Search

A direct ortho‐Csp2‐H acylalkylation of 2‐aryl‐2,3‐dihydrophthalazine‐1,4‐diones with unsubstituted and substituted allyl alcohols is achieved in high yields through Rh(III)‐catalyzed C−H bond activation process. The additional employment of Cu(OAc)2⋅2H2O as an oxidant detour the reaction towards [4+1] annulation, producing 13‐(2‐oxopropyl)‐13H‐indazolo[1,2‐b]phthalazine‐6,11‐diones in moderate yields. Interestingly, Lawesson's reagent‐mediated conditions accomplished intramolecular cyclization in ortho‐(formylalkylated)‐2,3‐dihydrophthalazine‐1,4‐diones to produce diazepino[1,2‐b]phthalazine‐diones in moderate yields. Furthermore, allyl alcohol showcased distinct reactivity in presence of different additives to produce ortho‐allylated, oxidative and non‐oxidative [4+2] annulated products. [ABSTRACT FROM AUTHOR]

An asymmetrical Schiff base triazole ligand (4-((3-mercapto-5-(naphthalen-1-ylmethyl)-4H-1,2,4-triazol-4-yl)imino)methyl)methoxy) (L) was used to generate novel micro complexes of Cr(III), VO(IV), and Mn(II) ions. Different spectroscopic techniques, including UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), flame atomic absorption, conductivity tests, CHNS elemental analysis, and magnetic susceptibility, were used to determine the structures of the Schiff base micro complexes. The density functional theory (DFT) calculation was screened to consider selected complexes. The observed data indicated their stability, and the expected chemical formula of vanadium(IV) was square pyramidal geometry in VO(L) complex formula. In contrast, the Cr(III) and Mn(II) complexes have octahedral geometry in the formulas. Frontier molecular orbitals calculations (MO) have also been performed to better understand the nature of orbitals, EHOMO, and ELUMO, allowing us to confirm the experimental finding. Pseudomonas aeruginosa and Bacillus subtilis, two types of potentially dangerous bacteria, were subjected to tests to see whether L and its metal complexes have any antibacterial activities or not. All compounds were also tested for their antifungal activity against two different types of fungi, Penicillium spp. and Aspergillus flavus. There is significant action has been noted in all cases for the complexes.

Comprehensive Summary: Hydrogermylation of alkenes and alkynes provides a straightforward synthetic route to organogermanium compounds that have been found applications in organic synthesis, medicinal chemistry, and material science. This paper reviews the advances in transition‐metal‐catalyzed hydrogermylation of unsaturated carbon‐carbon bonds, including alkenes, alkynes, dienes, and allenes, with the objective of providing readers with the status of the field. Progress, problems, and perspectives in this field are discussed. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Hydrogermylation of alkenes and alkynes provides a straightforward synthetic route to organogermanium compounds that have been found applications in organic synthesis, medicinal chemistry, and material science. This paper reviews the advances in transition‐metal‐catalyzed hydrogermylation of unsaturated carbon‐carbon bonds, including alkenes, alkynes, dienes, and allenes, with the objective of providing readers with the status of the field. Progress, problems, and perspectives in this field are discussed. [ABSTRACT FROM AUTHOR]

Second‐harmonic generation (SHG) is a fundamental optical property of nonlinear optical (NLO) crystals. Thus far, it has proved difficult to engineer large SHG responses, particularly in the mid‐infrared region, owing to the difficulty in simultaneously controlling the arrangement and density of functional NLO‐active units. Herein, a new assembly strategy employing functional modules only, and aimed at maximizing the density and optimizing the spatial arrangement of highly efficient functional modules, has been applied to the preparation of NLO crystals, affording the van der Waals crystal MoO2Cl2. This exhibits the strongest powder SHG response (2.1×KTiOPO4 (KTP) @ 2100 nm) for a transition‐metal oxyhalide, a wide optical transparency window, and a sufficient birefringence. MoO2Cl2 is the first SHG‐active transition‐metal oxyhalide effective in the infrared region. Theoretical studies and crystal structure analysis suggest that the densely packed, optimally‐aligned [MoO4Cl2] modules within the two‐dimensional van der Waals layers are responsible for the giant SHG response. [ABSTRACT FROM AUTHOR]

The cohesive energy of transition-metal nanoparticles is crucial to understanding their stability and fundamental properties, which are essential for developing new technologies and applications in fields such as catalysis, electronics, energy storage, and biomedical engineering. In this study, we systematically investigate the size-dependent cohesive energies of all the 3d, 4d, and 5d transition-metal nanoclusters (small nanoparticles) based on a plane-wave-based method within general gradient approximation using first-principles density functional theory calculations. Our results show that the cohesive energies of nanoclusters decrease with decreasing size due to the increased surface-to-volume ratio and quantum confinement effects. A comparison of nanoclusters with different geometries reveals that the cohesive energy decreases as the number of nanocluster layers decreases. Notably, monolayer nanoclusters exhibit the lowest cohesive energies. We also find that the size-dependent cohesive energy trends are different for different transition metals, with some metals exhibiting stronger size effects than others. Our findings provide insights into the fundamental properties of transition-metal nanoclusters and have potential implications for their applications in various fields, such as catalysis, electronics, and biomedical engineering. [ABSTRACT FROM AUTHOR]

It should be mentioned that so far electrocarboxylation has been mainly explored for the carboxylation of olefins and imines, and only a few reports have been published on direct electrocatalytic C(sp SP 3 sp )-H bond carboxylation reactions. In previous studies, transition-metal or transition-metal-free methodologies proceeded through C(sp SP 3 sp )-H bond carboxylation reactions via enolate chemistry to trap a CO SB 2 sb molecule in order to give carboxylation products. Recent Advances on the Carboxylations of C(sp3)-H Bonds Using CO2 as the Carbon Source Keywords: carbon dioxide; transition-metal; transition-metal-free; thermochemical strategy; visible-light-induced photocatalysis; electrocatalysis; reductive C-H carboxylations; carboxylic acids EN carbon dioxide transition-metal transition-metal-free thermochemical strategy visible-light-induced photocatalysis electrocatalysis reductive C-H carboxylations carboxylic acids 1327 1342 16 07/11/23 20230725 NES 230725 Graph 1 Introduction The carboxylic acid unit is omnipresent in bioactive drug molecules, pharmaceuticals, natural products, and agrochemicals. [Extracted from the article]

An important deliberation of this current work is the impending applications of bivalent transition metals doped with nano ferrites and to study their emerging properties of magnetically active ferrites, which constitute oxides of iron (different conformers most demanding γ-Fe2O3) and transition metal complexes of bivalent metal oxides like cobalt (Co(II)) and magnesium (Mg(II)). Fe3+ ions occupy tetrahedral sites; the rest of Fe3+ and the Co2+ ions occupy octahedral sites. For the synthesis, a self-propagating method of combustion at lower temperature was used. Zinc and cobalt nano ferrites are synthesized from the chemical coprecipitation method of 20 to 90 nm in average size, characterized thoroughly employing FTIR and PXRD and surface morphology studied using SEM. These results explain the existence of ferrite nanoparticles in cubic spinel. Magnetically active metal oxide nanoparticles are now commonly employed in main studies of sensing, absorption, and other properties. All studies showed the interesting results. [ABSTRACT FROM AUTHOR]

Quinazolines are a class of nitrogen-containing heterocyclic compounds with broad-spectrum of pharmacological activities. Transition-metal-catalyzed reactions have emerged as reliable and indispensable tools for the synthesis of pharmaceuticals. These reactions provide new entries into pharmaceutical ingredients of continuously increasing complexity, and catalysis with these metals has streamlined the synthesis of several marketed drugs. The last few decades have witnessed a tremendous outburst of transition-metal-catalyzed reactions for the construction of quinazoline scaffolds. In this review, the progress achieved in the synthesis of quinazolines under transition metal-catalyzed conditions are summarized and reports from 2010 to date are covered. This is presented along with the mechanistic insights of each representative methodology. The advantages, limitations, and future perspectives of synthesis of quinazolines through such reactions are also discussed.

Hausmannite is a common low valence Mn oxide mineral, with a distorted spinel structure, in surficial sediments. Although natural Mn oxides often contain various impurities of transitional metals (TMs), few studies have addressed the effect and related mechanism of TM doping on the reactivity of hausmannite with metal pollutants. Here, the reactivity of cobalt (Co) doped hausmannite with aqueous As(III) and As(V) was studied. Co doping decreased the point of zero charge of hausmannite and its adsorption capacity for As(V). Despite a reduction of the initial As(III) oxidation rate, Co-doped hausmannite could effectively oxidize As(III) to As(V), followed by the adsorption and fixation of a large amount of As(V) on the mineral surface. Arsenic K-edge EXAFS analysis of the samples after As(V) adsorption and As(III) oxidation revealed that only As(V) was adsorbed on the mineral surface, with an average As-Mn distance of 3.25–3.30 Å, indicating the formation of bidentate binuclear complexes. These results provide new insights into the interaction mechanism between TMs and low valence Mn oxides and their effect on the geochemical behaviors of metal pollutants. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic and magnetic properties of Janus MoSSe monolayer are modified with single TM atom. • Mo-, Re- and Os-MoSSe candidates stand out via a four-step NRR screening strategy. • Re-MoSSe exhibits better NRR catalytic activity than the reported conventional Re-MoS 2. • Origins of high NRR activity for Mo-, Re- and Os-MoSSe are systematically revealed. Designing efficient nitrogen reduction reaction (NRR) electrocatalysts for ammonia (NH 3) synthesis under mild conditions is an attracting and challenging theme in energy electrocatalysis. Herein, the catalytic activity of a series of 3d (Cr, Mn, Fe, Co, Ni), 4d (Mo, Tc, Ru, Rh, Pd) and 5d (W, Re, Os, Ir, Pt) transition-metal (TM) atoms anchored Janus MoSSe monolayers for NRR is systematically explored by means of the first-principles calculations. A four-step NRR screening strategy (ΔG(*N 2) < 0 eV, ΔG(*N 2 → *NNH) < 0.50 eV, ΔG(*NH 2 → *NH 3) < 0.50 eV and ΔG(*N 2) < ΔG(*H)) is designed and applied to 15 TM-MoSSe systems, and only the Mo-, Re- and Os-MoSSe stand out. The reaction mechanisms of NRR on Mo-, Re- and Os-MoSSe are all via the distal pathway and exhibit excellent catalytic activity (with the limiting potentials of −0.49, −0.39 and −0.49 V, respectively), especially the Re-MoSSe. The high NRR activity of the Mo-, Re- and Os-MoSSe can originate mainly from the effective activation of N 2 , high built-in electrical field and superior electrical conductivity. Present findings may suggest a reliable and effective NRR screening strategy for the design of NRR electrocatalysts and promote the further exploration and development of novel NRR electrocatalysts. [ABSTRACT FROM AUTHOR]

The development of nonlinear optical (NLO) materials has been hindered by competing microstructure requirements: the need to simultaneously engineer a large hyperpolarizability (a large second‐harmonic generation (SHG)) and a wide HOMO–LUMO gap (a wide band gap). Herein, a non‐centrosymmetric transition‐metal (TM) oxyfluoride K5(NbOF4)(NbF7)2 (KNOF) with an extremely high F/O ratio is constructed in high yield. KNOF exhibits an extremely wide band gap (5.88 eV) and a strong powder SHG response (4.0×KH2PO4)—both being the largest values for TM‐centered oxyfluorides—as well as a birefringence sufficient for applications. The dominant roles of the partially fluorinated [NbO2F4] and totally fluorinated [NbF7] groups in achieving the enlarged band gap in KNOF have been clarified by first‐principles calculations. Our results suggest that maximizing the fluorine content of oxyfluorides may unlock the promise of short‐wavelength‐transparent materials with exceptional NLO performance. [ABSTRACT FROM AUTHOR]

Based on the perturbation formulae of the spin Hamiltonian parameters (SHPs) for a tetragonally compressed octahedral 3d1 cluster, the defect structures and SHPs of V4+ in strontium-tellurium borate ((30-x)SrO-xTeO2-10TiO2-58B2O3-2V2O5 at distinct TeO2 contents x = 1, 2, 3, 4 and 5 mol %) glasses are systematically investigated. The involved model quantities (i.e. covalent factor N, tetragonal compression ratio τ, core polarization constant κ and reduction factor H) at various x reasonably reproduce the experimental SHPs, and these quantities are further fitted with uniform Fourier-type content functions (FTCF) with merely three adjusted parameters. The different content fluctuations of these quantities are ascribed to content declines of the strong network modifier SrO and hence the modulations in local tetragonal compression, system compactness and electron cloud distribution near vanadium in the glass network. [ABSTRACT FROM AUTHOR]

Alkyl fluorides modulate the conformation, lipophilicity, metabolic stability, and pKa of compounds containing aliphatic motifs and, therefore, have been valuable for medicinal chemistry. Despite significant research in organofluorine chemistry, the synthesis of alkyl fluorides, especially chiral alkyl fluorides, remains a challenge. Most commonly, alkyl fluorides are prepared by the formation of C−F bonds (fluorination), and numerous strategies for nucleophilic, electrophilic, and radical fluorination have been reported in recent years. Although strategies to access alkyl fluorides by C−C bond formation (monofluoroalkylation) are inherently convergent and complexity‐generating, they have been studied less than methods based on fluorination. This Review provides an overview of recent developments in the synthesis of chiral (enantioenriched or racemic) secondary and tertiary alkyl fluorides by monofluoroalkylation catalyzed by transition‐metal complexes. We expect this contribution will illuminate the potential of monofluoroalkylations to simplify the synthesis of complex alkyl fluorides and suggest further research directions in this growing field. [ABSTRACT FROM AUTHOR]

The recent decade evidenced a significant development in the construction of the C−S bond. The journey began with transitional‐metal catalysis and reached sustainable catalysis via oxidant, photo, and electro catalyzed methods. A variety of catalytic systems have been explored for the C−S bond formation using a variety of sulfur precursors. This personal account provides an inclusive discussion of these developed methods in terms of reactivity, sustainability and productivity. [ABSTRACT FROM AUTHOR]

Sulfonyl compounds have attracted considerable interest due to their extensive applications in drug discovery, agricultural, and material science. The access to the assembly of SO2‐containing compounds via the same oxidative‐state introduction of hypervalent sulfur has come to the fore in the recent years. Especially, the transition‐metal‐involved synthesis of hypervalent sulfur compounds is the most effective strategy since SO2 is easy to insert into the metal‐carbon bonds. This review discusses the application of the same oxidation‐state introduction of hypervalent sulfur strategy under the transition‐metal‐catalyzed conditions, and presents according to different metal catalysts and the synthesized diversity hypervalent sulfur‐containing compounds skeletons, including sulfonamides, sulfones, sulfinamides, sulfonyl acids and sulfonyl fluorides. [ABSTRACT FROM AUTHOR]

Synthetic exploration and theoretical characterization of metal clusters are actively developing branches of modern inorganic chemistry. Advances in these areas constantly expand the rich structural diversity of viable species, allowing a detailed study of the fundamental characteristics of bench‐stable compounds. In this minireview, we summarize recent achievements in synthesis and computational analyses of main‐group and heterometallic clusters containing multiple aromatic/antiaromatic units. These systems range from bare clusters to ligand‐decorated aggregates, providing a fundamental understanding of the aromaticity and antiaromaticity concepts in species exhibiting unprecedented shapes and composition. The review gives a comprehensive summary of bonding and magnetic response properties of such systems deciphered from the Adaptive Natural Density Partitioning (AdNDP) approach and induced magnetic field analyses. [ABSTRACT FROM AUTHOR]

Zhipeng Zhang (left) received his B.S. degree from Shandong University (China) in 2004, and his Ph.D. degree from the Shanghai Institute of Organic Chemistry (SIOC) in 2010 under the supervision of Professor Kuiling Ding. In 2011, he began his postdoctoral studies with Professor Benjamin List at the Max Planck Institute for Coal Research in Mülheim an der Ruhr, Germany. After three years of research on asymmetric organocatalysis, he joined the group of Professor Jin-Quan Yu at The Scripps Research Institute in La Jolla, California as a postdoctoral research associate in 2014. He subsequently worked at the Genomics Institute of the Novartis Research Foundation (GNF) from 2016, before he began his independent career as a professor at the East China University of Science and Technology (ECUST) in 2017. His current research interests include asymmetric catalysis and synthetic methodology, focusing on the design and development of novel chiral ligands and catalysts. Baoguo Zhao (right) received his B.S. degree from Wuhan University in 1996, his M.S. degree from Nanjing University under the supervision of Professor Jianhua Xu in 2002, and his Ph.D. degree from the Shanghai Institute of Organic Chemistry (SIOC) under the supervision of Professor Kuiling Ding in 2006. He subsequently worked with Professor Yian Shi for five years as a postdoctoral fellow at the Department of Chemistry of Colorado State University. In 2011, he joined Shanghai Normal University at the Department of Chemistry as a full professor. His current research interests are in the area of biomimetic asymmetric catalysis, including the development of bioinspired chiral catalysts and synthetic methodologies. [ABSTRACT FROM AUTHOR]

Indole is a core structure in many biologically important natural products such as heteroauxin, tryptophan, hypaphorine, bufotenine and gramine. Further, indole based natural products attracted the attention of many research groups due to their broad range of applications in pharmaceuticals, agrochemicals. Thus, it is essential to cover recent advances in the synthesis of indoles and its derivatives. Historically, indole and its derivatives are synthesized by numerous approaches, which is a vast subject and beyond the scope of this review. Herein, we particularly focused on the last five years progress in synthetic approaches for the construction of indole and its derivatives from the substituted 2‐ethynyl anilines using various approaches such as transition‐metal catalyzed cyclizations, metal‐free, and radical reactions. Therefore, we believe that summarizing these results may be very useful for chemists who are interested in the synthesis of heterocyclic compounds. [ABSTRACT FROM AUTHOR]

Electrochemical experiments performed on the complex Ce-IV[2-((BuNO)-Bu-t)py](4), where [2-((BuNO)-Bu-t)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(Bu4N)-Bu-n](2)[Ce(NO3)(6)] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with delta symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree throughtuning of its ligand-field environment.

Catalytic asymmetric transformations involving carbon‐carbon bond cleavages open intriguing strategies for the synthesis of chiral complex molecules. The transient organometallic species mainly generate from the oxidative addition of cyclic compounds with low valence metals or from β‐carbon elimination of tert‐alkoxyl metals. This overview covers the recent advances in transition‐metal‐catalyzed carbon‐carbon bond activation in asymmetric synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • LDH-derived mixed oxides - active in hydrodeoxygenation reaction at low H 2 pressure. • Cu-MgAlO has excellent catalytic activity in hydrodeoxygenation of benzyl alcohol. • 15 at. % Cu is the optimum content of the active component. • With 96% selectivity at 97% conversion, toluene is the main reaction product. M-MgAlO mixed oxide catalysts were prepared by controlled thermal decomposition of layered double hydroxides (LDH) precursors and were tested in the hydrodeoxygenation of benzyl alcohol. LDH with Mg/Al = 3 and 10 at. % M with respect to cations (M = Mn, Fe, Co, Ni, Cu and Zn) were obtained by coprecipitation. A second series of copper-containing catalysts with copper content from 5 to 20 at. % was also prepared. The solids were characterized by X-ray diffraction, N 2 adsorption/desorption, temperature-programmed reduction in H 2 atmosphere, temperature-programmed desorption of CO 2. The influence of the transition metal and, for the copper-containing samples, of the copper loading, reaction temperature, reaction time, amount of catalyst and reduction pre-treatment on the catalytic performance were investigated. With 97% alcohol conversion and 96% selectivity to toluene, Cu 15 MgAlO is the best hydrodeoxygenation catalyst. It was also tested in the hydrodeoxygenation of 1-heptanol. [ABSTRACT FROM AUTHOR]

The development of novel methodologies for catalytic enantioselective functionalization reactions enabled by chiral transient directing groups is accompanying in a paradigm shift in the field of asymmetric synthesis. In particular, these highly atom‐ and step‐economic enantioinduction processes commonly proceed either via enantioselective C−H functionalization, or via enantioselective hydroarylation of the pro‐chiral substrates generating point, axial or planar chirality. The use of the transient directing group strategy in C−H functionalizations precludes the stoichiometric installations and removal of directing groups and enables efficient, more compatible and economical chemical routes. This minireview highlights asymmetric transition‐metal‐catalyzed methodologies involving chiral transient directing groups together with the scope, utility and future perspective of the field. [ABSTRACT FROM AUTHOR]

The synthetic methods of isocoumarins and phosphaisocoumarins from the C‐H activation reaction of aromatic compounds having carboxylic acid and phosphoryl groups as directing groups activation with alkynes, vinyl acetates, cyclic 2‐diazo‐1,3‐diketones, benzoquinone‐1,3‐dienes, bromoalkynes, and epoxides were reviewed. CH activation followed by oxidative cyclization using aromatic carboxylic acids affords isocoumarin derivatives in good to excellent yields in the presence of a variety of transition metal catalysts such as rhodium, iridium, cobalt, ruthenium, and palladium. In addition, the synthetic methods used for obtaining phosphaisocoumarins were accessed using phosphoryl groups as directing groups through CH activation catalyzed by rhodium, ruthenium, and palladium. [ABSTRACT FROM AUTHOR]

During the past decade, many research groups have described catalytic methods for 1,2‐carboboration, allowing access to structurally complex organoboronates from alkenes. Various transition metals, especially copper, palladium, and nickel, have been widely used in these reactions. This review summarizes advances in this field, with a special focus on the catalytic cycles involved in different metal‐catalyzed carboboration reactions, as well as the regio‐ and stereochemical consequences of the underlying mechanisms. 1,2‐Carboboration of other unsaturated systems, such as alkynes and allenes, is outside of the scope of this review. [ABSTRACT FROM AUTHOR]

Using the first-principles calculations based on density functional theory (DFT-D2 method), we systematically study the structural, energetic, electronic and magnetic properties of toxic gas molecules (H 2 S, NH 3 and SO 2) adsorbed on pristine and transition metal (TM) atom (Fe, Mn) doped GaN monolayer (GaN-ML). The results show that the H 2 S and NH 3 are physisorbed on pristine GaN-ML with small adsorption energy, charge transfer, and long adsorption distance. While chemical adsorption character of SO 2 on GaN-ML can be obtained, which means that the pristine GaN-ML is sensitive to SO 2. We find that the adsorption ability of pristine GaN-ML can be improved by introducing TM dopants. TM (Fe, Mn) doping can increase adsorption energy and charge transfer of the adsorbed systems, except for SO 2 adsorbed Fe doped GaN-ML. The enhancing interaction between adsorbed molecules and the TM doped GaN-ML can dramatically induce electrical conductivity changes. Therefore, the TM doped GaN-ML is more suitable for gas molecules detection compared with the pristine GaN-ML. These present properties of gas molecules adsorbed on the pristine and TM doped GaN-ML will help to guide scientists to develop better two-dimensional GaN-based gas sensors in the future. • Adsorptions of toxic gas molecules on pristine and TM doped GaN-ML are studied by DFT-D2 method. • The H 2 S and NH 3 are physisorbed on pristine GaN-ML, while chemical adsorption character of SO 2 on GaN-ML can be obtained. • TM doping is promising to improve gas molecules adsorption ability of pristine GaN-ML. • The enhancing interaction between gas molecules and TM doped GaN-ML can induce electrical conductivity changes. [ABSTRACT FROM AUTHOR]

Abstract Luminescent complexes illustrate high interest as luminescent materials in the fields of optical communications, lighting, sensors and biomedical devices. This review gives the structural and luminescent studies on isonicotinic acid based complexes, and probably provides the structure-property relationship. These complexes display various luminescent properties, such as luminescent probe, different luminescence when immersed in different organic solvents. This review is divided into three sections to discuss, including transition-metal, lanthanide, lanthanide-transition heterometal. The approach will help design and synthesis of luminescent complexes as promising materials. [ABSTRACT FROM AUTHOR]

The absorption spectrum of antimony phosphate glass doped with Cr3+ is characterized by the presence of features on the 4T2g(4F) absorption band. These features result from the interaction of the 2Eg(2G) and 2T1g(2G) sharp levels with the vibrationally broadened 4T2g(4F) quasi-continuum via spin-orbit coupling called interference dips. We have analyzed this phenomenon through two models: Fano’s antiresonance and Neuhauser models. This analysis permits us to determine the electronic structure of the chromium ion Cr3+ based on the crystal field theory. As a result, Racah and crystal-field parameters have been reliably obtained. A good agreement between the theoretical and the experimental energy levels are obtained. [ABSTRACT FROM AUTHOR]

Abstract: In novel superatom chemistry, it is very attractive that all‐metal clusters can mimic the behaviors of nonmetal atoms and simple nonmetal molecules. Wizardly all‐metal halogen‐like superatom Al13 with 2P5 sub shell (corresponding to the 3p5 of chlorine) is the most typical example. In contrast, how to mimic the behaviors of magnetic transition‐metal atom using all‐nonmetal cluster is an intriguing challenge for superatom chemistry. In response to this based on human intuition, using quantum chemistry methods and extending jellium model from metal cluster to all‐nonmetal cluster, we have found out that all‐nonmetal octahedral B6 cluster with characteristic jellium electron configuration 1S21P62S21D8 in the triplet ground state can mimic the behaviors of transition‐metal Ni atom with electron configuration 3s23p64s23d8 in electronic configuration, physics and chemistry. Interestingly, the characteristic order of 1S1P2S1D for the B6 nonmetal cluster with short B‐B lengths is different from that of the traditional jellium model—1S1P1D2S for metal clusters with long M‐M lengths, which exhibits a novel size effect of nonmetal cluster on jellium orbital ordering. Based on the jellium electron configuration, the B6 with the spin moment value of 2μB is a new all‐nonmetal transition‐metal nickel‐like superatom exhibiting a new kind of all‐nonmetal magnetic superatom. Finding the application of the all‐nonmetal magnetic superatom, we encapsulate the magnetic superatom B6 inside fully hydrogenated fullerene forming a clathrate B6@C60H60 with the spin moment value of 2μB. As the C60H60 cage as a polymerization unit can conserve the spin moment of endohedral B6, the clathrate B6@C60H60 is a new all‐nonmetal magnetic superatom building block. Naturally, magnetic superatom structures of the B6 and B6@C60H60 may be metastable. [ABSTRACT FROM AUTHOR]

Abstract: Organic compounds containing multiple C=C bonds are attractive substrates for catalytic asymmetric hydrogenation. The full saturation of prochiral double bonds, controlling the creation of two or more stereocenters in one step, is obviously a remarkable goal. However, another fascinating and useful option is to selectively introduce a new defined stereogenic center while leaving other double bonds untouched. Thus, the retained functionalities can be further exploited in synthesis. Examples of regio‐ and enantioselective mono‐hydrogenations of polyolefins are highlighted in this Concept article, and are divided according to the nature of the reduced double bond and the transition‐metal catalyst used. Alkenes bearing coordinating functional groups are often preferentially hydrogenated by Rh‐ and Ru‐complexes, while the more recently developed Ir‐based catalysts promote the selective saturation on alkyl‐substituted olefins. Relevant applications of this effective methodology in the synthesis of natural products are included to demonstrate its value in organic synthesis. [ABSTRACT FROM AUTHOR]

• DFT study on the mechanism of Co(III)-catalysed [3+3] annulations. • Regioselectivity of Co(III) for ligand insertion into Co-C bond. • Energetic Span Model reveals the TDTS of the path. • Effect of level of theory on the global activation energy barrier. • Effect of various substituents on various step of reaction. C-H annulation of anilide with benzylallene under the catalysis of Co(III)-complex has been studied theoretically by employing density functional theory (DFT) to find out the plausible mechanistic path. Our findings reveal that the C-H activation prefers the formation of a four-membered cobalta benzoazetidine intermediate rather than six-membered 1,2,4-cobalta benzoxazine intermediate to generate the product. This fact reveals a new mechanism in contrast to the mechanism proposed earlier. The metal mediated annulation of various anilides include six steps - coordination of substrate with catalyst, N-H metalation, C-H metalation, insertion of benzylallene, proton abstraction and migration insertion. Moreover, it reveals regioselectivity of cobalt for allene insertion. The effect of substituents on the mechanism has also been studied and the high energetic span obtained for this catalytic cycle implies that very high temperature is required for this reaction. It is consistent with the experimental result. [Display omitted] [ABSTRACT FROM AUTHOR]

The volatility of noble metals prices, globally increasing demands, and its limited resources drive chemists to find alternatives in the place of expensive transition metal catalysts. So, this is a time for the scientific community to find alternative sources to replace Nobel metals, and it is making genuine changes in developing sustainable synthetic methods. Photoexcited transition-metal catalysis is revitalizing the research area for functionalizing diverse π-bond systems. The massive progression of the two conventional photochemical reactivity modes, photoredox catalysis, and synergetic photocatalyst/transition-metal catalysis, has fueled the search for a next-level mechanistic paradigm visible-light initiated excited-state transition-metal catalysis (Cu, Pd, Fe, Au, Co, Ni, W, and Mn), which can be deployed to harvest light energy and convert it into chemical energy in a single catalytic cycle. This review summarizes early examples of the visible-light-induced photocatalytic activities of conventional transition metals employed in C-H activation, π-bond functionalization, and annulation reactions of unsaturated compounds, and excluding the commonly used expensive photocatalysts (i.e., Ir-, and Ru-based pyridyl complexes). Unlike the other two classical photochemical approaches, the discrete inner-sphere mechanism associated with photoexcited transition metals facilitates reactive substrate-metal-complex interactions. It enables the direct involvement of excited-state catalysts in bond-forming or-breaking processes. • The light driven radical capture mechanism solve the long-standing slow oxidative addition problem of copper catalyst. • At higher oxidation state, iron metal acting as a of Lewis acid, and stimulating the π-bond activation reactions. • The "super nucleophilic" Co(III)* complexes can generate the carbon centered radicals via homolytic Co-C bond cleavage. • TBADT, a polyoxotungstate involved C-H bond activation via S H 2 mechanism is irrespective of substrate redox potential. • Manganese employed photochemical reactions mostly follow the atom transfer radical mechanism (ATRM). [ABSTRACT FROM AUTHOR]

Development of first-row transition-metal-based catalysts for oxygen evolution is a desirable goal due to the low cost and abundance of transition metals, relative to iridium. However, low stability of first-row transition metal catalysts in acidic electrolytes has impeded practical application. In this work, we proposed the role of Sb in metal oxide which enhance electrochemical stability in acid media. While a Co-Fe mixed oxide exhibited poor stability in acid, a FeCoSbO x electrode demonstrate superior stability of over 70 h under the same conditions. In-situ/Operando analysis results suggest that distortion occurred in the FeCoO x electrode under acidic conditions for oxygen evolution, while the structure of the FeCoSbO x electrode was maintained. As compared to an SbO x electrode, Sb in an FeCoSbO x electrode had a higher oxidation state and shorter lattice distance, indicating strong Sb-O bonding. Given the stronger oxide bond, we anticipated that incorporation of Sb would enhance stability in acidic media not only via greater thermodynamic stability but by inhibiting distortion during the reaction. A more stable structure prevents participation by lattice oxygen, resulting in enhanced electrode stability. This demonstration of a stabilizing structural element in a transition metal oxide offers new principles for designing electrocatalysts that are stable in acidic media. [Display omitted] • Mixed transition metal oxide electrodes were prepared by dip coating and heat treatment. • Sb incorporated CoFe oxides electrodes shows good stability for OER in acid media. • Distortion occurred in the FeCoO x electrode under acidic conditions for OER. • Structure of the FeCoSbO x electrode was maintained for OER in acidic media. • Strong Sb O bond prevents participation by lattice oxygen, resulting enhanced stability. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed decarboxylative dearomatization reaction of a heterocyclic substrate enables access to an uncommon reaction intermediate that rearomatizes in the presence of amine bases in a net C-H functionalization sequence. The dearomatized benzo[ b ]thiophene intermediate bears an exocyclic alkene that can be functionalized through cycloaddition and halogenation reactions to deliver complex heterocyclic products., Competing Interests: Conflict of Interest The authors declare no conflict of interest.

This work is devoted in first part to a study of the features observed on the 4 T 2g ( 4 F) absorption band of phosphate glasses containing Cr 3+ . These features results from interaction of the 2 E g ( 2 G) and 2 T 1g ( 2 G) sharp levels with the vibrationally broadened 4 T 2g ( 4 F) quasi-continuum via spin–orbit coupling and have been analyzed in the frame of the Fano׳s antiresonance model. In second part, the electronic structure of Cr 3+ ion occupying Oh site symmetry in the phosphate glasses is determined by the crystal-field analysis. The influence of the different oxides (Na 2 O, PbO, ZnO) on the spectroscopic properties of Cr 3+ is evaluated. In metaphosphate glasses, we found that Na 2 O and PbO oxides act as glass modifiers while ZnO enters the glass forming network. [ABSTRACT FROM AUTHOR]

Developing mesocrystal bimetal oxide solid solutions with distinctive architectures applied for VOCs elimination is of significant importance towards environmental catalysis. Herein, mesocrystal M x Ce 1-x O 2 (M = Ni, Cu, Zn) solid solution within hollow spheres has been readily synthesized via a facile solvothermal strategy, primarily aiming to boost catalytic acetone oxidation performance by tailoring transition-metal cations. The physicochemical properties of the synthesized mesocrystal catalysts have been analyzed using various means of characterizations and correlated with their catalytic acetone oxidation performances. Research results evidence that the catalytic acetone oxidation performance ranked in the order of CeO 2 < Ni 0.015 Ce 0.985 O 2 < Zn 0.015 Ce 0.985 O 2 < Cu 0.015 Ce 0.985 O 2 , in which Cu 0.015 Ce 0.985 O 2 indeed acted as the optimal catalyst that completely achieved 100% CO 2 selectivity and 100% acetone conversion at 210 °C under test conditions of 20 vol%O 2 , 80 vol%N 2 as the balance gas, WHSV = 90,000 mL/g cat ·h and 1000 ppm acetone. This fact can be mainly credited to the intrinsic discrepancy of transition-metal cations that resulted in different numbers of defective sites and active oxygen species together with varied reducible capabilities. Meanwhile, all synthesized mesocrystal catalysts exhibit both excellent long-term stabilities and strong water tolerances, mainly due to the integrated factors of the mesocrystal feature together with stable crystal phase meliorating thermal stability and the robust hollow spherical architecture suppressing structural collapse, demonstrating great potentials towards VOCs elimination. Highly boosting acetone oxidation performance has been achieved for the first time over mesocrystal M x Ce 1-x O 2 (M = Ni, Cu, Zn) solid solution within hollow spheres by tailoring transition-metal cations. [Display omitted] • Mesocrystal bimetal oxide solid solutions prepared by a facile solvothermal strategy. • Mesocrystal M x Ce 1-x O 2 (M = Ni, Cu, Zn) solid solutions within hollow spheres. • Highly enhanced acetone oxidation activity by tailoring transition-metal cations. • Improved long-term stability and water tolerance originated from the integrated factors. [ABSTRACT FROM AUTHOR]