L-聚乳酸固相缩聚的工艺研究

以L-乳酸单体为原料,采用复合催化剂通过直接熔融法合成低聚左旋聚乳酸(PLLA),然后分段控温进行固相缩聚(SSP).对固相缩聚的工艺条件进行了详细的研究.采用粘度法和凝胶渗透色谱法(GPC)对固相缩聚产物PLLA的特性粘数([η])和分子量进行了表征.用差示扫描量热(DSC)研究了固相缩聚产物的熔融行为和结晶度.结果...     

基于纳米材料修饰的高灵敏性L-苯丙氨酸印迹溶胶-凝胶传感器的研究

将氧化锌纳米膜(ZnO-NFs)、多壁碳纳米管(MWNTs)、纳米铜颗粒(Cu-NPs)和印迹溶胶-凝胶聚合物(MIP)依次修饰到碳电极(CE)表面,制备了一种对L-苯丙氨酸具有特异识别能力的印迹电化学传感器.采用电子扫描显微镜(SEM)对各修饰电极进行形貌表征;采用循环伏安法(CV)、示差脉冲伏安法(DPV)、安培时...     

6-硝基-L-多巴的合成

以3,4-二羟基-L苯丙氨酸为原料,通过羟基保护、硝化、脱保护、Boc保护等反应合成了药物中间体-6-硝基-L多巴,总收率58%,其结构经1H NMR和HPLC-MS确证.     

苯并咪唑-镍(Ⅱ)-L-α-氨基酸配合物的合成及其SOD活性

苯并咪唑(bim)和NiCl<,2>·6H<,m2>O分别与L-丙氨酸(L-ala),L-亮氨酸(L-leu)和L-精氨酸(L-arg)反应,合成了三种新的Ni-SOD模拟物:Ni(bim)<,2>(L-ala)<,2>(1),Ni(bim)2(L-leu)<,2>·H<,2>O(2)和Ni(bim)2(L-arg)<,2>(3),其结构经UV-Vis,IR,元素分析和摩尔电导率表征.用改进的氮蓝四唑(NBT)光还原法测定了1～3对O<,2><'->·歧化的催化作用,结果显示:1～3的IC<,50>值分别为0.24 μmol·L<'-1>,0.39 μmol·L<'-1>和0.37μmol·L<'-1>,表明1-3均具有良好的超氧化物歧化酶活性.     

顺式-4-氨基环戊-2-烯-1-羧酸的手性拆分

采用(±)-2-氮杂双环[2.2.1]庚-5-烯-3-酮开环酯化路线,以酒石酸为拆分试剂制得L-酒石酸(1S,4R) -4-氨基环戊-2-烯-1-羧酸甲酯(4),总收率45.5％,光学纯度99％.由4可合成制备帕拉米韦的中间体顺式-4-氨基环戊-2-烯-1-羧酸.     

卤代-D,L-苯丙氨酸盐酸盐的合成与表征

以乙酰氨基丙二酸酯和苄卤为原料,经缩合、碱性水解、脱羧和脱乙酰基,合成了一组卤代-D,L-苯丙氨酸盐酸盐,利片j核磁共振谱(1H NMR)和质谱(MS)表征了产物的结构,利用元素分析确定了其组成.     

苯磺酰甘氨酸合镨配合物的合成及晶体结构

以苯磺酰甘氨酸(BsglyH)为主配体合成了一维链状配位聚合物[Pr2(Bsgly)6(H2O)4]n·nDMF·1.25nH2O,表征了其晶体结构;采用圆滤纸片和琼脂平板法测定了配合物的抑菌性能.结果表明,配合物属三斜晶系,P1空间群,晶胞参数为:a=1.309 3(4)nm,b=1.644 1(4)nm,c=1.7...     

具有抗糖尿病活性（拟）二肽分子的设计、合成及生物活性

采用液相缩合法,保护的苯丙氨酸衍生物和氨基葡萄糖衍生物分别与Fmoc氨基酸偶联,简便地得到9个未见报道的L-对硝基苯丙氨酸二肽衍生物4a～i和4个2-氨基-β-D-葡萄糖拟二肽衍生物8a～d,收率为52．4％～88．1％．4a～i选择性碱性水解,得到9个对应的水解产物5a～i,收率为64．4％-90．4％．产物的化学结构经1HNMR,13CNMR和HRMS表征及证实．体外抗糖尿病活性测试结果表明,某些化合物具有很强的抗糖尿病活性,其中化合物4c和8b的过氧化物酶体增殖物激活受体反应元件（PPRE）相对激动活性分别达到150．59％和185．23％,EC50分别为1．37uM和0．64uM,作为新型抗糖尿病先导分子值得进一步研究．     

Explanation of Theoretical Mechanism of Isomerization of L-Alanine Conformation for Experimental Results

B3LYP/6-31＋＋G＊＊ method was applied to investigate the mechanism of alanine isomerization.12 minima and 22 transition states were obtained after optimization and several paths of isomerization were found.It is found that intramolecular single-bond rotation and proton transfer might lead to isomerization.The energy barrier of C–N bond rotation was lower than 2.52 kcal·mol 1,while the energy barrier ranges of the rotation of C–C and C–O were separately 0.43~ 7.01 and 4.69~12.19 kcal·mol 1,and the minimum energy barrier of proton transfer was 30.76 kcal·mol 1.The most probable isomerization path and mechanism for the two most stable conformations was discussed to find that the highest energy barrier to be crossed in this path was 11.87 kcal·mol 1.In order to understand the microscopic nature why only 4 conformations were detected in the experiment,thermodynamic properties of all conformations at the experimental temperature of 391 K was calculated.It is found that conformations XII,XI,X and IX can only unidirectionally convert into conformations rapidly with low energy and vanish immediately.The other conformations were distributed according to Maxwell-Boltzman＇s law,and the distribution probabilities of conformations I,II,III,IV,V,VI,VII and VIII were respectively 27.2%,26.5%,25.8%,6.4%,5.2%,4.8%,2.5% and 1.6%.Conformations I,II and III with bigger probability and stronger absorption peak were easy to detect in the experiment.Conformation IV had a relatively smaller probability（6.4%） and weak absorption peak which,however,could also be identified.The other conformations had too small probability to identify in the spectrum.     

L-半胱氨酸/普鲁士蓝复合修饰玻碳电极的制备及电化学性能

通过电聚合方法和脉冲沉积技术将普鲁士蓝(PB)与L-半胱氨酸(L-Cys)修饰在玻碳电极(GCE)表面,制得复合膜化学修饰电极(L-Cys/PB/GCE/CME),利用循环伏安法和计时安培法研究了对苯二酚在L-Cys/PB/GCE/CME上的电化学特征。结果表明,在0.1 mol/L PBS(pH 7.0)缓冲溶液中,L-Cys/PB/GCE/CME对对苯二酚的电化学氧化具有明显的催化作用,氧化峰电流相对于在裸玻碳电极上增加了5倍。在最佳实验条件下,对苯二酚浓度在0.18~120μmol/L范围内,修饰电极的电流响应与对苯二酚浓度呈线性关系,其相关系数为0.9962,检出限(S/N=3)为0.065μmol/L。本研究制备的对苯二酚传感器具有较好的重复性、重现性、选择性与稳定性,用于实际水样中对苯二酚的测定,结果满意。