Large Amplitude Motions in Fruit Flavors: The Case of Alkyl Butyrates

To accurately characterize the large amplitude motions and soft degrees of freedom of isolated molecules, sampling their conformational landscape by molecular mechanics and quantum chemical calculations may provide a valuable insight into the structure and dynamics. However, the resulting models need to be validated by a reliable experimental counterpart. For ethyl pentanoates, which belong to the family of fruit esters, benchmark calculations at different levels of theory showed that the C−C bond in proximity to the ester carbonyl group exhibits a large amplitude motion that is extremely sensitive to the choice of quantum chemical method and basis set. In such cases, insights from high-resolution molecular jet techniques are ideal to accurately identify and characterize soft degrees of freedom. Here, we report on the most abundant conformer of ethyl 2-ethyl butyrate using Fourier-transform microwave spectroscopy. We show that – unlike other structurally related pentanoates for which gas-phase and crystallographic data is available – ethyl 2-ethyl butyrate possesses a C_s symmetry plane under molecular jet conditions.     

CuO纳米片催化H2O2氧化降解亚甲基蓝

以十六烷基三甲基溴化铵(CTAB)为保护剂, 采用水热法成功制备了CuO纳米片. 将制备的CuO纳米片在H₂O₂存在下用于催化氧化降解亚甲基蓝, 探讨了其在不同反应条件(如温度、氧化剂浓度及催化剂用量)下对亚甲基蓝降解反应的影响. 该催化反应符合一级动力学模型, 活化能为54.0kJ/mol. CuO纳米片表现出非常高的催化活性, 但其稳定性与重复利用性有待于进一步提高.     

长周期光纤光栅对铜离子的检测研究

利用有机反应在长周期光纤光栅表面制备了一层高分子材料敏感膜,用扫描电子显微镜(SEM)、X射线型能谱仪(EDX)等检测手段对高分子敏感膜层进行了分析表征,并利用敏感膜时溶液中的铜离子进行了光学检测。结果表明,该高分子敏感膜能够较好地确定铜离子的存在,证明了利用长周期光纤光栅对铜离子进行检测是可行的。     

复合固体超强酸SO_4~(2-)/TiO_2-Fe_2O_3催化合成丁酸异丁酯

采用溶胶 凝胶法制备的复合固体超强酸催化剂ＳＯ2-果表明物质的量比ｎ(Ｔｉ)∶ｎ(Ｆｅ)=2∶1时催化剂活性最高,这与文献结果[2]有所不同。1　实验部分1 1　试剂和仪器丁酸、异丁醇、苯、表面活性剂(ＰＥＧ-600)、乙醇、三氯化铁等为分析纯;钛酸四丁酯为化学纯。上海产ＷＺＳ-1型阿贝折射仪;日本岛津ＧＣ-16Ａ气相色谱仪;ＧＥＭＩＮＩ2360型氮气吸附全自动表面分析仪。1 2　催化剂ＳＯ2-4/ＴｉＯ2-Ｆｅ2Ｏ3的制备、酸强度及ＢＥＴ表面积测定　　取一定量的钛酸四丁酯剧烈搅拌下缓慢滴加到80ｍｌ无水乙醇中,搅拌20ｍｉｎ,快速加入80ｍｌ2…     

Cu(BF4)2,Cu(C3H7COO)2与双(二苯膦基)烷烃配体形成配位化合物的红外光谱

用红外光谱法对二苯基膦系列配体及其分别与Cu(BF_4)_2和Cu(C_3H_7COO)_2。形成的系列配位化合物进行了研究,讨论了谱带的归属和Cu(Ⅰ)配合物形成前后相关谱带的变化规律,并参照元素分析、X-射线粉末衍射分析和热重分析的结果,讨论了所形成配位化合物的可能的结构模式。     

两个有机锡杂环羧酸酯配合物的合成、结构及抗癌活性

合成了2个有机锡杂环羧酸酯配合物：二（邻溴苄基）锡二（2-吡啶甲酸）酯（1）和三（2-甲基-2-苯基丙基）锡3-吲哚丁酸酯（2）。通过元素分析、红外光谱、核磁共振谱（¹H、¹³C和¹¹⁹Sn）、X射线衍射、热重分析进行了表征,用X射线单晶衍射方法测定了配合物的晶体结构,进行了配合物的结构量子化学从头计算和体外抗癌活性研究。结果显示：配合物均为单锡核分子,锡原子分别为六配位的畸变八面体构型和四配位的畸变四面体构型;配合物对人肝癌细胞（HUH7）、人肺癌细胞（A549）、人表皮癌细胞（A431）、人结肠癌细胞（HCT-116）和乳腺癌细胞（MDA-MB-231）的抑制活性均比临床使用的顺铂强。     

丁酸氯维地平的波谱学数据与结构确证

丁酸氯维地平是一种短效二氢吡啶类钙通道阻滞剂,对丁酸氯维地平的紫外吸收光谱（UV）、红外吸收光谱（IR）、核磁共振氢谱（¹H NMR）、氢-氢相关谱(¹H-¹H COSY)、核磁共振碳谱¹³C NMR、DEPT谱、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)及质谱（MS）进行了解析,对其所有的NMR谱信号进行了归属;讨论了红外光谱特征吸收峰所对应的官能团的振动形式,确证了丁酸氯维地平的结构.     

HPLC法拆分(-)-2(S)-苄基-4-酮-4-(顺式-全氢化异吲哚-2-基)丁酸钙对映体

目的：建立刺激胰岛素分泌的新型降糖药物(-)-2 (S)-苄基-4-酮-4-(顺式-全氢化异吲哚-2-基)丁酸钙对映体的HPLC拆分方法。方法：采用Sumichiral OA-3300手性柱(250 × 4.6 mm I.D., 5 μm), 柱温35℃,以0.05 mol·L-1醋酸铵的甲醇溶液为流动相,检测波长为210 nm。结果：本品两对映体在22分钟内实现良好分离,分离度达3以上,S－异构体分别在0.028 ~ 5.6 μg mL-1和0.03 ~ 6.0 μg mL-1范围内线性关系良好,回归方程分别为：Y=1.32×103x-2.54 (r=0.9997)和Y=1.15×103x-1.78 (r=0.9998),最低检测限分别为0.15 ng和0.10 ng,方法精密度RSD低于1.0% (n=5)。结论：建立的对映体分离方法可用于本品光学异构体的质量控制。     

2-(2-羟基-5-氯苯基)-1H-苯并咪唑-铜(Ⅱ)配合物作为NO荧光探针的初探

常温下合成了2-(2-羟基-5-氯苯基)-1H-苯并咪唑荧光化合物和其二价铜离子的配合物,并对配合物的结构和稳定性进行了表征,用荧光光谱、质谱、红外光谱等研究了配合物与NO反应的机理.结果表明,该配合物与NO的反应具有高度的选择性,不受其他常见干扰分子的影响.配合物应用于脂多糖(LPS)激活的小鼠巨噬细胞中NO的测定,能够得到具有较好分辨率的荧光成像结果.     

Highly selective transformation of poly[(R)-3-hydroxybutyric acid] into trans-crotonic acid by catalytic thermal degradation

Highly selective transformation of poly[(R)-3-hydroxybutyric acid] (PHB) into trans-crotonic acid was achieved by thermal degradation using Mg compounds: MgO and Mg(OH)₂ as catalysts. Through catalytic action, not only the temperature and E_a value of degradation were lowered by 40-50 °C and 11-14 kJ mol⁻¹, respectively, but also significant changes in the selectivity of pyrolyzates were observed. Notably, Mg(OH)₂ showed nearly complete selectivity (∼100%) to trans-crotonic acid. Kinetic analysis of TG profiles revealed that the catalytic thermal degradation of PHB was initiated by some random degradation reactions, followed by the unzipping β-elimination from crotonate chain-ends as a main process. It was suggested that the Mg catalysts promote the totality of the β-elimination reactions by acting throughout the beginning and main processes, resulting in a lowering in the degradation temperature and the completely selective transformation of PHB.