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A green and feasible synthetic protocol for α-polyfluoroarylalcohols was developed with polyfluoroarenes and alcohols via Lewis acid-assisted synergistic photoredox and hydrogen-atom transfer catalysis under batch or flow conditions.

The light spectrum is a key environmental cue involved in growth and reproduction in teleosts. This study investigated the effects of exposure on juvenile red spotted grouper exposed to white (control), red (590 nm), blue (480 nm), and green (520 nm) light-emitting diodes (LEDs) (12 h light:12 h dark) for two months. The body weight (BW), total length (TL), condition factor (CF), weight gain rate (WGR), gonadosomatic index (GSI), and hepatosomatic index (HSI) were assessed. Gonadal development was observed. The gene expression of growth-related hormones, such as growth hormone (GH), pre-pro-somatostatin-I (PSS-I), neuropeptide Y (NPY), and CCK, and of reproduction-related hormones, such as Kiss1, Kiss2, GPR54, sbGnRH, FSHβ, and LHβ, was analyzed. The results showed that the fish in the white LED group exhibited the best BW, TL, CF, WGR, and HSI after one or two months. The fish exposed to white LEDs showed the best growth after two months, but no significant differences in GH levels were detected. Contrarily, the expression levels of the PSS-I significantly increased (p < 0.05) in fish from the white group, suggesting the complex regulation of GH production and the limited effects of PSS-I on the inhibition of GH synthesis and somatic growth. The significantly increased NPY levels in the four LED groups (p < 0.05) indicated that these four LED spectra were effective in stimulating food intake and energy homeostasis. After two months, the gonads developed from chromatin nucleolar-stage oocytes to perinucleolar-stage oocytes in the four LED groups. The gene expression of Kiss2 and GPR54 in the four LED groups and of sbGnRH in the white and blue LED groups significantly increased when compared to that in the initial group (p < 0.05), while there were no significant differences in FSHβ and LHβ expression in the four LED groups. These results suggest that FSH and LH may not play important roles in gonadal development in juvenile red spotted grouper that are exposed to these four LED spectra.

Most current data-driven prognosis approaches suffer from their uncontrollable and unexplainable properties. To address this issue, this article proposes a physics-constraint variational neural network (PCVNN) for wear state assessment of the external gear pump. First, a response model of the pressure pulsation of the gear pump is constructed via a spectral method, and a compound neural network is utilized to extract features from the pressure pulsation signal. Then, the response model is formulated into an objective function to softly constrain the learning process of the neural network, forcing the learned features to have explicit physics meaning. Meanwhile, to characterize the system uncertainty, the variational inference is utilized to extend a Kullback-Leibler ( KL) divergence into the objective function. Finally, the wear state is evaluated based on the distance of learned physics features. Experimental results on an external gear pump validate the merits of the proposed method in explainable representation learning and system uncertainty estimation. It also offers a controllable and explainable perspective to understand the dynamic behavior of the system.

Polymeric carbon nitride materials show intriguing prospects in numerous light-to-energy conversion applications, but seldom studies focus on their triplet energy transfer, leading to the insufficient lifetime for the photochemical process. Inspired by the porphyrin molecular photocatalyst, single-atom sites (Fe-N4) as triplet sensitizing sites were fabricated in g-C3N4 for the preparation of Fe-g-C3N4, which processes a long-lived triplet emissive state (τPH = 4.93 μs). But under realistic condition for the large-scale production of catalyst, single atoms are inevitable to sinter, resulting in the formation of other metal species. Therefore, the photooxidation of 1,5-dihydroxynaphthalene (1,5-DHN) and the photocatalytic E-Z Isomerization of stilbene were selected as the model reactions to evaluate the influence of various Fe species on the triplet energy transfer. It was found that Fe-N4 sites promote the triplet energy transfer process, while Fe nanoclusters (Fe0) promote the electron transfer and inhibit triplet energy transfer. This finding provides guidance for the rational design of photocatalysts to efficiently improve triplet energy transfer process and its application.

An expeditious construction of an unsymmetrical tertiary 9-fluorenol skeleton was accomplished starting from readily available α-ketoester and aryl iodide. Inexpensive commercially available substituted aniline was utilized as a potent monodentate transient directing group (TDG) to assist palladium-catalyzed direct ortho-C-H arylation and tandem dual C-H activation of α-ketoesters to form two carbon-carbon bonds. To demonstrate practical applications, the reaction was enlarged to the gram scale, and subsequent one-step derivatization allowed facile access to structurally diversified useful derivatives. A series of control experiments were carried out to shed light on the possible catalytic mechanism.

Chlorosilanes are versatile reagents in organic synthesis and material science. A mild pathway is now reported for the quantitative conversion of hydrosilanes to silyl chlorides under visible-light irradiation using neutral eosin Y as a hydrogen-atom-transfer photocatalyst and dichloromethane as a chlorinating agent. Stepwise chlorination of di- and trihydrosilanes was achieved in a highly selective fashion assisted by continuous-flow micro-tubing reactors. The ability to access silyl radicals using photocatalytic Si-H activation promoted by eosin Y offers new perspectives for the synthesis of valuable silicon reagents in a convenient and green manner.

Hetero-MoO

An iron-catalyzed, peroxide-mediated cross-dehydrogenative coupling between 8-amidoquinolines and cycloalkanes has been developed for the site-selective alkylation of the quinoline nucleus at the C5 position. The reaction tolerates various substituted N -(quinolin-8-yl)benzamides and N -(quinolin-8-yl)alkylamides, affording the corresponding C5-alkylation products in good yields. On the basis of control experiments, a reaction mechanism involving the addition of an alkyl radical to an iron-chelated intermediate is proposed. Ministry of Education (MOE) This work was supported by the Singapore Ministry of Education Academic Research Fund Tier 2 (MOE2016-T2-2-043 to N.Y.) and Tier 1 (RG114/18 to N.Y.), the Fundamental Research Funds for China University of Petroleum (China East) (Grant No. 27RA2014007 to W.X.), and the China Postdoctoral Science Foundation (Grant No. 31CZ2019010, 05FW2014001 to W.X.).

Due to the distributed and dynamic characteristics of the Internet of Vehicles (IoV) and the continuous growth in the number of devices, content-centric decentralized vehicular named data networking (VNDN) has become more suitable for content-oriented applications in IoV. However, the existing centralized architecture is prone to the failure of single points, which results in trust problems in key verification between cross-domain nodes and consuming more power and reducing the lifetime. Focusing on secure key management and power-efficient routing, this article proposes a blockchain-based key management and green routing scheme for VNDN. A blockchain-based key management scheme is presented to achieve secure and efficient distribution and verification of keys. Specifically, all trusted agencies (TAs) form a consortium blockchain for storing public key hashes to ensure the authenticity of users’ public keys. A green global routing scheme based on node relaying pressure (GGNRP) is proposed to save power consumption and reduce the forwarding delay. A new node relay pressure metric is introduced to assist with routing decisions. Detailed experiments and analysis show that, compared with the existing scheme, the proposed scheme can achieve secure key management and GGNRP can decrease the power consumption and average delay by 15.8% and 63.2%, respectively.

Polymeric carbon nitrides (PCNs) have emerged as promising heterogeneous photocatalysts for organic transformations as they are metal-free, inexpensive, and possess suitable bandgaps, and excellent chemical- and photo-stability. However, current application of PCNs in organic synthesis is rather limited to several well-established materials, which limits the scope of reaction patterns and efficiency. We herein report the synthesis and fabrication of two new PCN nanosheets by incorporating nanostructure construction, element doping, and vacancy engineering into one hybrid platform. The heteroatom doped PCN nanosheets with vacancies feature highly porous structures with extremely large substrate-catalyst interface areas, enhanced charge separation, and improved lipophilicity. The generated heterogeneous catalysts demonstrate impressive photoredox catalytic performances in a variety of organic transformations (e.g., defluoroborylation, [2+2] cycloaddition, C-N, C-S, and C-O cross couplings), providing efficiencies comparable to reported optimized homogeneous catalysts and exceeding those with commonly utilized PCNs.

A tremendous amount of work is devoted to build an all-in-one energy storage equipment to meet the ever-increasing demand for flexible wearable electronics. At present, the flexible all-in-one zinc ion batteries have captured enormous attention owing to its high volume capacity, abundant reserve and robust security. Herein, the Mn-doped K0.23V2O5 nanobelts materials are innovatively prepared by introducing Mn and K ions into vanadium oxide, which will acquire an intensive conductivity and favorable Zn2+ storage. In the conventional aqueous zinc ion batteries, the Mn-doped K0.23V2O5 electrode offers a high discharge capacity of 269.1 mAh g−1 after 100 cycles at the moderate current density of 1.0 A g−1 and a remarkable cyclability (226.7 mAh g−1 after 5000 cycles at 10.0 A g−1). Moreover, the electrode also displays a good rate performance. Besides, the binder-free Mn-doped K0.23V2O5/CNT film is further constructed for flexible all-in-one batteries, which exhibits satisfactory cycling performance with high-capacity retention of greater than 84.1% after 2000 cycles under continuous bending. Thus, this work provides a facile strategy for new-generation convenient and wearable energy-storage facility.

We report herein an ortho‐C–H alkenylation reaction of aryl imines with alkenyl phosphates promoted by a cobalt–N‐heterocyclic carbene (NHC) catalytic system. While commercially available bulky NHC ligands exhibited only modest catalytic activity, elaboration of the nitrogen substituents and backbone of the NHC enabled the desired transformation to proceed in high yield at a mild temperature. The new Co–NHC system proved applicable to a variety of aryl imines and alkenyl phosphates to afford ortho‐alkenylated aryl imines, which serve as precursors to benzofulvene derivatives. MOE (Min. of Education, S’pore) Accepted version

Fluorinated organoboranes serve as versatile synthetic precursors for the preparation of value-added fluorinated organic compounds. Recent progress has been mainly focused on the transition-metal catalyzed defluoroborylation. Herein, we report a photocatalytic defluoroborylation platform through direct B-H activation of N-heterocyclic carbene boranes, through the synergistic merger of a photoredox catalyst and a hydrogen atom transfer catalyst. This atom-economic and operationally simple protocol has enabled defluoroborylation of an extremely broad scope of multifluorinated substrates including polyfluoroarenes, gem-difluoroalkenes, and trifluoromethylalkenes in a highly selective fashion. Intriguingly, the defluoroborylation protocol can be transition-metal free, and the regioselectivity obtained is complementary to the reported transition-metal-catalysis in many cases.

Summary Polymeric carbon nitrides (PCNs) have emerged as promising heterogeneous photocatalysts for organic transformations as they are metal-free, inexpensive, and possess tunable bandgaps, with excellent chemical stability and photo-stability. However, current application of PCNs in organic synthesis is rather limited to several well-established materials, which limits the scope of reaction patterns and efficiency. We herein report the synthesis and fabrication of two PCN nanosheets by incorporating nanostructure construction, element doping, and vacancy engineering into one hybrid platform. The heteroatom doped PCN nanosheets with vacancies feature highly porous structures with extremely large substrate-catalyst interface areas and enhanced charge separation. The generated heterogeneous catalysts demonstrate impressive photoredox catalytic performances in a variety of organic transformations (e.g., defluoroborylation; [2+2] cycloaddition; C–N, C–S, C–O cross-couplings; and an unprecedented regioselective hydrosilylation), providing efficiencies comparable to reported optimized homogeneous catalysts and exceeding those with commonly utilized PCNs.

N-alkyl and N-aryl imines have been frequently used as directing groups in rhodium- and cobalt-catalyzed hydroarylation reactions of olefins and alkynes. However, the scope of such hydroarylation reactions has been limited by the difficulty of preparation of sterically hindered imines by condensation, and also by the steric bulkiness of the imine group itself. Reported herein is that an N-H imine serves as an alternative and highly effective directing group for cobalt-catalyzed hydroarylation of olefins, and unlocks many of the limitations associated with the previously employed N-aryl imine directing group. The power of this minimal nitrogen directing group is manifested in a fourfold ortho alkylation of benzophenone imine, and it occurs rapidly at ambient temperature.

We report here that a cobalt catalyst generated from a cobalt(II) salt and a ligand using magnesium metal is capable of promoting hydroarylation reactions through chelation-assisted C−H activation. With the appropriate choice of the ligand and other reaction conditions, ketimine- or aldimine-directed branched selective hydroarylations of styrenes and ketimine-directed hydroarylations of vinylsilane have been achieved. The reported catalytic systems may serve as more convenient alternatives to previously developed catalytic systems employing Grignard reagents as reducing agents. MOE (Min. of Education, S’pore) Accepted version

Iron‐catalyzed ortho C−H arylation and methylation reactions of pivalophenone N−H imines are reported. The pivaloyl N−H imine proved an excellent directing group for the arylation with diarylzinc reagents in the presence of an iron‐diphosphine catalyst and 2,3‐dichlorobutane at room temperature. A similar catalytic system also allowed methylation with Me3Al at 70 °C. The pivaloyl imine of the product could be readily converted to a cyano group, thus allowing convenient preparation of ortho‐functionalized benzonitriles. Ministry of Education (MOE) Nanyang Technological University Accepted version This work was supported by the Ministry of Education (Singapore) and Nanyang Technological University (MOE2016-T2-2-043)

A cobalt-catalyzed, N–H imine-directed hydroarylation reaction of styrenes is reported. A variety of diaryl and aryl alkyl N–H imines participated in the reaction to afford the corresponding branched adducts in good yield and regioselectivity. Interestingly, unsymmetrical diaryl imines with modest electronic biases reacted regioselectively at one of the aryl rings. Furthermore, the branched selectivity was reversed for substrates bearing a secondary directing group or a bulky pivaloyl N–H imine. MOE (Min. of Education, S’pore) Accepted version

The depths of magma storage regions are critical for understanding the magma plumbing system and magma evolving processes, and are studied and constrained mainly using geophysical and petrological techniques. In this study, we review the geophysical studies that in recent years, focused on the Tianchi magma reservoirs and find that several studies consistently reported the existence of a wide magma storage region at about 10-15 km depth that narrows down to 15-40 km, under the Tianchi volcano. To provide an independent constraint, we used petrological thermodynamics simulation (phase equilibria) to reconstruct the depth and composition of the Tianchi volcano magma chamber. The results show that: (1) the Tianchi primitive magma may not have plagioclase fractional crystallized in the lithospheric mantle or deeper, and may only experienced a small degree of olivine fractional crystallization; (2) the lower MgO shield basalts erupted from the magma chamber that is located in the earths crust (18-27 km, 0.5-0.9 GPa), instead of being directly ejected from the lithospheric mantle as it was assumed previously; (3) the trachytic magma is stored at depth of about 15-18 km (0.5-0.6 GPa, in the upper crust) and evolved from alkali basalt; (4) the Tianchi volcanic magmatic system may be more complicated than previously thought. The basaltic magma should occupy the main crustal magma reservoirs, from the lower to the mid-upper crust, while the acidic magma accounts for only a very small proportion and is concentrated in the upper crust.

An iron-catalyzed, N−H imine-directed arene C−H silylation reaction with hydrosilane has been achieved. Pivalophenone N−H imine undergoes ortho C−H silylation with triethylsilane in the presence of [Fe3(CO)12] as a catalyst and norbornene as a hydrogen acceptor. The product can be readily transformed into ortho-silylated benzonitrile via conversion of the imine functionality to a cyano group under peroxide photolysis. MOE (Min. of Education, S’pore) Accepted version

A catalyst-free tandem reaction for synthesis of 4-nitromethyl-chromenes has been established from accessible α,β-unsaturated ketones and CH3NO2. Target products were obtained in non-toxic solvent under catalyst-free conditions. Especially, the scope of substrates was expanded to tricyclic α,β-unsaturated ketones for the synthesis of tetracyclic heterocompounds in medium to good yields.

A novel intramolecular oxidative coupling reaction has been established to prepare benzofuran derivatives via direct C(sp(2))-H functionalization for the formation of C-O bond. This transformation is mediated by I2/TBHP/NaN3 under metal-free conditions and a catalytic amount of NaN3 plays a crucial role in the reaction. Furthermore, the reaction tolerates a broad substrate scope with average to excellent yields.

A novel one-pot two-step protocol has been developed to synthesize various spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives from the three-component reaction of tetralones, 2-hydroxyphenyl functionalized α,β-unsaturated ketones, and iodine. One C–C bond and one C–O bond have formed during this process. The notable features of this protocol are simple and mild reaction conditions, applicable to a wide range of readily available starting materials, good yields (up to 91%), and excellent stereoselectivities (up to 97:3).

A tandem ring-closing reaction was developed for the synthesis of 9-arylfluorenes and their derivatives. The reaction is metal-free, straightforward and efficient under warm conditions and more than 99% yield is obtained.

A convenient metal-free method for the synthesis of 3-aryl isoindolinones via TfOH catalyzed aromatic C-H functionalization of electron-rich arenes with 2-formylbenzonitriles is developed. This process provided a new efficient strategy for the synthesis of isoindolinone derivatives in good to high yields and regioselectivities by forming two bonds.

The electron-rich complex Ni(PMe3)4 was utilized to react with perfluoropropene to obtain Ni(CF2═CFCF3)(PMe3)3 (1). The selective C–F bond activation process of the π-coordinated perfluoropropene in 1 was conducted with the promotion of Lewis acids (ZnCl2, LiBr, and LiI) under mild conditions to afford the products Ni(CF3C═CF2)(PMe3)2X (X = Cl (2), Br (3), I (4)). The structures of complexes 2 and 3 determined by X-ray single-crystal diffraction confirmed that the C–F bond activation occurred at the geminal position of the trifluoromethyl group. Surprisingly, CF3COOH as a protonic acid could also carry out a similar activation reaction to give rise to Ni(CF3C═CF2)(CF3COO)(PMe3)2 (7), while only the addition products Ni(CF2CFHCF3)(CH3COO)(PMe3) (5) and Ni(CF2CFHCF3)(CH3SO3)(PMe3) (6) were obtained with CH3COOH and CH3SO3H. The transmetalation products Ni(CF3C═CF2)Ph(PMe3)2 (8), Ni(CF3C═CF2)(p-MeOPh)(PMe3)2 (9), and Ni(CF3C═CF2)(C≡CPh)(PMe3)2 (10) were obtained through the reactions of Ni(CF3C═CF2)(PMe3)2Cl...

The synthesis and characterization of a series of Ni, Co, and Fe complexes bearing a tridentate bis(phosphino)silyl ligand (κ3-(2-Ph2PC6H4)2SiMeH, [PSiP]-H, 1) are reported. 1 reacted with Ni(PMe3)4 to afford the mononuclear nickel(0) complex [η2(Si–H)-PSiP]Ni(PMe3) (2). The halogeno nickel complexes [PSiP]Ni(X)(PMe3) (X = Cl (3), Br (4), I (5)) were synthesized in the reactions of 2 with Me3SiCl or MeHSiCl2, EtBr, and MeI. Complex 2 underwent ligand substitution of PMe3 by CO to give [η2(Si–H)-PSiP]Ni(CO) (6). Complex 3 reacted with NaOMe to deliver [PSiP]Ni(OMe)(PMe3) (7) through anionic ligand substitution, while the neutral ligand replacement of PMe3 by CO in 3 afforded the rare hexacoordinate 20-electron nickel(II) complex [PSiP]Ni(Cl)(CO)2 (8). Unexpectedly, reaction of 1 with NiMe2(PMe3)3 produced the tetracoordinate nickel(0) complex [Me2PSiP]2Ni (9). The complex [Me2PSiP]Ni(CO)2 (10) was acquired from 9 after the substitution of one [PSiP] ligand by two carbonyl ligands. 1 reacted with Co(PMe3)4 ...

2-Aminobenzophenone (1) reacted with NiMe2(PMe3)3 and CoMe3(PMe3)3 afforded N–H bond cleavage products, the tetra-coordinate square-planar nickel complex (2), and the hexa-coordinate octahedral dimethyl cobalt(III) complex (3) with a cationic [N, O]-chelate ligand while the reaction of Co(PMe3)4 with 2-aminobenzophenone (1) delivered only a π-(C O) coordinate complex (o-NH–C6H4–eta2-C( O)–C6H5)Co(PMe3)3 (4) in a tetrahedral coordination geometry. The structures of complexes 2–4 were determined by X-ray single crystal diffraction. The formation mechanism of complex 2 was discussed.

Pivalophenone N–H imine has been found to serve as a prominent substrate for directed C–H alkylation and arylation reactions with alkyl bromides and aryl chlorides, respectively, under cobalt–N-heterocyclic carbene (NHC) catalysis. Unlike the case of the parent pivalophenone imine, the increased steric bulk of the resulting ortho-substituted pivalophenone imines allows them to undergo clean imine-to-nitrile conversion under peroxide photolysis or aerobic copper catalysis conditions. Overall, these two-step transformations offer convenient synthetic methods for ortho-functionalized benzonitriles. MOE (Min. of Education, S’pore) Published version