Chinese Journal of Chemistry最新文献

Type II-dominant photosensitizers often suffer from reduced photodynamic efficacy under tumor hypoxia. We report a biotin-modified phenothiazine photosensitizer termed DHU-Blue-7, which converts type II methylene blue (MB)-like photosensitization into a type I pathway via regulating excited-state characteristics, while retaining its visible-to-near-infrared absorption. The incorporated biotin moieties serve as both tumor-targeting groups for cellular internalization and pendant electron donors. Under light irradiation, DHU-Blue-7 produced both ¹O₂ and O₂^•–, showing a 3.3-fold stronger fluorescence response associated with O₂^•– generation than that of MB. DFT/TD-DFT calculations and femtosecond transient absorption spectroscopy revealed that the folded conformation of DHU-Blue-7 enables singlet-excited-state photoinduced electron transfer from biotin moieties to the phenothiazine core, forming a relatively long-lived charge-separated state that favors type-I reactive oxygen species (ROS) generation. At the cellular level, DHU-Blue-7 achieves efficient light-activated elimination of cancer cells under both normoxic and hypoxic environments, while exhibiting negligible phototoxicity to normal cells. In the 4T1 tumor-bearing mouse model, DHU-Blue-7 coupled with light irradiation markedly suppressed tumor proliferation, with no evident damage to major organs. This study verifies that biotin modification serves as a facile yet effective strategy to equip phenothiazine photosensitizers with hypoxia-resistant type I photodynamic performance through conformation-governed singlet-excited-state electron transfer.

Non-covalent interactions with additives have been demonstrated to be intriguing in conferring racemic polymers with preferential one-handed helical conformation. However, these additives are normally chiral, and specific interactions are demanded. We report herein the modulation of helicity from thermoresponsive helical dendronized poly(phenylacetylene)s (PPAs) in aqueous media by using achiral aromatic additives at different temperatures. These dendronized PPAs carry dendritic oligo(ethylene glycol)s (OEGs), which exhibit characteristic thermoresponsive behavior with their cloud points (T_cps) governed by the peripherals of the dendritic OEGs. Notably, these polymers can undergo helical conformation inversion across their thermal phase transitions. However, such inversion can be modulated by the presence of achiral aromatic additives, including benzoic acid, phenol, and aniline. These aromatic achiral compounds increase hydrophobicity of the polymers to decrease their T_cps, and act as molecular glues to greatly enhance intermolecular aggregation of the helical PPAs at elevated temperatures. In contrast to the thermally aggregated micelles typically observed from thermoresponsive polymers above their T_cps, the presence of aromatic additives intriguingly promotes the formation of long helical fibers alongside double helices from aqueous polymer solutions above the T_cps. Molecular dynamics simulations are employed to elucidate the competitive interactions among the dendronized PPA chains, the additives, and water.

Organofluorides, including trifluoromethylthiolated compounds, play an important role in pharmaceuticals, agrochemicals and materials science. Although the synthesis of these organofluorides has been well studied, harsh conditions and specific substrates are usually involved, which limited the development of this field. Herein, we report a novel protocol to construct highly functionalized trifluoromethylthiolated and derived scaffolds via the trifluoromethyl- and difluoromethyl-chalcogenation of α-diazo compounds under mild and green conditions using a photochemical strategy. This multicomponent reaction exhibits broad substrate scope and good functional group tolerance (37 examples, up to >99% yield), which could be applied to late-stage modification of complex natural products. Additionally, the gram-scale synthesis and antibacterial assays were carried out to explore the application of this transformation, and the results showed good scalability (1.45 g, 69% yield) as well as promising antibacterial activity. Moreover, the mechanistic study indicates a cascade process via oxonium species.

Trifluoromethylated heterocycles represent privileged structural motifs in pharmaceuticals and agrochemicals, as the incorporation of a CF₃ group significantly enhances metabolic stability, lipophilicity, and bioactivity. Among these, α-trifluoromethyl pyrrolidines have garnered considerable interest; however, stereoselective access to polysubstituted variants remains a persistent synthetic challenge. To tackle this, we report a green light-driven, three-component reaction of α,β-unsaturated ketones, trifluoromethyl diazo compounds, and alkyl nitriles under metal- and photosensitizer-free conditions. This atom-economical and operationally simple protocol, followed by a sequential one-pot NaBH₄/AlCl₃ reduction, efficiently delivers pentasubstituted α-trifluoromethyl pyrrolidines with excellent yields (up to 99%) and exclusive diastereoselectivity (all >20 : 1 d.r.). Mechanistic studies elucidate a concise cascade initiated by photoinduced singlet carbene generation. These electrophilic species are captured by alkyl nitriles, which serve as both solvent and nitrogen donor, to form key fluoroalkyl ylides. Subsequent stereoselective 1,3-dipolar cycloaddition with α,β-unsaturated ketones, followed by reduction, constructs the complex skeleton. This work not only provides a highly practical and green route to valuable fluorinated heterocycles but also advances the fundamental understanding of singlet carbene reactivity, showcasing the remarkable utility of long-wavelength photochemistry in complex molecule synthesis.

Non-alkyl tin-oxo clusters (SnOCs) feature structural precision and designability, enabling their photophysical properties to be modulated through transition-metal doping and thus holding great promise for solar-driven photothermal conversion. However, such doped SnOCs still face a critical challenge of lacking controlled synthetic strategies. Herein, a redox-coordination hierarchical strategy is developed for non-alkyl SnOCs, exploiting the redox reaction between high-valent molybdenum source (Na₂Mo^VIO₄) and low-valent tin source (Sn^IICl₂) to achieve a structural transformation from hourglass-shaped Sn₇ to pedestal-hourglass-shaped Sn₇Mo₁₂. The resulting structure gives rise to strong Mo–Mo interactions and ligand-to-metal charge transfer (LMCT) that together dramatically reduce the optical bandgap from 4.35 eV (Sn₇) to 2.04 eV (Sn₇Mo₁₂). Consequently, Sn₇Mo₁₂ exhibits an extended absorption spectrum into the near-infrared region and achieves a high photothermal conversion efficiency of 85.61%. Moreover, the material demonstrates a solar-driven water evaporation rate of 0.97 kg·m^–2·h^–1 and an evaporation efficiency of 55.65%. This work not only provides new insights into the rational design and controlled synthesis of broadband-absorbing photothermal materials but also lays a crucial foundation for the functional development of heterometallic SnOCs.

The rapid removal of persistent aromatic organic micropollutants (OMPs) from water requires adsorbents with high affinity and excellent dispersibility. To overcome the inherent hydrophobicity and limited functionality of conventional hypercrosslinked polymers (HCPs), we designed a novel C₃-symmetric heptazine monomer (TPH) featuring multiple phenolic hydroxyl groups and an extended π-conjugated system. Two HCP-TPHs, HCP-TPH-1 and HCP-TPH-2, were synthesized directly from this hydrophilic TPH monomer, resulting in materials with high surface area, abundant functional groups, and intrinsic hydrophilicity. These structural characteristics enabled ultrafast adsorption of typical aromatic OMPs. For instance, in the adsorption of rhodamine B by HCP-TPH-1, the pseudo-second-order rate constant reached 61.453 g·mg^–1·min^–1, with a maximum adsorption capacity of 2658 mg·g^–1—both record-high values among all reported adsorbents to date. This study demonstrates a powerful monomer-level design strategy to create advanced HCPs for highly efficient water purification.

Selective electrocatalytic four-electron (4e) oxygen reduction reaction (ORR) is required in many new energy conversion technologies. Although Co porphyrins are active for electrocatalytic ORR, their selectivity for the 4e ORR is usually poor. Herein, we report the design and synthesis of Co porphyrin 1 bearing two tethered piperazine groups and its electrocatalytic performance for the selective 4e ORR in 0.10 M HClO₄ aqueous solutions. By tethering a piperazine group on each side of the porphyrin macrocycle, we introduced four amine units into Co porphyrin 1. These amine units can be protonated in acidic solutions, and the protonated amines can function as both intramolecular proton relays and positively charged groups to improve the four-electron ORR selectivity of Co porphyrins. With this structural modification, 1 electrocatalyzes ORR with a half-wave potential E_1/2 = 0.59 V versus RHE and a transferred electron number n = 3.90 in 0.10 M HClO₄ aqueous solutions. This work is therefore significant to present 1 as a highly selective electrocatalyst for the 4e ORR and demonstrate a new ORR electrocatalyst design strategy by employing multiple amine groups to enhance electrocatalytic 4e ORR in acidic aqueous solutions.

Fluorinated organophosphorus compounds are highly valuable in transition-metal catalysis and medicinal chemistry. Despite their significance, synthetic methods through catalytic hydrophosphination of β-CF₃-1,3-enynes remain unexplored, particularly for divergent synthesis of structurally distinct phosphine derivatives. Herein, we report a copper-catalyzed divergent hydrophosphination of β-CF₃-1,3-enynes with diarylphosphines. By fine-tuning the copper source, ligand, and base, this protocol enables selective access to fluorinated allenyl monophosphines and dienyl bisphosphines in good to excellent yields with excellent regio- and stereoselectivity. The transformation exhibits broad substrate scope and functional-group tolerance, proceeds under mild conditions, and enables versatile downstream derivatizations. Mechanistic studies indicate that the CF₃ group and ligands play crucial roles in controlling reactivity and chemoselectivity.

Aqueous electrosynthesis of hypervalent iodine(V) oxidants provides a sustainable and oxidant-free alternative to conventional chemical synthesis, but the electrooxidation of 2-iodobenzoic acid (IBA) to 2-iodoxybenzoic acid (IBX) is limited by sluggish reaction kinetics and competitive oxygen evolution. Herein, we report a Cu(I)/Cu(II) heterointerface-based CuI@CuO/CF electrocatalyst prepared by growing CuI@CuO on copper foam. The catalyst exhibits high selectivity for IBA electrooxidation in alkaline aqueous media, achieving 90.5% IBX selectivity and 71.4% Faradaic efficiency at 20 mA·cm^–2. Mechanistic studies and density functional theory calculations indicate that the CuI/CuO heterointerface promotes interfacial charge redistribution under anodic polarization, establishes a built-in electric field, and favors the formation of high-valent Cu–O(H)-type surface states. These features facilitate the adsorption and activation of IBA-derived species, reduce the energetic requirement of the reaction, and thereby contribute to the enhanced activity and selectivity. This work provides new insights into the rational design of highly active and selective electrocatalysts.