有机锡9-芴酮-4-甲酸酯的合成、结构及抗癌活性

合成了3个有机锡9-芴酮-4-甲酸酯:三苯基锡9-芴酮-4-甲酸酯[(C₆H₅)₃Sn(C₁₄H₇O₃)](1)、三环己基锡9-芴酮-4-甲酸酯[(C₆H₁₁)₃Sn(C₁₄H₇O₃)](2)和三(2-甲基-2-苯基丙基)锡9-芴酮-4-甲酸酯[(C₆H₅C(CH₃)₂CH₂)₃Sn(C₁₄H₇O₃)](3)。通过元素分析、红外光谱、核磁共振谱(¹H、¹³C和¹¹⁹Sn)、热重分析进行了表征;用单晶X射线衍射方法测定了化合物的晶体结构,并对其进行了量子化学计算和体外抗...     

芳茂铁阳离子聚合光引发剂引发活性研究

研究了7种不同芳烃结构的芳茂铁四氟硼酸盐作为阳离子紫外光聚合和光固化引发剂在环氧体系中的光引发活性,其中[C₅H₅Fe₂,5-(CH₃)₂CO^-C₆H₃]BF₄(Ⅵ)和[CH₃CO^-C₅H₄Fe₂,4-(CH₃)₂-C₆H₄]BF₄(Ⅶ)为新物质.研究发现,这7个芳茂铁四氟硼酸盐在370和450nm附近均有较强吸收;芳环上引入共轭CC和共轭CO使吸收峰发生红移,且使摩尔消光系数和感光速度均有所提高,更适合于以高压汞灯为辐射光源的长波紫外固化;芳茂铁四氟硼酸盐可以引发环氧树脂、脂环族和脂肪族缩水甘油基环氧单分子,通过加热或使用有机过氧化物[如过氧化苯甲酰(BPO)]可明显提高环氧化合物的聚合速度.     

二(β-羟亚胺)二氯化钛配合物的合成及催化乙烯聚合

报道了3个β-羟亚胺配体(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)OH(1a), (2,6-^emPr₂C₆H₃)N＝C·(Ph)CH₂C(Ph)₂OH(1b)和(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)OH(1c)及其二(β-羟亚胺)二氯化钛配合物[(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)O]₂TiCl₂(2a), [(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(Ph)₂O]₂·TiCl₂(2b)和[(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)O]₂TiCl₂(2c)的合成, 并对其结构进行了表征. 在助催化剂甲基铝氧烷(MAO)作用下, 以化合物2b为主催化剂, 研究了Al/Ti摩尔比、 反应时间、 温度和聚合压力等对乙烯聚合的影响, 发现该催化体系在较宽的反应条件下均可得到很高分子量的聚乙烯, 熔点均在140℃左右. 以化合物2a~2c为主催化剂对乙烯进行催化聚合, 发现在β碳位上取代基的立体位阻对催化剂活性有很大影响. 当化合物2b上引入2个苯基取代基时, 催化剂显示出最佳催化活性.     

亚乙基桥联双茚锆、铪配合物的合成及催化丙烯选择性齐聚研究:茚环3-位取代基的影响

设计并合成了12个亚乙基桥联双茚类锆、铪配合物meso-/rac-1～7[ansa-C₂H₄-(3-R-4,7-Me₂-C₉H₃)₂MCl₂:M=Zr R=ⁿBu (meso-/rac-1),ⁱPr (meso-2),CH₂Cy (meso-/rac-3),Bn (meso-/rac-4),CH₂C₆H₄(4-CH₃)(meso-/rac-5);M=Hf,R=CH₂C₆H₄(4-CH₃)(meso-/rac-7);ansa-C₂H₄-{2-Me-3-Bn-5,6-[1,3-(CH₂)₃]C₉     

均相催化丙二酸二甲酯加氢制1,3-丙二醇的研究

将系列o-二苯基膦苯胺配体构成的Ru(Ⅱ)配合物[(PPh₃)(o-PPh₂C₆H₄NH₂)RuCl₂]₂(1)、(o-PPh₂C₆H₄NHR)₂RuCl₂(R=H, 2; Me, 3; Et, 4; CH₂Ph, 5)和(o-PPh₂C₆H₄NH₂)[(CH₂NHR)₂]RuCl₂ (R=H, 6; Me, 7; Et, 8; iPr, 9)应用于催化丙二酸二甲酯加氢制3-羟基丙酸甲酯或1,3-丙二醇.围绕催化加氢性能,系统探究了配合物结构、助剂种类及用量以及溶剂等反应条件对底物转化率和目标产物收率的影响.研究发现,配合物8性能最优.同时,配合物8在催...     

新型金属-双二硫杂戊烯(M-BDT)配合物的合成、表征及X射线的指标化

合成了4个新型NiBDT配位化合物,BDT为具有9个S原子的杂戊烯.元素分析、IR谱、UV谱确定这4个新配合物的化学式分别为[(CH₃)₄N]₂[Ni(C₅S₉)₂](1),[(C₂H₅)₄N]₂·[Ni(C₅S₉)₂](2),[(C₄H₉)₄N]₂[Ni(C₅S₉)₂](3),[(C₆H₅)(CH₃)₃N]₂[Ni(C₅S₉)₂](4).采用Ito法对配合物1的X射线粉末图进行了指标化,确定该晶体属单斜晶系,简单晶格,晶胞参数:a=0.680nm,b=0.714nm,c=2.302nm,γ=111.4°,Z=2.     

双核茂金属催化剂的合成、表征与应用

使用桥连配体锂盐与MCl₄络合, 合成了4个不同结构的双核茂金属化合物[μ,μ-(CH₂)₃]{[C(H)·(η⁵-C₅H₄)(η⁵-C₁₃H₈)](MCl₂)}₂[M=Zr or Ti](4, 5)和[μ,μ-(CH₂)₃]{[C(H)(η⁵-C₅H₄)(η⁵-C₉H₆)]·(MCl₂)}₂[M=Zr or Ti](6, 7), 配体和化合物都经过核磁氢谱(¹H NMR)、 碳谱(¹³C NMR)、 红外光谱(IR)及元素分析等表征, 确认了化学结构. 以甲基铝氧烷(MAO)为助催化剂, 化合物4~7为催化剂催化丙烯聚合, 考察了聚合温度、 乙烯压力、 铝钛或铝锆比对催化剂活性及聚合物分子量的影响. 结果表明, 多亚甲基桥连双核茂金属是高活性乙烯和丙烯聚合催化剂, 乙烯聚合活性最高达到7.5× 10⁶ g PE/(mol Zr·h)(化合物6), 丙烯聚合活性达 10 × 10⁵ g sPP/(mol Zr·h)(化合物4). 所得间规聚丙烯(sPP)的间规度指数(SI, r) 达到90%. 在同样条件下, 双核化合物的催化活性、 聚合物分子量M_w(> 100000)以及分子量分布(MWD>2.5)均比相应的单核化合物高(M_w<70000, MWD≤2), 表明该体系中存在较强的核效应.     

Ru-Fe异金属化合物及其在Au表面上SAM的电化学研究

为使不对称Ru-Fe化合物能在表面上自组装形成单分子膜,对trans-RuCl(dppm)₂(C≡CFc)[Fc=C₅H₄FeC₅H₅,dppm=(C₆H₅)₂PCH₂P(C₆H₅)₂](1)进行修饰,得到Ru(dppm)₂(C≡CFc)(C≡CPhOCH₃)(2),[Ru(dppm)₂(C≡CFc)(N≡CCH₂CH₂NH₂)][PF₆](3)和[Ru(dppm)₂(C≡CFc)(N≡CCH₂CH₂NHC(O)·(CH₂)₁₀SH)][PF₆](4),并详细研究了该系列化合物的电化学性质.循环伏安结果显示出Ru周围配体得失电子能力的差别,直接影响了Ru中心的氧化-还原性,但这种影响并没有通过共轭的炔键传递到二茂铁中的Fe中心.化合物4可以在Au表面上自组装形成稳定、有序的单分子膜.还利用循环伏安法研究了单分子膜的形成过程及其表面覆盖率.     

新型双苯并环己酮芳亚胺镍(Ⅱ)催化降冰片烯与甲基丙烯酸丁酯共聚合

采用自制的新型双苯并环己酮芳亚胺镍催化剂双苯并环己酮-2,6-二甲基苯亚胺镍(Ⅱ)(Ni{C₁₀H₈(O)C[2,6-C₆H₃(CH₃)₂N]CH₃}₂, C1)和双苯并环己酮-2,6-二氯苯亚胺镍(Ⅱ)(Ni{C₁₀H₈(O)C[2,6-C₆H₃Cl₂N]CH₃}₂, C2)与三五氟苯硼[B(C₆F₅)₃]结合, 在一定的反应条件下可高效催化降冰片烯(NB)与甲基丙烯酸正丁酯(n-BMA)的乙烯基加成共聚合. 提出了催化聚合时存在的可能失活机理; 研究了不同单体投料比对催化活性、 产率及产物性能的影响. 根据Kelen-Tüdõs方法分别估算出2种单体在不同催化体系下的竞聚率, 即当催化体系为C1/B(C₆F₅)₃时, 竞聚率r_n-BMA=0.02, r_NB=16.28, r_NB·r_n-BMA=0.32; 当催化体系为C2/B(C₆F₅)₃时, r_n-BMA=0.01, r_NB=64.83, r_NB·r_n-BMA=0.65. 结果表明, 2种单体在2种体系催化下均为无规共聚合.     

咔唑及其衍生物的质谱研究

本文报道咔唑和十三个N-取代咔唑衍生物(R=CH₃,C₂H₅,n-C₃H₇,n-C₄H₉,n-C₅H₁₁,n-C₆H₁₃,n-C₇H₁₅,CH₂CH₂Cl,CH₂CH₂Br,CH(CH₃)₂,CH=CH₂,CH₂CH=CH₂和CH₂C₆H₅)的质谱裂解过程。结果表明:1.这些化合物都显示分子离子峰,它们的相对丰度似有随R链的增长而减弱的趋势;2.当R为碳原子数大于1的直链烷基时,各化合物的质谱中都有相同的、以m/z180和m/z167为母离子的两个碎片离子系列,即m/z180;152,127,90和m/z167,166,140,139,115,113;3.当R为乙烯基时,重排断裂是主要途径;而R为烯丙基时,断裂方式与直链烷基衍生物的相同,但α-断裂是主要的;4.R为CH₂CH₂Cl和CH₂CH₂Br时,β-断裂也有一定几率;R为CH₂C₆H₅时,主要的断裂过程是产生m/z91的(艹卓)鎓离子。     

Crystallographic and FTIR spectroscopic evidence of changes in Fe coordination upon reduction of the active site of the Fe-only hydrogenase from Desulfovibrio desulfuricans.

Fe-only hydrogenases, as well as their NiFe counterparts, display unusual intrinsic high-frequency IR bands that have been assigned to CO and CN(-) ligation to iron in their active sites. FTIR experiments performed on the Fe-only hydrogenase from Desulfovibrio desulfuricans indicate that upon reduction of the active oxidized form, there is a major shift of one of these bands that is provoked, most likely, by the change of a CO ligand from a bridging position to a terminal one. Indeed, the crystal structure of the reduced active site of this enzyme shows that the previously bridging CO is now terminally bound to the iron ion that most likely corresponds to the primary hydrogen binding site (Fe2). The CO binding change may result from changes in the coordination sphere of Fe2 or its reduction. Superposition of this reduced active site with the equivalent region of a NiFe hydrogenase shows a remarkable coincidence between the coordination of Fe2 and that of the Fe ion in the NiFe cluster. Both stereochemical and mechanistic considerations suggest that the small organic molecule found at the Fe-only hydrogenase active site and previously modeled as 1,3-propanedithiolate may, in fact, be di-(thiomethyl)-amine.     

Carbon Monoxide and Cyanide Ligands in a Classical Organometallic Complex Model for Fe-Only Hydrogenase

The Fe(I) organometallic complex [(μ-SCH(2)CH(2)CH(2)S)Fe(2)(CO)(6)] provides a structural model for the cyano-carbonyl diiron site of Fe-only hydrogenase as characterized by X-ray crystallography (the picture shows the structure (black) of the model overlaid with that of the Fe-Fe dimetallic site in the hydrogenase isolated from Desulfovibrio desulfuricans). Cyanide substitution of CO occurs readily and provides spectroscopic references for the active site.     

A QM/MM investigation of the activation and catalytic mechanism of Fe-only hydrogenases

Fe-only hydrogenases are enzymes that catalyze dihydrogen production or oxidation, due to the presence of an unusual Fe(6)S(6) cluster (the so-called H-cluster) in their active site, which is composed of a Fe(2)S(2) subsite, directly involved in catalysis, and a classical Fe(4)S(4) cubane cluster. Here, we present a hybrid quantum mechanical and molecular mechanical (QM/MM) investigation of the Fe-only hydrogenase from Desulfovibrio desulfuricans, in order to unravel key issues regarding the activation of the enzyme from its completely oxidized inactive state (Hoxinact) and the influence of the protein environment on the structural and catalytic properties of the H-cluster. Our results show that the Fe(2)S(2) subcluster in the Fe(II)Fe(II) redox state - which is experimentally observed for the completely oxidized form of the enzyme - binds a water molecule to one of its metal centers. The computed QM/MM energy values for water binding to the diferrous subsite are in fact over 70 kJ mol(-1); however, the affinity toward water decreases by 1 order of magnitude after a one-electron reduction of H(ox)(inact), thus leading to the release of coordinated water from the H-cluster. The investigation of a catalytic cycle of the Fe-only hydrogenase that implies formation of a terminal hydride ion and a di(thiomethyl)amine (DTMA) molecule acting as an acid/base catalyst indicates that all steps have reasonable reaction energies and that the influence of the protein on the thermodynamic profile of H(2) production catalysis is not negligible. QM/MM results show that the interactions between the Fe(2)S(2) subsite and the protein environment could give place to structural rearrangements of the H-cluster functional for catalysis, provided that the bidentate ligand that bridges the iron atoms in the binuclear subsite is actually a DTMA residue.     

Spectroscopic and crystallographic evidence for the N-protonated FeIFeI azadithiolate complex related to the active site of Fe-only hydrogenases

The complex [{(mu-SCH2)2N(CH2C6H4-2-Br)}Fe2(CO)6] and its N-protonated species, as structural models of the Fe-only hydrogenase active site, were identified spectroscopically and crystallographically, and their molecular structures show the 0.04-0.1 A lengthening of the three N-C bonds and an intramolecular HBr contact (2.82 Angstroms) in the crystalline state of the N-protonated species.     

化学模拟唯铁氢化酶研究进展

氢化酶(hydrogenase,简称H2ase)是一类存在于微生物体内的重要生物酶,它可以催化氢的氧化反应,也可以催化还原质子产生氢气.根据氢化酶活性中心金属的不同,可以大致分为三类:Fe-Fe氢化酶,Ni-Fe氢化酶和不含金属的氢化酶.本文主要介绍近年来唯铁(Fe-Fe)氢化酶的结构研究和化学模拟最新进展.     

LIMITING REACTIONS IN HYDROGEN PHOTOPRODUCTION BY CHLOROPLASTS AND HYDROGENASE

Abstract— Hydrogen was photoproduced from water in a system containing isolated chloroplasts, hy-drogenase, a coupling electron carrier (ferredoxin or methyl viologen), and an oxygen scavenger. The rate and extent of hydrogen production anaerobically was much less than the rate of aerobic electron-carrier reduction by chloroplasts and was not limited by hydrogenase. The limiting reaction in the coupled system was the extent of reduction of methyl viologen anaerobically rather than its oxidation by oxygen produced during the course of the reaction. Inhibition of photosystem II by 3-(3,4dichlorophenyl)-1,1-dimethylurea and addition of a photosystem 1 electron donor did not lead to photoproduction of hydrogen or photoreduction of methyl viologen. Extensive photosystem I hydrogen evolution was obtained when thiols were also present. Platinum asbestos or palladium asbestos replaced hydrogenase in a system coupled to chloroplasts.     

Density functional study on dihydrogen activation at the H cluster in Fe-only hydrogenases

Models simulating the catalytic diiron subcluster [FeFe](H) in Fe-only hydrogenases have often been designed for computational exploration of the catalytic mechanism of the formation and cleavage of dihydrogen. In this work, we extended the above models by explicitly considering the electron reservoir [4Fe-4S](H) which is linked to the diiron subcluster to form a whole H cluster ([6Fe-6S] = [4Fe-4S](H) + [FeFe](H)). Large-scale density functional theory (DFT) computations on the complete H cluster, together with simplified models in which the [4Fe-4S](H) subcluster is not directly involved in the reaction processes, have been performed to probe hydrogen activation on the Fe-only hydrogenases. A new intermediate state containing an Fe(p)...H...CN two-electron three-center bond is identified as a key player in the H2 formation/cleavage processes.     

Photoinduced hydrogen production by direct electron transfer from photosystem I cross-linked with cytochrome c3 to [NiFe]-hydrogenase

The photosynthetic reaction center is an efficient molecular device for the conversion of light energy to chemical energy. In a previous study, we synthesized the hydrogenase/photosystem I (PSI) complex, in which Ralstonia hydrogenase was linked to the cytoplasmic side of Synechocystis PSI, to modify PSI so that it photoproduced molecular hydrogen (H2). In that study, hydrogenase was fused with a PSI subunit, PsaE, and the resulting hydrogenase-PsaE fusion protein was self-assembled with PsaE-free PSI to give the hydrogenase/PSI complex. Although the hydrogenase/PSI complex served as a direct light-to-H2 conversion system in vitro, the activity was totally suppressed by adding physiological PSI partners, ferredoxin (Fd) and ferredoxin-NADP+-reductase (FNR). In the present study, to establish an H2 photoproduction system in which the activity is not interrupted by Fd and FNR, position 40 of PsaE from Synechocystis sp. PCC6803, corresponding to the Fd-binding site on PSI, was selected and targeted for the cross-linking with cytochrome c3 (cytc3) from Desulfovibrio vulgaris. The covalent adduct of cytc3 and PsaE was stoichiometrically assembled with PsaE-free PSI to form the cytc3/PSI complex. The NADPH production by the cytc3/PSI complex coupled with Fd and FNR decreased to approximately 20% of the original activity, whereas the H2 production by the cytc3/PSI complex coupled with hydrogenase from Desulfovibrio vulgaris was enhanced 7-fold. Consequently, in the simultaneous presence of hydrogenase, Fd, and FNR, the light-driven H2 production by the hydrogenase/cytc3/PSI complex was observed (0.30 pmol Hz/mg chlorophyll/h). These results suggest that the cytc3/PSI complex may produce H2 in vivo.     

PROFLAVIN CATALYZED PHOTOPRODUCTION OF HYDROGEN FROM ORGANIC COMPOUNDS

Abstract— Methyl viologen was reduced by EDTA and other organic compounds when aqueous solutions of these compounds were irradiated near 440 nm in the presence of catalytic quantities of proflavin. The photoreduced methyl viologen was readily oxidized in the dark by the enzyme hydrogenase or platinum asbestos. When the entire reaction was run in the light with hydrogenase or platinum, continuous production of hydrogen was observed. The yield of hydrogen was approximately stoichiometric to the EDTA present establishing that methyl viologen and proflavin were acting catalytically. To establish the structural requirements of the electron donor, eighty compounds were tested at seven pH values between 4 and 10. Of these, twenty served as electron donors for the photoproduction of hydrogen. The effective donors contained either a secondary or tertiary nitrogen atom with one or more carboxymethyl or β-hydroxyethyl groups, or a sulfhydryl group. The system could also reduce benzyl viologen but not methylene blue. Riboflavin did not replace proflavin for the photoproduction of hydrogen, This system may have potential for producing hydrogen with solar energy.     

Synthesis, structures and electrochemical properties of nitro- and amino-functionalized diiron azadithiolates as active site models of Fe-only hydrogenases

Complex [[(mu-SCH2)2N(4-NO2C6H4)]Fe2(CO)6] (4) was prepared by the reaction of the dianionic intermediate [(mu-S)2Fe2(CO)6](2-) and N,N-bis(chloromethyl)-4-nitroaniline as a biomimetic model of the active site of Fe-only hydrogenase. The reduction of 4 by Pd-C/H2 under a neutral condition afforded complex [[(mu-SCH2)2N(4-NH2C6H4)]Fe2(CO)6] (5) in 67 % yield. Both complexes were characterized by IR, 1H and 13C NMR spectroscopy and MS spectrometry. The molecular structure of 4, as determined by X-ray analysis, has a butterfly 2Fe2S core and the aryl group on the bridged-N atom slants to the Fe(2) site. Cyclic voltammograms of 4 and 5 were studied to evaluate their redox properties. It was found that complex 4 catalyzed electrochemical proton reduction in the presence of acetic acid. A plausible mechanism of the electrocatalytic proton reduction is discussed.