With the recent soaring production of natural gas, the use of methane and other light hydrocarbon feedstocks as starting materials in synthetic transformations is becoming increasingly economically ...attractive, although it remains chemically challenging. We report the development of photocatalytic C-H amination, alkylation, and arylation of methane, ethane, and higher alkanes under visible light irradiation at ambient temperature. High catalytic efficiency (turnover numbers up to 2900 for methane and 9700 for ethane) and selectivity were achieved using abundant, inexpensive cerium salts as photocatalysts. Ligand-to-metal charge transfer excitation generated alkoxy radicals from simple alcohols that in turn acted as hydrogen atom transfer catalysts. The mixed-phase gas/liquid reaction was adapted to continuous flow, enabling the efficient use of gaseous feedstocks in scalable photocatalytic transformations.
A general strategy for the cleavage and amination of C−C bonds of cycloalkanols has been achieved through visible‐light‐induced photoredox catalysis utilizing a cerium(III) chloride complex. This ...operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C−C bond cleavage and functionalization of unstrained secondary cycloalkanols.
Breaking (D)BAD: A general strategy for the cleavage and amination of C−C bonds of cycloalkanols has been achieved through visible‐light‐induced photoredox catalysis utilizing a cerium(III) chloride complex. This method represents the first example of catalytic C−C bond cleavage and functionalization of unstrained secondary cycloalkanols. DBAD=di‐tert‐butyl azodicarboxylate, Boc=tert‐butoxycarbonyl.
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•Photocatalytic alkoxy radical-mediated reactions.•Alkoxy radicals mediated CH functionalizations.•CC bond cleavage and functionalizations of alcohols.
Alkoxy radicals have been ...intensively studied as versatile synthetic intermediates with well-established reactivity and selectivity. Due to the difficulties associated with the generation of these transient and high-energy radicals, the utilization of the unique reactivity of alkoxy radicals in catalytic platforms has become a rather challenging task. Recent studies on the alkoxy radical-mediated transformations have benefited tremendously from advances in modern photoredox catalysis. In this digest, we aim to highlight reported transformations that utilize alkoxy radicals in a photocatalytic fashion, in particular, underline novel catalytic platforms which we anticipate will find broad application in the near future.
We demonstrate the application of ligand-to-metal charge transfer (LMCT) excitation to the direct catalytic generation of energetically challenging alkoxy radicals from alcohols through a ...coordination–LMCT–homolysis process with an abundant and inexpensive cerium salt as the catalyst. This catalytic manifold provides a simple and efficient way to utilize the characteristic reactivity and selectivity of transient alkoxy radicals for δ-selective C–H bond functionalization. Under mild redox-neutral conditions without the need for prefunctionalization, this method provides a versatile platform to access molecular complexity from simple and abundant alcohols.
We describe a synergistic utilization of cerium photocatalysis and photoinduced electron transfer catalysis that enables an atom- and step-economical ring expansion of readily available ...cycloalkanols. This operationally simple protocol provides rapid access to privileged and synthetically challenging bridged lactones. The mild catalytic manifold has been adapted to continuous flow for scale-up applications and employed for the concise synthesis of polycyclic core of nepalactones.
Multivariate Linear Regression (MLR) models utilizing computationally-derived and empirically-derived physical organic molecular descriptors are described in this review. Several reports ...demonstrating the effectiveness of this methodological approach towards reaction optimization and mechanistic interrogation are discussed. A detailed protocol to access quantitative and predictive MLR models is provided as a guide for model development and parameter analysis.
The utilization of physical organic molecular descriptors for the quantitative description of reaction outcomes in multivariate linear regression models is demonstrated as an effective tool for
a priori
prediction and mechanistic interrogation.
This study aims to investigate the impact of the stress–strain behaviour of cemented tailings backfill (CTB) on the stability of sill mat structures used in underhand cut-and-fill mining. A ...three-dimensional finite element model is established to simulate four types of sill mats with varying stress–strain relationships, namely ductile, intermediate ductile, intermediate brittle, and brittle. The results indicate that the stress–strain behaviour does not affect the damage evolution process of the sill mat but impacts its deformation and energy absorption capacity. The brittle sill mat exhibits severe damage and deformation, with a lower energy absorption ability than the ductile sill mat. Statistical analysis also suggests that the ductile sill mat is better at reducing damage inside the surrounding rock and has a higher structural strength than the brittle sill mat. Therefore, the study highlights the importance of considering the stress–strain behaviour of CTB in designing safe sill mat structures and suggests the potential benefits of using fibre-reinforced backfill.
Recent research in topological photonics has not only proposed and realized novel topological phenomena such as one‐way broadband propagation and robust transport of light, but also designed and ...fabricated photonic devices with high‐performance indexes, which are immune to fabrication errors such as defects or disorders. Photonic crystals, which are periodic optical structures with the advantages of good light field confinement and multiple adjusting degrees of freedom, provide a powerful platform to control the flow of light. With the topology defined in the reciprocal space, photonic crystals have been widely used to reveal different topological phases of light and demonstrate topological photonic functionalities. This review presents the physics of topological photonic crystals with different dimensions, models, and topological phases. The design methods of topological photonic crystals are introduced. Furthermore, the applications of topological photonic crystals in passive and active photonics are reviewed. These studies pave the way for applying topological photonic crystals in practical photonic devices.
For the ability to improve the robustness of photonic devices under different kinds of defects, topological photonic crystals have attracted increasing attention and have been used as a platform for studying intriguing physical phenomena and realizing novel functional devices. This review provides an introduction to the fundamental physics, optical design, and promising applications of topological photonic crystals in different dimensions.
In recent years, there have been more than 7 million college graduates in China every year. Management, teachers, teaching, family, and society. Finally, a summary of the whole article is made. Deep ...learning (DL) emphasizes the understanding, application, and creation of knowledge and forms a natural close relationship with the cultivation of innovation and entrepreneurship. DL with thinking training, knowledge migration, the flexible use of the learning method, learning state of balance and other characteristics, to improve college students’ knowledge absorptive capacity, knowledge integration capability, knowledge conversion capability, and knowledge application ability, improve students’ ability of knowledge creation, and then improve the ability of innovative undertaking. Therefore, the cultivation of college students’ innovation and entrepreneurship ability (EA) based on DL should start with the construction of teaching design, the reform of teaching methods and methods, and the innovation of teaching assessment methods. Deepening the reform of innovation and entrepreneurship education is an important way for universities to put students first, improve the talent training system, and improve the talent training level. It is the key content for universities to further promote the reform of innovation and entrepreneurship education to create specialized courses, build high-quality courses in innovation and entrepreneurship education, improve the teaching effectiveness of innovation and entrepreneurship education, and realize more effective learning for students.
Examining the early history of the Chinese translation of Buddhist scriptures, it is revealed that translators from the Eastern Han Dynasty to the Wei and Jin Dynasties, such as An Shigao, Lokakṣema, ...Kang Senghui and Dharmarakṣa, already paid much attention to and began translating Buddhist scriptures related to “filial piety”. They even, during the translation process, altered the original meanings of some words to promote the sinicization of Buddhism or brought together the contents of several sutras to provide a more culturally attuned interpretation of the Buddhist idea of “filial piety and repayment of kindness”, in accordance with Chinese culture. With their efforts, the Chinese gradually realized that Buddhism also preached filial ethics. Buddhists were not against the value of filial piety when embracing monastic life; instead, they could accumulate merits and dedicate them to their parents and relatives, rescuing them from samsara. This introduced a fresh perspective for traditional Confucian filial piety, and highlighted the importance of “filial piety” beyond the framework of “family and state as one.” Confucianism and Buddhism were able to agree on the significance of filial piety, and Buddhism also affected and complemented the ethical cultivation of the Chinese medieval society.
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