基于现代信息技术的结构化学一维势箱理论和HMO法“翻转课堂”教学设计

In the article, we presented an instructional design of "Particle in One-Dimensional Box Theory" and "HMO Theory" application based on flipped classroom teaching. The students are instructed to use both "Particle in One-Dimensional Box Theory" and "HMO Theory" to solve the electronic structure of olefins and enhance their understanding of quantum mechanics theory via comparison of "Particle in One-Dimensional Box Theory" and "HMO Theory".     

Making "wheels" and "cubes" from triangles

[Mn(IV)Mn(II)3] triangular units directed by the presence of tripodal alcohols self-assemble in the presence of azide and acetate ligands to form either a [Mn24] "wheel" or a [Mn32] "cube".     

Conformationally imprinted receptors: atropisomers with "write", "save", and "erase" recognition properties

[reaction: see text] An atropisomeric receptor with "write", "save", and "erase" recognition properties is presented. The receptor adopts a complementary conformation when heating in the presence of an ethyl adenine-9-acetate guest molecule. This complementary hydrogen bonding conformation is "saved" upon cooling to room temperature due to the reestablishment of restricted rotation and is stable even upon removal of the guest. Finally, the atropisomeric receptor can be "erased" by heating in the absence of the guest.     

"Clickable" polymersomes

Polymersomes, composed of amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA), with the periphery being covered with azide groups, were used for further functionalization using "click" chemistry.     

在化学类通识教育课程中开展“课堂辩论”对大学生能力培养的探索与实践

This paper explored "the classroom debates" in "nutrition chemistry" course. After evaluating the students' expectation in participating activities, the participating degree and their gains from the activity, it was found that the performance and gains from the "classroom debate" were influenced by provincial locations, genders and majors. The results showed that "the classroom debates" need to coordinate the students' speculative thinking ability, creative thinking, team playing, medical ethics and professional education as a whole. This would help the students to form a way of critical thinking as well as the right outlook on life and value system.     

Algorithm for coding DNA sequences into "spectrum-like" and "zigzag" representations

An algorithm for encoding long strings of building blocks, like 4 DNA bases (adenine-A, cytosine-C, thymine-T, and guanidine-G), 20 natural amino acids (from Alanine Ala to Valine-Val, plus the stop triplet), or all 64 possible base triplets (from AAA to TTT), into "zigzag" or "spectrum-like" representations is suggested. The new encoding scheme can be derived in the 3-, 2-, or 1-dimensional form depending on the user's wishes. The only information, besides the string for which the "spectrum-like" representation is sought, is the initial positioning of the complete set of units from which the string is composed, i.e., four positions for A, C, G, and T, or 20 positions for natural amino acids plus stop, etc. This initial positioning can be initialized in either the 3-, 2-, or 1-D form. As an illustration of the suggested encoding scheme of the visual and chemometric comparison of the first 10 exon strings of the beta globin gene of 10 different species, each string consisting of about 100 basic amino acids long is shown.     

Amphiphilic Janus gold nanoparticles via combining "solid-state grafting-to" and "grafting-from" methods

Despite the great efforts that have been made toward obtaining Janus architectures, synthesizing sub-10 nanometer Janus nanoparticles (NPs) modified with different types of polymers remains a challenging task. In this Communication, "solid-state grafting-to" and "grafting-from" methods were combined to obtain Janus gold NPs (AuNPs) modified with two types of polymer chains on the opposite sides of the NP. We used functionalized polymer single crystals as the solid substrates to immobilize AuNPs. We then used atom transfer radical polymerization to grow polymer chains on the "free" side of the AuNPs. Amphiphilic polyethylene oxide (PEO)-Au-poly(methyl methacrylate), PEO-Au-poly(tert-butyl acrylate) and hydrophilic PEO-Au-poly(acrylic acid) were synthesized. The Janus nature was demonstrated using a platinum-nanoparticle-decoration method. Using polymer single crystals as the reaction substrates is advantageous because they afford higher throughput compared with self-assembled monolayers. Dissolution of the single crystal also leads to NPs with defined polymer patches. We anticipate that our approach could serve as a generic method for synthesizing polymer-functionalized, sub-10 nm Janus NPs. This unique system holds promises for achieving controlled assembly and tunable optic and electronic properties of NPs.     

Basic concepts of "cation pool" and "cation flow" methods and their applications in conventional and combinatorial organic synthesis

Carbocations have been generally considered to be relatively unstable and transient species. But the "cation pool" method enables the easy accumulation of carbocations in conventional reaction media such as dichloromethane. In the "cation pool" method, carbocations are generated by low-temperature electrochemical oxidation and accumulated in a solution. In the next step, the carbocations thus produced are allowed to react with various nucleophiles. Combinatorial parallel synthesis based upon the "cation pool" method has also been developed. The applicability of the "cation pool" method depends upon the stability of the cation that is accumulated. This problem can be overcome by the "cation flow" method. In the "cation flow" method, carbocations are generated in a microflow electrochemical system. Short residence times and efficient temperature control of the microflow system are advantageous. Combinatorial sequential synthesis has been achieved based on the "cation flow" method.     

"Polysiloxane-Pd" nanocomposites as recyclable chemoselective hydrogenation catalysts

Polysiloxane-encapsulated "Pd"-nanoclusters were generated by reduction of Pd(OAc)(2) with polymethylhydrosiloxane, which functions as a reducing agent as well as a capping material for production and stabilization of catalytically active "Pd"-nanoparticles. Chemoselective hydrogenation of functional conjugated alkenes was achieved by in-situ- or ex-situ-generated polysiloxane-stabilized "Pd"-nanoclusters under mild reaction conditions in high yields. Electron microscopy, UV-vis, and NMR studies of the reaction mixture during the catalytic transformation were performed and, in conjunction with catalyst poisoning experiments, demonstrated unequivocally the role of polysiloxane-encapsulated "Pd"-nanoclusters as the real catalytic species. The recyclability of the "Pd"-nanoclusters was established by reusing the solid left after the reaction.     

Synthesis of "solid solution" and "core-shell" type cobalt--platinum magnetic nanoparticles via transmetalation reactions

In this article, we report the synthesis of "solid solution" and "core-shell" types of well-defined Co--Pt nanoalloys smaller than 10 nm. The formation of these alloys is driven by redox transmetalation reactions between the reagents without the need for any additional reductants. Also the reaction proceeds selectively as long as the redox potential between the two metals is favorable. The reaction between Co(2)(CO)(8) and Pt(hfac)(2) (hfac = hexafluoroacetylacetonate) results in the formation of "solid solution" type alloys such as CoPt(3) nanoparticles. On the other hand, the reaction of Co nanoparticles with Pt(hfac)(2) in solution results in "Co(core)Pt(shell)" type nanoalloys. Nanoparticles synthesized by both reactions are moderately monodispersed (sigma < 10%) without any further size selection processes. The composition of the alloys can also be tuned by adjusting the ratio of reactants. The magnetic and structural properties of the obtained nanoparticles and reaction byproducts are characterized by TEM, SQUID, UV/vis, IR, EDAX, and XRD.     

试论化学教学中的"自我对话"教育

“自我对话”教育强调学习者的主体作用和能动作用,它符合新课程理念和建构主义学习理论。实施“自我对话”教育必须注意激发学生的“自我对话”意识,并通过学前“知我性对话”、学中“生成性对话”和学后“反思性对话”等形式加以落实。     

Synthesis of cyclic dendronized polymers via divergent "graft-from" and convergent click "graft-to" routes: preparation of modular toroidal macromolecules

Cyclic dendronized polymers represent a new class of polymers which exhibit a donut-like "toroidal" shape. Two previous unreported methods for preparing this architecture, the divergent "graft-from" and the convergent click "graft-to" approaches, are explored and the resulting products fully characterized. This route is particularly attractive because it enables production of exact linear and cyclic dendronized analogues, enabling direct comparison of their physical properties. In this preliminary work, the divergent "graft from" approach appears to lead to materials with broad PDI at high DP, whereas the "graft to" approach yields more well-defined dendronized cyclic polymers at larger DP. On the basis of reports to date, a combination of click cyclization followed by click "grafting to" provides the most versatile route for the synthesis of cyclic dendronized polymers.     

周期律的“不规则性”

本文对周期律的“不规则性”及其理论阐释进行了探讨。     

"Orthogonal" separations for reversed-phase liquid chromatography

A general procedure is proposed for the rapid development of a reversed-phase liquid chromatographic (RP-LC) separation that is "orthogonal" to a pre-existing ("primary") method for the RP-LC separation of a given sample. The procedure involves a change of the mobile-phase organic solvent (B-solvent), the replacement of the primary column by one of very different selectivity, and (only if necessary) a change in mobile phase pH or the use of a third column. Following the selection of the "orthogonal" B-solvent, column and mobile phase pH, further optimization of peak spacing and resolution can be achieved by varying separation temperature and either isocratic %B or gradient time. The relative "orthogonality" of the primary and "orthogonal" RP-LC methods is then evaluated from plots of retention for one method versus the other. The present procedure was used to develop "orthogonal" methods for nine routine RP-LC methods from six pharmaceutical analysis laboratories. The relative success of this approach can be judged from the results reported here.     

关于为拔尖人才培养开设的"学科前沿"类课程的探讨

With the implementation of the basic discipline of "Top Talent Training Program" (the "East Ever Project"), more and more new reforms and attempts are being made in various universities. In the process of innovation and exploration, a new curriculum is being implemented, that is, the "the frontier aspects of disciplines" course. Through investigation and research, we found that many colleges and universities in China are carrying out or trying to carry out such courses, and the students who participated have different benefits. This paper mainly discusses the current situation of the development of the frontier courses of many universities in China, and gives suggestions based on the two courses of Tang Aoqing Honors Program in Science of chemistry in Jilin University. This paper provides reference for other colleges and universities to open such courses.     

"Black swan events" in organic synthesis

When a research area "goes viral", the event typically occurs in conjunction with a major change in "conventional wisdom". In retrospect, the literature often contains earlier hints that the original judgment was not correct. These antecedents are referred to as "Black Swan" events. The picture shows research on homogeneous gold catalysis "going viral".     

"Demonstration" vs. "designation" of measurement competence: the need to link accreditation to metrology

Formal acceptance of the results of chemical laboratories is increasingly organized through a) accreditation of measuring laboratories nationally and b) mutual recognition of accreditation internationally (through formal Multilateral Recognition Agreements, MRAs). However, real comparability of results of measurements is realized by using common (internationally agreed) measurement scales which make these results traceable to this scale, i.e. "traceable" to the same (internationally agreed) value of the unit of that scale. In addition, the criterion against which the evaluation is done, should be "external" to the measurement laboratories which are being evaluated. This is realized in IRMM's International Measurement Evaluation Programme (IMEP) where evaluation is performed against values which are anchored using "metrology", the science of measurement with its own rules, which offers a sound foundation for measurement in all scientific disciplines. It is argued in this paper that the demonstration of measurement capability against values on such scales provides a result-oriented rather than a procedure-oriented evaluation. Thus, competence can be "demonstrated" rather than just "designated" and this can be shown to both customers and regulators. It inspires more confidence.     

Resonance CARS study of the structure of "green" and "red" chromophores within the red fluorescent protein DsRed

Vibrational spectra of red fluorescent protein DsRed have been studied for the first time by polarization-sensitive multiplex coherent anti-Stokes Raman scattering at two excitation wavelengths, 545 and 583 nm, in resonance with the absorption bands of the immature "green" and mature "red" protein chromophores. Overall vibrational patterns of both DsRed chromophores were found to be similar to each other and to differ from that of S65T-GFP at pH8. The combined analysis of our CARS data and published structural information suggest that both "green" and "red" DsRed species possess an extended chromophore structure. Consequently, our data suggest that pi-bonding system extension during isomerization around the cis peptide bond between Phe 65 and Gln 66 is a necessary but not sufficient step in DsRed chromophore maturation.     

"Volatilizable" supports for high-throughput organic synthesis

The concepts and use of "volatilizable" solid supports are presented. Such supports, which are completely removed by volatilization following decomposition, improve the efficiency of the solid-phase synthesis of both individual and mixtures of low-molecular weight acyclic and heterocyclic compounds as well as peptides, peptidomimetics, and protected peptide fragments. The "volatilizable" silica-based solid supports and linkers used to illustrate this concept were found to be completely removed by their decomposition and ultimate "volatilization" during the final cleavage step of synthetic process to yield solely the desired synthetic product(s) in the final reaction vessel.