We report a silver-catalyzed hydrogen isotope exchange reaction that enables direct deuteration of quinones and related scaffolds, using readily available D2O as an isotopic source. The homogeneous Ag2SO4 system provides high isotopic enrichment, up to 99%, with excellent regioselectivity across diverse frameworks, including substituted para-naphthoquinones, anthraquinones, coumarins, quinolinones, and chromones. We also developed a heterogeneous version of the same reaction by supporting silver nanoparticles on carbon nanotubes. The nanohybrid catalyst maintains high performance and allows for easy removal of the catalyst from the final product through filtration. The dual homogeneous/heterogeneous approaches pioneer quinone hydrogen isotope exchange, providing practical and straightforward access to isotopologues.
Visible light-induced free carbene transfer reactions have attracted much attention over the past decades. Whereas photoinduced C─X insertion and halogenation reactions with halohydrocarbons are rare due to many other competitive carbene transformations. Herein, we disclose a blue light-induced C─X (X = Cl, Br, I) insertion reaction of 3-diazo-3H-indoles with halohydrocarbons, leading to the gem-haloalkylation products in moderate to good yields under mild and neutral conditions. Moreover, starting from the same reagents, the halogenation products could be obtained selectively under acidic conditions in the presence of quantitative AcOH. This method offers a complementary approach for the synthesis of halogenated indoles, which are useful synthetic building blocks and essential structural motifs in bioactive molecules. Further synthetic applications could be envisioned for the construction of C─C and C─X bonds via visible light-induced free carbene transfer reactions.
The hydrogenation of CO2 to synthesize liquid hydrocarbons (such as aromatics, gasoline, jet fuels, and diesel) is one of the important ways to achieve carbon cycling and sustainable fuel production. Spinel catalysts (AB2O4) have attracted increasing attention due to their flexible lattice structure, thermal stability, adjustable oxygen vacancies, and tunable metal-support interaction. However, most existing reviews focus on the static design of catalysts while neglecting the dynamic structural evolution of spinels under actual reaction conditions. This review systematically elaborates on the dynamic formation process of the active interface of spinel catalysts. By integrating in situ characterization with density functional theory (DFT) calculations, this study elucidates the nature of active sites and the reaction mechanism of spinel catalysts during CO2 hydrogenation to liquid hydrocarbons. Based on this, guided by the target product selection behavior, a series of precise construction strategies such as defect engineering, doping effects, interface engineering, and morphological structures were summarized to achieve efficient C─C coupling and liquid hydrocarbon generation. Finally, the current key challenges and future development directions were discussed, providing theoretical guidance for the development of efficient, low-energy-consuming, and industrially applicable spinel catalysts.
The syntheses of frustrated Lewis pairs (FLPs) based on a 4,5-difunctionalised xanthene backbone, and featuring the pentachlorophenyl-containing boryl groups, are reported. At a general level, this allows for systematic comparison of these systems in H2 activation as a function of the Lewis acid component, both internally and with respect to B(C6F5)2-containing FLPs. Incorporation of C6Cl5 groups over C6F5 diminishes the thermodynamic ability of these systems to activate H2, reflecting greater steric bulk and a disincentivized pyramidal geometry at boron. Diisopropylphosphino systems featuring -B(C6Cl5)2 and -B(C6Cl5)(C6F5) groups activate dihydrogen reversibly at room temperature; solution-phase VT-NMR studies, however, uncover unprecedented behavior at lower temperatures. On cooling, the extent of H2 uptake first increases (due to the reduced magnitude of the unfavorable TΔS° term); at even lower temperatures, phosphonium-borate formation is forced to compete with intermolecular FLP aggregation via aromatic stacking between the C6Cl5 rings. This leads to the observation of V-shaped van't Hoff plots with inflection points at 263 K (for xanth(PiPr2){B(C6Cl5)2}) and 268 K (for xanth(PiPr2){B(C6Cl5)(C6F5)}). The behavior of these systems is shown to rely on the balance between the thermodynamics of H2 activation and aggregation, and shows explicitly (but counter-intuitively) how non-covalent assembly can impede the activation of H2 by FLPs.
In this study, we describe the synthesis and reactivity of naphthalene diimide (NDI)-functionalized N-heterocyclic carbene (NHC) iridium complexes that display uncommon multi-stimuli-responsive behavior combining redox activity, photochemical responsiveness, and photocatalytic reactivity within a single molecular platform. Structural and spectroscopic studies reveal the presence of an unusually strong intramolecular Ir-Cl(lp)···π interaction involving the NDI unit, whose energetic parameters were determined experimentally by variable-temperature NMR analysis. Treatment of the parent NDI-NHC complex with basic anions promotes an unexpected solvolytic transformation leading to a rare chelating NHC-iminolate napthalene-monoimide (NMI) complex, illustrating the noninnocent reactivity of the diimide-functionalized ligand scaffold. Both complexes undergo efficient visible-light-induced reduction in the presence of triethylamine, generating stable radical-anion species through photoinduced electron transfer processes. The resulting photoreduced species operate as photocatalysts for the hydrodehalogenation of aryl halides through consecutive photoinduced electron transfer (conPET) pathways and enable photochemical C─C bond formation reactions.
Herein, we explore the fundamental concept of combining the molecular curvature of a molecular fragment of buckminsterfullerene with the pronounced spatial separation of HOMO and LUMO orbitals of a non-alternant polycyclic aromatic hydrocarbon (PAH) within a single molecule. To this end, we report the first synthesis of azulene-sumanene hybrids (6 and 7), two isomeric, bowl-shaped PAHs. Integration of azulene and sumanene motifs into a single molecular framework yields dual-responsive systems exhibiting unprecedented regioisomer-dependent electronic properties. Distinct orientations of the polarized azulene moiety relative to the curved sumanene core confer divergent receptor properties in 6 and 7, as reflected in their distinct proton-induced colorimetric responses and fluorescence enhancement upon binding alkali metal cations. These regioisomeric conjugates display markedly different selectivity toward alkali metal cations in aqueous media, with preferentially binding rubidium ions or selective detection of sodium ions, both with low detection limits at the µM level, demonstrating the electronic control of ion recognition in curved non-alternant π-systems. By tuning the electronic polarity of curved π-surfaces, this represents a significant advance in the chemistry of sumanene receptors, typically selective for cesium ions. We believe this work will stimulate future advances in the basic and applied sciences of π-conjugated and bowl-shaped nanographenes.
Fluorinated (hetero)cyclic compounds have garnered attention over the years, offering key building blocks in medicinally relevant molecules. However, the synthesis of fluorinated tetrahydrofurans remains a synthetic challenge to reach. Herein, we developed an efficient and robust approach for the synthesis of cis-(ethoxycarbonyl)difluoromethylated tetrahydrofurans. Using the inexpensive Pd/C catalyst, the diastereoselective hydrogenation of functionalized CF2CO2Et-containing furans was achieved under mild reaction conditions. Access to unprecedented cis-fluorinated tetrahydrofurans with isolated yields of up to 74% and diastereomeric ratios up to 95:5 (12 examples) was reached. Pleasingly, under slightly modified reaction conditions, 5-arylated CF2CO2Et-containing furans were smoothly converted into the valuable α,α-difluoro-β-hydroxyesters (five examples, up to 66% yield). Overall, the protocol exhibited good functional-group tolerance and was easily scaled up. The synthetic utility of the CF2CO2Et moiety was further illustrated by its conversion into various other fluorinated groups.
Electrocatalytic nitrate (NO3 -) reduction offers a sustainable route for simultaneous NO3 - remediation and ammonia (NH3) production, yet its efficiency is limited by the competing hydrogen evolution reaction (HER) and the imbalance between NO3 - activation and hydrogen supply. Herein, Co-Cu bimetallic sulfide nanoflowers were synthesized via a one-step hydrothermal method and optimized for NO3 - to NH3 conversion. The Co0.9Cu0.1S nanoflowers, assembled from two-dimensional nanosheets, delivered 97.83% ± 1.71% nitrate conversion, nearly complete NH4 +-N selectivity, and a Faradaic efficiency of 98.52% ± 0.83% at -0.75 V vs. RHE. Systematic Co/Cu-ratio studies, electrochemical kinetics, Bode analysis, hydrogen adsorption/desorption behavior, and XPS results reveal that Cu promotes NO3 - activation and electronically modulates Co sites, while Co facilitates reactive hydrogen generation and utilization. This synergy enables on-demand hydrogen supply, directing hydrogen toward NO3 - hydrogenation rather than HER. pH-dependent tests further identify a neutral electrolyte as favorable for balancing proton supply and competitive HER.
The "soft" pyridine stabilized FLP tBu2In(py)CH2PtBu2 (1·py) was reacted with SO2, PhNCO, PhNSO, azobenzene, pyridazine, 1,2,4,5-tetrazine, tosylaziridine, and hydrazine, respectively. The reactivity can be roughly classified into three types of FLP activation. (a) Typical FLP-type reactivity is observed for the reaction with azobenzene and tosylaziridine, with the formation of 1,2-addition or ring-opening products, respectively. (b) "Soft" FLP-type reactivity occurs toward substrates containing multiple sites for FLP attack-in this case 1·py prefers coordination to the "softer" binding site, resulting in the formation of "soft" isomers of possible FLP adducts, as was demonstrated for PhNCO and PhNSO. (c) An unexpected reactivity results that can be described as a "masked" In/C-FLP; when 1·py was reacted with SO2, an insertion dimer formed, with the methylene bridge connected to the sulfur atom; the reaction of 1·py with hydrazine afforded a four-membered hydrazide heterocycle, under loss of the methylene bridge as MePtBu2, instead of the reaction with the PtBu2 fragment, pyridine, or excess hydrazine. The products were characterized by a variety of NMR spectroscopy methods supported by X-ray crystallography as well as quantum-chemical calculations for insights into the thermodynamics and selectivity of product formation.
Phenalenones (PNs), popular as antifungal, antimicrobial, and anticancer agents, are a fascinating class of naturally occurring photosensitizers. In spite of their importance, doping of the main core of PNs remains unexplored. Herein, we report a facile and green approach to prepare N-doped PNs or aza phenalenones (APNs) for the first time. We accomplished the goal by trapping unstable peri-naphthoisatogen, prepared using a modified aldrone condensation reaction. Different types of primary amines were used as nucleophile to synthesize seven APNs. Structures of the APNs were unambiguously characterized using NMR spectroscopy, mass spectrometry, and x-ray crystallography. Anticancer activities of the APNs were evaluated against oral cancer cells. Among them, the APN derivative of 3-aminopyridine demonstrated the most potent anticancer activity with high selectivity against oral cancer cells. We further investigated the mechanism underlying the anticancer activity of this lead compound.
The synthesis and characterization of organo-selenium compounds have attracted considerable interest for decades, driven by the search for efficient catalysts and bioinspired antioxidants; the investigation and exploitation of selenium─metal motifs in biological and medicinal chemistry represent a recent development and constitute the focus of this review. Selenoproteins are targets of metal ions like mercury and cadmium, whose toxicity is associated with the formation of stable selenium─metal bonds impairing protein function. On the other hand, selenium─metal bonding provides a strategy for tuning both chalcogen and metal reactivity, potentially enhancing the pharmacological performance of metallodrugs. Coordination to transition metals can modify redox potentials, bond polarization, and reactivity, thereby enabling multifunctional compounds combining metal-based pharmacophores with the redox activity of selenium. These systems may modulate reactive oxygen species, inhibit enzymes, and enhance selective cytotoxicity toward cancer cells. The formation of selenium─metal bonds in biological environment can also alter the function of metalloproteins, accounting for the toxicity of organoselenides. By combining experimental structural and reactivity properties with mechanistic insights from computational chemistry, we highlight the unifying concepts that govern selenium─metal bonding and to illustrate how these concepts can guide the rational design of new classes of selenium-based functional molecules.
The synthesis of bioactive molecules through one-pot multicomponent reactions under mild conditions is of significant interest for medicinal chemistry, though largely unexplored and challenging. Herein, we have reported a new Y(III)-based chemically stable framework, IITKGP-65, with abundant active catalytic sites, which exhibited excellent stability in open air, water, and even in acidic medium. The activated framework, IITKGP-65a, has been utilized as a Lewis acid-driven heterogeneous catalyst for the synthesis of bioactive chromeno[2,3-d]pyrimidin-8-amine derivatives. Notably, synthesis of these compounds has not yet been reported in the literature using any coordination polymer (CP) or metal-organic framework (MOF)-based catalyst. Interestingly, a good to excellent yield was achieved even with a low catalyst loading of our developed catalyst for a wide range of substrate scopes, along with excellent recyclability without any loss of structural integrity. Most importantly, to demonstrate practical applicability, we synthesized four chromeno[2,3-d]pyrimidin-8-amine derivatives exhibiting antibacterial activity using a green ethanol medium. The facile accessibility, robust structural framework, outstanding catalytic performance, and excellent recyclability collectively underscore the potential of the developed framework, IITKGP-65, as an efficient catalyst. Furthermore, these attributes extend its applicability to the environmentally friendly synthesis of complex bioactive molecules.
Monomeric, two-coordinate 13-electron PdI complexes are exceptionally rare due to their intrinsic instability and propensity for dimerization. In this study, we report that the bulky N-heterocyclic carbene (NHC) ligand DiMeIHeptCl (1,3-bis[2,6-bis(1-propylbutyl)phenyl]-4,5-dichloro-1,3-dihydro-2H-imidazol-2-ylidene) enables the generation and stabilization of a series of such species. Reduction of the dichloro PdII precursor affords PdCl(DiMeIHeptCl) (3), which serves as a platform for accessing Pd(OtBu)(DiMeIHeptCl) (4), Pd[N(SiMe3)2](DiMeIHeptCl) (5), and Pd(NH-2,4,6-tri-tertbutyl-C6H2)(DiMeIHeptCl) (6). These complexes adopt pseudolinear or bent geometries, as established by EPR spectroscopy, x-ray crystallography, and DFT calculations. Complexes 3 and 4 react with nucleophiles by an associative mechanism, which becomes impossible for sterically over-crowded 5. Kinetic and spectroscopic studies reveal divergent decay pathways, with 3 undergoing disproportionation and 4-6 decomposing via Pd─X bond homolysis to generate Pd0 species and transient organic radicals. Notably, these PdI complexes do not undergo oxidative addition with aryl halides, excluding PdI/III reactivity under these conditions. Electronic structure analysis shows the unpaired electron resides primarily on Pd and the X ligand, with minimal NHC involvement. These findings provide insight into low-coordinate PdI intermediates that may prove relevant to Pd(NHC) precatalyst activation.
Olympicene, or 6H-benzo[cd]pyrene, is a polycyclic aromatic hydrocarbon (PAH) with five fused six-membered rings arranged in a pattern reminiscent of the Olympic symbol. While functionalized olympicene-based materials have captivated attention for their unique graphene-fragment topology and aromaticity, their photoluminescent properties remain virtually unexplored. Here, we synthesize olympicene-core functionalized derivatives and report their "anomalous" photophysical properties. These olympicene derivatives display extensive vibronic structure and highly interacting electronic states. Such effects give rise to excited-state dynamics that are rare and unconventional in small PAH systems. Specifically, these olympicene derivatives exhibit dual fluorescence upon photoexcitation, accompanied by pronounced excitation-dependent emission behavior. Spectroscopic evidence demonstrates these behaviors arise from multiple singlet emissive states-an anti-Kasha locally excited (LE) state (Sn, n ≥ 2) and an intramolecular charge transfer (ICT) state. This work positions olympicene-functionalized derivatives as a new platform to study fundamental photophysics. Exploring these properties will lead to new and advanced optoelectronic applications.
Self-assembled macrocyclic dodecamers were found in the crystals of new pseudo-polymorphs of iso-tellurazole N-oxides. These structures are formed by molecules connected by NTe…O chalcogen bonds and are folded in a pattern that defines 89-153 Å3 cavities, which are large enough to host solvent molecules. These crystals only grow in the presence of molecular species that can act as guests alone (cyclohexane) or in combination with sodium cations (1,4-dioxane, tetrahydrofuran, and pyrazine). A solution rich in a sodium salt yielded a crystal featuring a cage-like aggregate of three tetramers bridged by sodium cations, suggesting a plausible route for the formation of the new macrocycles by reorganization of the chalcogen bonds.
This work reports the synthesis, characterization, and solution photophysical properties of para-trisubstituted triphenylamine (TPA) derivatives that preserve the threefold symmetry around the central nitrogen atom. By functionalizing the TPA core with three units of one of two representative boron-containing chromophores-BODIPY and subphthalocyanine (SubPc)-we directly compare how chromophore identity and molecular topology determine the optical response of the resulting star-shaped architectures. Whereas neither family exhibits significant solvatochromism in absorption, their fluorescence is strongly governed by both the solvent and the molecular architecture. The SubPc-based trimer undergoes efficient fluorescence quenching in all but the least polar solvent studied (Φ ≤ 2%, partially restored to 10% in methylcyclohexane), consistent with an effective intramolecular excited-state deactivation pathway. In contrast, the BODIPY-based trimer remains strongly quenched in polar media while developing a new red-shifted emission band (λem = 606 nm) with a markedly enhanced fluorescence quantum yield (Φ = 26%) in toluene. Comparison with the corresponding monomeric reference compounds demonstrates that these distinctive photophysical properties arise primarily from the threefold star-shaped architecture rather than from the intrinsic optical properties of the individual chromophores. These findings establish molecular topology as an effective design parameter for tuning excited-state dynamics in multichromophoric TPA-based systems.
Hydrogels have garnered significant interest as soft materials due to their flexibility, high water content, and biocompatibility. Alginate/polyacrylamide (Alg/PAAm) double-network (DN) hydrogels are particularly promising for wearable electronics, strain sensors, and soft electrolytes owing to their toughness and structural stability. However, the conventional soaking method for ion incorporation requires prolonged diffusion and often generates internal concentration gradients, leading to structural heterogeneity. This study introduces a one-pot strategy that incorporates NaCl directly into the precursor solution, enabling simultaneous gelation and ion integration. Elemental analyses indicate a more spatially consistent Na and Cl distribution across the examined surface regions of the one-pot hydrogel compared with the soaking-derived hydrogel. Furthermore, NaCl incorporation influences network formation primarily by modifying the ionic environment and hydration state rather than by creating new covalent bonds. The resulting hydrogels exhibit a composition-dependent trade-off between mechanical reinforcement and ionic transport. NaCl concentrations of 1.5-2.0 wt% provide a favorable balance among stiffness, strength, and deformability, whereas ionic conductivity reaches its maximum at 12.5 wt%. These findings indicate that no single NaCl concentration is optimal for all performance requirements and that the salt content should instead be tailored to the intended application.
Modification of boranils with dual state emissions in solution and solid states have been targeted by introducing free amine functional group at the terminal position. Herein, we designed and synthesized four new primary amine-substituted benzothiazole-based boranils from substituted salicylaldehyde. Their photophysical properties were investigated through steady-state absorption and emission measurements in both solution- and solid-states. X-ray structure analysis of the boranils revealed that the benzothiazole rings bearing the amine functional group are highly twisted, thereby avoiding the detrimental exciton interaction between the dimers and enabling emission in the solid state. In the solution-state, the naphthalene and methoxy substituted boranils exhibited significant intramolecular charge transfer and a large Stokes shift of > 150 nm. Julolidine or diethylamine substituted boranils exhibited reversible acid-base responsiveness via fluorescence ON-OFF properties. On the other hand, protonation and deprotonation of naphthalene and methoxy substituted boranils showed reversible blue and red shift emission. Computational studies revealed that the photo-induced electron transfer (PET) and photo-induced charge transfer (PICT) process were responsible for fluorescence enhancement and wavelength shift upon trifluoroacetic acid (TFA) treatment. Based on the solvent dependent wide emissive range, methoxy substituted boranil was further utilized for the generation of white light emission with anthracene as an ancillary component.
