ABSTRACT Using new complexes of Group 4 metals with saligenin (2‐hydroxymethylphenol) ligands, it was shown that only titanium compounds activated by Al/Mg cocatalysts (Et 2 AlCl or Et 3 Al 2 Cl 3 + Bu 2 Mg) exhibit catalytic activity in ethylene polymerization. The authors attribute the lack of activity of the Zr and Hf complexes to differences in the redox potentials of these metals, based on the assumption that the catalytically active particle contains reduced Ti(III). Traditional activators—alkylaluminoxanes, tetrakisperfluorophenylborates, and simple organoaluminum compounds (OAC)—are unable to activate these complexes. A prerequisite for catalytic activity is the presence of Mg compounds, indicating the heterometallic (Ti‐Mg) nature of the active particle. Titanium complexes catalyze the synthesis of UHMWPE with a productivity of up to 3940 kg of PE mol −1 h −1 atm −1 . UHMWPE films obtained by solventless processing with subsequent uniaxial orientation drawing have a tensile modulus up to 120 GPa and tensile strength up to 2.3 GPa, which indirectly proves the low degree of macromolecule's entanglements. Titanium complexes, stabilized with dichlorosaligenin ligand, are also capable of catalyzing the synthesis of high molecular weight ethylene‐propylene‐5‐ethylidene‐norbornene terpolymers (EPDM).
ABSTRACT We designed two intelligent composites based on hyaluronic acid (HA) coated Ag(I) complexes with cascade dual‐stimuli‐responsive Ag + release to tackle the escalating threat of drug resistance while minimizing the off‐target toxicity originating from the always‐on Ag + release and degradation of an additional carrier. The Ag(I) complexes assembled with pH‐sensitive coordination bonds (Ag–N in 1 and Ag–S in 2 ) integrate antimicrobial activity, carrier function, and acid response, offering a new design logic for an antibiotic‐free, carrier‐free, and resistance‐targeting bactericide. HA coating further functions as a hyaluronidase‐responsive gatekeeper, suppressing the premature Ag + release under physiological conditions and promoting Ag + release upon hyaluronidase stimulation. Cascade dual‐stimuli‐responsive is integrated by hyaluronidase‐triggered degradation of HA coating, followed by acid‐induced cleavage of coordination bonds, leading to Ag + release from exposed Ag(I) complexes. The resulting dual‐stimuli‐responsive Ag + release ratios (44.13% for 1 @HA and 56.09% for 2 @HA) exceeded those of each individual stimulus and their theoretical additive sums. Under simulated dual stimuli, minimum inhibitory concentrations of the composites decreased to 16 mg/L against Pseudomonas aeruginosa and carbapenem‐resistant Escherichia coli . Correlation of crystal structure, Ag + release, and antimicrobial activity further elucidated that the antimicrobial efficacy of Ag(I) complexes was governed not only by Ag + release but also by their ligand‐exchange capability with biological ligands at bacterial targets. By facilely integrating enzymatic targeting and pH‐amplified Ag + release into a single system, this work successfully establishes an antibiotic‐free antimicrobial platform translating infection signals into targeted therapeutic actions.
ABSTRACT Disulfide compounds, as the important industrial chemicals are widely used in rubber production, vulcanizing agents, agrochemicals and fabrication of advanced materials. However, the conventional synthesis methods of disulfide compounds are hitherto suffering from the limitations of low yield, toxic and unstable reagents, and a cumbersome preparation process. Thus, electrochemical coupling pathways as the emerging approach to synthesize the disulfide compounds have received myriad attention. Here, we provided an environmentally friendly and maneuverable protocol for the effective construction of S–S bond with the absence of oxygen and strong acid or alkaline environment based on Ce/Ti‐bimetal MOF catalyst. Significantly, Ce/Ti‐bimetal MOF exhibited excellent electrocatalytic performance for the construction of S–S bond. Based on the gentle reaction conditions, the production of disulfide compounds was up to 99%. Besides, further investigation proved that the yield of disulfide would not be significantly influenced by different substituents on the thiophenol.
ABSTRACT The development of heterogeneous catalysts for the efficient construction of acetamide frameworks under mild conditions is of great significance for green pharmaceutical synthesis. An efficient and reusable heterogeneous Cu@UiO‐67‐bpy catalyst is synthesized by a standard solvothermal method and post‐synthetic metalation (PSM) procedures. This catalyst is fully characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), Fourier transform infrared spectra (FT‐IR), X‐ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller (BET) method. The catalyst efficiently promotes the regioselective C–N coupling of arylamines with terminal alkynes, affording bioactive acetamide‐based pharmaceutical intermediates in excellent yields under visible light with O 2 as the oxidant. Owing to the heterotic nature of the catalyst, it can be easily separated by simple filtration from the reaction mixture and reused five times without obvious activity loss.
ABSTRACT Herein, we report the efficient Suzuki–Miyaura cross‐coupling reactions of N ‐acylglutarimides—directly derived from primary amides—with arylboronic acids, catalyzed by an oxazoline‐fused acenaphthoimidazolylidene palladium catalyst, thus enabling the indirect and highly efficient activation of primary amides. At ppm‐level loading (0.05 mol%, 500 ppm), the catalyst afforded 99% yield of aryl ketones in 5 h, with a TON of 34,800 and TOF of 2650 h −1 , outperforming reported NHC‐Pd systems. It features broad substrate scope, compatible with arylboronic acids (EDGs, EWGs, polycyclic, alkenyl, and heterocyclic) and N‐acylglutarimides from aromatic, heteroaromatic, and aliphatic primary amides. Notably, it achieved 93% yield in 5 h for the green synthesis of a flumorph key intermediate using THF as solvent.
