含杂环并具有高自旋基态的双自由基体系的理论设计

以—·N—O—为自旋中心(SC),间苯为铁磁耦合单元(FC),苯、吡啶、哒嗪、嘧啶、吡嗪、三嗪为端基(EG),设计一系列新型稳定高自旋分子.另外以—·N—O—为SC,苯、吡啶、哒嗪、嘧啶、吡嗪、三嗪为FC,苯为EG,又设计另一系列新型稳定高自旋分子,并通过AM1—CI方法计算,研究了不同杂环作为端基或耦合单元对高自旋分子自旋多重度稳定性的影响.     

含嘧啶氨基的三氨基取代三嗪衍生物的设计、合成及抗苹果树腐烂病菌活性

依据三嗪和嘧啶衍生物的抗菌特性以及生物活性叠加原理, 以三聚氯氰为起始原料, 设计、合成了系列新的含嘧啶氨基的2,4,6-三氨基取代-1,3,5-三嗪化合物. 化合物的结构经1H NMR, ESI-MS和元素分析等表征. 化合物的抗苹果树腐烂病菌活性测试结果表明, 大部分化合物对苹果树腐烂病菌具有显著的抑制作用, 如化合物2aa, 2ba, 2ca, 2da, 3ba和3ea在200 μg/mL浓度下的抑制率分别为96.33%, 98.17%, 97.25%, 97.71%, 98.39%和94.50%, 在100 μg/mL浓度下的抑制率也均在74%以上.     

强碱性阴离子交换树脂对水中磺胺二甲基嘧啶的吸附特性

以强碱性阴离子交换树脂作为吸附剂,对模拟废水中的磺胺二甲基嘧啶进行吸附实验。静态吸附实验结果表明,温度为25℃,p H=7,磺胺二甲基嘧啶的初始浓度为10mg/L,吸附平衡时间为40min的条件下,强碱性阴离子交换树脂对磺胺二甲基嘧啶的吸附量为0.244mg/g。经准二级动力学方程拟合出的qe为0.263mg/g与实验所得值0.244mg/g接近,且相关系数R~2=0.9991,能较好地描述强碱性阴离子交换树脂对SM2的吸附行为。通过Langmuir吸附模型拟合的qm为0.274mg/g,与实验值更接近,且R~2=0.9972。吸附动力学和吸附热力学的分析表明,强碱性阴离子交换树脂对磺胺二甲基嘧啶的吸附行为是物理吸附为主的单分子层吸附。而动态吸附实验结果表明,当温度为25℃,p H=7,磺胺二甲基嘧啶的初始浓度为10mg/L时,动态吸附穿透时间为250min,吸附饱和时间为670min,动态吸附过程中强碱性阴离子交换树脂对磺胺二甲基嘧啶的最大吸附量为0.231mg/g。     

嘧啶并嘧啶类化合物的合成研究进展

综述了近几十年来在医药和农药领域具有广泛用途的嘧啶并嘧啶类化合物的合成研究进展,介绍了三大类嘧啶并嘧啶类化合物的主要结构类型:嘧啶并[1,2-a]嘧啶类化合物、嘧啶并[4,5-d]嘧啶类化合物、嘧啶并[5,4-d]嘧啶类化合物的相关合成方法及新进展.     

嘧啶类化合物的合成及抗菌活性研究进展

嘧啶类化合物因其广泛的生物活性在医药、农药等领域备受关注. 将不同基团引入嘧啶结构中, 经过结构修饰能产生一系列具有抗菌活性的嘧啶衍生物, 它在新型农药创制中发挥着越来越重要的作用. 对嘧啶类化合物的合成及杀菌活性的研究进行了分类综述, 并展望了它的发展趋势和应用前景.     

TiO_2光催化降解胸腺嘧啶的动力学和机理（英文）

考察了用于降解来自嘧啶家族的一种核酸—胸腺嘧啶(C5H6N2O2)的高级氧化过程.结果发现,在光催化剂TiO2作用下,胸腺嘧啶的光降解进行得很快,且在紫外光照射和水溶液中时更为明显.研究了胸腺嘧啶在TiO2催化剂上的吸附、降解动力学、以及pH值对光催化降解胸腺嘧啶性能的影响.另外,考察了胸腺嘧啶降解产物的矿化;比较和讨论了在光催化过程中胸腺嘧啶的消失和矿化速率.同时还研究了氮的矿化,确立了中间产物的识别方法.最后,采用电子密度计算提出了在紫外光照射下TiO2催化剂上胸腺嘧啶降解的可能化学途径.     

Ti基电极上光化学沉积Hg用于吸附溶出伏安法测定磺胺嘧啶

该研究发现采用紫外光照射钛电极表面氧化钛层能够光催化还原Hg2+生成Hg微粒,在Ti基电极上光化学沉积Hg比电化学沉积Hg对磺胺嘧啶具有更强的吸附作用,基于光化学沉积Hg/Ti电极建立了一种吸附溶出伏安法测定磺胺嘧啶的方法.详细考察了溶液pH值、吸附富集时间、溶出起始电位、扫描速率等对测定的影响.结果表明,在pH 2.0 的B-R缓冲溶液中,磺胺嘧啶在0.48 V左右处产生1个灵敏的氧化峰,其峰电流与磺胺嘧啶的浓度在1.2×10-8～1×10-6 mol/L范围内呈良好的线性关系(r=0.997 2),检出限达4.35 nmol/L.     

取代基对腺嘌呤与胸腺嘧啶氢键复合物体系结合能的影响

优化得到了17个取代胸腺嘧啶与腺嘌呤形成的氢键复合物的结构, 并计算了这些复合物的结合能, 探讨了胸腺嘧啶上不同取代基对结合能的影响. 结果表明, CF₃取代的胸腺嘧啶与腺嘌呤间的结合能大于胸腺嘧啶与腺嘌呤间的结合能, 这可能是屈氟尿苷具有阻止病毒及肿瘤扩散功能的原因所在. SO₃H, CN和NO₂取代的胸腺嘧啶与腺嘌呤间具有更大的结合能, 表明这3个基团取代的胸腺嘧啶也可能具有潜在的抗肿瘤作用. 分子中原子理论与自然键轨道分析表明, 在所有体系中, 氢键N—H…N最强, N—H…O=C次之, C—H…O=C最弱, 轨道作用在氢键作用中占有重要地位.     

多聚磷酸存在下取代6-苄硫基嘧啶与羧酸的环合反应研究

以多聚磷酸(PPA)为催化剂, 对取代6-苄硫基嘧啶与羧酸的反应进行了研究. 当羧酸为脂肪酸时, 在60-80 ℃下反应, 可选择性地得到6-苄硫基嘌呤衍生物; 改用芳香酸时, 则得到硫上的苄基被脱除的6-巯基嘌呤和嘧啶并[5,4-d]噻唑; 如果将嘧啶4-位上伯胺取代基变成仲胺取代基, 只得到嘧啶并[5,4-d]噻唑. 通过双途径反应机理对上述现象进行了解释.     

聚苯胺负载铜催化嘧啶-2-胺的Buchwald-Hartwig偶联反应

Buchwald-Hartwig偶联反应可用于嘧啶-2-胺的修饰.由于嘧啶-2-胺结构在药物中广泛存在,该反应有重要的工业应用价值.聚苯胺负载铜催化剂可由苯胺在铜盐存在下氧化聚合来合成,该催化剂可催化嘧啶-2-胺的BuchwaldHartwig偶联反应.由于聚苯胺载体上氮本身就具有配位性能,该反应无需添加额外配体,即可以较高转化数(TON)催化反应.作为非均相催化剂,聚苯胺负载铜可回收利用,从而显著降低催化剂成本,符合工业应用需求.     

Functional monomers and polymers. LXXI. Conformation and interaction studies of poly-L-lysine derivatives with pendant nucleic acid bases

Copolymers of L -lysine and L -lysine derivatives which contained nucleic acid bases substituted on the N^ε position were synthesized by grafting nucleic acid derivatives onto poly-L -lysine. The conformation and interaction of these copolymers in solution were studied by using spectroscopic measurements. They existed in helical conformation at neutral pH values, and the polymer complex formation among them was examined by ultraviolet (UV) measurements in organic solvents. A decrease in the nucleic acid base content of the copolymers resulted in a decrease in helical structures and also in interactions with the polymer-containing complementary bases.     

光响应性有机-无机杂化分子印迹聚合物的制备及表征

以4-硝基苯酚、 2,4-二氯苯氧乙酸和3-氯丙基三乙氧基硅烷为原料, 经氧化偶合、 酰化、 酯化反应合成了共价结合模板分子2,4-二氯苯氧乙酸(2,4-D)的光响应性含有机硅的偶氮苯功能单体, 通过溶胶-凝胶法制备了光响应性的有机-无机杂化分子印迹聚合物(OIHMIP). 研究了该分子印迹聚合物光响应性能、 对2,4-D的吸附性能和选择识别及光控释放与吸收能力, 用原子力显微镜对其形貌进行了表征. 结果表明, 制得的OIHMIP具有规则的球形, 粒径介于150～200 nm之间. OIHMIP对2,4-D具有良好的吸附和选择识别能力, 在365和440 nm的紫外-可见光交替照射下, 可控制2,4-D的释放与吸收.     

Graft copolymers of nucleic acid bases on polyethyleneimine: Interaction of the polymers

Interactions of the graft copolymers of nucleic acid bases on polyethyleneimine with polynucleotides were studied. The backbone of the polymer is linear or branched polyethyleneimine. The nucleic acid bases are adenine and thymine. The polynucleotides used were polyadenylic acid (poly-A) and polyuridylic acid (poly-U). Interactions between these polymers were measured by ultraviolet (UV) absorption and the results were compared with the vinyl-type nucleic acid model polymer.     

Functional monomers and polymers. CXXXII. Template polymerization of methacrylamide derivatives containing nucleic acid bases

Free-radical polymerizations of methacrylamide derivatives containing nucleic acid bases were studied in the presence of the polymethacrylamide having complementary nucleic acid bases as template polymers. The rate of the polymerization did not show remarkable difference in the presence or the absence of the template polymer. A stable polymer complex, however, was precipitated from the polymerization system, and was found to be different in a thermal analysis from the polymer complex which was obtained by mixing of the complementary polymers in solution. Free-radical copolymerizations in the presence of the template polymers also supported the template polymerization.     

Functional monomers and polymers. LXIII. A study on the polymer–polymer interaction between nucleic acid base-substituted poly-L-lysines

A study of polymer-polymer interaction was made on several poly-L -lysines that contained pendant nucleic acid bases substituted on the N′ position. Conformation and interaction of these polypeptides were studied in solution by spectroscopic measurement. The results obtained suggest that the high-molecular-weight polymers form polymer complexes in a helical conformation by specific adenine-thymine base pairing. On the other hand, no interaction could be observed for the low-molecular-weight polymers, which existed in a random coil structure.     

Transport Selectivity of a Diethylene Glycol Dimethacrylate- Based Thymine-imprinted Polymeric Membrane over a Cellulose Support for Nucleic Acid Bases

The binding mechanism between 9-vinyladenine and pyrimidine base thymine in methanol was studied with UV-visible spectrophotometric method. Based on this study, using thymine as a template molecule, 9-vinyladenine as a novel functional monomer and diethylene glycol dimethacrylate as a new cross-linker, a specific diethylene glycol dimethacrylate-based molecularly imprinted polymeric membrane was prepared over a cellulose support. Then, the resultantly polymeric membrane morphologies were visualized with scanning electron microscopy and its permselectivity was examined using thymine, uracil, cytosine, adenine and guanine as substrates. This result showed that the imprinting polymeric membrane prepared with diethylene glycol dimethacrylate exhibited higher transport capacity for the template molecule thymine and its optimal analog uracil than other nucleic acid bases. The membrane also took on higher permselectivity than the imprinted membrane made with ethylene glycol dimethacrylate as a cross-linker. When a mixture including five nucleic acid bases thymine, uracil, cytosine, adenine and guanine passed through the diethylene glycol dimethacrylate-based thymine-imprinted polymeric membrane, recognition of the membrane for the template molecule thymine and its optimal analog uracil was demonstrated. It was predicted that the molecularly imprinted membrane prepared with diethylene glycol dimethacrylate as cross-linker might be applicable to thymine assay of absolute hydrolysates of DNA or uracil assay of absolute hydrolysates of RNA in biological samples because of its high selectivity for the template molecule thymine and its optimal analog uracil.     

Synthesis and characterization of nucleic acid–(co)polymer conjugates: application to diagnostics

This paper provides a survey of the synthesis of oligodeoxyribonucleotides (ODNs)–(co)polymer conjugates for application to diagnostics. Reactive copolymers containing various chemical functions (carboxylic acid groups under the form of activated esters or aldehyde) were used to covalently link ODNs. It was found that this immobilization reaction was dependent upon several parameters including the chemical reactivity of the functional group, the structural parameters (conformation) of the polymer, and the hydrogen bonding capability between the two macromolecular partners. Analysis of the conjugation products by size exclusive chromatography – light scattering displayed higher molecular weights than expected because of a concomitant aggregation process resulting from either hydrogen bonding between ODNs and polymer chains or side reactions from heterocyclic base amino groups. The extent of this aggregation process was dependent on the chemical nature of the polymer and base composition of the probes and it could be partly or totally avoided upon decreasing the capacity of the nucleic acids to form hydrogen bonds. These conjugates were tested in nucleic acid detection and they were shown to improve assay in both capture and signal efficiency for a long double-stranded DNA. © 1998 John Wiley & Sons, Ltd.     

Water soluble nucleic acid analogs: Preparation and properties

In order to prepare water soluble natural and synthetic polymers, which contain nucleic acid base units as the functional side groups, a different sort of polymers, such as poly(ethyleneimine), poly(amino acids) and so on were used as the base materials. The properties of the polymers derived, in particular the specific interaction between nucleic acid base containing complementary polymers was studied in detail. Introduction of the base units onto hyaluronic acid was also carried out. Applicabilities of these polymers obtained, for example as the controlled release system by using reversible photodimerization reaction of thymine bases were also shown.     

Two-dimensional LNA/DNA arrays: estimating the helicity of LNA/DNA hybrid duplex

We measured the helical repeats of a non-natural nucleic acid, locked nucleic acid (LNA), by incorporating LNA strands into the outer arms of a DNA double crossover (DX) molecule; atomic force microscopy (AFM) imaging of the two-dimensional (2D) arrays self-assembled from these DX molecules allows us to derive the helical repeat of the LNA/DNA hetero-duplex to be 13.2 +/- 0.9 base pairs per turn.     

Electrochemically Deposited Polymer‐Coated Gold Electrodes Selective for 2,4‐Dichlorophenoxyacetic Acid

Electropolymerized membranes on gold electrodes doped with 2,4‐dichlorophenoxyacetic acid (2,4‐D) were prepared from a solution containing resorcinol, o‐phenylenediamine and 2,4‐D. Fourier Transform Infrared (FTIR) spectroscopy was used to evaluate the incorporation and interaction of 2,4‐D with the polymer matrix prior to and after the sensing experiments. The FTIR data indicate that 2,4‐D does not leach appreciably from the polymer matrix under experimental conditions employed for the sensing studies. The electrochemical current response for 2,4‐D is compared for the doped polymer‐coated and control polymer‐coated electrode. The response of the doped polymer‐electrode was dependent on increasing concentrations of 2,4‐D and 2,4‐dichlorophenol while unresponsive to benzoic acid.