两种溴代苯甲酸-铽配合物的合成、晶体结构与性质表征

溶液法合成了2种配合物[Tb(2-BrBA)₂(CH₃COO)(2，2′-bipy)]₂ (1)和[Tb(3-BrBA)₃(2，2′-bipy)]₂·2(3-HBrBA)·2H₂O (2)(2-BrBA=2-bromobenzoate，3-BrBA=3-bromobenzoate，2，2′-bipy=2，2′-bipyridine)，并用X-射线单晶衍射方法测定了其晶体结构。配合物1和2均属于三斜晶系和P1空间群。四元混配配合物1是具有反演中心的二聚体，其中Tb³⁺离子同时与2种不同的羧酸配体配位。4个2-BrBA以双齿桥联的方式把2个Tb³⁺离子联结起来，而乙酸根和2，2′-bipy分子则分别以双齿螯合的方式与Tb³⁺离子配位。配合物2是三元混配配合物，2个Tb³⁺离子通过4个双齿桥联的3-BrBA联结而成具有反演中心的二聚体，每个Tb³⁺离子还同时与1个双齿螯合的3-BrBA和1个2，2′-bipy分子配位。配合物1和2在紫外灯照射下能发出强烈的绿光，而且在它们的荧光光谱中都存在4条谱线：489、545、585和621 nm，分别对应于Tb³⁺离子的 ⁵D₄ → ⁷F₆、 ⁵D₄ → ⁷F₅、 ⁵D₄→ ⁷F₄和 ⁵D₄→ ⁷F₃跃迁。     

双核铕与2，5-二氟苯甲酸及2，2′-联吡啶配合物的合成、晶体结构及表征

用溶液法合成了混配配合物[Eu(2,5-DFBA)₃(2,2′-bipy)]₂(2,5-DFBA=2,5-二氟苯甲酸根,2,2′-bipy=2,2′-联吡啶),并测定了其晶体结构。该晶体属于三斜晶系,P1空间群。在配合物中,2个Eu³⁺离子被4个2,5-二氟苯甲酸根以双齿桥联和三齿桥联2种方式连接;每个Eu³⁺离子的配位数为9,分别与4个桥联2,5-二氟苯甲酸根的5个氧原子、1个双齿螯合2,5-二氟苯甲酸根的2个氧原子以及1个2,2′-联吡啶分子的2个氮原子配位。该配合物在紫外灯照射下发出强烈的红光,在荧光光谱的580、591、613、648和693 nm处出现5条谱线,分别是由Eu³⁺离子的⁵D₀ → ⁷F_j (j=0～4)跃迁产生的。     

2-氯-4-氟苯甲酸与 5， 5′-二甲基-2， 2′-联吡啶镧系配合物的晶体结构、 光谱和热行为

合成并表征了2个双核配合物[Pr(2-Cl-4-FBA)₃(5,5′-DM-2,2′-bipy)]₂ (1)和[Dy(2-Cl-4-FBA)₃(5,5′-DM-2,2′-bipy)]₂·2(2-Cl-4-FHBA)(2),其中2-Cl-4-FHBA=2-氯-4-氟苯甲酸,5,5′-DM-2,2′-bipy=5,5′-二甲基-2,2′-联吡啶。配合物1以八配位的Pr³⁺为中心,其周围的配位环境为扭曲的三角十二面体。配合物2的结构是独特的,它包含2个自由的2-氯-4-氟苯甲酸分子,并以九配位的Dy³⁺为中心与周围的氮、氧原子形成扭曲的三棱镜几何构型。这2个配合物均结晶于三斜晶系P1空间群,并通过氢键相互作用和π-π堆积作用形成了一维和二维超分子结构。研究了配合物的热分解过程,结果表明配合物1和2分别分为4步和5步进行分解。同时对配合物的三维红外堆积图进行了研究,结果表明,整个热分解过程中释放出的主要气态产物是水、二氧化碳和有机小分子碎片。配合物2的荧光性质研究表明,它可以发射出Dy³⁺的特征跃迁对应的荧光。     

一维链状3-碘苯甲酸铽配合物的合成、晶体结构和性质表征

溶液法合成了配合物{[Tb(3-IBA)₃(H₂O)₂]·0.5(4,4′-bipy)}_n(3-IBA=3-碘苯甲酸根;4,4′-bipy=4,4′-联吡啶),并通过X-射线衍射单晶结构分析、红外光谱、紫外光谱、荧光光谱以及热重分析对配合物进行了结构和性质表征。配合物晶体属三斜晶系,P1空间群。该配合物具有一维链状结构。Tb³⁺离子与8个O原子配位,其中6个O原子来自5个3-碘苯甲酸根,2个O原子来自水分子。相邻Tb³⁺离子通过2个双齿桥联的3-碘苯甲酸根联结成一维链状结构。未配位的4,4′-联吡啶分子与配位水分子之间形成氢键,并将相邻的一维链联结起来形成二维网状结构。沿a轴的分子堆积形成一维孔道,是由于相邻一维链的苯环之间部分重叠而形成的。在紫外光照射下,配合物发出很强的绿色荧光。配合物的荧光光谱中,4个峰位于490、544、583和619 nm,分别对应于Tb³⁺离子的⁵D₄→⁷F₆、⁵D₄→⁷F₅、⁵D₄→⁷F₄和⁵D₄→⁷F₃跃迁。     

铕与2，4-二氯苯甲酸一维链状配位聚合物的合成，晶体结构和发光性质

溶液法合成了一个新的铕配位聚合物[Eu(2,4-DClBA)₃(CH₃CH₂OH)₂]_n(2,4-DClBA=2,4-二氯苯甲酸根),并用X-射线单晶衍射分析确定了其晶体结构。配合物晶体属于三斜晶系,P1空间群。标题配合物是无限一维链状聚合物,中心Eu³⁺离子通过桥联双齿2,4-二氯苯甲酸根氧原子连接。Eu³⁺离子的配位数为8     

吡嗪缩氨基脲配体铜/锌配合物的晶体结构及荧光性质

合成并通过单晶X射线衍射、元素分析及红外光谱表征了配合物[Cu₂（L）₂Br₂]·CH₃OH（1）和[Zn₂（L）₂（CH₃COO）₂]·2CH₃OH（2）的结构（HL为3-乙基-2-乙酰吡嗪缩4-苯基氨基脲）。单晶衍射结果表明,配合物1中,中心Cu（Ⅱ）离子与来自1个三齿缩氨基脲配体阴离子和2个μ²-桥联的溴离子配位,拥有扭曲的四方锥配位构型。配合物2中Zn（Ⅱ）离子配位构型与配合物1中Cu（Ⅱ）离子的相同,周围的供体原子为N₂O₃。配合物2中的2个醋酸根的配位模式不尽相同,其中一个为μ-OCO双齿桥联,另外一个为μ-O单齿桥联。甲醇溶液中,配合物1和2的荧光发射峰与配体HL相似。     

Salen型双肟铜(Ⅱ)和钴(Ⅱ)配合物的合成、晶体结构及热性质

一种新的Salen型双肟配体H₂L（H₂L=4,4′-二溴-6,6′-二氯-2,2′-[乙二氧双(氮次甲基)]二酚）分别与一水合乙酸铜或四水合乙酸钴反应,合成了2种配合物即[Cu(L)] (1)和[Co(L)(H₂O)₂]_n (2)。X-射线单晶衍射分析结果表明,配合物1是单核结构,由1个Cu²⁺离子和1个四齿配位的L^2-单元组成。中心Cu^Ⅱ原子的配位数为4,配合物的几何构型为扭曲的四面体。配合物2含有1个Co²⁺离子、1个配体L^2-单元（提供N₂O₂给予体）、2个配位的水分子,其中心Co^Ⅱ原子具有六配位的稍微扭曲的八面体几何构型。该配合物通过分子间氢键和π-π堆积作用形成了线性延伸的金属-水链状超分子结构。     

N-苯基亚氨基二乙酸桥联的双核铜配合物的合成、表征与晶体结构

由Cu(Ⅱ)、2，2′-联吡啶(邻菲咯啉)与N-苯基亚氨基二乙酸在溶液中组装得到2个双核配合物[Cu₂(L)₂(2，2′-bipy)₂]·8H₂O (1)、[Cu₂(L)₂(phen)₂]·2H₂O (2)(H₂L=N-苯基亚氨基二乙酸，2，2′-bipy=2，2′-联吡啶，phen=邻菲咯啉)。用元素分析、红外光谱、热重分析等进行了表征，并测定了其晶体结构。晶体结构表明，配合物1的晶体属三斜晶系，空间群P1;配合物2的晶体属单斜晶系，空间群P2₁/c。在这2个双核配合物中，中心铜离子的配位形式均为五配位的畸变四方锥构型，配体L中的N原子没有参与配位，而是采用1个羧基的1个氧原子与Cu²⁺离子螯合、另1个羧基上的1个氧原子以μ₂-桥联的配位模式连接2个Cu²⁺离子。     

含咔唑基团联吡啶衍生物为中性配体的铕配合物的合成和发光性质研究

以2,2′-联吡啶(L1)为基础,合成了5,5′-二溴-2,2′-联吡啶(L2),5-咔唑-5′-溴-2,2′-联吡啶(L3),5,5′-二咔唑-2,2′-联吡啶(L4)3个N,N-双齿配体,然后以二苯甲酰甲烷(DBM)作为第一配体合成了这4种配体相应的铕配合物。在387 nm激发条件下,配合物都表现出非常强的铕离子⁵D₀-⁷F_J (J=0,1,2,3,4)的特征发射。引入咔唑基团后,不仅扩大了配合物吸收光能的范围、增强了配合物的吸收强度,而且提高了配合物的光致发光性能。     

三个包含酰胺型配体铜/锌配合物的合成、结构及荧光性质

合成并通过单晶衍射表征了3个配合物[CuLCl₂]·CH₃CN(1),[CuLBr₂]·CH₃CN(2)和[ZnL(NO₃)₂]·CH₃CN(3)(L=2-(5-氯-8-喹啉氧基)-1-(吡咯烷-1-基)乙酮)。在配合物1和2中,五配位的铜离子采取扭曲的四方锥配位构型,与来自配体L的2个氧原子和1个氮原子及2个卤离子配位。而在配合物3中,锌离子与1个三齿配位的配体L,1个单齿配位的硝酸根和1个双齿配位的硝酸根配位,配位构型为扭曲的八面体。乙腈溶液中,配合物1和2在410 nm处的最大荧光发射峰与配体L的相似,强度有所降低。而配合物3由于配体到锌离子之间的能量转移,最大荧光发射峰红移至430 nm。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.