氢元素教学内容的重构

近二十年来,有关氢元素的化学研究在基础研究和应用领域都得到了迅速的发展,尤其是氢键和氢能领域的研究。氢键已成为化学、生物、物理和材料科学等多学科所共同关注的基本学科问题,而氢能则是未来新能源中最重要的清洁能源之一,与此相关的氢能制备、储氢材料等研究也取得了重要的进展。然而,在氢元素的教学中,却未能及时补充这些研究成果。此外,与放射性、核能等相关的氢原子同位素也需要更新。本文从氢的同位素、氢键、氢能三个方面,探讨了无机化学教学中氢元素教学内容的重构。     

Designing Self-Assembled Rosettes: Why Ammeline is a Superior Building Block to Melamine

In supramolecular chemistry, the rational design of self-assembled systems remains a challenge. Herein, hydrogen-bonded rosettes of melamine and ammeline have been theoretically examined by using dispersion-corrected density functional theory (DFT-D). Our bonding analyses, based on quantitative Kohn–Sham molecular orbital theory and corresponding energy decomposition analyses (EDA), show that ammeline is a much better building block than melamine for the fabrication of cyclic complexes based on hydrogen bonds. This superior capacity is explained by both stronger hydrogen bonding and the occurrence of a strong synergy.     

Hydrogen-Bond-Donor Solvents Enable Catalyst-Free (Radio)-Halogenation and Deuteration of Organoborons

A hydrogen bond donor solvent assisted (radio)halogenation and deuteration of organoborons has been developed. The reactions exhibited high functional group tolerance and needed only an ambient atmosphere. Most importantly, compared to literature methods, our conditions are more consistent with the principals of green chemistry (e.g., metal-free, strong oxidant-free, more straightforward conditions).     

环芳酰胺的合成及自组装行为

本文主要综述了近年来由三中心氢键和远程位阻效应促进的环芳酰胺合成,以及利用该类化合物进行自组装行为的研究进展. 在研究一步高效成环的基础上,对合成不同孔径刚性大环的方法进行了探讨. 改变大环周边侧链的性质可以调控这类大环分子的自组装行为. 最后对环芳酰胺的应用进行了简单介绍     

环糊精在金属酶模拟中的应用

非共价作用（如氢键、静电和疏水作用）普遍存在于天然金属酶中,对酶活化或底物催化过程有重要的协同作用.近年来基于超分子化学理论的金属酶模拟研究不断向酶的活性中心亚稳态和次层结构的生物功能模拟方向发展.本文将根据报道的文献并结合本课题组的研究工作,对环糊精（一种重要的超分子主体）构建金属酶模型的研究进行综述.     

Superacid-Mediated Late-Stage Aromatic Polydeuteration of Pharmaceuticals

The field of medicinal chemistry is currently witnessing a deuterium rush owing to the remarkable properties of this element as bioisoster of hydrogen atom. Aromatic hydrogen isotope exchange (HIE) is one of the most studied strategies nowadays as it promises to access deuterium-modified drugs directly from their non-labeled parents. While most of the recent studies focus on metal-catalyzed C−H activation strategy, the use of superacidic conditions has been largely overlooked. This study shows that the use of TfOD as reaction medium allows the late-stage polydeuteration of a broad library of pharmaceuticals bearing a wide array of functional groups, complementing existing procedures.     

Polarization charge densities provide a predictive quantification of hydrogen bond energies

A systematic density functional theory based study of hydrogen bond energies of 2465 single hydrogen bonds has been performed. In order to be closer to liquid phase conditions, different from the usual reference state of individual donor and acceptor molecules in vacuum, the reference state of donors and acceptors embedded in a perfect conductor as simulated by the COSMO solvation model has been used for the calculation of the hydrogen bond energies. The relationship between vacuum and conductor reference hydrogen bond energies is investigated and interpreted in the light of different physical contributions, such as electrostatic energy and dispersion. A very good correlation of the DFT/COSMO hydrogen bond energies with conductor polarization charge densities of separated donor and acceptor atoms was found. This provides a method to predict hydrogen bond strength in solution with a root mean square error of 0.36 kcal mol(-1) relative to the quantum chemical dimer calculations. The observed correlation is broadly applicable and allows for a predictive quantification of hydrogen bonding, which can be of great value in many areas of computational, medicinal and physical chemistry.     

Visible Light Driven Hydro‐/Deuterodefunctionalization of Anilines

The defunctionalization of anilines is an important strategy in aromatic‐substitution chemistry. Herein, we report on visible light mediated hydro‐ and deuterodediazonations in solutions of DMF. The mild reaction conditions (DMF, RT, no additives) tolerate various functional groups and allow the site‐specific introduction of D atoms to the arene. Mechanistic investigations indicate the participation of photoredox and radical chain pathways and competing abstraction of methyl and formyl hydrogen atoms from DMF.     

1H‐1,2,3‐Triazole: From Structure to Function and Catalysis

The heterocyclic family of azoles have recently become one of the most widely used members of the N‐heterocycles; the most prominent one being 1H‐1,2,3‐triazole and its derivatives. The sudden growth of interest in this structural motif was sparked by the advent of click chemistry, first described in the early 2000s. From the early days of click chemistry, when the accessibility of triazoles made them into one of the most versatile linkers, interest has slowly turned to the use of triazoles as functional building blocks. The presence of multiple N‐coordination sites and a highly polarized carbon atom allows for metal coordination and the complexation of anions by both hydrogen and halogen bonding. Exploitation of these multiple binding sites makes it possible for triazoles to be used in various functional materials, such as metallic and anionic sensors. More recently, triazoles have also shown their potential in catalytic systems, thus increasing their impact far beyond the initial purpose of click chemistry. This report gives an overview of the structure, functionalities, and use of triazoles with a focus on their use in catalytic systems.     

The study of interaction between PFOA/PFOS and uracil by topology quality and spectroscopic analysis

It has been established that perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) can be considered as emerging persistent organic pollutants. In recent years, there was increasing distribution of PFOA/PFOS in environmental systems, and accumulation and toxic effects of PFOA/PFOS in human body. In this paper, quantum chemistry methods were employed to study the interaction between perfluorinated organic pollutants and base (uracil). The results showed that there were four stable binding modes between the two perfluorinated compounds with uracil, especially the second mode which caused the most detrimental physiological functional response. NBO analysis showed that reactive hydrogen in the two perfluorinated compounds had the greatest effect on the hydrogen bond. The nature of the hydrogen bond formed between the two perfluorinated compounds and base was investigated using the AIM theory. The changes of spectroscopic properties in complexes were analyzed by IR and NMR spectra.     

Supramolecular architectures generated by self-assembly of guanosine derivatives

Nature's use of a simple genetic code to enable life's complex functions is an inspiration for supramolecular chemistry. DNA nucleobases carry the key information utilizing a variety of cooperative and non-covalent interactions such as hydrophobic, van der Waals, pi-pi stacking, ion-dipole and hydrogen bonding. This tutorial review describes some recent advances in the form and function provided by self-assembly of guanine (G) based systems. We attempt to make connections between the structures of the assemblies and their properties. The review begins with a brief historical context of G self-assembly in water and then describes studies on lipophilic guanosine analogs in organic solvents. The article also focuses on examples of how G analogs have been used as building blocks for functional applications in supramolecular chemistry, material science and nanotechnology.     

Bioinspired catalysis at the crossroads between biology and chemistry: A remarkable example of an electrocatalytic material mimicking hydrogenases

There is an increasing need for new, efficient and cheap chemical catalysts, as part of the emerging “green” chemistry field. Living organisms provide a wealth of fascinating enzymes, with exceptional catalytic efficiencies and selectivities, which can be either directly exploited in biotechnological synthetic systems or imitated by chemists. The bioinspired catalysis approach exploits the basic chemical principles on which a biological enzyme active site is built in order to generate original functional analogs of this site. This is illustrated here with a molecular electrode material inspired from hydrogenases, metalloenzymes involved in hydrogen metabolism, and displaying exceptional electrocatalytic properties for hydrogen production and oxidation, thus with potential applications for electrolyzer and fuel cell technologies.     

Hierarchical Architectures Based on Ru Nanoparticles/Oxygen-Rich-Carbon Nanotubes for Efficient Hydrogen Evolution

Highly active and durable electrocatalysts are essential for producing hydrogen fuel through the hydrogen evolution reaction (HER). Here, a uniform deposition of Ru nanoparticles strongly interacting with oxygen-rich carbon nanotube architectures (Ru-OCNT) through ozonation and hydrothermal approaches has been designed. The hierarchical structure of Ru-OCNT is made by self-assembly of oxygen functionalities of OCNT. Ru nanoparticles interact strongly with OCNT at the Ru/OCNT interface to give excellent catalytic activity and stability of the Ru-OCNT, as further confirmed by density functional theory. Owing to the hierarchical structure and adjusted surface chemistry, Ru-OCNT has an overpotential of 34 mV at 10 mA cm⁻² with a Tafel slope of 27.8 mV dec⁻¹ in 1 M KOH, and an overpotential of 55 mV with Tafel slope of 33 mV dec⁻¹ in 0.5 M H₂SO₄. The smaller Tafel slope of Ru-OCNT than Ru-CNT and commercial Pt/C in both alkaline and acidic electrolytes indicates high catalytic activity and fast charge transfer kinetics. The as-proposed chemistry provides the rational design of hierarchically structured CNT/nanoparticle electrocatalysts for HER to produce hydrogen fuel.     

Intermolecular Hydrogen Bonding Modulates O‐H Photodissociation in Molecular Aggregates of a Catechol Derivative

The catechol functional group plays a major role in the chemistry of a wide variety of molecules important in biology and technology. In eumelanin, intermolecular hydrogen bonding between these functional groups is thought to contribute to UV photoprotective and radical buffering properties, but the mechanisms are poorly understood. Here, aggregates of 4‐t‐butylcatechol are used as model systems to study how intermolecular hydrogen bonding influences photochemical pathways that may occur in eumelanin. Ultrafast UV‐visible and mid‐IR transient absorption measurements are used to identify the photochemical processes of 4‐t‐butylcatechol monomers and their hydrogen‐bonded aggregates in cyclohexane solution. Monomer photoexcitation results in hydrogen atom ejection to the solvent via homolytic O‐H bond dissociation with a time constant of 12 ps, producing a neutral semiquinone radical with a lifetime greater than 1 ns. In contrast, intermolecular hydrogen bonding interactions within aggregates retard O‐H bond photodissociation by over an order of magnitude in time. Excited state structural relaxation is proposed to slow O‐H dissociation, allowing internal conversion to the ground state to occur in hundreds of picoseconds in competition with this channel. The semiquinone radicals formed in the aggregates exhibit spectral broadening of both their electronic and vibrational transitions.     

Direct Synthesis of Polysubstituted Aldehydes via Visible‐Light Catalysis

Aldehydes are among the most versatile functional groups for synthetic chemistry. However, access to polysubstituted alkyl aldehydes is very limited and requires lengthy synthetic routes that involve multiple‐step functional‐group conversion. This paper reports a one‐step synthesis of polysubstituted aldehydes from readily available olefin substrates using visible‐light photoredox catalysis. Despite a number of competing reaction pathways, commercial styrenes react with vinyl ethers selectively in the presence of an acridinium salt photooxidant and a disulfide hydrogen‐atom‐transfer catalyst under blue LED irradiation. Alkyl aldehydes with different substitution patterns are prepared in good yields. This strategy can be applied to structurally sophisticated substrates.     

Atomic defects,functional groups and properties in Mxenes

MXenes,a new family of functional two-dimensional(2 D) materials,have shown great potential for an extensive variety of applications within the last decade.Atomic defects and functional groups in MXenes are known to have a tremendous influence on the functional properties.In this review,we focus on recent progress in the characterization of atomic defects and functional group chemistry in MXenes,and how to control them to directly influence various properties(e.g.,electron transport,Li⁺ adsorption,hydrogen evolution reaction(HER) activity,and magnetism) of 2 D MXenes materials.Dynamic structural transformations such as oxidation and growth induced by atomic defects in MXenes are also discussed.The review thus provides perspectives on property optimization through atomic defect engineering,and bottom-up synthesis methods based on defect-assisted homoepitaxial growth of MXenes.     

Hydrogen‐Transfer‐Mediated α‐Functionalization of 1,8‐Naphthyridines by a Strategy Overcoming the Over‐Hydrogenation Barrier

A general catalytic hydrogen transfer‐mediated α‐functionalization of 1,8‐naphthyridines is reported for the first time that benefits from a hydrogen transfer‐mediated activation mode for non‐activated pyridyl cores. The pyridyl α‐site selectively couples with the C8‐site of various tetrahydroquinolines (THQs) to afford novel α‐functionalized tetrahydro 1,8‐naphthyridines, a class of synthetically useful building blocks and potential candidates for the discovery of therapeutic and bio‐active products. The utilization of THQs as inactive hydrogen donors (HDs) appears to be a key strategy to overcome the over‐hydrogenation barrier and address the chemoselectivity issue. The developed chemistry features operational simplicity, readily available catalyst and good functional group tolerance, and offers a significant basis for further development of new protocols to directly transform or functionalize inert N‐heterocycles.     

Hydrogen Isotope Exchange by Homogeneous Iridium Catalysis in Aqueous Buffers with Deuterium or Tritium Gas

We have studied the highly selective homogeneous iridium-catalyzed hydrogen isotope exchange (HIE) with deuterium or tritium gas as an isotope source in water and buffers. With an improved water-soluble Kerr-type catalyst, we have achieved the first insight into applying HIE reactions in aqueous media with varying pH. Density functional theory (DFT) calculations gave consistent insights in the calculated energies of transition states and coordination complexes, further explaining the observed reactivity and guidance on the scope and limitations for HIE reactions in water. Finally, we successfully adapted these findings to tritium chemistry.     

Radical conversion and migration in electron capture dissociation

Electron capture dissociation (ECD) is an important analytical technique which is used frequently in proteomics experiments to reveal information about both primary sequence and post-translational modifications. Although the utility of ECD is unquestioned, the underlying chemistry which leads to the observed fragmentation is still under debate. Backbone dissociation is frequently the exclusive focus when mechanistic questions about ECD are posed, despite the fact that numerous other abundant dissociation channels exist. Herein, the focus is shifted to side chain loss and other dissociation channels which offer clues about the underlying mechanism(s). It is found that the initially formed hydrogen abundant radicals in ECD can convert quickly to hydrogen deficient radicals via a variety of pathways. Dissociation which occurs subsequent to this conversion is mediated by hydrogen deficient radical chemistry, which has been the subject of extensive study in experiments which are independent from ECD. Statistical analysis of fragments observed in ECD is in excellent agreement with predictions made by an understanding of hydrogen deficient radical chemistry. Furthermore, hydrogen deficient radical mediated dissociation likely contributes to observed ECD fragmentation patterns in unexpected ways, such as the selective dissociation observed at disulfide bonds. Many aspects of dissociation observed in ECD are easily reproduced in well-controlled experiments examining hydrogen deficient radicals generated by non-ECD methods. All of these observations indicate that when considering the means by which electron capture leads to dissociation, hydrogen deficient radical chemistry must be given careful consideration.     

Supramolecular amphiphiles

Supramolecular amphiphiles (SA), also named superamphiphiles, refer to amphiphiles that are formed by non-covalent interactions. This tutorial review focuses on the molecular architectures of SAs, including diversified topologies such as single chain, double chain, bolaform, gemini and rotaxane types. Non-covalent syntheses that have been employed to fabricate SAs are driven by hydrogen bonding, electrostatic attraction, host-guest recognition, charge transfer interaction, metal coordination and so on. It should be noted that SAs can be either small organic molecules or polymers. SAs allow for tuning of their amphiphilicity in a reversible fashion, leading to controlled self-assembly and disassembly. This line of research has been enriching traditional colloid chemistry and current supramolecular chemistry, and the application of SAs in the field of functional supramolecular materials is keenly anticipated.