聚(2-甲氧基-5-辛氧基)对苯乙炔/单壁碳纳米管复合材料的光物理性能研究

采用原位脱氯化氢缩合聚合法制备了聚(2-甲氧基-5-辛氧基)对苯乙炔/单壁碳纳米管(PMOCOPV/SWNTs)复合材料. 红外光谱和拉曼光谱证实了在SWNTs表面的包覆层为PMOCOPV. 高分辨透射电子显微镜观察发现, PMOCOPV/SWNTs复合材料直径为4~7 nm, 其中PMOCOPV包覆层厚度约为2~5 nm. 紫外-可见吸收光谱表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs的吸收发生蓝移且强度提高. 荧光光谱研究表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs的最大发射波长发生蓝移且强度减小, SWNTs与PMOCOPV之间形成了光致电子转移体系, 使π电子离域程度增加, 导致荧光量子效率降低. 根据E_g与入射光子能量hν的关系, 拟合了PMOCOPV/SWNTs薄膜的光学禁带宽度, 发现随着SWNTs含量的增加, E_g逐渐减小. 采用简并四波混频方法测试其三阶非线性极化率χ⁽³⁾, 结果表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs复合体的非线性光学响应逐渐增强, 说明PMOCOPV与SWNTs之间形成了分子间光致电子转移体系, 产生了复杂的分子间π-π电子非线性运动.     

聚(2-甲氧基-5-丁氧基)对苯乙炔/Eu2O3纳米复合材料的合成及其光学效应

采用原位脱氯化氢缩合聚合法制备了聚(2-甲氧基-5-丁氧基)对苯乙炔/氧化铕(PMOBOPV/Eu2O3)纳米复合材料. 傅里叶变换红外(FT-IR)光谱证实了在Eu2O3表面的包覆层为PMOBOPV. 高分辨透射电子显微镜(HRTEM)观察发现, PMOBOPV/Eu2O3纳米复合材料具有核-壳结构, 直径为75-145 nm, 其中PMOBOPV包覆层厚度约为25 nm. 紫外-可见(UV-Vis)吸收光谱表明, 随着Eu2O3含量增加, PMOBOPV/Eu2O3的最大吸收峰发生红移且强度提高. 荧光光谱研究表明, 随着Eu2O3含量增加, PMOBOPV/Eu2O3的最大发射波长发生蓝移且强度提高, Eu2O3与PMOBOPV之间形成了光致电子转移体系, 使π电子离域程度增加, 并且导致荧光量子效率提高. 根据光学禁带宽度(Eg)与入射光子能量(hυ)的关系, 拟合了PMOBOPV/Eu2O3薄膜的光学禁带宽度, 发现随着Eu2O3含量增加, Eg逐步减小. 采用简并四波混频方法测试它们的三阶非线性极化率(χ(3)), 发现随着Eu2O3含量增加, PMOBOPV/Eu2O3纳米复合体的非线性光学响应逐渐增强, 这说明PMOBOPV与Eu2O3之间形成了分子间光致电子转移体系, 产生了复杂的分子间离域π电子非线性运动.     

Fe3O4@Au核-壳纳米复合材料的制备及对农药福美双的SERS检测研究

首先采用热分解法制备了Fe₃O₄纳米材料, 再将其作为磁性核, 分别采用种子沉积法和种子介导生长法制备了Fe₃O₄-Au核-卫星纳米复合材料和Fe₃O₄@Au核-壳纳米复合材料, 并对其形貌和性能进行了表征分析. 结果表明, 所制备的Fe₃O₄-Au核-卫星和Fe₃O₄@Au核-壳纳米复合材料粒径均匀, Au纳米颗粒均匀沉积/包覆在Fe₃O₄纳米材料表面, 且样品均具有良好的磁响应性. 使用4-氨基苯硫酚(4-ATP)作为拉曼探针分子, 对比了这两种纳米复合材料作为SERS基底时的拉曼信号增强效果. 结果显示, Fe₃O₄@Au核-壳纳米复合材料是更优秀的SERS基底, 且该SERS基底具有良好的信号再现性. 最后, 使用Fe₃O₄@Au核-壳纳米复合材料作为SERS基底, 成功地在苹果皮上检测出残留福美双的SERS信号.     

Bi2Ti2O7/TiO2/Bi4Ti3O12多异质结的构筑及其增强的可见光催化性能

以静电纺丝技术制备的TiO₂纳米纤维为基质,硝酸铋为铋源,KOH为矿化剂,成功制备了多异质结Bi₂Ti₂O₇/TiO₂/Bi₄Ti₃O₁₂复合纳米纤维光催化剂。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-Vis DRS)等一系列表征,对其物相组成、微观形貌和光学性质等进行分析。结果表明：TiO₂纳米纤维的介入,将Ⅰ型异质结Bi₂Ti₂O₇/Bi₄Ti₃O₁₂分离为2个Ⅱ型异质结Bi₂Ti₂O₇/TiO₂和Bi₄Ti₃O₁₂/TiO₂。Bi₂     

双(2,4,6-苯三酚)方酸掺杂的SiO2凝胶薄片的制备及其光物理性能(英文)

方酸染料是一种重要的有机功能材料。本文用改进的溶胶-凝胶工艺,将它均匀地掺杂到无机的SiO₂凝胶薄片中,制成一种新型的有机/无机凝胶杂化物。并用吸收光谱、荧光光谱等技术研究了该方酸染料在乙醇溶液中和掺杂在SiO₂凝胶网络中的光物理性能。结果发现在固、液两种介质中,其光物理性能有很大差异。方酸染料在SiO₂凝胶网络中,吸收光谱和荧光发射光谱的最大峰位置比在乙醇介质中有了明显蓝移,并且吸收域值随掺杂浓度增加而增大,荧光发射强度比在乙醇介质中也有了很大增强。首次对这些现象进行了解释:认为是由于方酸染料分子被包封在SiO₂凝胶网络中形成分子簇集体,它的共轭π-电子和分子构型受到刚性纳米网络微孔的限域,产生了类似于无机半导体纳米粒子的量子尺寸效应。     

分散液-液微萃取快速、直接测定有机化合物lgP值

用3-氯丙基三甲氧基硅烷对Fe₃O₄纳米球的表面进行改性, 制得表面疏水的Fe₃O₄/SiCH₂CH₃Cl纳米球. 将Fe₃O₄/SiCH₂CH₃Cl纳米球均匀预分散在正辛醇中, 利用分散液-液微萃取建立了快速、 直接测定有机化合物lgP值的新方法. 待测有机化合物可在3 min内在两相达到分配平衡, 通过磁铁吸引含有Fe₃O₄/SiCH₂CH₃Cl纳米球的正辛醇小液滴, 可实现两相快速完全分离. 在萃取过程中, 由于Fe₃O₄/SiCH₂CH₃Cl纳米球被正辛醇包围, 失去对待测化合物的吸附能力, 因此Fe₃O₄/SiCH₂CH₃Cl纳米球对测定有机化合物分配平衡的影响很小. 通过该方法测定了14种不同有机化合物的lgP值, 结果均与文献报道一致. 与其它直接测定方法相比, 该方法快速、 准确、 简单且样品消耗少.     

1,4-双(4′-N,N-二甲基氨基苯乙烯基)萘的合成及荧光性质

利用Wittig反应合成了一个以萘为π-Center的对称型“D-π-D”有机绿色发光化合物1,4 双(4′-N,N-二甲基氨基苯乙烯基)萘(BDASN),并测试了其在不同环境中的光谱性质.在378nm激发波长的激发下,BDASN显示出很强的荧光发射峰,峰位在521nm(CH₂Cl₂).随着溶剂极性增大,最大发射波长红移且荧光强度降低,与“D-π-A”分子具有相似的分子内电荷转移(TICT)行为.在β-环糊精(β-CD)中BDASN的绿色发光带被猝灭,同时在450nm附近蓝发光带的荧光强度骤增.     

表面水热碳层对磁性NiFe2O4八面体光催化活性的影响

采用葡萄糖水热碳化法合成了一系列碳层包覆的NiFe₂O₄核壳八面体(NiFe₂O₄@C). 通过调控葡萄糖的含量可以有效控制NiFe₂O₄表面包覆的碳层厚度. 利用X射线衍射(XRD)、 拉曼光谱(Roman)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和紫外-可见漫反射光谱(UV-Vis DRS)等对NiFe₂O₄@C的组成、 结构、 形貌和光学性能进行了表征. 考察了表面水热碳层对NiFe₂O₄光催化降解亚甲基蓝(MB)性能的影响. 结果表明, NiFe₂O₄的光催化活性很大程度上依赖于在其表面包覆的碳层厚度, 碳层厚度为5.5 nm的NiFe₂O₄@C-3展现了最佳的光催化活性. 荧光光谱(PL)、 瞬态光电流和电化学阻抗谱(EIS)表征结果证明, NiFe₂O₄@C的光催化性能的提升归因于在NiFe₂O₄核和碳壳之间形成了异质结, 有效地促进了光生载流子的传输和分离效率. NiFe₂O₄@C复合材料展现了较好的稳定性和可回收性, 在污水处理方面有很大的应用潜力.     

ZnCo2O4纳米粒子的可见光催化性能

研究了共沉淀分解法制备的ZnCo₂O₄纳米粒子的光学和可见光催化性能,并对其晶体结构和微观结构用X射线衍射、热重/差热分析、透射电镜和高分辨透射电镜等手段进行了表征.结果表明,制备的纳米粒子为纯相的ZnCO₂O₄,平均粒径约为10-20 nm.紫外-可见吸收光谱估计出ZnCo₂O₄纳米粒子的能带隙为3.39和2.09 eV.可见光（λ>420 nm）照射下,纳米粒子表现出降解亚甲基蓝溶液的光催化活性.ZnCo₂O₄纳米粒子的光催化活性可以归结为紫外和可见光下纳米粒子吸收光子（能量大于能带隙）的能力,以及它们的纳米尺寸,基于实验结果,本文提出了ZnCO₂O₄可能的能带结构.     

氮苄叉基苯胺分子的平面扭曲驱动力的DFT研究

为了探索DFT方法中氮苄叉基苯胺分子的扭曲驱动力, 通过把非平面氮苄叉基苯胺(NBA)分子的DFT能量分成π和σ的方法, 分析了垂直离域能ΔE^V(θ)及σ-π轨道作用能ΔE^σπ(θ)的失稳定性, 并讨论了在扭曲过程中它们所起的作用. 在B3LYP/6-31G*, 6-311G*, 6-31G(2d), 6-311G(2d)水平下的计算结果显示: 与经典观点不同, π电子的离域是失稳定的, 且平面时失稳定性最强, 是分子扭曲的动力; 但σ-π轨道作用也是失稳定的, 随着扭角的增大其失稳定性增强, 是分子扭曲的阻力. NBA分子的大扭角构象, 是包含π-π, σ-π轨道作用在内的各种电子相互作用共同作用的结果.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.