinated to six Se atoms, the M atom is tetrahedrally coordinated to four Se atoms, and the A atom is coordinated to a bicapped trigonal prism of eight Se atoms. Because there are no Se-Se bonds in the structure, the oxidation state of A is 1+ (Cs) or 2+ (Ba), that of Ln is 3+ (Gd) or 4+ (Zr, U), and that of M is 1+ (Cu) or 2+ (Zn). CsGdZnSe3 and BaGdCuSe3, which are paramagnetic, obey the Curie-Weiss law and have effective magnetic moments of 7.87(6) and 7.85(5) muB for Gd(3+), in good agreement with the theoretical value of 7.94 muB. Optical transitions at 1.88 and 2.92 eV for CsGdZnSe3 and 1.96 eV for BaGdCuSe3 were deduced from diffuse reflectance spectra.     

Eu~(3+)-Dy~(3+)稀土配合物的合成及其发光性质

以2,4,6-吡啶三甲酸为配体,通过水热方法合成出含Eu3+和Dy3+两种稀土离子的一系列配合物;测定了配合物的发光性质.结果表明,通过掺杂不同比例的Dy3+可以得到荧光强度不同的配合物,其在紫外光照射下发出Eu3+的特征红色荧光;随着Dy3+含量的增加,Eu3+的特征荧光逐渐减弱.这说明该系列配合物中的Dy3+对Eu3+的荧光产生猝灭作用;其原因可能是配体吸收的激发能被Dy3+在近红外区的辐射跃迁所损耗.     

The carbonate radical: its reactivity with oxygen, ammonia, amino acids, and melanins

The carbonate radical (CO 3 (*-)) is of importance in biology and chemistry. We used pulse radiolysis to generate the CO 3 (*-) radical and show there is no reaction with oxygen. However, in the presence of ammonia the CO 3 (*-) radical is removed by NO (*), which itself arises from the scavenging of NH 2 (*) by oxygen, and the mechanism of this process is reported. The CO 3 (*-) radical shows complex decay patterns in the presence of ammonia, which can be understood as a balance between the radical-radical reaction CO 3 (*-) + CO 3 (*-) and CO 3 (*-) + NH 2 (*) (the amino radical). Also, we report reactivity with glycine and alanine and with melanin models. The CO 3 (*-) reacts with both dopa-melanin (DM, a model of black eumelanin) and with cysteinyl-dopa-melanin (CDM, a model of red/blond phaeomelanin). However, the reaction rate constant is much higher with CDM than with DM.     

Photo-aquation of cis-[RuCl2(mPTA)4](CF3SO3)4 in water (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane)

On irradiating the complex cis-[RuCl(2)(mPTA)(4)](CF(3)SO(3))(4) (2) with near UV light at room temperature, (OC-6-13)-[RuCl(2)(mPTA)(3)(H(2)O)](CF(3)SO(3))(3) (3) was obtained. Complex 3 is the product of the substitution in 2 of one mPTA by a H(2)O molecule and the rearrangement from cis to trans of the two chlorides. The selective photo-reaction of 2 is produced with radiation of 300 < λ < 400 nm or with λ = 367 nm in 50 min (Φ(367 nm) (D(2)O) = 0.18 ± 0.01). The reaction is not reversible with visible light. The transformation of 2 into 3 is not dependent on the pH but only on the radiation used. Reaction of 3 with NaCl leads to (OC-6-21)-[RuCl(3)(mPTA)(3)](CF(3)SO(3))(2) (4) which could be directly obtained by irradiation of 2 with λ = 367 nm in water and 5 eq. of NaCl (Φ(367 nm) (D(2)O) = 0.17 ± 0.01). Complex 4 turns slowly to 2 in water with 1 eq. of mPTA under light of λ > 416 nm. Complete conversion of 4 into 2 was achieved after more than one day. All complexes were characterized by elemental analysis, IR and NMR spectroscopy, and 2, 3 and 4 by single crystal X-ray determination. An easy synthesis for the ligand mPTA(CF(3)SO(3)) is also reported.