B(C_6F_5)_3催化吡啶的串联还原反应

<正>Angew.Chem.Int.Ed.2017,56,5817~5820吡啶的还原反应是有机合成研究中非常重要的课题,其还原产物哌啶或者四氢吡啶等含氮杂环是许多药物及生物活性分子的构成片段.过渡金属催化是工业中最常用的吡啶还原方法,然而,这些方法多使用贵金属,经济性和官能团兼容性都不够理想.近期,南开大学化学学院王晓晨课题组使用B(C_6F_5)_3作为催化剂,二苯基硅烷(或频哪醇     

稀土冠醚配合物的XPS研究 Ⅰ.Ln(NO_3)_3·C_(14)H_(20)O_5和Ln(NO_3)_3·C_(20)H_(24)O_6的Ln 3d_(5/2)光电子能谱及其伴峰

X光电子能谱(XPS)已成功地应用于过渡元素配合物电子结构的研究.在以往的十多年里,也用XPS研究了稀土元素及其化合物的内壳和价带谱、混合价态谱以及伴峰现象.稀土冠醚配合物的光电子能谱未见文献报道.我们按文献方法叫合成了Ln(NO_3)_23·C_(14)H_(20)O_5(La～Sm),Ln(NO_3)_3·C_(14)H_(20)O_5·3H_2O·(CH_3)_2CO(Eu,Gd)和Ln(NO_3)_3·C_(20)H_(24)O_6(La～     

C_(60)在高压条件下可转变为金刚石

法国格林诺伯(Grenoble)极低温研究中心的Regueiro和P.Monceau、J.L.Hodeau已经证实,在室温条件下对C_(60)对称性足球状分子快速施加20GPa的压力而非静压力时,大量的C_(60)即刻转变为多晶金     

C_(60)碱金属掺杂有机超导体K_3C_(60)中C_(60)旋转的研究

从分子间相互作用的角度对有机超导体K_3C_(60)中C_(60)的旋转动力学进行了研究,确定了常温下C_(60)的旋转运动被冻结在一个小旋转角范围内(0°～50°),并指出冻结原因是物理的相互作用而非几何的结构位阻,对其他一些具有超导性的碱金属掺杂物A_xA′_(3-x)C_(60)(x=1,2,3;A,A′=K,Rb,Cs)中的相互作用也进行了计算,发现它们的超导转变温度T_c与其间相互作用相关,此与业已发现的T_c与晶格常数a的相关性一致。     

Synthesis and the Fluorescent,Magnetic and Thermal Stability Properties of a New Terbium(Ⅲ) Complex Tb(C_(20)H_(14)O_3N)_3(C_(12)H_8N_2)(H_2O)·H_2O

A new terbium(Ⅲ complex Tb(C_(20)H_(14)O_3N)_3(C_(12)H_8N_2)(H_2O)·H_2O has been synthesized with 2-diphenylanine carbonyl benzoic acid and 1,10-phenanthroline as ligands. Crystal data for the complex are as follows: triclinic, space group P1, a =11.6034(6), b = 16.2465(8), c = 16.4427(8) ?, α = 73.168(5)o, β = 88.655(4)o, γ = 82.865(4)o, V = 2943.7(3) ?~3, Dc = 1.494 g/cm~3, Z = 2, μ(MoK α) = 1.272 mm~(-1), F(000) = 1348, the final R = 0.0535 and w R = 0.0809. The Tb(Ⅲ) ion is coordinated by nine atoms to give a monocapped square antiprism coordination geometry. The complex shows four fluorescence emission bands arising from the transitions of Tb~(3+): ~5D_4 → ~7F_6(491 nm), ~5D_4 → ~7F_5(546 nm), ~5D_4 → ~7F_4(585 nm) and ~5D_4→~7F_3(621 nm). Also reported are the magnetic and thermal stability properties of the complex.     

浸渍法制备C_(18)反相高效液相色谱固定相

提出了一种浸渍法制备C_(18)高效液相色谱固定相的方法。以十八烷二甲基氯硅烷(ODC)为键合试剂、六甲基二硅氮烷(HMDS)为封尾试剂,通过浸渍法制备得到C_(18)高效液相色谱固定相。采用红外光谱(FTIR)、元素分析(EA)和氮气吸附与解吸附(BET)对该合成材料进行了表征,并通过SRM870评价体系对其疏水选择性、金属离子以及硅羟基活性进行评价。与商品柱Kromasil C_(18)相比,浸渍法制备的C_(18)固定相具有较少的金属离子活性及较低的硅羟基残余量。通过重复性考察,说明浸渍法制备的C_(18)柱键合层稳定,对溶质的保留重现性良好。     

C_(60)与MoO_3混合材料做空穴注入层的单层有机电致发光器件

我们制备研究了基于结构为氧化铟锡(ITO)/C_(60)(1.2nm):MoO_3(0.4nm)/1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯(TPBi):三(2-苯基吡啶)铱[Ir(ppy)_3](33%,90 nm)/LiF (0.7 nm)/Al (120 nm)的高效绿色磷光单层有机发光二极管(OLED)。分别将C_(60),MoO_3与C_(60):MoO_3混合物作为空穴注入层(HIL)作为对比。TPBi在发光层中起着主体以及电子传输材料的双重作用。在使用电子传输型主体的单层OLED中,空穴注入层性质对于调节电子/空穴注入以获得电荷载流子传输平衡起重要作用。因此,适当调节空穴注入层是实现高效单层OLED的关键因素。由于MoO_3较大的电子亲和能(6.37 eV)会诱导电子从C_(60)的最高占据分子轨道(HOMO)能级转移至MoO_3,从而形成C_(60)阳离子,并使得Mo元素的价态从+6降至+5,C_(60):MoO_3混合就可以较好的调节空穴注入性质。最终实现最大电流效率为35.88 cd·A~(-1)的单层有机发光器件。     

Hetisine型C_(20)二萜生物碱绣线菊碱Ⅳ和Ⅺ的全合成

正以抗心律失常药关附甲素为典型代表的hetisine型C_(20)二萜生物碱具有丰富多样的生物活性和复杂的化学结构,数十年来一直是有机合成化学研究的热点,很多国际上著名的全合成小组相继进行了全合成研究.基于目前对C_(20)二萜生物碱的合成研究,hetisine型C_(20)二萜生物碱全合成的挑战在于C(14)—C(20)键和C(6)—N键的构建.重庆大学     

基于二醛微晶纤维素功能化C_(18)的反相/亲水色谱固定相的制备（英文）

通过十八烷基胺的氨基与二醛微晶纤维素的醛基共价键合,制备了基于二醛微晶纤维素(DMCC)官能化C_(18)的新型反相/亲水色谱固定相(C_(18)-DMCC/SiO_2),该色谱固定相被用于反相色谱(RPLC)和亲水相互作用色谱(HILIC)模式。C_(18)-DMCC/SiO_2色谱柱展现了良好的疏水选择性和芳香选择性,在反相色谱模式下可分离烷基苯和多环芳烃(PAHs)。苯胺类、酚类和糖苷类等极性化合物被用于评估该色谱柱在反相色谱模式下的极性选择性,商品C_(18)柱作对照柱,色谱评价结果令人满意。核酸碱基被用于评估C_(18)-DMCC/SiO_2色谱柱的亲水色谱性能。通过考察有机溶剂含量对分析物保留的影响,发现该新型色谱固定相具有反相/亲水色谱的典型特征。     

水合苯并—15—冠—5四溴合铟(Ⅲ)酸钠(NaInBr_4)_2(C_(14)H_(20)O_5)_3·2H_2O的晶体结构

本文报道了在乙醇—氯仿混合溶剂中首次获得组份为(NaInBr_4)_2(C_(14)H_(20)O_5)_3·2H_2O的晶体配合物.用元素分析确定了其组份.通过红外光谱的研究证实配合物晶体中的阳离子与醚氧原子及水分子发生了配合作用。 用X-射线衍射法测定了配合物的晶体结构,晶体属单斜晶系,M=1755.3,a=14.393(8)A,b=28.494(9)A,c=15.191(8)A,β=96.63(5)°,V=6189A~3’,D_c=1.88g·cm~(-3),Z=4,空间群为C_(2h)~5——P2_1/n。晶体结构研究表明不对称单位中包含两个配阳离子Na~(+)(B15C5)(B15C5)代表C_(14)H_(20)O_5分子)。两个配阴离子InBr_4~-、两个H_2O分子和一个未被金属离子配合的B15C5分子。配合物的晶体结构测定结果对于阐明与该晶体相对应的萃取体系In(Ⅲ)/NaBr/B15C5—1,2C_2H_4Cl_2的萃取机理提供了理论依据。     

The negative differential resistance mechanism of a molecular device based on double‐cage fluorinated fullerene C20F18(NH)2C20F18: A theoretical study

The electronic transport properties of the molecular device based on double‐cage fluorinated fullerene C₂₀F₁₈(NH)₂C₂₀F₁₈ were studied theoretically. The results show that the device exhibits two negative differential resistance (NDR) peaks in its I‐V curve. The NDR peak under low bias voltage originates from the bias‐induced alignment of the molecular orbitals, and the conduction channel being suppressed at a certain bias voltage is the main reason for the NDR peak under a relatively high bias voltage.     

Electron switch in the double-cage fluorinated fullerene anions, e(-)@C20F18(XH)2C20F18 (X = N, B): new candidates for molecular quantum-dot cellular automata

A new type of molecular quantum-dot cellular automata (MQCA) candidates is suggested using the double-cage fluorinated fullerene molecules, e(-)@C(20)F(18)(XH)(2)C(20)F(18) (X = N, B), which have bistable charge configurations that could be used to encode binary information. The electron switch between the two cages leads to the QCA function.     

Synthesis, structure and theoretical study of mixed fluoro-trifluoromethyl derivatives of C60. Molecular structures of C60F18(CF3)6 and C60F16(CF3)6

A series of novel mixed C60Fn(CF3)m compounds has been produced by trifluoromethylation of C60F18 with CF3I in ampoules at 380-420 degrees C. Two of these compounds, C60F18(CF3)6 and C60F16(CF3)6, have been characterized by X-ray crystallography, which has revealed addition of six CF3 groups to the C3v-C60F18 for the former and replacement/elimination of two outermost F atoms in the latter. Quantum chemical calculations have been employed to predict the most stable possible isomers of C60F16/18(CF3)6 in order to rationalize the experimental results.     

Search for more stable C58X18 isomers: stabilities and electronic properties of seven-membered ring C58X18 fullerene derivatives (X = H, F, and Cl)

Stimulated by recent preparation and characterization of the first C58F18 fullerene derivative, with a heptagon in the framework (Science, 2005, 309, 278), we have performed systematic density functional studies on the stabilities and electronic properties of two different structures C58X18 (A) and C58X18 (B), where X = H, F, and Cl. The large energy gaps between the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals (between 2.64 and 3.45 eV) and the aromatic character (with nucleus independent chemical shifts from -10.0 to -13.9 ppm) of C58X18 (A) and C58X18 (B) indicate that they possess high stabilities. Further investigations show that the heats of formation of C58X18 fullerene derivatives are highly exothermic, suggesting that adding nine X2's releases much of the strain of pure C58 fullerene and leads to stabilities of the derivatives. Lower in energy and stronger in aromatic character than C58F18 (B), which has been experimentally characterized, C58F18 (A) should also be isolated. In addition, C58F18 and C58Cl18 are predicted to possess large electron affinities, especially for C58F18 (B) and C58Cl18 (B) with values of 3.00 and 3.06 eV, respectively, even larger than that (2.50 eV) of C60F18. Hence, C58F18 and C58Cl18 can serve as good electron-acceptors with possible photonic/photovoltaic application. The IR spectra of C58X18 are simulated to facilitate identification of different isomers experimentally. In addition, the electronic spectra and second-order hyperpolarizabilities of C58X18 are predicted by ZINDO and sum-over-states model. With the addition of 9X2, both the static and frequency-dependent second-order hyperopolarizabilities of C58X18 greatly decrease compared to those of C58.     

Changes of coupling between the electrodes and the molecule under external bias bring negative differential resistance

We report a first-principles study of electrical transport and negative differential resistance (NDR) in a single molecular conductor consisting of a borazine ring sandwiched between two Au(100) electrodes with a finite cross section. The projected density of states (PDOS) and transmission coefficients under various external voltage biases are analyzed, and it suggests that the variation of the coupling between the molecule and the electrodes with external bias leads to NDR. Therefore, we propose that one origin of NDR in molecular devices is caused by the characteristics of both the molecule and the electrodes as well as their cooperation, not necessarily only by the inherent properties of certain species of molecules themselves. The changes of charge state of the molecule have minor effects on NDR in this device because the Mulliken population analysis shows that electron occupation variation on the molecule is very small when different external biases are applied.     

Formation of novel sulfur-containing C60F16 cycloadducts between tetrathiafulvalene and C60F18; a unique six-electron cycloaddition of a fullerene involving F2 loss

Co-evaporation of solutions of C(60)F(18) and tetrathiafulvalene in toluene produces an unsymmetrical C(60)F(16):tetrathiafulvalene adduct through a unique six-electron cycloaddition involving displacement of two fluorine atoms by a terminal Cdbond;C double bond of the fulvalene. The adduct rearranges into two further adducts, one of which is characterised as a new type of fullerene derivative, a thiiranofullerene, formed by elimination of a thioketene moiety from the tetrathiafulvalene adduct. The initial addition also produces a bisadduct in which the addends comprise one tetrathiafulvalene molecule and one in which carbon disulfide has been eliminated. The latter adduct involves cycloaddition of an unsaturated aromatic dithiolactone moiety.     

Electrophilic aromatic substitution by the fluorofullerene C60F18

The FeCl3-catalysed arylation of C60F18 gives tri-substituted compounds C60F15Ar3, where Ar=phenyl, 4-tolyl, 4-methoxyphenyl, 4-phenoxyphenyl, 4-chlorophenyl, 3,4-dichlorophenyl, 2-biphylenyl and 2-fluorenyl, together with some bis- and mono-substituted product. Bis-substitution was achieved with biphenylene and fluoranthene, and mono-substitution with biphenylene (2-position), pyrene (1-position), and naphthalene (1- and 2-positions); the tris-phenyl and tris-biphenylene derivatives are fluorescent. The 2-naphthyl substituent freely rotates at 328 K, whereas rotation of the 1-naphthyl substituent is prevented by interaction of the peri-hydrogen atom with fluorine. The 1-naphthyl derivative eliminates a molecule of HF during EI mass spectrometry, whilst the 2-naphthyl derivative eliminates HF and all fluorenes to give a naphthaleno[60]fullerene. The reaction rate is relatively unaffected by electron supply in the aryl rings, but no product was obtained with benzotrifluoride which defines the lower reactivity limit. The low discrimination between aromatics makes it possible to isolate derivatives having different aryl groups attached to the cage. Reactions occur mainly when the reagent solutions (or solutions in 1,2-dichlorobenzene) are evaporated to dryness. In most FeCl3-catalysed reactions, unreacted C60F18 was recovered, more if the less effective SnCl4 was used as a catalyst; use of AlCl3 resulted in polyarylation and degradation of the C60F18. The structure of C60F17(1-biphenylyl) was confirmed by single-crystal X-ray analysis. Reaction of C60F18 with perylene/FeCl3/o-dichlorobenzene gave red fluorescent "tagliatelli"-like threads (up to 1 cm long) of self-assembled pi-stacked tetrachloroperylene arising from chlorination by FeCl3.     

Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups

We investigate the electronic transport properties for a molecular device model constructed by a phenylene ethynylene oligomer molecular with different side groups embedding in a carbon chain between two graphene electrodes. Using the first-principles method, the unusual dual conductance, negative differential resistance (NDR) behavior with large peak to valley ratio, and obvious rectifying performance are numerically observed in such proposed molecular device. The analysis of the molecular projected self-consistent Hamiltonian and the evolution of the frontier molecular orbitals (MOs) as well as transmission coefficients under various external voltage biases gives an inside view of the observed results, which suggests that the dual conductance behavior and rectifying performance are due to the asymmetry distribution of the frontier MOs as well as the corresponding coupling between the molecule and electrodes. But the NDR behavior comes from the conduction orbital being suppressed at certain bias. Interestingly, the conduction properties can be tuned by introducing side groups to the molecule and the rectification as well as the NDR behavior (peak to valley ratio) can be improved by adding different side groups in the device model.     

Electron transfer reduction of a highly electron-deficient fullerene,C60F18

Electron transfer reduction of a highly electron-deficient fullerene, C60F18, to the defluorinated anion, C60F17- occurs efficiently by a relatively weak one-electron reductant, p-chloranil radical anion; the one-electron reduction potential of C60F18 is evaluated as 0.04 V (vs. SCE) by comparison of the rate constant for electron-transfer from 10,10'-dimethyl-9,9',10,10'-tetrahydro-9,9'-biacridine to C60F18 with those of other one-electron reductants.     

Synthesis of the C(18)-C(34) fragment of amphidinolide C and the C(18)-C(29) fragment of amphidinolide F

A convergent synthesis of the C(18)-C(34) fragment of amphidinolide C and the C(18)-C(29) fragment of amphidinolide F is reported. The approach involves the synthesis of the common intermediate tetrahydrofuranyl-β-ketophosphonate via cross metathesis, Pd(0)-catalyzed cyclization, and hydroboration-oxidation. The β-ketophosphonate was coupled to three side chain aldehydes using a Horner-Wadsworth-Emmons (HWE) olefination reaction to give dienones, which were reduced with l-selectride to give the fragments of amphidinolide C and F.