Search Results (69)

Visible-light-driven decarboxylative alkylation faces challenges from the inertness of Pd-catalyzed oxidative addition of unactivated alkyl halides and the complexity of dual photoredox/metal systems. In this study, we present the first utilization of unsymmetrical N,C,Se-pincer NHC-Pd(II) complexes as single-component photocatalysts for the coupling of arylacrylic acids with unactivated alkyl bromides under blue light. The reaction is conducted at room temperature with catalyst loading of 0.5 mol%, delivering a wide range of alkenylalkane products in yields ranging from 31% to 88%, exhibiting excellent tolerance to halogens and unprotected phenols. Control studies have revealed that the selenoether donor stabilizes active Pd species and enables a radical-mediated pathway. This work extends the utility of N,C,Se-pincer Pd catalysts to reductive C−C coupling and provides a practical platform for biomass valorization. Full article

The performance of coatings, corrosion barriers, photocatalysts, and tribological materials is greatly influenced by in situ surface properties, requiring highly sensitive and reproducible operando surface characterization methods. We previously developed a temperature-programmed photoelectron emission (TPPE) method to clarify electron transfer behavior on light-irradiated metal surfaces. TPPE is sensitive to surface temperature and prior chemical exposure, which affect the total photoemitted electron count (N_T), the photothreshold, and the activation energy derived from Arrhenius plots of N_T obtained during heating–cooling cycles. This study examines the reproducibility of TPPE data and the TPPE mechanisms for Cu₂O/Cu surfaces subjected to mechanical abrasion, cleaning, plasma treatment, and subsequent immersion in organic liquids. The resulting Arrhenius plots reveal both positive and negative activation energies, depending on the treatment conditions. Negative activation energies during cooling are associated with photoredox-mediated emission. TPPE is attributed to oxygen vacancies within the Cu₂O surface layer, which is interfaced with metallic Cu, serving as a direct probe of these vacancy-related states. The TPPE characteristics (N_T intensity and activation energy) following exposure to various polar and nonpolar organic molecules (e.g., acetone, toluene, hexane, and ethanol) correlate with the electronic properties of these vacancies, consistent with previous observations for ambient air, alcohol, and water vapor exposure. Under illumination, Cu₂O vacancy states enhance photocarrier extraction (electrons and holes) and accelerate surface redox reactions within adsorbed thin films, thereby improving photocatalytic performance. Notably, the solvent’s reciprocal dielectric constant significantly influences TPPE, indicative of electrostatic surface–solvent interactions. Finally, the TPPE mechanism is discussed in the context of antiviral inactivation at the metallic copper–environment interface. Full article

The catalytic enantioselective formation of carbon–sulfur (C–S) bonds is a rapidly evolving field in modern organic synthesis, driven by the importance of chiral sulfur-containing motifs in pharmaceuticals, agrochemicals, and functional materials. Despite their significance, asymmetric C–S bond-forming reactions remain challenging due to the strong coordinating ability and nucleophilicity of sulfur species, catalyst deactivation, and difficulties in controlling sulfur- or carbon-centered stereogenicity. Recent advances in transition-metal catalysis, organocatalysis, and emerging electrocatalytic strategies have enabled efficient access to diverse chiral organosulfur frameworks, including sulfides, sulfoxides, sulfilimines, sulfoximines, and sulfinamides, with high levels of enantioselectivity. These methodologies have significantly expanded the synthetic toolbox for constructing C–S bonds under mild and sustainable conditions. This review provides a concise and critical overview of catalytic enantioselective C–S bond formation, emphasizing reaction design, catalytic systems, and mechanistic aspects of enantiocontrol. Key transformations such as asymmetric allylic substitution, conjugate addition, cross-coupling, photoredox-enabled processes, and emerging electrochemical approaches are discussed. Particular attention is given to strategies for the generation and control of sulfur-centered stereogenicity. Finally, current limitations and future opportunities, including dual catalysis, late-stage functionalization, and sustainable catalytic systems, are highlighted to guide further developments in asymmetric organosulfur chemistry. Full article

The spiroindoline framework is a privileged scaffold in medicinal chemistry, appearing in natural products and in synthetic bioactive compounds, such as BAY 1214784, RO8994, and RK-287107, with reported activities ranging from antimitotic effects to kinase inhibition. This review covers the methods developed between 2020 and 2025 for constructing spiroindoline frameworks, organized first by the site of spirocyclization (C2 versus C3 of the indole) and then by catalyst class: second- and third-row transition metals, first-row transition metals and main-group Lewis acids, organocatalysis, and visible-light photoredox. For each method we discuss the reaction design, the accessible substrate scope, and mechanistic insights, with particular attention to how stereochemistry is controlled. We also highlight representative downstream transformations that demonstrate the synthetic utility of the produced spiroindolines. Progress over the past five years has been substantial, particularly in enantioselective methods that create a single stereocenter and in cascade designs that build complex polycyclic frameworks in a single operation. Asymmetric construction of multiple adjacent stereocenters, gram-scale demonstrations, and genuinely sustainable conditions remain less developed; these areas are priorities for future work. Full article

The combination of photochemistry with stereoselective catalysis has emerged as an effective strategy to achieve stereocontrol in light-driven transformations. Chiral phosphoric acids (CPAs) have recently attracted attention in this context due to their ability to activate substrates while providing a defined chiral environment. This minireview highlights recent developments in CPA-enabled asymmetric photochemical transformations, focusing on systems in which CPAs incorporate a chromophore on the chiral backbone or form light-absorbing CPA-substrate complexes that enable photoactivation without the presence of an external photocatalyst. The main catalytic strategies, mechanistic features, and current limitations are discussed. Full article

9-Mesitylacridinium salts are widely recognized as efficient organic photoredox catalysts owing to their strong excited-state oxidizing power and stability under visible-light irradiation. In this study, a new mesityl acridinium derivative bearing a di-tert-butylphenyl substituent on the nitrogen atom was synthesized. The introduction of tert-butyl groups on the N-aryl moiety was primarily aimed at improving solubility and chemical stability of the acridinium salt. Starting from a 9(10H)-acridinone precursor, the target compound was obtained in high overall yield through a concise synthetic sequence. The synthesis consists of a copper-catalyzed C–N coupling reaction to install the aryl substituent on the nitrogen atom, followed by a Grignard reaction and subsequent acid treatment to afford the corresponding acridinium salt. All transformations proceeded smoothly, providing efficient access to the desired novel acridinium derivative. This work presents a practical example of the structural modification of mesitylacridinium derivatives directed toward enhanced solubility and stability, and provides a useful synthetic platform for the preparation of structurally diverse acridinium salts. Full article

Phenazine derivatives are promising metal-free chromophores with strong redox and photophysical properties, yet their use in photocatalytic hydrogenation remains limited. Here, we report a homogeneous phenazine-based system for the visible-light-driven hydrogenation of nitroarenes under mild conditions. Using nitrobenzene as a model substrate and triethanolamine as a sacrificial hydrogen source, the photocatalyst achieved aniline yields of up to 81% after 12 h of irradiation at 390 nm. Systematic variation in reaction parameters revealed that catalyst structure, solvent, and light wavelength strongly influence performance. Kinetic analysis indicated that prolonged irradiation reduces overall yield due to the reconversion of reactive intermediates. The system exhibited higher efficiency toward nitroarenes bearing electron-withdrawing groups, while aliphatic nitro compounds underwent only partial reduction. Mechanistic studies using UV–Vis, fluorescence, and EPR spectroscopy confirmed the formation of persistent radical species and supported a stepwise electron and proton transfer mechanism. This work showcases the potential of phenazine-based photocatalysts as metal-free platforms for nitroarene reduction under visible light. Full article

Unsaturated carbon–carbon bonds are fundamental building blocks in organic compounds. The difunctionalization of olefins allows for the rapid construction of drugs and complex molecular architectures. This transformation, which simultaneously installs two distinct functional groups across a carbon–carbon double bond, has therefore emerged as prominent research frontier in organic chemistry. In recent years, the synergy between photoredox and transition metal catalysis has emerged as a powerful and sustainable platform for constructing C-X bonds. This review covers advances since 2018 in the asymmetric difunctionalization of olefins enabled by synergistic visible light photoredox and transition metal catalysis, encompassing the construction of both carbon–carbon and carbon–heteroatom bonds. It systematically summarizes the reaction conditions, substrate scope, mechanisms, and merits and limitations of these catalytic systems, aiming to provide a useful reference for researchers in this field. Full article

Fluorinated organic molecules have become indispensable in modern chemistry, owing to the unique properties imparted by fluorine to other compounds, including enhanced metabolic stability, controlled lipophilicity, and improved bioavailability. The site-selective incorporation of fluorine atoms into organic frameworks is essential in pharmaceutical, agrochemical, and material science research. In recent years, catalytic fluorination has become an important methodology for the efficient and selective incorporation of fluorine atoms into complex molecular architectures. This review highlights advances in catalytic fluorination reactions over the past six years and describes the contributions of transition metal catalysts, photocatalysts, organocatalysts, and electrochemical systems that have enabled site-selective fluorination under a variety of conditions. Particular attention is given to the use of well-defined fluorinating agents, including Selectfluor, N-fluorobenzenesulfonimide (NFSI), AlkylFluor, Synfluor, and hypervalent iodine reagents. These reagents have been combined with diverse catalytic systems, such as AgNO₃, Rh(II), Mo-based complexes, Co(II)-salen, and various organocatalysts, including β,β-diaryl serine catalysts, isothiourea catalysts, and chiral phase-transfer catalysts. This review summarizes proposed mechanisms reported in the original studies and discusses examples of electrophilic, nucleophilic, radical, photoredox, and electrochemical fluorination pathways. Recent developments in stereoselective and more sustainable protocols are also examined. By consolidating these strategies, this article provides an up-to-date perspective on catalytic fluorination and its impact on synthetic organic chemistry. Full article

Fabricating efficient photocatalysts that can be used in solar-to-fuel conversion and to enhance the photochemical reaction rate is essential to the current energy crisis and climate changes due to the excessive usage of nonrenewable fossil fuels. To attain high photo-to-chemical conversion efficiency, it is important to fabricate cost-effective and durable catalysts with high activity. One-dimensional cadmium sulfides (1D CdS), with higher surface area, charge carrier separation along the linear direction, and visible light harvesting properties, are promising candidates for converting solar energy to H₂, reducing CO₂ to commodity chemicals, and remediating environmental pollutants. The main disadvantage of CdS is photocorrosion due to the leaching of S²⁻ ions during the photochemical reactions, and further charge recombination rate leads to low quantum efficiency. Therefore, the implementation of core–shell heterostructured morphology, i.e., the growth of the shell on the surface of the 1D CdS, which offers unique features such as protection of CdS from photocorrosion, a tunable interface between the core CdS and shell, and photogenerated charge carrier separation via heterojunctions, provides additional active sites and enhanced visible light harvesting. Therefore, the viability of the core–shell synthesis strategy and synergetic effects offer a new way of designing photocatalysts with enhanced stability and improved charge separation in solar energy conversion systems. This review highlights some critical aspects of synthesizing 1D CdS core–shell heterostructures, underlying reaction mechanisms, and their performance in photoredox reactions. Finally, some challenges and considerations in the fabrication of 1D CdS-based core–shell nanostructures that can overcome the current barriers in industrial applications are discussed. Full article

Visible-light photoredox catalysis using biacetyl (BA) as a low-cost photosensitizer enables the efficient formation of triarylethylenes (TAEs) via a Mizoroki–Heck-type coupling. The reaction proceeds efficiently in acetonitrile upon blue LED irradiation under anaerobic conditions. Alternatively, supramolecular viscoelastic gels have also been explored as reaction media, allowing the possibility of working under aerobic atmosphere. Mechanistic investigations by means of transient absorption spectroscopy and quenching experiments support a charge-separated intermediate pathway. Reaction quantum yield measurements further validate the efficiency of BA, demonstrating its potential as an alternative to transition-metal catalysts. Overall, this work presents a sustainable and scalable strategy for TAEs synthesis, integrating photoredox catalysis with soft material engineering. These findings pave the way for broader applications in green chemistry and functional materials. Full article

Nitrogenous compounds have been extensively utilized as hydrogen atom transfer (HAT) catalysts in photoredox reactions, with nitrogenous radical cations being the actual hydrogen atom abstractors. Building upon our previous work, 120 thermodynamic graphs of nitrogenous radical cations abstracting hydrogen atoms, which encompass seven vital thermodynamic parameters, are designed and established to elucidate their redox characteristics. Furthermore, the applications of thermodynamic graphs to select appropriate photocatalysts, assess the feasibility of the HAT process, and diagnose the possible activation mechanism were discussed, which would enable the utilities of nitrogenous compounds as HAT catalysts or nitrogenous radical cations as hydrogen atom abstractors in photoredox reactions. Full article

Photoredox-catalyzed phosphonylation of bromo-substituted 1,10-phenanthrolines under visible light irradiation was studied. The reaction was shown to proceed under mild conditions with Eosin Y as a photocatalyst in DMSO under blue light irradiation. It is transition-metal-free and affords the target phosphonate-substituted 1,10-phenanthrolines in moderate yields (26–51%) in 22 to 40 h. The rate and selectivity of the reaction depend largely on the position of the bromine atom, as well as on the nature and position of other substituents in the 1,10-phenanthroline core. Full article

Converting carbon dioxide (CO₂) into high-value-added chemicals using solar energy is a promising approach to reducing carbon dioxide emissions; however, single photocatalysts suffer from quick the recombination of photogenerated electron–hole pairs and poor photoredox ability. Herein, silver (Ag) nanoparticles featuring with localized surface plasmon resonance (LSPR) are combined with g-C₃N₄ to form a Schottky junction for photothermal catalytic CO₂ reduction. The Ag/g-C₃N₄ exhibits higher photocatalytic CO₂ reduction activity under UV-vis light; the CH₄ and CO evolution rates are 10.44 and 88.79 µmol·h⁻¹·g⁻¹, respectively. Enhanced photocatalytic CO₂ reduction performances are attributed to efficient hot electron transfer in the Ag/g-C₃N₄ Schottky junction. LSPR-induced hot electrons from Ag nanoparticles improve the local reaction temperature and promote the separation and transfer of photogenerated electron–hole pairs. The charge carrier transfer route was investigated by in situ irradiated X-ray photoelectron spectroscopy (XPS). The three-dimensional finite-difference time-domain (3D-FDTD) method verified the strong electromagnetic field at the interface between Ag and g-C₃N₄. The photothermal catalytic CO₂ reduction pathway of Ag/g-C₃N₄ was investigated using in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS). This study examines hot electron transfer in the Ag/g-C₃N₄ Schottky junction and provides a feasible way to design a plasmonic metal/polymer semiconductor Schottky junction for photothermal catalytic CO₂ reduction. Full article

The oxidation of benzylic alcohols is an important transformation in modern organic synthesis. A plethora of photoredox protocols have been developed to achieve the aerobic oxidation of alcohols into carbonyls. Recently, several groups described that ultraviolet (UV) or purple light can initiate the aerobic oxidation of benzylic alcohols in the absence of an external catalyst, and depicted different mechanisms involving the photoinduction of ^•O₂⁻ as a critical reactive oxygen species (ROS). However, based on comprehensive mechanistic investigations, including control experiments, radical quenching experiments, EPR studies, UV–vis spectroscopy, kinetics studies, and density functional theory calculations (DFT), we elucidate here that HOO^•, which is released via the H₂O₂ elimination of α-hydroxyl peroxyl radicals [ArCR(OH)OO^•], serves as the real chain carrier for the autocatalytic photooxidation of benzylic alcohols. The mechanistic ambiguities depicted in the precedent literature are clarified, in terms of the crucial ROS and its evolution, the rate-limiting step, and the primary radical cascade. This work highlights the necessity of stricter mechanistic analyses on UV-driven oxidative reactions that involve aldehydes’ (or ketones) generation. Full article