辣根过氧化物酶在亲水性离子液体中的活性与稳定性研究

基于辣根过氧化物酶对过氧化氢氧化愈创木酚这个显色反应的催化作用,研究了辣根过氧化物酶在七种亲水性离子液体[C2mim][BF4]、[C4mim][BF4]、[C6mim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3、[C4mim][CF3CO2]中的活性与稳定性变化.结果表明辣根过氧化物酶在不同离子液体中均有不同程度的失活,辣根过氧化物酶活性随离子液体极性增强而降低.辣根过氧化物酶在含[C4mim]Cl离子液体的介质中,随着温度升高,[C4mim]Cl对辣根过氧化物酶的失活过程起加速作用,离子液体浓度越高,酶的热稳定性越差.紫外-可见光谱研究表明,在含[Cnmim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3的介质中,辣根过氧化物酶血红素中心最大吸收峰没有发生变化,但吸收值增强,证明离子液体使酶的血红素基团暴露于介质中而增强了吸收;而在含[C4mim][CF3CO2]的介质中,辣根过氧化物酶血红素基团最大吸收峰区发生蓝移,证明有部分血红素基团被离子液体破坏而脱落.     

酸性离子液体的合成和光谱表征

合成了基于N-甲基咪唑、2-吡咯烷酮阳离子的两个Br nsted酸性离子液体系列:[Hmim]HSO4/BF4、[Hnhp]HSO4/BF4以及两种—SO3H功能化酸性离子液体1-(3-磺酸基)丙基-3-甲基咪唑硫酸氢盐([C3SO3Hmim]HSO4)、N-(3-磺酸基)丙基吡咯烷酮硫酸氢盐([C4SO4Hnnp]HSO4)。其中,[Hnhp]HSO4/BF4,[C4SO4Hnnp]HSO4是本实验设计合成的新型酸性离子液体,而咪唑类离子液体用于对照。上述6种离子液体均以核磁共振、电喷雾质谱、红外光谱和紫外光谱分析法对结构加以表征并确认;并以它们作为溶剂和催化剂对乙酸、乙醇酯化反应进行初步试验,结果表明所合成的新型酸性离子液体(尤其是引入磺酸基的)是酯化反应较理想的绿色液体酸催化剂。     

己内酰胺功能化离子液体的合成及其催化酯化性能的研究

以价格低廉的己内酰胺为原料,制备和表征了4种己内酰胺功能化离子液体:1-(3-磺丙基)己内酰胺硫酸氢盐([C3SO3HCP]HSO4)、1-(3-磺丙基)己内酰胺对甲苯磺酸盐([C3SO3HCP]PTSA)、1-(3-磺丙基)己内酰胺磷酸氢盐([C3SO3HCP]H2PO4)、1-(3-磺丙基)己内酰胺四氟硼酸盐([C3SO3HCP]BF4).以乙酸和乙醇的酯化反应考察4种酸性离子液体的催化活性,并与3种具有不同氮杂环的SO3H-功能化离子液体和浓硫酸相对照.结果表明:当n(C2H5OH)∶n(CH3COOH)=1∶1.5,催化剂[C3SO3HCP]HSO4用量为酸醇总质量的5%,反应温度80℃,反应时间6 h,酯收率可达93.8%,离子液体经真空干燥重复使用10次后,仍具有较高的催化活性,而且对奥氏体316 L不锈钢试样的腐蚀率不到浓硫酸的1/6.还考察了以[C3SO3HCP]HSO4为催化剂催化合成系列乙酯也获得了较高的酯收率,且离子液体均能与酯产物自动分相.与传统硫酸催化酯化相比,此类离子液体催化酯化具有生产成本低、过程清洁、腐蚀率低、使用周期长等优点,具有替代传统浓硫酸催化醇酸酯化反应的潜力.     

新型离子液体介质中长链烯烃氢甲酰化反应

合成和表征了离子液体[Rmim][p-CH3C6H4SO3](R=CH3(CH2)n—, n=3, 7, 11, 15), 并以所合成的离子液体为反应介质, 考察了水溶性铑膦络合物HRh(CO)(TPPTS)3[TPPTS: P(m-C6H4SO3Na)3]对长链烯烃氢甲酰化反应的催化性能. 结果表明, 离子液体[Rmim][p-CH3C6H4SO3]中R基团链长的变化对催化活性具有重要的影响；而在相同离子液体中, 氢甲酰化反应活性随着烯烃链长的增加明显下降. 与文献报道中广泛使用的离子液体[Bmim]BF4、[Bmim]PF6相比, 该催化体系对长链烯烃氢甲酰化反应具有更好的活性和化学选择性, 在3.0 MPa, 100 ℃的条件下, 1-己烯氢甲酰化反应转化频率(TOF)高达2736 h-1. 反应完成后, 水溶性铑膦络合物能很好地溶解在离子液体中, 与有机物自动分层, 催化剂的循环使用易于实现.     

咪唑类离子液体中合成β-烯胺酮的研究

本文通过修饰阴阳离子合成了一系列咪唑型离子液体,以β-烯胺酮的合成为反应探针,考察离子液体结构和活性之间的关系。结果表明:阴阳离子对离子液体的活性都有显著的影响。阴离子为BF4-时,阳离子活性顺序为[Hmim]+[bmim]+,[emim]+[bmmim]+,其中[Hmim]BF4作反应介质,反应时间为10min,产率可达96%。当阳离子为[Hmim]+时,阴离子BF4-,Tsa-,Br-和NO3-活性均较高,产率达到93%以上,但阴离子HSO4-显著降低离子液体的活性,反应30min,产物收率仅有60%;阳离子为[bmim]+时,[bmim]Br[bmim]PF6[bmim]BF4,产率达到85%以上;而阴离子为HSO4-和H2PO4-时,离子液体活性变差,收率低于70%。离子液体[Hmim]BF4重复使用5次,β-烯胺酮产率基本不变,反应10min后,仍达89%。     

离子液体介质中钌纳米粒子催化苯乙酮及其衍生物的不对称加氢反应

采用水溶性三(间-磺酸钠苯基)膦(TPPTS)作稳定剂, 在离子液体1-丁基-3-甲基-咪唑四氟硼酸盐([BMIM]BF4)或1-丁基-3-甲基-咪唑对甲基苯磺酸盐([BMIM][p-CH3C6H4SO3])介质中用氢气还原RuCl3·3H2O, 得到钌纳米粒子. 将此钌纳米粒子与(1S, 2S)-1,2-二苯基乙二胺(简称(1S, 2S)-DPEN)、KOH在离子液体/异丙醇介质中原位生成一种不对称加氢催化剂, 用于催化苯乙酮及其衍生物的不对称加氢反应. 实验结果表明, 离子液体介质中的纳米钌催化剂体系具有良好的催化活性和对映选择性. 在优化反应条件下, 催化苯乙酮获得了100%的转化率和79.1%的对映选择性. 并且产物经正己烷萃取后, 含有钌纳米粒子的离子液体可以循环使用.     

多羧基咪唑离子液体的酸性表征

通过电位滴定法测得多羧基咪唑离子液体的离解常数pKa值(25 ℃)在1.43～1.92范围内, 说明多羧基咪唑离子液体酸性接近乙二酸, 比丁二酸以及乙酸强. 由于多羧基咪唑离子液体结构中咪唑环具有较强的吸电子诱导效应, 使多羧基咪唑离子液体具有中等强度的酸性. 三羧基咪唑离子液体酸性比含相同阴离子的二羧基咪唑离子液体酸性强. 阳离子相同、阴离子不同的多羧基咪唑离子液体酸性强弱顺序为: HSO4－ ＞ NO3－ ＞ PF6－ ＞ H2PO4－＞ Cl－、Br－ ＞ CF3CO2－ ＞ BF4－ ＞ CF3SO3－. 同时, 吡啶红外光谱探针法研究表明, 多羧基咪唑离子液体具有Brønsted酸性.     

吡咯烷酮酸性离子液体的合成及其对酯化反应的催化活性

合成并表征了 2-吡咯烷酮硫酸氢盐([Hnhp]HSO4)、 1-甲基-2-吡咯烷酮硫酸氢盐([Hnmp]HSO4)、 1-甲基咪唑硫酸氢盐([Hmim]HSO4)、 1-(3-磺酸基)-丙基-3-甲基咪唑硫酸氢盐([C3SO3Hmim]HSO4)和1-(3-磺酸基)-丙基-2-吡咯烷酮硫酸氢盐([C3SO3Hnhp]HSO4)等以HSO-4为阴离子的质子酸离子液体,并以乙酸和正丁醇的酯化反应考察了这些离子液体的催化活性.结果表明,当n(n-BuOH):n(MeCO2H):n([C3SO3Hnhp]HSO4)=1.2:1:0.005,反应温度为120 ℃和反应时间为 1 h 时,酯收率可达99%以上;反应结束后离子液体与酯产物可分成两相,而且该离子液体重复使用8次,催化活性没有明显下降.探讨了阳离子结构及Brnsted酸性对催化活性的影响,考察了离子液体与酯化反应相关组分的互溶性.结果表明,离子液体的分相性能对催化效果有较大的影响,离子液体的催化活性与其酸性、溶解性密切相关.     

Brønsted酸性离子液体中的二甘醇脱水环化反应

首次报道了Brønsted酸性离子液体介质中的二甘醇的脱水环化反应,考察了不同的离子液体、离子液体/二甘醇摩尔比、反应温度和时间对反应的影响。结果表明,Brønsted酸性离子液体作为反应介质能够促进脱水环化反应的有效进行,且在离子液体1-(3-磺酸根丙基)-3-甲基咪唑硫酸氢盐([SPmim]HSO4)中,二甘醇的转化率和1,4-二氧六环的选择性更高。采用Hammett指示剂法测定了离子液体的酸度函数H0,其酸性强弱顺序为[SPmim]HSO4 > [Bmim]HSO4 > [Amim]HSO4 > [Hmim]BF4> [Bmim]H2PO4 >[Amim]H2PO4 > [Hmim]Tsa,这与离子液体在脱水环化反应中的催化效果一致。当温度为170 ˚C,离子液体/二甘醇摩尔比为1:1时,二甘醇在[SPmim]HSO4中反应2 h,转化率可达到97.0%,1,4-二氧六环的选择性为89.3%。     

酸功能化离子液体催化合成聚缩醛二甲醚

对以酸功能化离子液体[Hnmp]HSO4、[Hnmp]H2PO4、[Hnmp]PTSA和[PyN(CH2)3SO3H]HSO4催化三聚甲醛和甲醇缩合制备聚缩醛二甲醚(PODEn,n1)的反应进行了研究,考察了催化剂用量、物料配比、温度和时间等对反应活性的影响。结果表明,离子液体的催化活性与其酸性相关。[PyN(CH2)3SO3H]HSO4具有较高的催化活性;当[PyN(CH2)3SO3H]HSO4的用量为2.0%、甲醇和三聚甲醛的物质的量比为2.0、反应温度110℃、反应压力2.0 MPa、反应时间6 h时,三聚甲醛的转化率和PODE3~8的选择性分别为97.69%和32.54%。反应结束后,[PyN(CH2)3SO3H]HSO4与产物可自动分成两相。     

离子液体对木瓜蛋白酶催化特性的影响

研究了以1-丁基-3-甲基咪唑、四乙基铵及N-乙基吡啶为阳离子, 配以多种阴离子(H₂PO₄^-, ClO₄^-, HSO₄^-, CH₃COO^-, Cl^-, Br^-, NO₃^-, SCN^-, BF₄^-, PF₆^-)的离子液体对木瓜蛋白酶催化N-苯甲酰-L-精氨酸乙酯(BAEE)水解的活性及热稳定性的影响. 通过分析含离子液体体系中木瓜蛋白酶的水解活性和热力学失活参数, 发现该酶活性及稳定性与离子液体的Kosmotropicity性质无关. 因此, 离子的Hofmeister效应并不适合解释离子液体对木瓜蛋白酶催化特性的影响规律. 当以BF₄^-为阴离子, 改变阳离子结构时, 仅[BMIm][BF₄]可提高酶活性, 其它含官能团的咪唑类离子液体则降低酶活性, 但大部分离子液体明显提高木瓜蛋白酶的热稳定性. 在所研究的离子液体中, 基于PF₆^-或BF₄^-阴离子的离子液体可提高木瓜蛋白酶的活性及其热稳定性. 在含[BMIm][PF₆]介质中, 木瓜蛋白酶的水解活性最高; 在含[HOEtMIm][BF₄]介质中其热稳定性最好.     

Thermodynamic characterization of the biocompatible ionic liquid effects on protein model compounds and their functional groups

The stability of proteins under co-solvent conditions is dependant on the nature of the co-solvent; the co-solvent can alter a protein's properties and structural effects through bimolecular interactions between its functional groups and co-solvent particles. Ionic liquids (ILs) represent a rather diverse class of co-solvents that are combinations of different ions, which are liquids at or close to room temperature. To quantify the bimolecular interactions of protein functional groups with biocompatible ILs, we report the systematic and quantitative apparent transfer free energies (ΔG'(tr)) of a homologous series of cyclic dipeptides (CDs) from water to aqueous solutions of ILs through solubility measurements, as a function of IL concentration at 25 °C under atmospheric pressure. The materials investigated in the present work included the CDs of cyclo(Gly-Gly), cyclo(Ala-Gly), cyclo(Ala-Ala), cyclo(Leu-Ala), and cyclo(Val-Val). The ILs used such as diethylammonium acetate ([Et(2)NH][CH(3)COO], DEAA), triethylammonium acetate ([Et(3)NH][CH(3)COO], TEAA), diethylammonium dihydogen phosphate ([Et(3)NH][H(2)PO(4)], DEAP), triethylammonium dihydogen phosphate ([Et(3)NH][H(2)PO(4)], TEAP), diethylammonium sulfate ([Et(3)NH][HSO(4)], DEAS) and triethylammonium sulfate ([Et(3)NH][HSO(4)], TEAS). We observed positive values of ΔG'(tr) for CDs from water to ILs, indicating that interactions between ILs and CDs are unfavourable, which leads to stabilization of the native structure of CDs. The experimental results were further used for estimating the transfer free energies (Δg'(tr)) of the peptide bond (-CONH-), the peptide backbone unit (-CH(2)C=ONH-), and various functional groups from water to IL solutions. Our results explicitly elucidate that a series of all ammonium ILs act as stabilizers for tested model compounds through the exclusion of ILs from CDs surface.     

New terphenyl based mercury ensemble for detection of acetate ions in a plasma like system

A new terphenyl based chemosensor 3 has been designed and synthesized. The binding behavior of 3 and its chemosensing ensemble 3-Hg toward various anions (F(-), Cl(-), Br(-), I(-), HSO(4)(-), H(2)PO(4)(-), CH(3)COO(-), NO(3)(-), N(3)(-), SO(4)(2-), SO(3)(2-), and Cr(2)O(7)(2-)) has been investigated by UV-Vis, fluorescence and NMR spectroscopy. Compound 3 shows a sensitivity for both F(-) and CH(3)COO(-) ions among various anions tested, whereas the ensemble 3-Hg shows a better selectivity for CH(3)COO(-) ions. The ensemble is utilized for CH(3)COO(-) recognition in a blood plasma like system.     

醋酸铜热解制备无氯Cu2O/AC催化剂及其催化氧化羰基化

以醋酸铜为前驱物, 采用浸渍法负载后进行热处理使醋酸铜热解, 获得了负载型无氯Cu2O/AC(活性炭)催化剂, 并通过催化甲醇直接气相氧化羰基化合成碳酸二甲酯(DMC). 在氮气和惰性气体气氛下, 一水合醋酸铜Cu(CH3COO)2·H2O在30~450 ℃范围内产生3个失重过程, 其中在150~300 ℃范围内Cu(CH3·COO)2热解生成Cu2O; 而在300~450 ℃范围内生成单质Cu. 在200~350 ℃范围内, 将Cu(CH3COO)2·H2O/AC加热处理4 h后, 催化剂上逐步形成了Cu2O, 到350 ℃时, 水合醋酸铜几乎全部转化为Cu2O, 并有极少量单质Cu形成. 在300~350 ℃热处理4 h后, 催化剂中铜主要以Cu2O形式存在, 并表现出良好的氧化羰基化催化活性. 在n(CO)∶n(MeOH)∶n(O2)=4∶10∶1及SV=5600 h-1条件下, 于300 ℃热处理4 h所制备的催化剂的甲醇转化率达到6.21%, DMC的时空收率为128.16 mg·g-1·h-1, 选择性为64.26%.     

Regioselective nucleophilic addition of triphenylphosphine to the nitrosylruthenium alkynyl complexes having a hydrotris(pyrazol-1-yl)borate: formation of phosphonio-alkenyl, alkynyl, and allenyl species

A nitrosylruthenium alkynyl complex of TpRuCl(C[triple bond]CPh)(NO)(1a) was reacted with PPh3 in the presence of HBF4.Et2O at room temperature to give a beta-phosphonio-alkenyl complex (E)-[TpRuCl{CH=C(PPh3)Ph}(NO)]BF4(2.BF4). On the other hand, for gamma-hydroxyalkynyl complexes TpRuCl{C[triple bond]CC(R)2OH}(NO)(R = Me (1b), Ph (1c), H (1d)), similar treatments with PPh3 were found to give gamma-phosphonio-alkynyl [TpRuCl{C[triple bond]CC(Me)2PPh3}(NO)]BF4(3.BF4),alpha-phosphonio-allenyl [TpRuCl{C(PPh3)=C=CPh2}(NO)]BF4(4.BF4), and a novel product of gamma-hydroxy-beta-phosphonio-alkenyl (E)-[TpRuCl{CH=C(PPh3)CH2OH}(NO)]BF4(5.BF4), respectively. Dominant factors for the selectivity in affording 3-5 were associated with the steric congestion and electronic properties at the gamma-carbons, along with those around the metal fragment. From the bis(alkynyl) complex TpRu(C[triple bond]CPh)2(NO)6, a bis(beta-phosphonio-alkenyl)(E,E)-[TpRu{CH=C(PPh3)Ph}2(NO)](BF4)2{7.(BF4)2} was produced at room temperature. However, similar reactions at 0 degrees C gave an alkynyl beta-phosphonio-alkenyl complex (E)-[TpRu(C[triple bondCPh){CH=C(PPh3)Ph}(NO)]BF4(8.BF4) as a sole product, of which additional hydration in the presence of HBF4.Et2O afforded a [small beta]-phosphonio-alkenyl ketonyl (E)-[TpRu{CH2C(O)Ph}{CH=C(PPh3)Ph}(NO)]BF(.9BF4). Five complexes, 2-5 and 7 were crystallographically characterized.     

Nature of urea-fluoride interaction: incipient and definitive proton transfer

1,3-bis(4-nitrophenyl)urea (1) interacts through hydrogen bonding with a variety of oxoanions in an MeCN solution to give bright yellow 1:1 complexes, whose stability decreases with the decreasing basicity of the anion (CH3COO- > C6H5COO- > H2PO4- > NO2- > HSO4- > NO3-). The [Bu4N][1.CH3COO] complex salt has been isolated as a crystalline solid and its molecular structure determined, showing the formation of a discrete adduct held together by two N-H...O hydrogen bonds of moderate strength. On the other hand, the F- ion first establishes a hydrogen-bonding interaction with 1 to give the most stable 1:1 complex, and then on addition of a second equivalent, induces urea deprotonation, due to the formation of HF2-. The orange-red deprotonated urea solution uptakes carbon dioxide from air to give the tetrabutylammonium salt of the hydrogencarbonate H-bond complex, [Bu4N][1.HCO3], whose crystal and molecular structures have been determined.     

Synthesis and reactivity of fluorinated ferracarborane anions

The ferracarborane [N(PPh3)2][6,6,6,10,10,10-(CO)6-closo-6,10,1-Fe2CB7H8] reacts in CH2Cl2 with 3 molar equivalents of Ag[PF6] to yield the trifluoro-substituted species [N(PPh3)2][7,8,9-F3-6,6,6,10,10,10-(CO)6-closo-6,10,1-Fe2CB7H5]. Compound undergoes structural rearrangement in toluene at reflux temperatures, forming [N(PPh3)2][8,9,10-F3-6,6,6,7,7,7-(CO)6-closo-6,7,1-Fe2CB7H5]. Alternatively, reaction of either or with a 10-fold excess of Ag[PF6] in CH2Cl2 forms two species: namely, [N(PPh3)2][2,7,9,10-F4-6,6,6,8,8,8-(CO)6-closo-6,8,1-Fe2CB7H4], in which one further B-F substitution has occurred and the {Fe2CB7} cluster core has rearranged, plus a mono-iron co-product, [N(PPh3)2][3,8,9-F3-7,7,7-(CO)3-closo-7,1-FeCB7H5] that is formed by polyhedral contraction. Treatment of with [NO][BF4] in CH2Cl2 results in CO substitution at the 4-connected iron vertex [Fe10], producing the zwitterionic complex [7,8,9-F3-6,6,6,10,10-(CO)5-10-NO-closo-6,10,1-Fe2CB7H5]. Addition of Me3NO to a mixture of and PEt3 in CH2Cl2 also results in CO substitution, forming the isomeric species [N(PPh3)2][7,8,9-F3-6,6,m,10,10-(CO)5-n-PEt3-closo-6,10,1-Fe2CB7H5] [m=6, n=10; m=10, n=6] in a 5:1 ratio. Treatment of with [NO][BF4] and then CNBut in CH2Cl2 allows further, successive CO substitution at Fe10 to yield first a neutral, zwitterionic complex [7,8,9-F3-6,6,6,10-(CO)4-10-NO-10-PEt3-closo-6,10,1-Fe2CB7H5] and then [7,8,9-F3-6,6,6-(CO)3-10-CNBut-10-NO-10-PEt3-closo-6,10,1-Fe2CB7H5]. The molecular structures of compounds and have been established by X-ray diffraction.     

含二茂铁基的酰氧基二-(甲基环戊二烯基)钛衍生物的合成和性能研究

本文合成了十种新的含二茂铁基的酰氧基二-(甲基环戊二烯基)钛(η^5-CH~3C~5H~4)~2TC~2-nYn(Y=二茂铁羧酸基)。进行了元素分析, 讨论了它们的紫外和红外光谱, 及核磁共振谱。     

A new family of chelating diphosphines with a transition metal stereocenter in the backbone: novel applications of "chiral-at-rhenium" complexes in rhodium-catalyzed enantioselective alkene hydrogenations

The title compounds are accessed by sequences starting with racemic and enantiomerically pure [(eta5-C5H5)Re(NO)(PPh3)(CH3)]. Reactions with chlorobenzene/HBF4, PPh2H, and tBuOK give the phosphido complex [(eta5-C5H5)Re(NO)(PPh3)(PPh2)] (3). Reactions with Ph3C+ BF4-, PPh2H, and tBuOK give the methylene homologue [(eta5-C5H5)Re(NO)(PPh3)(CH2PPh2)] (9). Treatment of 3 or 9 with nBuLi or tBuLi and then PPh3Cl gives the diphosphido systems [(eta5-C5H4PPh2)Re(NO)(PPh3)((CH2)nPPh2)] (n = 0/1, 5/11). Reactions of 5 and 11 with [Rh(NBD)Cl]2/AgPF6 (NBD = norbornadiene) give the rhenium/rhodium chelate complexes [(eta5-C5H4PPh2)Re(NO)(PPh3)((mu-CH2)nPPh2)Rh(NBD)]+ PF6- (n = 0/1, 6+/12+ PF6-; 30-32% overall from commercial Re2(CO)10). The crystal structures of 6+ PF6- and 12+ PF6- are compared to those of 3 and 9, and other rhodium complexes of chelating bis(diphenylphosphines). The chiral pockets defined by the PPh2 groups show unusual features. Four alkenes of the type (Z)-RCH=C(NHCOCH3)CO2R' are treated with H2 (1 atm) and (R)-6+ PF6- or (S)-12+ PF6- (0.5 mol%) in THF at room temperature. Protected amino acids are obtained in 70-98% yields and 93-82% ee [(R)-6- PF6-] or 72-60% ee [(S)-12+ PF6-]. Pressure and temperature effects are defined, and turnover numbers of > 1600 are realized.