海萤荧光素衍生物发光反应关键步骤的理论研究

用不同取代基对化学发光物质6-芳基-2-甲基咪唑[1,2-α]吡嗪-3-(7H)酮环(海萤发光的类似物)的芳基位进行取代,形成系列海萤荧光素类似物MIPa-MIPd;并采用B3LYP/6-311+G(d,p)方法,通过电子抽取能(EEP)的计算和自然电荷布居分析(NPA),研究了在气相、二甲亚砜(DMSO)和二甘醇二甲醚(DG)中海萤发光的类似物从阴离子变化到自由基过程中取代基的作用.结果表明:在这个过程中,吲哚在DG中作为取代基(MIPb)时的EEP最小,电荷变化最大,说明这种取代基有利于反应的进行.     

杀螟丹中间体与异构体互变[JZ]异构理论研究

研究了合成杀虫剂杀螟丹的关键中间体2-N,N-二甲胺基-1,3-二硫氰基丙烷(有效体)及其异构体1-N,N-二甲胺基-2,3-二硫氰基丙烷(无效体)互变异构反应中溶剂和温度的影响. 采用密度泛函理论B3LYP/6-31G(d)方法研究了其在气相中的反应机理, 确定了相应的过渡态和反应活化能. 量子化学计算结果表明, 反应首先通过分子内亲核取代环化生成吖丙啶鎓盐活性中间体, 硫氰基进攻N-三元环中间体过程中发生了分子内重排转位, 转化为异构体. 采用极化连续(Polarizable continuum model, PCM)模型研究了反应体系在甲苯、氯仿、丙酮、乙醇、甲醇、乙腈和DMSO溶液中的溶剂效应. 结果表明, 该重排反应溶剂化效应非常明显, 极性溶剂有利于过渡态的稳定, 降低反应活化能, 提高反应速率. 理论研究结果与实验观察结果相符, 很好地解释了有关实验现象.     

反-4-(4-R-苯乙烯基)吡啶光二聚反应的研究

通过反-4-(4-R-苯乙烯基)吡啶[R=H(Ⅰa),Me(Ⅰb),OMe(Ⅰc),OH(Ⅰd),Me2N(Ⅰe)］在稀盐酸中的光二聚反应合成了4个r-1,c-2,t-3,t-4-1,3-双(4-R-苯基)-2,4-二(4-吡啶基)环丁烷[R=H(Ⅱa),Me(Ⅱb),OMe(Ⅱc),OH(Ⅱd)］,除Ⅱa外,其余为新化合物.光二聚反应具有高度立体选择性且几乎是定量完成的.研究发现,随着取代基供电子能力的提高,光二聚反应速率下降.反应的高度立体选择性以及该反应不受空气中氧气影响的事实表明光二聚反应是按激发单重态历程进行的.研究还发现Ⅰa～Ⅰd在有机溶剂中主要发生反-顺异构化反应,随着溶剂极性增加,反-顺异构化速度加快,表明其反-顺异构化反应亦经激发单重态历程.本文检测到了Ⅰa在稀盐酸溶液中的激基缔合物荧光.     

二苯甲酰甲烷互变异构反应机理溶剂效应的理论研究

采用密度泛函B3LYP方法,在6-31+G(d,p)基组水平上对二苯甲酰甲烷质子转移引起的酮式-烯醇式互变异构反应机理进行了计算研究,获得了零点能、总能量、吉布斯自由能及质子转移过程的反应焓、活化能、活化吉布斯自由能和速率常数等参数.3种非质子溶剂中的优化和频率计算采用Onsager模型进行计算.计算结果表明,不论在气相还是3种溶剂中,二苯甲酰甲烷的烯醇式较酮式稳定,烯醇式向酮式气相转变需要较高的活化能垒,在不同极性的溶剂中,随着溶剂介电常数的增大,异构化反应活化能垒减小,反应速率常数增大.     

取代1-吲酮的α-溴代反应

从取代3-苯丙酸出发,在多聚磷酸中直接环合(或先生成酰氯,再以三氯化铝催化环合)得到12个取代1-吲酮(Ⅰa~Ⅰl)。Ⅰ10 mmol溶于40 mL混合溶剂[V(乙酸乙酯)∶V(氯仿)=1∶1]中,搅拌下回流,分3批加入溴化铜(60%,24%和16%),经α-溴代反应得取代2-溴-1-吲酮(Ⅱa~Ⅱl,其中Ⅱf,Ⅱj,Ⅱk和Ⅱl未见文献报道),收率67.2%~91.5%。新化合物的结构经1H NMR确证。     

1-卤代-3-甲基-3-羟基辛烯-1及其衍生物的合成

在三氯化铝存在下,将己酰溴与乙炔反应,得到了氯代反式辛烯-1-酮-3(Ⅰc),并推测了反应历程。氯代辛烯酮(Ⅰc)可在戊酮-2或甲基异丁基酮中与溴化锂发生交换反应,得溴代辛烯酮(Ⅰd),此物与甲基溴化镁进行格氏反应,再用二氢吡喃或三甲基氯硅烷保护羟基,得相应的四氢吡喃醚(Ⅱd)或硅醚(Ⅱe),并拟用1,4-加成方法将其引入取代的环戊烯酮中作为15-甲基前列腺素的侧链。     

4(3H)-嘧啶酮及其类似物互变异构的理论研究

采用密度泛函理论,在B3LYP/6-311G**基组水平上,计算并考察了4(3H)-嘧啶酮及其类似物(5-氟-4(3H)-嘧啶酮、4-巯基嘧啶和5-氟-4-巯基嘧啶)醇式结构和酮式结构进行结构互变质子迁移过程中的2种可能途径:(a)分子内质子迁移;(b)水助质子迁移.计算结果表明,途经b所需要的活化能较小.研究还表明,氢键在降低反应活化能方面起着重要的作用.     

二甲基亚砜在锂二次电池中的应用

采用二甲基亚砜(DMSO)作为锂二次电池的电解液, 研究了锂在DMSO中的沉积形貌和循环效率. 比较了六氟磷酸锂(LiPF₆)在DMSO、 碳酸丙烯酯(PC)和1,3-二氧环戊烷(DOL)3种溶剂中的沉积形貌和循环效率, 并研究了LiPF₆、 四氟硼酸锂(LiBF₄)、 高氯酸锂(LiClO₄)和二(三氟甲基磺酰)亚胺锂(LiTFSI)4种锂盐在DMSO中的沉积形貌和循环效率. 结果表明, 锂在DMSO中沉积得到的表面光滑平整且致密均匀, 循环效率在前10周要高于在PC中的, 溶剂DMSO有望用于金属锂二次电池中.     

锗苯与亲二烯体的Diels-Alder反应的理论研究

采用密度泛函理论方法在B3LYP/6-311G(d,p)水平上研究了锗苯与一些亲二烯体的Diels-Alder反应的微观机理和势能剖面, 考察了取代基和苯溶剂对反应势能剖面的影响, 探讨了杂Diels-Alder反应中区域选择性的起源. 计算结果表明, 所研究反应均以协同的方式进行. 亲二烯体分子碳原子上的苯基取代基对杂Diels-Alder反应中2个新键形成的非同步性和活化能垒的影响与最终产物中苯基和锗原子间的相对位置有关, 锗苯分子中锗原子上的CCl3取代基在热力学和动力学上均有利于反应的进行. 苯溶剂对所研究反应的势能剖面影响较小. 实验观察到的杂Diels-Alder反应的区域选择性由动力学因素所控制.     

1,4-二氮杂二环[2.2.2]辛烷(DABCO)催化联烯的[4+2]串联反应:合成苯并噻吩并吡喃衍生物（英文）

发展了1,4-二氮杂二环[2.2.2]辛烷(DABCO)催化硫代橙酮类似物与联烯酸酯之间的串联环化反应,以甲醇为溶剂,以较好的选择性和收率获得两类苯并噻吩并吡喃衍生物.同时,该反应条件温和、底物适应性广,吸电子基或供电子基取代的硫代橙酮类似物都能以较好的选择性和收率生成目标产物.该反应为苯并噻吩并吡喃衍生物的合成提供了一种便利的方法.     

Identification of 3-enol sulfate of Cypridina luciferin,Cypridina luciferyl sulfate,in the sea-firefly Cypridina (Vargula) hilgendorfii

Cypridina luciferin from the luminous ostracod Cypridina (Vargula) hilgendorfii has an imidazopyrazinone core structure (3,7-dihydroimidazopyrazin-3-one), which is identical to that of coelenterazine. Cypridina luciferyl sulfate (3-enol sulfate of Cypridina luciferin) was isolated for the first time and the chemical structure was identified by LC/ESI–TOF–MS analysis. Furthermore, Cypridina luciferyl sulfate was chemically synthesized, and its absorption and MS/MS spectra were in agreement with that of Cypridina luciferyl sulfate isolated. Using the crude extracts of Cypridina specimens, Cypridina luciferyl sulfate could be converted to Cypridina luciferin in the presence of adenosine 3′,5′-diphosphate (PAP), and Cypridina luciferin was converted to Cypridina luciferyl sulfate in the presence of 3′-phosphoadenosine 5′-phosphosulfate (PAPS). These results suggested that a sulfotransferase catalyzes the reversible sulfation of Cypridina luciferin in Cypridina hilgendorfii. In aqueous solution, Cypridina luciferyl sulfate was more stable than Cypridina luciferin and might be a storage form of Cypridina luciferin.     

Luciferins, bioluminescent substances

The bioluminescence of the American firefly Photinus is due to the reaction of 2-(6-hydroxybenzothiazol-2-yl)-Δ²-1,3-thiazoline-4-carboxylic acid (“firefly luciferin”) with the enzyme luciferase in the presence of ATP and magnesium ion. In the crustacean Cypridina, on the other hand, the bioluminescence is due to the reaction of a luciferase with 8-(3-guanidinopropyl)-6-indol-3-yl-2-(1-methylpropyl)-3,7-dihydroimidazo[1,2-a]-pyrazin-3-one (“Cypridina luciferin”). The luciferin in Latia is 1,3,3-trimethyl-2-(4-formyloxy-3-methyl-3-butenyl)-1-cyclohexene and that in Renilla is a tryptamine derivative that has not yet been accurately identified; the luciferins of other luminescent organisms are not yet known. A review is given of the investigations which have been carried out on the above luciferins and the course of the luciferin-luciferase reaction is examined. Numerous spectral data obtained during the examination of these compounds are included in the text.     

Enzymatic Conversion of Cypridina Luciferyl Sulfate to Cypridina Luciferin with Coenzyme A as a Sulfate Acceptor in Cypridina (Vargula) hilgendorfii

In the luminous ostracod Cypridina (presently Vargula) hilgendorfii, Cypridina luciferyl sulfate (3‐enol sulfate of Cypridina luciferin) is converted to Cypridina luciferin by a sulfotransferase with 3′‐phosphoadenosine‐5′‐phosphate (PAP) as a sulfate acceptor. The resultant Cypridina luciferin is used for the luciferase–luciferin reaction of Cypridina to emit blue light. The luminescence stimulation with major organic cofactors was examined using the crude extracts of Cypridina specimens, and we found that the addition of coenzyme A (CoA) to the crude extracts significantly stimulated luminescence intensity. Further, the light‐emitting source in the crude extracts stimulated with CoA was identified as Cypridina luciferyl sulfate, and we demonstrated that CoA could act as a sulfate acceptor from Cypridina luciferyl sulfate. In addition, the sulfate group of Cypridina luciferyl sulfate was also transferred to adenosine 5′‐monophosphate (5′‐AMP) and adenosine 3′‐monophosphate (3′‐AMP) by a sulfotransferase. The sulfated products corresponding to CoA, 5′‐AMP and 3′‐AMP were identified using mass spectrometry. This is the first report that CoA can act as a sulfate acceptor in a sulfotransferase reaction.     

Identification of the biosynthetic units of Cypridina luciferin in Cypridina (Vargula) hilgendorfii by LC/ESI-TOF-MS

In a luminous ostracod Cypridina (Vargula) hilgendorfii, Cypridina luciferin with an imidazopyrazinone structure (3,7-dihydroimidazopyrazin-3-one) is utilized for the luminescence reaction. To identify the biosynthetic units of Cypridina luciferin, the stable isotope labeled compounds were examined by feeding experiments with living Cypridina specimens. The incorporation of the labeled compounds into Cypridina luciferin was identified by the method of LC/ESI-TOF-MS analyses and these results suggested that l-tryptophan, l-arginine and l-isoleucine are structural units of Cypridina luciferin.     

Syntheses and evaluation of the bioluminescent activity of (S)-Cypridina luciferin and its analogs

Cypridina luciferin is the substrate in the bioluminescence of a luminous ostracod Cypridina (Vargula) hilgendorfii. Cypridina luciferin contains a chiral center in the sec-butyl moiety. Here, we report a convenient method for the preparation of (S)-Cypridina luciferin by the condensation of (S)-1,1-diethoxy-3-methylpentan-2-one with ethioluciferin. The light yield of the synthesized (S)-luciferin in the presence of Cypridina luciferase was about 1.7 times as active as that of racemic form. Furthermore, several luciferin analogs prepared by the same condensation with different α-ketoacetal derivatives showed moderate light yield with Cypridina luciferase. These readily available Cypridina luciferin and analogs are applicable to the bioluminescent detection of Cypridina luciferase.     

Chemiluminescence of 6-aryl-2-methylimidazo[1,2-a]pyrazin-3(7H)-ones in DMSO/TMG and in diglyme/acetate buffer: support for the chemiexcitation process to generate the singlet-excited state of neutral oxyluciferin in a high quantum yield in the Cypridina (Vargula) bioluminescence mechanism

The chemiluminescence of 6-aryl-2-methylimidazo[1,2-a]pyrazin-3(7H)-ones (Cypridina luciferin analogues) in DMSO/1,1,3,3-tetramethylguanidine and in diglyme/acetate buffer was investigated. The results indicate that the reaction mechanism that produces a high chemiluminescence quantum yield involves a chemiexcitation process from a neutral dioxetanone intermediate possessing an electron-donating aryl group (σ_Ar <−0.6) to the singlet-excited state of neutral acetamidopyrazine. This result may be applied to the reaction mechanism for Cypridina (Vargula) bioluminescence.     

Mechanically Assisted Bioluminescence with Natural Luciferase

Mechanochemical analogues have recently been established for several enzymatic reactions, but they require periodic interruption of the reaction for sampling, dissolution, and (bio)chemical analysis to monitor their progress. By applying a mechanochemical procedure to induce bioluminescence analogous to that used by the marine ostracod Cypridina (Vargula) hilgendorfii, here we demonstrate that the light emitted by a bioluminescent reaction can be used to directly monitor the progress of a mechanoenzymatic reaction without sampling. Mechanical treatment of Cypridina luciferase with luciferin generates bright blue light which can be readily detected and analyzed spectroscopically. This mechanically assisted bioluminescence proceeds through a mechanism identical to that of bioluminescence in solution, but has higher activation energy due to being diffusion‐controlled in the viscous matrix. The results suggest that luciferases could be used as light‐emissive reporters of mechanoenzymatic reactions.     

酰胺多胺配体Cu(Ⅱ)配合物的稳定性和酸分解动力学

合成了酰胺多胺配体(L),测定了5,10,15和25℃时其Cu(Ⅱ)配合物的稳定常数,用标准摩尔焓变ΔHm0和标准摩尔熵变ΔSm0解释了温度对稳定性的影响,并利用停流技术(Stopped-flow)研究了CuL配合物在0.04～2.3mol/L(I=2.34mol/LNaCl)盐酸溶液中的酸分解动力学.提出了反应机理,并求得了速控步骤的活化能Ea,标准摩尔活化熵Δ≠Sm0和标准摩尔活化焓Δ≠Hm0     

Theoretical study on the gas phase reaction of dimethyl sulfoxide with atomic chlorine in the presence of water

We have investigated theoretically the gas phase reactions of dimethyl sulfoxide (DMSO) with atom Cl in the absence and presence of a single water molecule. The calculations of the potential energy surfaces in the water-free and water-assisted along the different channels are performed at the CCSD(T)/6-311++G(2df,2p)//MP2/6-31G(d) level. The calculated results show that energy barriers of the H_c-abstraction reaction are reduced due to one water molecule added. The computed rate constants of H_c-abstraction reaction indicate that the reaction with water is faster than the value of the naked reaction. However, H_a-abstraction reaction, path2, path3, and path4 are slower without water than hydrous channels.