手性胶束的不对称诱导作用不对称苯偶姻缩合反应

胶束体系是模拟酶的简单模型之一。手性胶束对反应有手性诱导作用。在表面活性剂(1R，2S)-(-)-N-十二烷基-N-甲基麻黄素溴化物和(1R，2S)-(-)-N-十六烷基-N-甲基麻黄素溴化物形成的胶束体系中进行的苯偶姻缩合反应，生成了光学活性的α-羟基酮。     

“线上线下-虚实结合”在有机化学实验教学中的应用探索——以正溴丁烷的制备实验为例

In response to the impact of the Covid-19 epidemic on organic chemistry laboratory teaching, this article analyzes and discusses the current limitation of traditional organic chemistry laboratory teaching. Taking the "preparation of n-bromobutane" as an example, a new "online-offline and virtual-actual combination" teaching mode with the combination of "Tencent Meeting, MLabs, laboratory and WeChat group" is introduced. The practice of the new mode of teaching includes the following steps: pre-class online guiding by teacher, student preview and practice based on the virtual simulation platform, students and teacher discussion and operation in laboratory, and post-classcomprehensive assessment and Q&A", and good teaching effects have been received. It is significant in cultivating and improving the independent innovation and practical ability, and provides reference for the organic chemistry laboratory teaching reform and also lays a foundation for the construction of "outstanding course" of organic chemistry.     

通过脱碳控制全球平均温度

Establishing a reliable method to predict the global mean temperature (T_e) is of great importance because CO₂ reduction activities require political and global cooperation and significant financial resources. The current climate models all seem to predict that the earth's temperature will continue to increase, mainly based on the assumption that CO₂ emissions cannot be lowered significantly in the foreseeable future. Given the earth's multifactor climate system, attributing atmospheric CO₂ as the only cause for the observed temperature anomaly is most likely an oversimplification; the presence of water (H₂O) in the atmosphere should at least be considered. As such, T_e is determined by atmospheric water content controlled by solar activity, along with anthropogenic CO₂ activities. It is possible that the anthropogenic CO₂ activities can be reduced in the future. Based on temperature measurements and thermodynamic data, a new model for predicting T_e has been developed. Using this model, past, current, and future CO₂ and H₂O data can be analyzed and the associated T_e calculated. This new, esoteric approach is more accurate than various other models, but has not been reported in the open literature. According to this model, by 2050, T_e may increase to 15.5 ℃ under "business-as-usual" emissions. By applying a reasonable green technology activity scenario, T_e may be reduced to approximately 14.2 ℃. To achieve CO₂ reductions, the scenario described herein predicts a CO₂ reduction potential of 513 gigatons in 30 years. This proposed scenario includes various CO₂ reduction activities, carbon capturing technology, mineralization, and bio-char production; the most important CO₂ reductions by 2050 are expected to be achieved mainly in the electricity, agriculture, and transportation sectors. Other more aggressive and plausible drawdown scenarios have been analyzed as well, yielding CO₂ reduction potentials of 1051 and 1747 gigatons, respectively, in 30 years, but they may reduce global food production. It is emphasized that the causes and predictions of the global warming trend should be regarded as open scientific questions because several details concerning the physical processes associated with global warming remain uncertain. For example, the role of solar activities coupled with Milankovitch cycles are not yet fully understood. In addition, other factors, such as ocean CO₂ uptake and volcanic activity, may not be negligible.     

Reversible wettability of a chemical vapor deposition prepared ZnO film between superhydrophobicity and superhydrophilicity

A superhydrophobic ZnO thin film was fabricated by the Au-catalyzed chemical vapor deposition method. The surface of the film exhibits hierarchical structure with nanostructures on sub-microstructures. The water contact angle (CA) was 164.3 degrees, turning into a superhydrophilic one (CA < 5 degrees) after UV illumination, which can be recovered through being placed in the dark or being heated. The film was attached tightly to the substrate, showing good stability and durability. The surface structures were characterized by scanning electron microscopy and atomic force microscopy.     

Fourier transform infrared spectroscopy study of the effect of pH on anion and cation adsorption onto poly(acrylo‐amidino diethylenediamine)

The role of hydrogen bonding in the chemistry of transition‐metal complexes remains a topic of intense scientific and technological interest. Poly(acrylo‐amidino diethylenediamine) was synthesized to study the effects of hydrogen bonding on complexes at different pHs. The polymer was synthesized through the coupling of diethylene triamine with polyacrylonitrile fiber in the presence of AlCl₃ · 6H₂O addition. The adsorption capacity of this polymer was 11.4 mequiv/g. The ions used for the adsorption test were CrO, PO, Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺. All experiments were confirmed with Fourier transform infrared. In the study of anion adsorption, at low pHs, only ionic bonds existed, whereas at high pHs, no bonds existed. However, in the middle pH region, both ionic bonds and hydrogen bonds formed between poly(acrylo‐amidino diethylenediamine) and the chromate ion or phosphate ion. When poly(acrylo‐amidino diethylenediamine) and metal ions (Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺) formed complexes, a hydrogen‐bonding effect was not observed with Fourier transform infrared. The quantity of metal ions adsorbed onto poly(acrylo‐amidino diethylenediamine) followed the order Ag⁺ > Cu²⁺ > Fe²⁺ > Ni²⁺. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2010–2018, 2004     

Synthesis and Crystal Structure of 1,7,7-Trimethyl- 4-（4-methoxyphenyl）-4,6,7,8-tetrahydroquinoline- 2,5（1H,3H）-diones under Microwave Irradiation

1 INTRODUCTION Various quinolone derivatives are known to dis- play interesting biological properties ranging from microbial activity to cytotoxicity[1]. They have been reported as antiviral (HIV-1)[2] and antitumor agents[3] as well as used as tubulin[4], topoisomerase[5] and thrombocyte inhibitors[6]. As a member of the quino- lone family, substituted N-phenyl-2-quinolones re-present the structural basis of many biologically active compounds, such as protein kinase inhibitors, immunodu…     

Synthesis and spectroscopic analysis of tetraphenylporphyrinatoantimony(V) complexes linked to boron-dipyrrin chromophore on axial ligands

Tetraphenylporphyrinatoantimony(V) complexes, linked to boron-dipyrrin chromophores on axial ligands, were synthesized. The fluorescence spectra of 1a, 1b and 1c (3-[4-(N,N′-difluorobornyl-5-dipyrrinyl)phenyl]propoxo(methoxo)antimony(V) tetraphenylporphyrin bromide (1a); 6-[4-(N,N′-difluorobornyl-5-dipyrrinyl)phenyl]hexyloxo(methoxo)antimony(V) tetraphenylporphyrin bromide (1b); bis{3-[4-(N,N′-difluorobornyl-5-dipyrrinyl)phenyl]propoxo}antimony(V) tetraphenylporphyrin bromide (1c)) were analyzed under the excitations of N,N′-difluorobornyl-5-dipyrrinylphenyl (Bdpy) and tetraphenylporphyrinatoantimony(V) (Sb(TPP)) chromophores. Under the irradiation of Bdpy chromophore, the excitation energy was transferred from Bdpy chromophore to the Sb(TPP) moiety at 0.13–0.40 of the quantum yields, even in a polar solvent. On the other hand, the emission of Sb(TPP) chromophores was quenched by Bdpy chromophores at rate constants of 10⁸–10⁹ s⁻¹, independent of on the solvent polarity. Under the excitation of the Bdpy chromophore of 1d (3-[4-(N,N′-difluorobornyl-5-dipyrrinyl)phenyl]propoxo(phenyloxo)antimony(V) tetraphenylporphyrin bromide) involving both the Bdpy and the phenoxy chromophores on the axial ligands, the excited singlet state of the Sb(TPP) chromophore generated by the energy transfer from the Bdpy chromophore was quenched by the phenoxy ligand via non-radiative processes involving electron transfer. However, rapid back electron-transfer may occur because no absorption of the anion radical of Sb(TPP) was observed by nanosecond laser photolysis.     

Comparison of enantiomer separation on two chiral stationary phases derived from (+)-18-crown-6-2,3,11,12-tetracarboxylic acid of the same chiral selector

Liquid chromatographic comparisons for enantiomer resolution of α-amino acids and chiral primary amino compounds were made using chiral stationary phases (CSPs) prepared by covalently bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) of the same chiral selector. The resolution of all α-amino acids on CSP 1 developed in our group was found to be better than that on CSP 2 reported by Machida et al. All α-amino acids examined in this study were well enantioseparated on CSP 1 (α=1.22–2.47), while four analytes were not resolved or all the other analytes were poorly resolved on CSP 2 than on CSP 1. However, in resolving the primary amino compounds without a carbonyl group, CSP 1 was comparable with CSP 2. Although (+)-18-C-6-TA of the same chiral selector was used to prepare CSP 1 and CSP 2, this study showed that different connecting methods for the CSPs might influence their ability to resolve the analytes depending on their structures related to the chiral recognition mechanism.     

New Acetylcholinesterase‐Inhibitory Pregnane Glycosides of Cynanchum atratum Roots

Three new pregnane glycosides, cynatroside A ( 1 ), cynatroside B ( 2 ), and cynatroside C ( 3 ), isolated from the roots of Cynanchum atratum (Asclepiadaceae), were characterized as 7β‐{[O‐α‐L ‐cymaropyranosyl‐(1→4)‐O‐β‐D ‐digitoxopyranosyl‐(1→4)‐β‐D ‐oleandropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐6α‐hydroxy‐4b‐ methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 1 ), 7β‐{[O‐β‐D ‐cymaropyranosyl‐(1→4)‐O‐α‐L ‐diginopyranosyl‐(1→4)‐β‐D ‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 2 ), and 7β‐{[O‐α‐L ‐cymaropyranosyl‐(1→4)‐O‐β‐D ‐digitoxopyranosyl‐(1→4)‐β‐L ‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 3 ), respectively. In addition, ten known constituents were identified, i.e., cynascyroside D ( 4 ), glaucoside C ( 5 ), glaucoside D ( 6 ), atratoside A ( 7 ), 2,4‐dihydroxyacetophenone ( 8 ), 4‐hydroxyacetophenone ( 9 ), syringic acid ( 10 ), azelaic acid ( 11 ), suberic acid ( 12 ), and succinic acid ( 13 ). Among these compounds, 1 – 4 significantly inhibit acetylcholinesterase activity.