Effects of Cyclopentadienyl and Phosphine Ligands on the Basicities and Nucleophilicities of Cp'Ir(CO)(PR(3)) Complexes

Basicities of the series of complexes CpIr(CO)(PR(3)) [PR(3) = P(p-C(6)H(4)CF(3))(3), P(p-C(6)H(4)F)(3), P(p-C(6)H(4)Cl)(3), PPh(3), P(p-C(6)H(4)CH(3))(3), P(p-C(6)H(4)OCH(3))(3), PPh(2)Me, PPhMe(2), PMe(3), PEt(3), PCy(3)] have been measured by the heat evolved (DeltaH(HM)) when the complex is protonated by CF(3)SO(3)H in 1,2-dichloroethane (DCE) at 25.0 degrees C. The -DeltaH(HM) values range from 28.0 kcal/mol for CpIr(CO)[P(p-C(6)H(4)CF(3))(3)] to 33.2 kcal/mol for CpIr(CO)(PMe(3)) and are directly related to the basicities of the PR(3) ligands in the complexes. For the more basic pentamethylcyclopentadienyl analogs, the -DeltaH(HM) values range from 33.8 kcal/mol for the weakest base CpIr(CO)[P(p-C(6)H(4)CF(3))(3)] to 38.0 kcal/mol for the strongest CpIr(CO)(PMe(3)). The nucleophilicities of the Cp'Ir(CO)(PR(3)) complexes were established from second-order rate constants (k) for their reactions with CH(3)I to give [Cp'Ir(CO)(PR(3))(CH(3))](+)I(-) in CD(2)Cl(2) at 25.0 degrees C. There is an excellent linear correlation between the basicities (DeltaH(HM)) and nucleophilicities (log k) of the CpIr(CO)(PR(3)) complexes. Only the complex CpIr(CO)(PCy(3)) with the bulky tricyclohexylphosphine ligand deviates dramatically from the trend. In general, the pentamethylcyclopentadienyl complexes react 40 times faster than the cyclopentadienyl analogs. However, they do not react as fast as predicted from electronic properties of the complexes, which suggests that the steric size of the Cp ligand reduces the nucleophilicities of the CpIr(CO)(PR(3)) complexes. In addition, heats of protonation (DeltaH(HP)) of tris(2-methoxyphenyl)phosphine, tris(2,6-dimethoxyphenyl)phosphine, and tris(2,4,6-trimethylphenyl)phosphine were measured and used to estimate pK(a) values for these highly basic phosphines.     

Highly efficient Beckmann rearrangement and dehydration of oximes

Under mild conditions, Beckmann rearrangement of a variety of ketoximes could proceed in the presence of chlorosulfonic acid using toluene as a solvent with excellent conversion and selectivity. This procedure could also be applied in the dehydration of aldoximes for obtaining the corresponding nitriles.     

QSAR Studies on the COX-2 Inhibition by 3,4-Diarylcycloxazolones Based on MEDV Descriptor

Selective inhibition of cyclooxygenase-2 (COX-2) might avoid the side effects of current available nonsteroidal antiinflammatory drugs while retaining their therapeutic efficacy. A novel variable selection and modeling method based on prediction is developed to construct the quantitative structure-activity relationships (QSAR) between the molecular electronegativity distance vector (MEDV) based on 13 atomic types and the biological activities of a set of selective cyclooxygenase-2 inhibitory molecules, 3,4-diarylcycloxazolones (DAA) plus indomethacin,naproxen, and celecoxib. Using multiple linear regression, a 5-variable linear model is developed with the calibrated correlation coefficient of 0.9271 and root mean square error of 0.17 in modeling stage and the validated correlation coefficient of 0.9030 and root mean square error of 0.20 in leave-one-out validation step, respectively. To further test the predictive ability of the model, 20 DAA compounds are picked up to construct a training set which is used to build a QSAR model and then the model is employed to predict the biological activities of the balance compounds. The predicted correlation coefficient and root mean square error are 0.9332 and 0.19, respectively.     

聚乙二醇嵌段树枝状聚赖氨酸共聚物的合成及其基因载体研究

采用液相多肽合成法制备得到窄分子量分布、结构可控的生物相容性聚乙二醇嵌段共聚树枝状聚赖氨酸阳离子功能大分子(PEG-b-Dendritic PLL). 运用¹H NMR核磁共振、凝胶电泳以及荧光淬灭滴定手段对所得阳离子两嵌段大分子的化学结构及其与质粒DNA (pDNA)结合作用与复合行为进行了研究. 结果表明聚乙二醇嵌段树枝状聚赖氨酸与pDNA分子可以在缓冲溶液中形成稳定的胶束, pDNA与阳离子树枝赖氨酸嵌段通过静电相互作用形成胶束核, 其水溶性聚乙二醇嵌段形成水溶性胶束壳, 提高了阳离子大分子/pDNA复合胶束的稳定性. 同时发现随着阳离子嵌段树枝状赖氨酸代数的增加, 阳离子两嵌段大分子与pDNA的结合作用增强, 有利于其作为基因转染生物功能载体的应用.     

多枝[1,3,4]-噁二唑衍生物的双光子吸收和光功率限幅特性

采用非线性透过率法测定了多枝[1,3,4]-噁二唑衍生物的双光子吸收性质. 测定了化合物的单光子荧光光谱和双光子荧光光谱, 在800 nm波长的激光激发下, 9-乙基-3,6-双{5-(4-叔丁基苯基)-[1,3,4] 噁二唑-2-苯乙烯基}-咔唑(3)和三-{5-(4-叔丁基苯基)-[1,3,4] 噁二唑-2-苯乙烯基-4-苯基}-胺(4)能够发出很强的蓝色和黄绿色双光子上转换荧光, 荧光峰分别位于485和547 nm. 这些多枝结构化合物的双光子吸收截面较大(数值超过104 GM), 并具有很强的光限幅效应. 多枝分子中重复单元的推拉电子结构和协同效应有效地增强了分子的双光子吸收性质.     

超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查染发剂中32种染料成分

建立了超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查和分析染发剂中32种禁限用染料的分析方法。样品经甲醇-2 g/L抗坏血酸水溶液溶解提取,正己烷净化,用ZORBAX Eclipse Plus C_(18)(3.0 mm×100 mm,1.8μm)色谱柱分离,以甲醇-5 mmol/L乙酸铵水溶液为流动相进行梯度洗脱,采用正、负离子切换同时测定了32种染料成分,显著提高了检测通量。以全扫描模式下提取的保留时间和一级母离子精确质量数以及同位素丰度比,实现对染发剂中多种染料成分的快速筛查;以自动触发采集的二级碎片离子精确质量数进行确证。32种染料在相应的质量浓度范围内线性关系良好,相关系数(r~2)均大于0.99;定量下限(LOQ)为0.2～40μg/g,回收率为81.0%～110%,相对标准偏差(RSD)为3.3%～9.9%。该方法简单、准确、快速,适用于染发剂中多种禁限用染料成分的高通量快速定性筛查和定量分析。     

高铁酸钾氧化脱除模拟轻质油中的含硫化合物

考察了K2FeO4对模拟轻质油中苯并噻吩（BT）及二苯并噻吩（DBT）的氧化性能。结果表明，水相中K2FeO4对BT、DBT的氧化活性比较低，水的存在使K2FeO4水解成黄色的Fe(OH)3而失去氧化有机硫化物的能力；在冰乙酸反应介质中，K2FeO4对BT及DBT的氧化活性有了明显的提高；固体催化剂KM的加入显著提高了乙酸反应介质中K2FeO4对BT及DBT的氧化活性。常温、常压，醋酸/模拟油体积比为1.0，K2FeO4/S摩尔比为1.0，KM/K2FeO4质量比为1.0的条件下，DBT的转化率达98.4%，BT的转化率为70.1%。     

纳米金刚石粉酸处理前后性能结构的表征

自从1963年爆炸法合成纳米金刚石[1]以来,纳米金刚石已在科研和工业领域得以广泛应用.但是工业合成的纳米金刚石粉由于其工艺的限制存在一些杂质,其中主要包括纳米石墨、非晶碳和爆炸过程中产生的金属离子.因此,在实际科研工作前对纳米金刚石粉进行纯化处理就显得十分重要,以往的研究表明不同的处理方法各有利弊[2].在以下的研究中,我们采用盐酸消解的方法对商业购买的纳米金刚石粉进行纯化处理,通过对比纯化处理前后的IR、Raman以及ICP表征,分析讨论了酸处理方法的纯化效果.     

氢化喹啉及其芳(杂)环稠合衍生物的合成

通过环己二酮与β-二腈基苯乙烯的Michael加成得到2-氨基-3-氰基-4-芳基-5-氧代-1,4,5,6,7,8-六氢喹啉(1); 4-苯基六氢喹啉(1a)与环己二酮发生胺的加成缩合反应生成2-N-(3-氧代-1-环己烯基)氨基-3-氰基-4-苯基-5-氧代-1,4,5,6,7,8-六氢喹啉(2), 在碱性和氯化亚铜催化下进一步环合成4-苯基-5-氨基-二-(2-氧代环己烷)并[b,g]-1,3-二氢萘啶(3). 芳醛、α-萘胺和环己二酮在乙醇中共回流, 则一锅法完成9-芳基-5,6,7,8,9,10-六氢苯并[c]吖啶酮(4)的合成. 对合成中所涉及的化学反应机理进行了尝试性的讨论. 新化合物1a～4c均经IR, ¹H NMR 及元素分析证明其结构.     

NaNO2/FeSO4存在下聚苯乙烯大分子引发剂的合成及嵌段共聚

用NaNO2/FeSO4·7H2O体系替代TEMPO在有机相中合成分子量可控的聚苯乙烯大分子引发剂,引发苯乙烯聚合及酯类单体[如甲基丙烯酸甲酯(MMA)、丙烯酸甲酯(MA)和丙烯酸乙酯(EA)等]聚合,得到两嵌段共聚物.其多分散性指数小于1.5,体现了可控聚合的特征.用大分子引发剂引发苯乙烯进行活性链增长,单体的转化率较高.嵌段共聚物的实测分子量与理论分子量相近,结构经1HNMR和GPC表征.NaNO2/FeSO4·7H2O体系在纯有机相中的应用降低了活性聚合的成本,有利于工业化应用.