基于3，3′，4，4′-四羧基偶氮苯构筑的三个金属配合物的合成、晶体结构及性质

在水热条件下利用H₄ddb配体合成了3个过渡金属配合物[Co₂（ddb）（phen）₂（H₂O）₆]·3H₂O（1）,[Co（ddb）_0.5（bpy）_0.5（H₂O）₃]_n（2）和{[Ag（dpe）]·0.5（H₂ddb）·H₂O}_n（3）（H₄ddb=3,3'',4,4''-四羧基偶氮苯,bpy=4,4''-联吡啶,dpe=1,2-二（4-吡啶基乙烯））,并用元素分析、红外光谱、X射线粉末衍射、X射线单晶衍射对其进行了表征。配合物1为双核结构,基于丰富的氢键作用扩展形成三维超分子网结构。配合物2为基于钴离子通过ddb^4-配体以μ₄：η¹,η¹,η¹,η¹的配位模式连接而成的二维网结构。配合物3是由Ag（Ⅰ）离子与dpe配体形成的直链结构,客体分子H₂ddb^2-通过氢键作用将其扩展为三维超分子结构。此外还研究了配合物1~3的荧光性质和热稳定性。     

二聚体C2H4-nFn···LiH (n=0, 1, 2)中π锂键的性质和弱方向性

采用二级微扰理论(MP2)量子化学研究方法, 对C₂H_4-nF_n···LiH (n=0, 1, 2)二聚体的结构和π锂键性质进行了分析. 结果表明氟原子的取代改变了乙烯分子的π电子云形状, 从而使二聚体体系中的π锂键发生偏移、伸长和弯曲. 通过与类似的π氢键体系C₂H_4-nF_n···HF (n=0, 1, 2)比较, 发现π锂键在二级弱相互作用的影响下, 发生了明显的弯曲, 表现出弱的方向性. 在CCSD(T)/6-311++G(3df, 3pd)理论水平下, 二聚体的相互作用能强弱顺序为: 33.85 kJ·mol^-1 (C₂H₄-LiH)>27.32 kJ·mol^-1 (C₂H₃F-LiH)>21.34 kJ·mol^-1 (cis-C₂H₂F₂-LiH)>20.25 kJ·mol^-1 (g-C₂H₂F₂-LiH), 说明氟取代削减了乙烯分子与LiH之间的相互作用.     

Evaluation of Huggins' Constant,Kraemer's Constant and Viscosity Concentration Coefficient of Polymer Dextran in Urea,Glycine and Glucose

Abstract

Reduced viscosity (η_sp/c) and Inherent viscosity (In η_rel/c) of dilute solution of water soluble polysaccharide polymer “Dextran” has been calculated by measuring the flow time of the polymer solution in solvents like 6(M) Urea, 2(M) Glycine and 50% Glucosc at three different temperatures ? 25°C, 30°C and 35°C. From extrapolation of curve (η_sp/c) versus (c) and (In η_rel/c) versus (c), thermo viscosity parameters like Huggins' constant (k′_H) Kraemer's constant (k″_H) and viscosity concentration coefficient (a ₂) have been estimated which enable us to know the fate of the polymer molecules in these solvents.     

基于1H-苯并咪唑-2-羧酸的三个镧系超分子化合物的结构、热分解动力学和荧光性质

在水热条件下合成了三个镧系超分子化合物[Ln(HBIC)₃]_n [Ln=Sm (1), Ho (2), Yb (3); H₂BIC=1H-苯并咪唑-2-羧酸], 其中化合物1、2呈单晶态, 化合物3则为粉末样品; 借助单晶X射线衍射(XRD)、粉末衍射、元素分析、红外(IR)光谱、热分析等手段对化合物进行了表征. 结构分析表明, 1-3为同构化合物, 都呈现二维的平面结构, 其中每一个镧系金属中心与来自五个HBIC^-配体的三个氮原子和五个氧原子以两种新的配位模式配位形成一个轻微扭曲的双帽三棱柱几何构型, 相邻的二维(2D)平面进一步通过强的氢键作用形成了一个三维(3D)的超分子结构. 热重分析结果表明, 化合物1-3在360 ℃前均保持稳定, 呈现出良好的热稳定性. 基于Kissinger和Ozawa-Doyle两种方法, 通过差示扫描量热(DSC)技术研究得到了化合物1热分解的动力学参数(指前因子A_K=1.286×10⁸ s^-1; 活化能E_K=199.3 kJ·mol^-1, E_O=205.2 kJ·mol^-1). 另外, 也研究了室温下化合物1和3的固态发光性能, 结果表明, 化合物1和3分别在可见光区和近红外光区呈现出相应镧系金属离子的特征发射.     

Synthesis and antimicrobial activity of new derivatives of pyrano[4',3':4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidine and new heterocyclic systems

Taking into account previously obtained biological results on some polyheterocyclic compounds (containing different heteroatoms) and in particular on several 8-amino-5-isopropyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines Ia-v we have carried out the synthesis of twentyone 8-amino-5-isobutyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines 6. Therefore we have slightly modified the structure of the previously studied I introducing at C-5 an isobutyl group instead of the previously examined isopropyl ones in order to see if this variation (changing a little the lipophilicity) will affect the biological activity. Furthermore thieno[3,2-d]pyrimidine-8-thione 7 and their S-alkylated 8 were synthesized. Finally by alkylation of 5-isobutyl-2,2-dimethyl-10-thioxo-1,4,10,11-tetrahydro-2H-pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-8(9H)-one 3 with alkyl dichlorides (bifunctional reagents) we realized the cyclization of a thiazole or thiazine ring on the [b] side of the pyrimidine ring with formation of the new condensed pentaheterocyclic systems: pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d][1,3]thiazolo[3,2-a]pyrimidin-8-one 11 and pyrano[4''',3''':4'',5'']pyrido[3'',2'':4',5']thieno[3',2':4,5]pyrimido[2,1-b][1,3]thiazin-8-one 12. It was found that some of the synthesized compounds showed interesting antimicrobial activity (by agar diffusion method) against some gram-positive and gram-negative bacilli strains.     

1，1'-二羟基-5，5'-联四唑的镧系金属配合物的合成、表征及热行为

以1,1′-二羟基-5,5′-联四唑(H_2BTO)为配体,镧系金属离子作为金属中心,采用溶剂热法制备了5种金属配合物:[La_2(BTO)_3(H_2O)_8]·2H_2O (1)、[Ce_2(BTO)_3(H_2O)_8]·2H_2O (2)、[Pr_2(BTO)_3(H_2O)_8]·2H_2O (3)、[Sm_2(BTO)_3(H_2O)_8]·2H_2O (4)和[Nd_2(BTO)_3(DMF)_4]·6H_2O (5)。通过单晶X射线衍射和元素分析对5种配合物的结构进行了表征。结果表明,5种配合物均属于单斜晶系,P2_1/n空间群。利用差示扫描量热法研究了配合物1～4的热稳定性,采用Kissinger法和Ozawa法分别计算了其热分解动力学参数。     

Conformational analysis of three pyrophosphate model species: Diphosphate,methyl diphosphate,and triphosphate

Whereas theoretical investigations of the energetic origin of hydrolyzing a pyrophosphate linkage abound, few studies have focused on the energetics of the rotation of this linkage. This less-studied property of the pyrophosphate linkage was investigated here by use of ab initio calculations to characterize the conformational space of three model species of pyrophosphate anions: diphosphate (P₂O), methyl diphosphate (CH₃P₂O), and triphosphate (P₃O). By carefully selecting conformationally distinct rotational isomers of the three model compounds, their potential surfaces were thoroughly explored. In addition to showing that a terminal phosphate group is indeed very flexible in accordance with the general perception of free rotation, a number of intriguing features of this linkage emerged from the ab initio calculations, which include an influential sp3-hybridized C HO intramolecular hydrogen bond in methyl diphosphate, and a highly restricted rotational space pertaining to the central pyrophosphate linkage of the triphosphate anion. These ab initio findings were then evaluated by, and proved insightful in, follow-up examinations of experimentally determined complex structures of proteins and their dinucleotide or adenine and guanine triphosphate ligands. © 1999 John Wiley & Sons, Inc. J Comput Chem 20: 1702–1715, 1999     

Ge4+、Sn4+掺杂尖晶石LiMn2O4的合成与电化学表征

使用Ge⁴⁺、Sn⁴⁺作为掺杂离子, 通过高温固相法制备四价阳离子掺杂改性的尖晶石LiMn₂O₄材料. X射线衍射(XRD)和扫描电子显微镜(SEM)分析表明, Ge⁴⁺离子取代尖晶石中Mn⁴⁺离子形成了LiMn_2-xGe_xO₄ (x=0.02,0.04, 0.06)固溶体; 而Sn⁴⁺离子则以SnO₂的形式存在于尖晶石LiMn₂O₄的颗粒表面. Ge⁴⁺离子掺入到尖晶石LiMn₂O₄材料中, 抑制了锂离子在尖晶石中的有序化排列, 提高了尖晶石LiMn₂O₄的结构稳定性; 而在尖晶石颗粒表面的SnO₂可以减少电解液中酸的含量, 抑制酸对LiMn₂O₄活性材料的侵蚀. 恒电流充放电测试表明, 两种离子改性后材料的容量保持率均有较大幅度的提升, 有利于促进尖晶石型LiMn₂O₄锂离子电池正极材料的商业化生产.     

联苯二甲酸构筑的镍配合物的合成、晶体结构及对罗丹明B的光催化性能

通过水热方法获得了2个镍配合物:[Ni(3,3′-dpdc)(dpp)]n(1),[Ni(2,2′-dpdc)(phen)(H2O)2]n(2)(3,3′-H2dpdc=3,3′-联苯二甲酸,2,2′-H2dpdc=2,2′-联苯二甲酸、phen=菲咯啉,dpp=1,3-二(4-吡啶基)丙烷),通过X射线单晶衍射的方法测定了其晶体结构。配合物1为二维网格型结构,中心金属离子为扭曲的[NiO4N2]八面体构型,3,3′-dpdc配体的2个羧基采取双齿螯合的配位模式与Ni髤离子配位形成Ni-(3,3′-dpdc)一维链结构,dpp配体采取单氮原子桥连的配位模式连接2个Ni髤离子形成Ni-dpp一维链,两种链相互贯穿形成二维网格型结构,二维网格结构之间通过氢键C15D-H15…O2、C21-H21A…O1形成三维超分子结构。配合物2为一维之字链结构,中心金属离子为扭曲的[NiO_4N_2]八面体构型,2,2′-dpdc的2个羧基均采取单齿桥连配位模式连接2个Ni髤离子形成一维之字型链结构,一维链之间通过O-H…O和C-H…π弱作用力连接形成三维超分子结构。探究了2种配合物对有机染料罗丹明B的光催化降解性能,结果表明配合物可以高效地降解罗丹明B。     

3,5-二(2',5'-苯二羧酸)苯甲酸构筑的金属有机配合物的荧光识别及磁性

设计合成了3种新颖的金属有机配合物（MOCs）：{[Pb₂（HL）（phen）]·2H₂O}_n（1）,{[Ni（H₃L）（4,4''-bipy）_1.5（H₂O）₄]·6H₂O}_n（2）和{[Ni₂（HL）（1,4-bibb）（H₂O）]·（CH₃CN）·H₂O}_n（3）（H₅L=3,5-二（2'',5''-苯二羧酸）苯甲酸,phen=1,10-菲咯啉,4,4''-bipy=4,4''-联吡啶,1,4-bibb=1,4-二（苯并咪唑）苯）,并通过单晶X射线衍射、红外光谱（IR）、热重分析（TG）和粉末衍射对它们进行结构表征。结构分析表明1是基于[Pb₂（μ₂-COO）₂（μ₁-COO）₄]SBUs的一维链状结构;2是二维层状结构,其拓扑符号为{4.6²}₂{4².6².8²};3是一个3D网络结构,其拓扑符号为{6².8⁴}{6⁴.8²}₂。进一步研究了配合物荧光和磁性能。荧光检测显示,配合物1在水溶液中可以高灵敏识别Fe³⁺和Cr₂O₇^2-离子。同时研究了配合物1对Fe³⁺和Cr₂O₇^2-猝灭机理。磁性分析表明配合物3中的Ni（Ⅱ）离子之间存在反铁磁相互作用。     

Amyloid Aggregates,Presenilins, and Alzheimer's Disease

The cooperative action of three proteases is required to process the APP protein (695–770 amino acids) into small β-amyloid peptides (Aβ, 40–42 amino acids). Aβ aggregates are found in the senile plaques of patients with Alzheimer's disease and play a major role in the onset of this disorder. The functional analysis of several factors that contribute to the production and aggregation of Aβ has enhanced our knowledge of the mechanism of amyloid formation and increased the potential for effective therapeutic treatment.     

Nitrido-Sodalithe. III [1]. Synthese,Struktur und Eigenschaften von Zn8[P12N24]X2 mit X = O,S, Se,Te

Nitrido-Sodalites. III. Synthesis, Crystal Structure, and Properties of Zn₈[P₁₂N₂₄]X₂ with X = O, S, Se, Te The P? N-sodalites Zn₈[P₁₂N₂₄]X₂ with X = O, S, Se, Te are obtained by the reaction of HPN₂ with the corresponding zinc chalcogenide ZnX at 750°C. They crystallize in a filled up variant of Zn₇[P₁₂N₂₄]Cl₂ and are isotypic to Zn₈[B₁₂O₂₄]O₂ (I4 3m, a = 823 to 830 pm, Z = 1). The P? N-sodalites contain in the center of their β-cages XZn₄⁶⁺ units which can be described as sections of II/VI-semiconductors. The UV/Vis-spectra of the compounds show in comparison with binary bulk zinc chalcogenides a blue shift of the absorption edge according to the size quantization effect.     

三个有机锡2，2'-联苯二甲酸酯的微波溶剂热合成、结构及体外抗癌活性

以 2,2''-联苯二甲酸(H₂DPA)分别与双(三(2-甲基-2-苯基丙基)锡)氧化物、三环己基氢氧化锡和二丁基氧化锡反应,合成了3个有机锡2,2''-联苯二甲酸酯：[((PhC(Me)₂CH₂)₃Sn)₂(DPA)] (1)、[(Cy)₃Sn(DPA)]_n (2)和[(n-Bu)₂Sn(DPA)]_n (3)。通过IR、NMR、元素分析、热重及X射线单晶衍射对配合物进行表征分析。配合物1、2、3均属单斜晶系,配合物1为双核结构,配合物2、3为一维链状结构,锡原子的配位数依次增大,分别为4、5、6。体外抗癌活性实验表明,配合物1、2、3对人肺癌细胞(NCI-H460)、人乳腺腺癌细胞(MCF-7)、人肝癌细胞(HepG2)的增殖具有较强的抑制作用。     

辅助配体导向合成两个锌金属配位聚合物:结构,稳定性和荧光性质

以二苯-4,4''-二羧酸和六水硝酸锌为原料,在相同反应条件下,通过改变不同的辅助配体(2,2''-二甲基-4,4''-联吡啶和三乙烯二胺),合成出2个金属有机配位聚合物:{[Zn(DBA)(dmbpy)_0.5]·2H₂O}_n (1)和[Zn₂(DBA)₂(dabco)]_n (2)(H₂DBA=二苯-4,4''-二羧酸,dmbpy=2,2''-二甲基-4,4''-联吡啶,dabco=三乙烯二胺)。通过元素分析、红外光谱、差热分析、X射线粉末衍射和X射线单晶衍射等手段对配合物进行了结构表征。结果显示,化合物1为二维(4,4)网络结构,2个二维结构在平行方向上通过互锁进一步形成2D→2D的互锁网络结构。化合物2为一维带状结构。热稳定性表明化合物1能够稳定到370℃;而化合物2稳定性差。荧光分析表明常温固态下配合物1和2均发射蓝色荧光,荧光寿命分别为231.4 ns和2.33 ns。     

4,4'-联吡啶桥联的三个铜有机膦酸配合物的合成、结构及磁性

在水热条件下,以N-氧化-2-吡啶膦酸（H2L）为主配体,4,4＇-联吡啶（bpy）为桥联配体,合成了3个铜有机膦酸配合物： {[CuL（bpy）0.5（H₂O）]·2H₂O}_n（1）, {[Cu（HL）₂（bpy）]·4H₂O}_n（2）和{[Cu₂（L）₂（bpy）]·3H₂O}_n（3）。配合物1中,相邻的铜离子由2个膦酸根连成二聚体,二聚体之间通过bpy桥联成一维链。配合物2中,单核[Cu（HL）₂]被bpy连接成一维链。配合物3中,四聚体[Cu₂（L）₂]₂被bpy连接成“砖块状”结构的二维层。磁性研究表明,配合物1和3中铜离子之间存在反铁磁性耦合。     

Zeise,Liebig, Jensen,Hückel,Dewar, and the Olefin π‐Complex Bonds

Zeise's salt, KPt(C₂H₄)Cl₃, was the first characterized organometallic compound; it was also the first olefin π‐complex. It was published in 1825–1830 in the middle of a fight between Dumas on the one hand and Berzelius and Liebig on the other, who defended the etherin (ethylene) and radical theories, respectively. Although Zeise's formulation as a compound containing ethylene was vindicated, the fight went on for many years. This was a time when the theories of organic chemistry were being developed, before any clear understanding of the nature of molecules, bonding, and structure. Zeise thought of the structure of his salt as a product of the addition of PtCl₂ to ethylene. Jensen assumed a central bonding to ethylene but needed theoretical assistance to explain it. His attempt to obtain such an explanation from Hückel failed, and it was Dewar who explained the nature of π‐complexes in molecular orbital terms in 1951.