N,N′‐Diethyl‐4‐nitrobenzene‐1,3‐diamine, 2,6‐bis(ethylamino)‐3‐nitrobenzonitrile and bis(4‐ethylamino‐3‐nitrophenyl) sulfone

N,N′‐Diethyl‐4‐nitrobenzene‐1,3‐diamine, C₁₀H₁₅N₃O₂, (I), crystallizes with two independent molecules in the asymmetric unit, both of which are nearly planar. The molecules differ in the conformation of the ethylamine group trans to the nitro group. Both molecules contain intramolecular N—H...O hydrogen bonds between the adjacent amine and nitro groups and are linked into one‐dimensional chains by intermolecular N—H...O hydrogen bonds. The chains are organized in layers parallel to (101) with separations of ca 3.4 Å between adjacent sheets. The packing is quite different from what was observed in isomeric 1,3‐bis(ethylamino)‐2‐nitrobenzene. 2,6‐Bis(ethylamino)‐3‐nitrobenzonitrile, C₁₁H₁₄N₄O₂, (II), differs from (I) only in the presence of the nitrile functionality between the two ethylamine groups. Compound (II) crystallizes with one unique molecule in the asymmetric unit. In contrast with (I), one of the ethylamine groups, which is disordered over two sites with occupancies of 0.75 and 0.25, is positioned so that the methyl group is directed out of the plane of the ring by approximately 85°. This ethylamine group forms an intramolecular N—H...O hydrogen bond with the adjacent nitro group. The packing in (II) is very different from that in (I). Molecules of (II) are linked by both intermolecular amine–nitro N—H...O and amine–nitrile N—H...N hydrogen bonds into a two‐dimensional network in the (10) plane. Alternating molecules are approximately orthogonal to one another, indicating that π–π interactions are not a significant factor in the packing. Bis(4‐ethylamino‐3‐nitrophenyl) sulfone, C₁₆H₁₈N₄O₆S, (III), contains the same ortho nitro/ethylamine pairing as in (I), with the position para to the nitro group occupied by the sulfone instead of a second ethylamine group. Each 4‐ethylamino‐3‐nitrobenzene moiety is nearly planar and contains the typical intramolecular N—H...O hydrogen bond. Due to the tetrahedral geometry about the S atom, the molecules of (III) adopt an overall V shape. There are no intermolecular amine–nitro hydrogen bonds. Rather, each amine H atom has a long (H...O ca 2.8 Å) interaction with one of the sulfone O atoms. Molecules of (III) are thus linked by amine–sulfone N—H...O hydrogen bonds into zigzag double chains running along [001]. Taken together, these structures demonstrate that small changes in the functionalization of ethylamine–nitroarenes cause significant differences in the intermolecular interactions and packing.     

4-氯-7H-吡咯并[2,3-d]嘧啶与2,4-二氯-7H-吡咯并[2,3-d]嘧啶的合成研究

报道了以廉价易得的丙二酸二乙酯为起始原料,经过α-烷基化、环合、氯化、烯键氧化和SNAr/环化五步反应,高收率地得到目标产物4-氯-7H-吡咯并[2,3-d]嘧啶(6)和2,4-二氯-7H-吡咯并[2,3-d]嘧啶(10)(总收率分别达到45.8%和44.8%)的合成方法,并对中间体和产物的化学结构进行了表征.     

无溶剂条件下活性炭固载硫酸催化酮和芳香醛的Cross-Aldol缩合反应

以活性炭固载硫酸(acsa)为催化剂,在无溶剂条件下催化酮和芳香醛的Cross-Aldol反应,成功合成了16个相应的α,β不饱和缩合产物,反应时间30～100min,产率可达65%～94%.该方法不仅反应时间短,产率高,催化剂可以重复利用,后处理简单,而且还对环境友好.产物经熔点,IR,1HNMR,13CNMR确证.     

离子液体双水相萃取-蒸气发生原子荧光法测定痕量镉

研究了离子液体1-异戊基-3-甲基咪唑溴代盐-K2HPO4-水双水相体系对镉-双硫腙络合物的萃取性能,建立了测定痕量镉的蒸气发生-原子荧光光谱法.经离子液体双水相萃取后,在离子液体相中的镉-双硫腙络合物经酸化后可直接与还原剂(NaBH4)混合进行蒸气发生反应,并经气液分离后将蒸气引入原子化器中进行原子荧光检测,离子液体的存在不影响蒸气发生过程.考察了双水相系统的组成以及相关实验条件对镉-双硫腙络合物萃取的影响.在最佳实验条件下,样品体积为1 mL时,测定痕量镉的线性范围为0.25～5.0 μg/L,检出限为0.07 μg/L; 相对标准偏差为3.4%(n=9, 2.0 μg/L Cd2+).用国家标准物质GBW08608(水中镉、铬、铜、镍、铅、锌成分分析标准物质)验证了方法的准确性,并对实际水样中的痕量镉进行了测定.     

pH区带逆流色谱法分离纯化马钱子中马钱子碱和士的宁

建立了pH区带逆流色谱分离制备马钱子中生物碱类成分马钱子碱和士的宁的方法。溶剂系统为V(甲基叔丁基醚):V(乙腈):V(水)=2:2:3,静置分层后,上相加入三乙胺,使其浓度为10mmol/L,作为固定相;下相加入HCl,使其浓度为10mmol/L,作为流动相。从308mg马钱子总生物碱中分离得到50mg马钱子碱和120mg士的宁,得率分别为72.8%和85.1%;纯度分别为96.8%和98.3%。并采用LC-ESI-MS和13CNMR对目标化合物的结构进行了鉴定。     

Electronic structures and nonlinear optical properties of highly deformed halofullerenes C3v C60F18 and D3d C60Cl30

Electronic structures and nonlinear optical properties of two highly deformed halofullerenes C_3v C₆₀F₁₈ and D_3d C₆₀Cl₃₀ have been systematically studied by means of density functional theory. The large energy gaps (3.62 and 2.61 eV) between the highest occupied and lowest unoccupied molecular orbitals (HOMOs and LUMOs) and the strong aromatic character (with nucleus‐independent chemical shifts varying from ?15.08 to ?23.71 ppm) of C₆₀F₁₈ and C₆₀Cl₃₀ indicate their high stabilities. Further investigations of electronic property show that C₆₀F₁₈ and C₆₀Cl₃₀ could be excellent electron acceptors for potential photonic/photovoltaic applications in consequence of their large vertical electron affinities. The density of states and frontier molecular orbitals are also calculated, which present that HOMOs and LUMOs are mainly distributed in the tortoise shell subunit of C₆₀F₁₈ and the aromatic [18] trannulene ring of C₆₀Cl₃₀, and the influence from halogen atoms is secondary. In addition, the static linear polarizability and second‐order hyperpolarizability of C₆₀F₁₈ and C₆₀Cl₃₀ are calculated using finite‐field approach. The values of and for C₆₀F₁₈ and C₆₀Cl₃₀ molecules are significantly larger than those of C₆₀ because of their lower symmetric structures and high delocalization of π electrons. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010     

An effective sequence characterized amplified region‐PCR method derived from restriction site‐amplified polymorphism for the identification of female Schistosoma japonicum of zoonotic significance

In the present study, restriction site‐amplified polymorphism (RSAP) markers were used to examine the genetic variability of Schistosoma japonicum isolates from different endemic provinces in mainland China. Of the 45 pairs of primers screened, 10 RSAP markers showed a clear banding pattern with good resolution; however, only six exhibited a polymorphism among different isolates. Among six RSAP markers, one pair of primers (R8+R10) was able to differentiate male and female parasites, and amplified one constant specific band for female S. japonicum isolates. The specific band was recovered, re‐amplified and sequenced, and a sequence of 162 bp was obtained. Based on this sequence, a pair of specific primers was designed and used to develop sequence characterized amplified region (SCAR)‐PCR assay for identification and differentiation of female S. japonicum isolates. The SCAR‐PCR assay allowed the specific identification of female S. japonicum, with no amplicons being amplified from male S. japonicum, Fasciola hepatica, Clonorchis sinensis, S. mansoni (male and female parasite). DNA sequencing confirmed the identity of the amplified products. The minimum amount of DNA detectable using SCAR‐PCR assay was 0.3 ng for female S. japonicum. The SCAR‐PCR was able to differentiate effectively the male and female S. japonicum worms collected from 12 geographical origins in eight endemic provinces, the gender of which was known based on the morphological and biological features. These results showed that SCAR‐PCR provides an effective tool for the sex differentiation studies of S. japonicum, identification of female S. japonicum, diagnosis and epidemiological survey of S. japonicum infections in animals and human.     

Mechanistic and kinetic investigations of N2H4 + OH reaction

The reaction of N₂H₄ with OH has been investigated by quantum chemical methods. The results show that hydrogen abstraction mechanism is more feasible than substitution mechanism thermodynamically. The calculated rate constants agree with the available experimental data. The calculated results show that the variational effect is small at lower temperature region, while it becomes significant at higher temperature region. On the other hand, the small‐curvature tunneling effect may play an important role in the temperature range 220?3000 K. Moreover, the calculated rate constants show negative temperature dependence at the temperatures below 500 K, which is in accordance with Vaghjiani's report that slightly negative temperature dependence is found over the temperature range of 258?637 K. The mechanism of the major product (N₂H₃) with OH has also been investigated theoretically to understand the title reaction thoroughly. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

用于疾病诊断的Gd~Ⅲ/量子点多模态成像探针的构建

结合核磁共振成像(MRI)和荧光成像技术,以钆离子、近红外低毒量子点、二氧化硅和聚丙烯酸(PAA)等为原料,采用一系列纳米载体自组装技术,构建出MRI弛豫率/荧光效率高和生物相容性好的GdⅢ/量子点多模态纳米探针.结果表明,与未螯合GdⅢ的量子点纳米探针相比,GdⅢ/量子点多模态纳米探针具有更高的弛豫率;t1-加权MRI成像也证实了GdⅢ/量子点多模态纳米探针具有很好的阳性造影功效.     

Low-density extraction solvent-based solvent terminated dispersive liquid–liquid microextraction combined with gas chromatography-tandem mass spectrometry for the determination of carbamate pesticides in water samples

A simple and fast method of low-density extraction solvent-based solvent terminated dispersive liquid–liquid microextraction (ST-DLLME) was developed for the highly sensitive determination of carbamate pesticides in the water samples by gas chromatography-tandem mass spectrometry (GC-MSMS). After dispersing, the obtained emulsion cleared into two phases quickly when an aliquot of acetonitrile was introduced as a chemical demulsifier into the aqueous bulk. Therefore, the developed procedure does not need centrifugation to achieve phase separation. It was convenient for the usage of low-density extraction solvents in DLLME. Under the optimized conditions, the limits of detection for all target carbamate pesticides were in range of 0.001–0.50 ng mL⁻¹ and the precisions were in the range of 2.3–6.8% (RSDs, 2 ng mL⁻¹, n = 5). The proposed method has been successfully applied to the analysis of real water samples and good spiked recoveries over the range of 94.5–104% were obtained.