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ABSTRACT Copper complexes exhibit promising anticancer properties, which can be further promoted by suitable ligands. In this study, we synthesized and investigated the anticancer effects of three copper(I) complexes with N‐heterocyclic carbene (NHC) ligands derived from phenanthroline‐functionalized imidazole salts. The synthesis of these NHC‐copper(I) complexes (Cu1‐Cu3) was meticulously characterized using NMR and elemental analysis; their crystal structures were further delineated by X‐ray diffraction. Our findings illustrate the unique geometric configurations of these complexes: Cu1 features a dinuclear arrangement with off‐linear geometry; Cu2 and Cu3 are characterized by a bi‐copper core stabilized by two phenanthroline‐modified carbene ligands. Crucially, in vitro cytotoxic evaluations revealed that these complexes possess suitability anticancer activity. Among them, Cu2 exhibited enhanced cytotoxicity activity, achieving a half‐maximal inhibitory concentration (IC50) of 4.36 ± 0.25 μM in colon cancer cell line HCT‐116, markedly surpassing the efficacy of cisplatin. Subsequent investigations elucidated that Cu2 notably increases intracellular reactive oxygen species (ROS) levels and induces mitochondrial membrane depolarization and endoplasmic reticulum stress, leading to oxidative stress‐mediated apoptosis of colon cancer cells. [ABSTRACT FROM AUTHOR]

ABSTRACT N‐Heterocyclic carbenes (NHCs) are molecules with exceptional catalytic properties in a wide range of reactions. Recently, there has been a growing interest in using them as catalysts for biomass conversion. In this review, we examine the current state of glycerol valorisation (GV) using several catalytic systems, including metallic complexes bearing NHCs as ligands, polymeric building blocks and organocatalysts. The study covers literature published in the last 15 years, detailing the catalyst scope, reaction conditions and products of GV. This analysis emphasises the importance of varying the steric and electronic properties of NHCs within the reviewed catalytic systems. Furthermore, a critical evaluation of the proposed mechanistic pathways complements these results. A comprehensive understanding of the challenges of using such catalytic systems will emerge by compiling literature on the use of NHCs for the studied reactions. Additionally, this will promote new opportunities for further research in both academic and industrial fields. [ABSTRACT FROM AUTHOR]

Fluorinated asymmetric aryl ketones represent a pivotal class of organic synthesis intermediates, which have garnered widespread application in the realms of organic chemistry, materials science, and drug discovery. Herein, we report a pioneering nucleophilic aromatic substitution (SNAr) reaction involving aryl aldehydes and polyfluoroarenes, elegantly catalyzed by N-heterocyclic carbene (NHC). This innovative strategy yields bis(hetero)aryl ketone products in yields ranging from moderate to exceptional (40–83%), all achieved under gentle conditions, devoid of both transition metals and directing groups. The versatility of this method is underscored by its compatibility with a broad spectrum of substrates, particularly exhibiting remarkable resilience toward alkoxy functional groups. Notably, we have successfully transformed an array of biologically active molecules, crafting a series of their corresponding derivatives with precision. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]

A new eco-friendly method for the synthesis of mono- and multifunctional organosulfur compounds, based on the process between ynals and thiols, catalyzed by bulky N-heterocyclic carbene (NHC), was designed and optimized. The proposed organocatalytic approach allows the straightforward formation of a broad range of thioesters and sulfenyl-substituted aldehydes in yields above 86%, in mild and metal-free conditions. In this study, thirty-six sulfur-based derivatives were obtained and characterized by spectroscopic methods. [ABSTRACT FROM AUTHOR]

β‐Chiral carboxylic acids and their derivatives are highly valuable structural motifs in the fields of asymmetric synthesis and medicinal chemistry. However, the introduction of a sterically demanding sidechain to the β‐carbon, such as an all‐carbon quaternary center, remains a significant challenge in classical polar processes. Recently, N‐heterocyclic carbene (NHC) mediated coupling reactions involving persistent ketyl radicals have emerged as a promising strategy to assemble highly crowded carbon‐carbon bonds. Nevertheless, achieving enantioselectivity in these reactions remains highly challenging. In this work, we report our recent progress in controlling enantioselectivity for relay coupling of perfluoroalkyl and persistent vinylogous ketyl radicals. We developed a chiral bifunctional NHC‐squaramide catalyst that achieves high facial selectivity in a critical bond‐forming event involving the coupling of a congested tertiary carbon radical and vinylogous ketyl radical. Chiral carboxylates bearing an all‐carbon quaternary center at the β‐position can be prepared in good yield and excellent enantiomeric excess. Results from density functional theory (DFT) calculations and nuclear Overhauser effect (NOE) experiments indicate that the N,N'‐diaryl squaramide motif adopts an unusual syn‐syn conformation, enabling hydrogen bonding interactions with the enolate oxygen, thereby rigidifying the overall conformation of the transition state. [ABSTRACT FROM AUTHOR]

Carbodicarbenes are strong C‐donor ligands, which have found numerous applications in organometallic and main group element chemistry. Herein, we report a structurally distinct carbodicarbene ligand, which is formed by dinitrogenative coupling of a Fischer carbene complex with an N‐heterocyclic diazoolefin. The resulting carbonyl complex serves as a stable source for the mixed Arduengo‐Fischer carbodicarbene ligand. Facile ligand transfer reactions were demonstrated to occur with gold(I), copper(I), palladium(II), and rhodium(I) complexes. [ABSTRACT FROM AUTHOR]

Developing methods to directly transform C(sp3) −H bonds is crucial in synthetic chemistry due to their prevalence in various organic compounds. While conventional protocols have largely relied on transition metal catalysis, recent advancements in organocatalysis, particularly with radical NHC catalysis have sparked interest in the direct functionalization of "inert" C(sp3) −H bonds for cross C−C coupling with carbonyl moieties. This strategy involves selective cleavage of C(sp3) −H bonds to generate key carbon radicals, often achieved via hydrogen atom transfer (HAT) processes. By leveraging the bond dissociation energy (BDE) and polarity effects, HAT enables the rapid functionalization of diverse C(sp3)−H substrates, such as ethers, amines, and alkanes. This mini‐review summarizes the progress in carbene organocatalytic functionalization of inert C(sp3)−H bonds enabled by HAT processes, categorizing them into two sections: 1) C−H functionalization involving acyl azolium intermediates; and 2) functionalization of C−H bonds via reductive Breslow intermediates. [ABSTRACT FROM AUTHOR]

A series of naphthalene‐diimide (NDI) and perylene‐diimide (PDI) connected bis‐N‐heterocyclic carbene complexes of iridium(III) have been prepared and fully characterized. The analysis of their NMR spectroscopic features, together with their molecular structures show that these species display lone‐pair‐π interactions between the chloride ligands of the Ir(III) complex and the heterocycles of the NDI/PDI moieties. The detection of this type of interaction in solution is due to the formation of two atropisomers, which are formed as a result of the restricted rotation about the Ir−Ccarbene bond imposed by the (Cl)lp⋅⋅⋅π interaction. Variable‐temperature 1H NMR analysis allowed the determination of the strength of this non‐covalent interaction, which lies between ΔH=6.6 and 10 kcal/mol. The computational studies performed fully support the experimental findings. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Axially chiral biaryls represent the most important class of atropisomers, and they widely exist in natural products and biologically active molecules. They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis. The development of synthetic methods to obtain such chiral compounds has received widespread attention, among which catalytically atroposelective ring‐opening of configurationally labile compounds represents one of the most attractive strategies. Various substrates with strained cyclic structures, such as the renowned Bringmann's lactones, can undergo asymmetric transformation into stable atropisomers. Known advancement primarily relies on metal catalyst combined with well‐designed chiral ligands, the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce. In this study, we disclosed a N‐heterocyclic carbene (NHC)‐catalyzed asymmetric ring‐opening reaction of biaryl lactams via direct atroposelective nucleophilic activation. The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions, affording the desired product with good to excellent yields and atroposelectivity. [ABSTRACT FROM AUTHOR]

Encephalitozoon intestinalis is an opportunistic microsporidian parasite that primarily infects immunocompromised individuals, such as those with HIV/AIDS or undergoing organ transplantation. Leishmaniasis is responsible for parasitic infections, particularly in developing countries. The disease has not been effectively controlled due to the lack of an effective vaccine and affordable treatment options. Current treatment options for E. intestinalis infection and leishmaniasis are limited and often associated with adverse side effects. There is no previous study in the literature on the antimicrosporidial activities of Ag(I)-N-heterocyclic carbene compounds. In this study, the in vitro antimicrosporidial activities of previously synthesized Ag(I)-N-heterocyclic carbene complexes were evaluated using E. intestinalis spores cultured in human renal epithelial cell lines (HEK-293). Inhibition of microsporidian replication was determined by spore counting. In addition, the effects of the compounds on Leishmania major promastigotes were assessed by measuring metabolic activity or cell viability using a tetrazolium reaction. Statistical analysis was performed to determine significant differences between treated and control groups. Our results showed that the growth of E. intestinalis and L. major promastigotes was inhibited by the tested compounds in a concentration-dependent manner. A significant decrease in parasite viability was observed at the highest concentrations. These results suggest that the compounds have potential anti-microsporidial and anti-leishmanial activity. Further research is required to elucidate the underlying mechanisms of action and to evaluate the efficacy of the compounds in animal models or clinical trials. [ABSTRACT FROM AUTHOR]

Reaction of various chloroacetamides with n-methyl imidazole afforded imidazolium salts of composition 1-methyl-3-N-(Ar)acetamido-1,3-imidazolium chloride (Ar = cyanophenyl, chlorophenyl, diphenyl). Treatment of latter prepared salts with NiCl2.6H2O in presence of excess K2CO3 yielded their respective complexes [{1-methyl-3-N-(Ar)acetamido-1,3-imidazol-2-ylidine}2Ni] (Ar = p-cyanobenzene (2a), p-chlorobenzene (2b) and [{1-methyl-3-N-(diphenyl)acetamido-1,3-imidazol-2-ylidine}2NiCl2] (2c). All the synthesized complexes were characterized by IR, NMR (1H, 13C{1H}) spectroscopy and microanalysis. The molecular structure of complex [{1-methyl-3-N-(4-cyanophenyl)acetamido-1,3-imidazol-2-ylidine}2Ni] 2a was established through single crystal-X-ray diffraction analysis. Subsequently, these complexes were studied as a catalyst for Suzuki Miyaura cross coupling reaction between 2-haloarene (halo = Cl, Br; arene = Ph, Nap, Py, Pym) and phenylboronic acid. [ABSTRACT FROM AUTHOR]

The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene (NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Axially chiral biaryls represent the most important class of atropisomers, and they widely exist in natural products and biologically active molecules. They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis. The development of synthetic methods to obtain such chiral compounds has received widespread attention, among which catalytically atroposelective ring‐opening of configurationally labile compounds represents one of the most attractive strategies. Various substrates with strained cyclic structures, such as the renowned Bringmann's lactones, can undergo asymmetric transformation into stable atropisomers. Known advancement primarily relies on metal catalyst combined with well‐designed chiral ligands, the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce. In this study, we disclosed a N‐heterocyclic carbene (NHC)‐catalyzed asymmetric ring‐opening reaction of biaryl lactams via direct atroposelective nucleophilic activation. The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions, affording the desired product with good to excellent yields and atroposelectivity. [ABSTRACT FROM AUTHOR]

The control of noncarbon stereogenic centers is of profound importance owing to their enormous interest in bioactive compounds and chiral catalyst or ligand design for enantioselective synthesis. Despite various elegant approaches have been achieved for construction of S‐, P‐, Si‐ and B‐stereocenters over the past decades, the catalyst‐controlled strategies to govern the formation of N‐stereogenic compounds have garnered less attention. Here, we disclose the first organocatalytic approach for efficient access to a wide range of nitrogen‐stereogenic compounds through a desymmetrization approach. Intriguingly, the pro‐chiral remote diols, which are previously not well addressed with enantiocontrol, are well differentiated by potent chiral carbene‐bound acyl azolium intermediates. Preliminary studies shed insights on the critical importance of the ionic hydrogen bond (IHB) formed between the dimer aggregate of diols to afford the chiral N‐oxide products that feature a tetrahedral nitrogen as the sole stereogenic element with good yields and excellent enantioselectivities. Notably, the chiral N‐oxide products could offer an attractive strategy for chiral ligand design and discovery of potential antibacterial agrochemicals. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Poly‐NHC‐based organometallic assemblies 3‐PF6, 3‐SbF6 and 3‐OTf were obtained and verified by NMR spectroscopy, ESI mass spectrometry and single‐crystal X‐ray diffraction analyses. Controllable structural interconversion was observed between the poly‐NHC‐based organometallic assemblies and their self‐aggregated dimers in solution affected by concentration, solvent and metal ion. 1H NMR spectra of assembly 3‐PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion, and 19F NMR spectrum of assembly 3‐PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals. In addition, single‐crystal X‐ray diffraction analysis provided clear evidence that in the solid state, two assemblies 3‐PF6 were vertically stuck, forming a self‐aggregated dimer with an encapsulated hexafluorophosphate anion. Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli‐responsive functional system. [ABSTRACT FROM AUTHOR]

Intermolecular pnictogen bonding (PnB) catalysis has received increased interest in non‐covalent organocatalysis. It has been demonstrated that organic electron‐deficient pnictogen atoms can act as prospective Lewis acids. Here, we present a catalytic approach for the asymmetric synthesis of chiral PIII compounds by combining intramolecular PnB interactions and carbene catalysis. Our design features a pre‐chiral phosphorus molecule bearing two electron‐withdrawing benzoyl groups, resulting in the formation of a σ‐hole at the P atom. X‐ray and non‐covalent interaction (NCI) analysis indicate that the model substrates exhibit intrinsic PnB interaction between the oxygen atom of the formyl group and the phosphorus atom. This induces a conformational locking effect, leading to the crystallization of the phosphorus substrate in a preferred conformation (P212121 chiral group). Under the catalysis of N–heterocyclic carbene, the aldehyde moiety activated by the pnictogen bond selectively reacts with an alcohol to yield the corresponding chiral monoester/phosphorus product with excellent enantioselectivity. This Lewis acidic phosphorus center, aroused by the non‐polarized intramolecular pnictogen bond interaction, assists in conformational and selective regulations, providing unique opportunities for catalysis and beyond. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: We report herein an unprecedented N‐heterocyclic carbene‐catalyzed formal [3 + 3] annulation of ynals with N‐Ts indolin‐3‐ones under the oxidation condition affording the functionalized pyrano[3,2‐b]indol‐2‐ones. The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation. This method features a broad substrate scope and mild conditions, including axially chiral skeletons with suitable substitutions. [ABSTRACT FROM AUTHOR]

The preparations of homo‐ and hetero‐bimetallic complexes as well as thiourea and selenourea derivatives of a mesoionic Janus‐type N‐heterocyclic dicarbene (diNHC) are reported. Analogues of its monocationic intermediate NHC have also been obtained for comparison. Using the main group adducts, the π‐acceptor properties of both NHCs were determined using low temperature 77Se NMR spectroscopy completing their stereoelectronic profiling. Moreover, catalytic investigations reveal that the mesoionic dipalladium Janus‐diNHC complex can be used in the sequential C2‐ and C5‐arylation of 1‐methylpyrrole for the preparation of non‐symmetrical 2,5‐diarylpyrroles. [ABSTRACT FROM AUTHOR]

Organoseleniums exhibit a diverse set of biological activities that are pivotal for drug discovery and are widely explored in synthetic chemistry and material science. While many transformations have been developed for non-enantioselective C–Se bond formations, the catalyst-controlled stereoselective preparation of chiral organoseleniums continues to be of considerable challenge. In particular, there are limited studies on the enantioselective seleno-Michael addition reactions to access chiral selenium functional molecules. Here, we disclose a carbene-catalyzed highly enantioselective nucleophilic C–Se bond construction through formal [3 + 3] annulations between selenocarboxamides and bromoenals, affording seleno-thiazinone products with good yields and excellent enantioselectivities. The choice of a weak inorganic base was pivotal to suppressing the unproductive racemization and decomposition of the selenium products. Notably, the catalytically generated chiral selenium-containing heterocyclic products feature remarkable antimicrobial activities that could serve as promising lead scaffolds for further agrochemical development. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: We report herein an unprecedented N‐heterocyclic carbene‐catalyzed formal [3 + 3] annulation of ynals with N‐Ts indolin‐3‐ones under the oxidation condition affording the functionalized pyrano[3,2‐b]indol‐2‐ones. The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation. This method features a broad substrate scope and mild conditions, including axially chiral skeletons with suitable substitutions. [ABSTRACT FROM AUTHOR]

The pincer complexes [NiIIBr(CNC)]Br (4), [CrIIIBr3(CNC)] (5 a) and [CrIIIBr2.3Cl0.7(CNC)] (5 b), where CNC=3,3′‐(pyridine‐2,6‐diyl)bis(1‐mesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene), were obtained from the novel ligand CNC, generated in situ from the precursor (CHNCH)Br2 and [NiIIBr2(PPh3)2] or from [CrII{N(SiMe3)2}2(THF)2] and (CHNCH)Br2 by aminolysis, respectively. The tetrahedrally distorted square planar (τ4≅0.30) geometry and the singlet ground state of Ni in 4 were attributed to steric constraints of the CNC backbone. Computational methods highlighted the dependence of the coordination geometry and the singlet‐triplet energy difference on the size of the N‐substituent of the tetrahydropyrimidine wingtips and contrasted it to the situation in 5‐membered imidazolin‐2‐ylidene pincer analogues. The octahedral CrIII metal center in 5 a and 5 b is presumably formed after one electron oxidation from CH2Cl2. 4/MAO and 5 a/MAO were catalysts of moderate activity for the oligomerization and polymerization of ethylene, respectively. The analogous (CH^N^CH)Br2 precursor, where (CH^N^CH)=3,3′‐(pyridine‐2,6‐diylbis(methylene))bis(1‐mesityl‐3,4,5,6‐tetrahydropyrimidin‐1‐ium), was also prepared, however its coordination chemistry was not studied due to the inherent instability of the resulting free C^N^C ligand. [ABSTRACT FROM AUTHOR]

A series of supported N‐heterocyclic carbene silver complexes (NHC‐Ag(I)) were prepared and characterized as catalysts for the borono‐Minisci reaction. After characterization, the synthesized catalysts were evaluated in batch mode to determine the reaction performance and kinetics. Interestingly, cyclic voltammetric analysis showed that the structure of both the complex and the ligand significantly influences the Ag(I)/Ag(II) redox potential and, in turn, the catalytic efficiency. Among the tested catalysts, the Si‐supported NHC‐Ag(I) 6 afforded the desired products in good to excellent yields in only 15 min, providing a complementary tactic to standard homogeneous approaches. [ABSTRACT FROM AUTHOR]

The authors of this work have optimized a novel synthetic route towards glucose‐based PdII‐bis(NHC) complexes in only 4 steps with total yields up to 73 %. The synthesis route encompasses an Appel reaction towards 6‐iodo‐glucopyranosides, followed by acyl‐protection, then quaternization with imidazoles and finally the conversion of these acyl‐protected glucosyl imidazolium salts to their respective palladium(II)bis(NHC) complexes, via an intermediary silver(I) complex. Overall, 11 acyl‐protected glucosyl imidazolium iodides as NHC‐precursors and 15 complexes have been synthesized. The structure‐activity relationships of different functionalizations in these complexes and their reactivity in a model Suzuki‐Miyaura between bromobenzene and 4‐tolueneboronic acid reaction has been investigated, and a highly reactive complex leading to >99 % yield at 0.005 mol% catalytic loading has been found. [ABSTRACT FROM AUTHOR]

This article explores the use of N-heterocyclic carbenes (NHCs) in photochemical and electrochemical catalysis for organic synthesis. NHCs have unique catalytic properties and are cost-effective and environmentally friendly. The article discusses various reactions mediated by NHCs, including the formation of C-O and C-N bonds. It also highlights the combination of NHC catalysis with photoredox catalysis for radical reactions, such as alkylation and benzylation of alkenes. The article emphasizes the potential of NHC and photoredox catalysis in enabling the construction of diverse organic compounds under mild conditions. Additionally, it presents examples of NHC-mediated reactions and discusses future research opportunities in this field. [Extracted from the article]

A series of mixed N‐heterocylic carbene (NHC) palladium complexes bearing C^N bidentate ligands derived from benzylamine, phenethylamine, and biphenylamine were prepared and fully characterized by NMR spectroscopy, ESI‐MS spectrometry, and X‐ray diffraction analyses. The complexes were potent in inhibiting proliferation of HepG2 and Caco2 cancer cells, and a SAR (structure–activity relationship) study revealed C^N ligands with stronger electron donation and moderate steric hindrance are more cytotoxic. DNA binding study through UV–vis absorption titration indicated that such complexes bound stronger to CT‐DNA molecules with higher binding constants. Additional molecular docking of the best performer suggested a groove binding mode through hydrogen bonding and π‐π stacking interactions. The apoptosis induced by the two best performers of α,α‐dimethylbenzylamine and S‐α‐methylbenzylamine ligated complexes was further analyzed by morphology change, cell cycle distribution, ROS production, and mitochondrial membrane potential studies. [ABSTRACT FROM AUTHOR]

The synthesis is demonstrated for a heteroleptic Ni(II) complex, with a tridentate ligand bearing N-heterocyclic carbene (NHC), aryloxide, and picolyl donor groups. The compound was reacted with a variety of hydroxide sources, several of which resulted in complex mixtures. Reaction with [NH4]OH affords a bis-ligated nickel compound, in which the ligands are each bound in a bidentate fashion through the NHC and aryloxide donor groups. A desired nickel(II)-hydroxo product was not observed. DFT studies suggest that ligand redistribution is thermodynamically preferred over stabilization of a Ni-hydroxo in either a monomeric or dimeric form. [ABSTRACT FROM AUTHOR]

The control of potato virus Y (PVY) induced crop failure is a challengeable issue in agricultural chemistry. Although many anti‐PVY agents are designed to focus on the functionally important coat protein (CP) of virus, how these drugs act on CP to inactivate viral pathogenicity, remains largely unknown. Herein, a PVY CP inhibitor ‐3j (S) is disclosed, which is accessed by developing unusually efficient (up to 99% yield) and chemo‐selective (> 99:1 er in most cases) carbene‐catalyzed [3+4] cycloaddition reactions. Compound ‐3j bears a unique arylimidazole‐fused diazepine skeleton and shows chirality‐preferred performance against PVY. In addition, ‐3j (S) as a mediator allows ARG191 (R191) of CP to be identified as a key amino acid site responsible for intercellular movement of virions. R191 is further demonstrated to be critical for the interaction between PVY CP and the plant functional protein NtCPIP, enabling virions to cross plasmodesmata. This key step can be significantly inhibited through bonding with the ‐3j (S) to further impair pathogenic behaviors involving systemic infection and particle assembly. The study reveals the in‐depth mechanism of action of antiviral agents targeting PVY CP, and contributes to new drug structures and synthetic strategies for PVY management. [ABSTRACT FROM AUTHOR]

Fatal pathogenic organisms have been detected by various point‐of‐care tests (PoCTs) in clinical samples. PoCTs based on portable electrical devices are able to detect organisms in simple and rapid method. Although electrical PoCT devices show ultra sensitivity when detecting pathogens in standard samples, their industrialization has been limited due to low reproducibility, sensitivity, and specificity, resulting from nonspecific binding issues by media. In this research, a perpendicular N‐heterocyclic carbene self‐assembled monolayer (NHC‐SAM) conjugated on graphene micropattern field‐effect transistors (NGMFETs) is first demonstrated for monitoring pathogens. Two single bonds of NHCSAM on GM are investigated via density functional theory (DFT) and surface analyses. Bioreceptors are conjugated on the side gate‐modulated NGMFET for ultra‐stable on‐site detection. The side‐gated BNGMFETs system displayed remarkable performance in the detection of the following: i) SARS‐CoV‐2 spike protein S1 (limit of detection (LOD): ≈10 pg mL−1) in CTM, ii) O. tsutsugamushi Ab (LOD: ≈1 pg mL−1), and iii) E. coli (LOD: 10° CFU mL−1) in serum. Compared to commercial methodology, the platform presents 102 times higher LODs towards those pathogens in clinical samples with higher reproducibility. Based on these results, side‐gated BNGMFETs can be utilized as universal PoCT during pandemics. [ABSTRACT FROM AUTHOR]

This work reports the cooperative reactivity of rare‐earth aryloxide complexes with N‐heterocyclic carbene (NHC) or N‐heterocyclic olefin (NHO), showcasing their synergistic effect on the activation of H2 and diverse organic substrates. Reactions of RE(OAr)3 (RE=La, Sm, and Y; Ar=2,6‐tBu2−C6H3) with unsaturated NHC ItBu (:C[N(R)CH]2, R=tBu) isolated abnormally bound RE metal NHC complexes RE/aNHC. In contrast, no metal‐NHO adducts were formed when RE(OAr)3 were treated with NHO (R2C=C[N(R)C(R)]2, R=CH3). Both RE/aNHC and RE/NHO Lewis pairs enabled cooperative H2 activation. Furthermore, RE(OAr)3 were found to catalyze the hydrogenation of the exocyclic C=C double bond of NHO under mild conditions. Moreover, treatment of the La/aNHC complex with benzaldehyde produced a La/C4 1,2‐addition product. The La/NHO Lewis pair could react with (trimethylsilyl)diazomethane and α, β‐conjugated imine, affording an isocyanotrimethylsilyl lanthanum amide complex and a La/C 1,4‐addition product, respectively. [ABSTRACT FROM AUTHOR]

Cyanoketene is a fundamental molecule that is actively being searched for in the interstellar medium. Its deprotonated form (cyanoketenate) is a heterocumulene that is isoelectronic to carbon suboxide whose structure has been the subject of debate. However, the investigation of cyanoketene and its derivatives is hampered by the lack of practical synthetic routes to these compounds. We report the first synthesis of the cyanoketenate anion in [K(18‐crown‐6)][NCCCO] (1) as a stable molecule on a multigram scale in excellent yields (>90 %). The structure of this molecule is probed crystallographically and computationally. We also explore the protonation of 1, and its reaction with triphenylsilylchloride and carbon dioxide. In all cases, anionic dimers are formed. The cyanoketene could be synthesized and crystallographically characterized when stabilized by a N‐heterocyclic carbene. The cyanoketenate is a very useful unsaturated building block containing N, C and O atoms that can now be explored with relative ease and will undoubtedly unlock more interesting reactivity. [ABSTRACT FROM AUTHOR]

A diverse array of simple benzoin compounds featuring aryl and heteroaryl substituents were prepared from corresponding aldehydes, achieving moderate to excellent yields. To achieve this, a library of NHC precursors was designed and synthesized from imidazole and benzimidazole. Our custom‐designed NHC precursors (L1–L10) varied in size and structure. Built on imidazolinium and benzimidazolinium salts, these catalysts sported substituents at the N1 and N3 positions ranging from compact groups like butyl or benzyl to the much bulkier anthracenyl group. Treatment with a base transforms these salts into highly effective NHC precursors. After being activated, these NHCs become highly effective catalysts for the benzoin condensation reaction. We tested all the NHC precursors we made and found that L10, the one containing the large and bulky anthracenyl group attached to a benzimidazolium ring, worked the best for making benzoin derivatives. [ABSTRACT FROM AUTHOR]

Amidation synthesis stands as a significant area in organic chemistry. Incorporating cutting-edge amidation methods into basic organic chemistry laboratory teaching can enhance educational content and foster integration between undergraduate teaching and research achievements. Herein, we report an experiment focusing on the umpolung of aldehydes catalyzed by N-heterocyclic carbene (NHC) for amide synthesis. Utilizing benzaldehyde and nitrosobenzene as substrates, N-hydroxy-N-phenylbenzoylamide was efficiently synthesized under anhydrous and oxygen-free conditions. The reaction progress was monitored via thin-layer chromatography (TLC), and the product structure was confirmed by infrared and nuclear magnetic resonance spectroscopy. This experiment offers simplicity in operation, mild reaction conditions, high atom economy, and excellent repeatability, rendering it highly suitable for undergraduate laboratory teaching. By amalgamating the pivotal concept of umpolung with the cuttingedge science of N-heterocyclic carbene catalysis, this experiment aims to stimulate and nurture students' interest in scientific inquiry. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of novel ruthenium(ii) complexes with nitron-type N-heterocyclic carbene ligands containing chelating (N -arylcarbamoyl)methyl or carboxymethyl groups have been synthesized. Their evaluation as precatalysts in the hydrogenation of ketones has revealed that the complex containing three N -mesityl groups (one on the carbamoyl- methyl moiety and two on the triazole moiety) is the most efficient one. [ABSTRACT FROM AUTHOR]

Typically reactions of N‐heterocyclic carbenes with transition metals are straightforward and require a carbene salt, a base strong enough to deprotonate such a salt and a metal. Yet when carbene precursors are in the form of triazolium salts, reaction may not proceed as easily as expected. In our work, we intended to obtain a triazolylidene complex of iron(II) chloride, but due to the presence of small amounts of water in the tetrahydrofuran solvent used, bis(acetonitrile)tetrakis(1‐benzyl‐1H‐1,2,4‐triazole‐κN4)iron(II) μ‐oxido‐bis[trichloridoferrate(III)] acetonitrile disolvate, [Fe(C9H9N3)4(CH3CN)2][Fe2Cl6O]·2CH3CN – an interesting anion with a linear geometry of the O atom – was formed instead of the iron carbene complex. Reaction proceeded via cleavage of the alkyl N‐substituent of the triazolium salt. The formation of the product was confirmed by X‐ray crystallography. The crystal structure and possible reaction pathways are discussed. [ABSTRACT FROM AUTHOR]

The theoretical study on the fixation and release of nitric oxide (NO) by N‐heterocyclic carbenes (NHCs) is explored by utilizing a multivariate linear regression approach. We utilized data‐driven tools to establish correlations between molecular descriptors of NHC and reaction outputs of the formation and NO release of NHC nitric oxide radicals (NHCNOs). A key electronic parameter, the singlet‐triplet energy gap (ΔEST), plays a pivotal role in the thermodynamics of NHCNO formation (ΔGf) and NO release (ΔGr). The activation energy models highlight HOMO energy level (EHOMO), C–N bond length (dC–N), and NBO charge on N atom (qNBON) as crucial factors for the formation of NHCNO (ΔG‡f), while the activation energy for the NO release (ΔG‡r) significantly correlates with free energy difference (ΔGr), resulting a strong ΔEST dependency. This study provides valuable insights into the thermodynamics and kinetics of NHCNO processes, offering predictive capabilities to design NHCs tailored for NO release. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbene (NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the design, synthesis, and application of these corresponding cages have garnered substantial scholarly interest. In recent years, we have witnessed the successful fabrication of diverse NHC-based cages through a range of synthetic methodologies, which hold significant potential for applications in molecular recognition and catalysis. In this review, we delve into the foundational synthetic strategies that underlie the creation of NHC-based cages, employing approaches encompassing metal–NHC chelation, coordination assembly, and covalent bonding. Additionally, we compile the diverse applications of these cages within catalytic processes and molecular recognition. Lastly, we shed light on the current limitations of synthesis and outline future trends in the development of NHC-based cages. [ABSTRACT FROM AUTHOR]

The germylone dimNHCGe (5, dimNHC=diimino N‐heterocyclic carbene) undergoes a [2+2] cycloaddition with isocyanates RNCO (R=4‐tolyl or 3,5‐xylyl) to furnish novel alkyl carboxamido germylenes 7 (R=4‐tolyl) and 8 (R=3,5‐xylyl), featuring a C−C bond between the former carbene carbon and the isocyanate moiety. Heating a mixture of 8 with 4‐tolyl isocyanate to 100 °C results in isocyanate metathesis, demonstrating reversible C−C bond formation on the reduced germanium compound. DFT calculations suggest that this process occurs via the reductive dissociation of isocyanate from 8 that regenerates the parent Ge(0) compound 5. [ABSTRACT FROM AUTHOR]

Stable and efficient deep‐blue organic light‐emitting diodes (OLEDs) are in high demand for display and lighting applications but are rarely reported due to their poor operational lifetimes. Herein, the study designs and synthesizes two novel N‐heterocyclic carbene (NHC)‐based tetradentate Pt(II) complexes PtON5‐dtb and PtON5N‐dtb, and thoroughly investigate their electrochemical and photophysical properties. Functionalization of the NHC moieties can increase the metal‐to‐ligand charge transfer (1/3MLCT) characters in their lowest triplet excited‐states, resulting in significantly shortened photoluminescent lifetimes and remarkably improved device performance. A deep blue OLED employing PtON5N‐dtb as an emitter exhibits a narrow spectral bandwidth with a full‐width at half maximum (FWHM) of 30 nm and a CIEy value of 0.17 and demonstrates a maximum external quantum efficiency (EQE) of 20.4% with a small efficiency roll‐off, which maintains a high EQE of 18.5% at 1000 cd m−2. Moreover, the deep blue OLED also realizes a long‐measured operational lifetime LT90 (time to 90% of the initial luminance) of 71 hours with an initial brightness of 1134 cd m−2, corresponding to an estimated device lifetime LT90 of 85 h at 1000 cd m−2. This represented an eightfold lifetime improvement for PtON5N‐dtb‐based deep blue OLED compared to PtON7‐dtb in the same device setting. [ABSTRACT FROM AUTHOR]

The need for an accurate and rapid diagnosis platform for highly contagious viruses, such as pandemic viruses, has rapidly increased. Conventional diagnostic methods in the initial stage of quarantine for the prevention of epidemic spread have encountered limitations such as a long operation time, occupation of a large space, and high cost per single operation. Here, a highly sensitive and selective portable diagnostic platform based on solid‐phase photonic polymerase chain reaction (SP‐PCR) is reported. The thermal cycle is operated by the photothermal energy converted from the photon energy of a light‐emitting diode (LED) through a gold layer to phonons. The formation of an amplicon, which is immobilized through N‐heterocyclic carbene, is confirmed through fluorescence on the surface of the miniaturized SP‐PCR chip. The practical applicability of the newly developed diagnosis platform for the recognition of the presence of a SARS‐CoV‐2‐specific genome sequence is demonstrated utilizing 100 clinical samples, including 72 COVID‐19‐positive clinical samples and 28 negative samples. [ABSTRACT FROM AUTHOR]

Silver and gold are the most used plasmonic metals for surface-enhanced Raman spectroscopy (SERS), accounting for the vast majority of the published literature in this field. These two metals are preferred due to their excellent plasmonic enhancement, stability, and relative ease of synthesis and functionalization of their associated nanostructures. However, both silver and gold face earth abundance limitations, and so alternatives should be sought, particularly for large-scale plasmonic applications such as plasmon-enhanced photovoltaics or optical cloaking. In this work, a method to produce effective and scalable copper-based substrates for electrochemical SERS (EC-SERS) is introduced, utilizing commercially available carbon screen-printed electrodes (SPE) and physical vapor deposition (PVD). The carbon black particles present on the working electrode of the SPE serve as an efficient scaffold for the fabrication of copper nanostructures. Several test molecules were used to illustrate the performance of these sensors in the SERS analysis. This work also highlights the first reported formation of an electrochemically generated N-heterocyclic carbene (NHC) self-assembled monolayer (SAM) on a nanostructured copper surface under potential control in an aqueous electrolyte. [ABSTRACT FROM AUTHOR]

Very recently, N-heterocyclic carbenes (NHCs) have found a wide range of applications in the fields of catalysis and nonlinear optics. Herein, we have employed 1,3-bis-(1(S)-benzyl)-4,5-dihydro-imidazol-based carbene as a reference molecule and substituted one H atom from each CH2 of the benzyl groups in both sides by CH3, NH2, and CF3 to study the thermodynamic and opto-electronic properties of NHCs theoretically. It was observed that the enthalpy (H), Gibb's free energy (G), specific heat capacity (Cv), and entropy (S) increase significantly in the presence of the electron-withdrawing groups compared to the electron-donating groups. The IR active in-plane bending vibrations of the CH (NHC) group are shifted to the higher frequency region for the considered substituted molecules compared to the reference carbene. The analysis of the electronic properties shows that the CH3-substituted carbene is more reactive for catalytic activities compared to other NHCs. The calculated nonlinear optical (NLO) properties reveal that the NH2-substituted NHC has the largest hyperpolarizability value whereas the CH3-substituted NHC has the largest dipole moment and polarizability among all, making them potential candidates for the development of NLO materials. [ABSTRACT FROM AUTHOR]

Six novel palladium N-heterocyclic carbene complexes bearing different ancillary ligands such as pyridine, 1-methylimidazole, 4,5-dimethylthiazole and 3-bromoquinoline have been successfully prepared in a one-step process. These complexes were used as pre-catalysts in the Buchwald–Hartwig amination of cyclic secondary amines with aryl chlorides. A range of cyclic secondary amines were tolerated to a wide variety of aryl chlorides in presence of 1 mol% catalyst loading under mild conditions. Under the tested reaction conditions, the expected N-arylamines were obtained in moderate to high yields. The results showed that these novel palladium complexes are effective catalysts for the Buchwald–Hartwig amination. [ABSTRACT FROM AUTHOR]

The weak base method in continuous flow is currently one of the most sustainable and attractive approaches towards the synthesis of transition metal N‐heterocyclic carbene (NHC) complexes. Herein we broaden the scope of this method by using it to produce [M(IPr)(OC(H)(CF3)2)] complexes, including copper, silver, and gold. These compounds bear the alkoxide ligand within the coordination sphere of the catalysts, which can open up new ways to benefit from the unique properties offered by HFIP (1,1,1,3,3,3‐hexafluoroisopropanol) in catalysis, while minimizing the needed amount. [ABSTRACT FROM AUTHOR]

Herein, an efficient, atom‐economic, environmentally benign catalytic protocol has been developed for synthesising ketones and aldehydes by acceptorless dehydrogenation of alcohols. The protocol employs C, C chelated Ir (III) NHC complexes to promote acceptorless dehydrogenation of both secondary and primary alcohols. Notably, oxidation of primary alcohol selectively yields the corresponding aldehyde where forming ester byproducts is possible. Using C, C chelated Ir (III) NHC complexes (0.1 mol%), and a catalytic amount of base tBuONa (5 mol%), several aliphatic and aromatic aldehydes and ketones including more challenging carbonyl compounds bearing heterocyclic rings were obtained in moderate to high yields. Moreover, the protocol is also efficient for synthesising industrially important molecules like heliotropin and 3,4,5‐trimethoxy acetophenone in moderate yields. Remarkably, the catalytic system allows the straightforward synthesis of the potentially bio‐active compound cholest‐4‐en‐3‐one through acceptorless dehydrogenation followed by double bond isomerisation under the reaction conditions. Low catalyst loading, mild reaction conditions, high selectivity, short reaction time, and broad‐substrate scopes are a few interesting characteristics of the catalytic protocol described herein. [ABSTRACT FROM AUTHOR]

An unprecedented non‐AAIPEX protocol has been developed to access diverse monosubstituted cationic polycyclic heteroaromatic compounds (cPHACs) from the readily available azolium salts and phenacyl bromides via Ru(II)‐catalyzed tandem annulation cum aromatization. This atom‐economic protocol executes a range of intermediate steps e. g. double C−H activation, nucleophilic addition, annulation, and dehydration cum aromatization in one‐pot manner under the generation of H2O as the sole byproduct. Moreover, the systematic tunability of photo‐physical and electrochemical properties of these new class of cPHACs can be authenticated from the DFT calculated frontier molecular orbital energies that might be beneficial for their potential applications in optoelectronics and DNA intercalation. [ABSTRACT FROM AUTHOR]

The design, inspired by the core‐structure of oxicam has allowed the enantioselective synthesis of benzopyranothiazinone motifs employing N‐heterocyclic carbene (NHC) catalysis. The NHC‐mediated transformation involves the reaction of α,β‐unsaturated aldehydes with suitable substituted benzothiazinone derivatives. This process encompasses the initial formation of α,β‐unsaturated acylazoliums from ynals and concurrent generation of enolates from benzothiazinone. The culmination of these reactions results in an efficient annulation, yielding the desired products with reasonable yields and high stereoselectivities. This study underscores the potential of NHC catalysis in the streamlined synthesis of complex heterocyclic structures. [ABSTRACT FROM AUTHOR]