Applied Organometallic Chemistry最新文献

The Bi_xO_yI_z and CoFe₂O₄ combination enhances photocatalytic degradation of tetracyclines (TCs). Three TC antibiotics including TC, oxytetracycline (OTC), and chlortetracycline (CTC) with high concentration (50 mg L⁻¹) were utilized as target pollutant. Bi₅O₇I/Bi₄O₅I₂, with its Z-scheme, improves removal efficiency to 1.6 times that of Bi₅O₇I and 1.4 times that of Bi₄O₅I₂. Ternary Bi₅O₇I/Bi₄O₅I₂/CoFe₂O₄ (I/I/Co) composites further increase efficiency, with I/I/Co-2 achieving 1.6 times that of I/I-2. The improved performance is due to an optimized microstructure, which promotes light absorption and carrier transfer. CoFe₂O₄ nanoparticles on nanosheets create a double-Z band structure, enhancing redox activity. Radical trapping experiments indicated the major active species (•O₂⁻, OH⁻, and h⁺) in photocatalytic process of I/I/Co-2. Based on their enhanced removal efficiencies for high-concentration TCs, proper magnetic separation capacity, and recycling performance, the practical applications of I/I/Co composites to treat real TC wastewater might be implemented.

In this study, a functionalized magnetic powder complex porous carbon derived from ZIF-8 (ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C)) was prepared and applied for the waste liquid containing MB, TC, and Cu²⁺ adsorption removal. The ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) perfectly inherited the feature of parent ZIF-8, posed a high specific surface area (SBET = 812.73 m² g⁻¹), be rich in surface nitrogen functional groups, and resulting in a good dynamic adsorption of the MB, TC, and Cu²⁺. The ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) exhibited the best adsorption performance of high-concentration waste liquid containing MB, TC, and Cu²⁺, with equilibrium adsorption capacity of MB (408 mg g⁻¹), TC (417 mg g⁻¹), and Cu²⁺ (386 mg g⁻¹), respectively. The acetone and toluene adsorption were spontaneously and exothermic, given the negative values of free energy (ΔG) and enthalpy (ΔH). The difference of MB, TC, and Cu²⁺ adsorption on ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) attributed to the affinity difference (polarity and molecular diameter) and the nitrogen-containing functional groups (π-π interaction and electrostatic attraction). Therefore, it was found that ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) could effectively adsorb MB, TC, and Cu²⁺, and ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) could remove more than 70% of the above pollutants after repeated use for four times; it has a good application prospect.

The versatile application of metal-based nanoparticles has led to a recent rise in interest in the low-cost and eco-friendly green chemistry-based development of metal oxide nanoparticles. This work focuses on the photocatalytic and antibacterial uses of the zinc oxide nanoparticles (ZnONPs) that were produced based on a green approach employing stem extract of Piper chaba. The formation of ZnONPs was preliminary validated by the appearance of an absorption band at 373 nm and a stretching band due to ZnO at 480 cm⁻¹ in UV–Vis and FTIR spectrum, respectively. The crystalline nature of ZnONPs with a hexagonal wurtzite phase and an average crystallite size of 25 nm was validated by XRD analysis. ZnONPs' crystalline nature was further supported by TEM, which further showed that they were mostly cubic in form and had an average length of 30 nm. Synthesized ZnONPs demonstrated significant antibacterial activity against Salmonella typhi, Vibrio cholerae, Escherichia coli, and Staphylococcus aureus and lucrative photocatalytic activity with the rate constant value of 0.0273 min⁻¹ towards the degradation of methylene blue under sunlight exposure. Therefore, a facile, affordable, and ecologically sustainable method like this might be used for the large-scale synthesis of ZnONPs.

Inspired by the multienzymatic relay catalysis in nature, herein, we reported a pioneering bio-inspired Cu/Pd bimetallic composite microspheres (Cu/CMC@Pd/C) as a simple and efficient relay catalyst for the homo-coupling of arylboronic acids. In this composite, Pd/C was encapsulated by Cu(II)-crosslinking carboxymethyl cellulose (Cu/CMC). Cu/CMC@Pd/C microspheres were easily achieved by adding a mixture solution of Pd/C and carboxymethyl cellulose into a Cu(II) solution through an ion exchange reaction between carboxylate groups of CMC and Cu(II) ions. The morphology and composition of the as-prepared Cu/CMC@Pd/C microspheres were well characterized using various analytical tools such as FT-IR, XRD, XPS, SEM, TEM, elemental mapping, EDS, and ICP-AES. The analysis indicated that the composite microspheres have a porous structure and Pd/C is uniformly distributed within the interior of the composite microspheres. The porous structure facilitates mass transfer of the substrate and increases the contact area of the catalyst, thus improving reaction efficiency. The performance of Cu/CMC@Pd/C microspheres was assessed in the homo-coupling of arylboronic acid for the synthesis of symmetric biaryl without the need for an aryl halide as a partner. This process mimics a multienzyme catalysis through a relay Cu(I)-catalyzed halogenation of one portion of arylboronic acid and a Pd(0)-catalyzed Suzuki–Miyaura cross-coupling between the in situ generated aryl halide and another portion of arylboronic acid. The results showed that this bio-inspired Cu/CMC@Pd/C has excellent relay catalytic activity with tolerance of broad functional groups, producing the desired symmetrical biaryls in excellent yields within a short reaction time under mild conditions. Moreover, the catalyst can be easily recovered through simple filtration and still has good catalytic activity after six cycles. Consequently, this innovative pseudo-homogeneous Cu/Pd relay catalyst emerges as a convenient and efficient alternative for the synthesis of asymmetric biaryls.

An air-tolerant, simple yet highly efficient copper-catalyzed methoxylation of (hetero)aryl bromides and some activated chlorides has been developed by using copper(II) chloride/2,2-bipyridine as catalyst precursor. A wide range of (hetero)aryl bromides and electron-deficient chlorides could be efficiently methoxylated in good to excellent yields at 1-mol% catalyst loading albeit showing a functional group compatibility dependent on the electronic properties of aryl ring. Applications of the practical protocol have been demonstrated in multigram synthesis of 3,4,5-trimethoxytoluene.

Using palladium hydrazone complex as a homogeneous catalyst for SMC, we synthesized a library of 15 variant 3-arylcoumarins. In this context, we report a set of four coordinated palladium(II) hydrazone complexes 1 and 2 having the general formula [Pd(L)(Cl)(PPh₃)] by reacting the precursor complex [PdCl₂(PPh₃)₂] with the hydrazone ligands HL₁ or HL₂. Single crystal XRD and conventional spectroscopic techniques were employed to characterize both complexes. From the catalytic application point of view, the new complexes 1 and 2 were tested as homogeneous catalysts towards the conversion of 3-chlorocoumarins into 3-arylcoumarins by activating the challenging CCl functionality. A minimal catalyst loading of complex 2 (0.01 mol%), afforded a series of 3-arylcoumarins with a maximum of 92% yield and reusability up to five cycles. The present methodology is simple and easy to carry out at room temperature utilizing a green solvent (ethanol) in an open flask with a spectrum of aryl boronic acids.

Constrained geometry complexes (CGCs) are homogeneous olefin polymerization catalysts that have been improved because of their considerably high activity and their copolymerization abilities for ethylene with α-olefins. The ancillary ligands in CGCs comprise bridged 6π-electron moieties (e.g., cyclopentadienyl (Cp) and fluorenyl) and amide donors. In this study, we investigated the effect of changing the 6π-electron moieties to a diphenylmethyl moiety (Ph₂C) on the polymerization activity of [Me₂Si(Ph₂C)(^tBuN)]ZrCl₂(thf) (thf = tetrahydrofuran). We synthesized [Me₂Si(Ph₂C)(^tBuN)]ZrCl₂(thf) and characterized it via ¹H nuclear magnetic resonance analysis and single-crystal X-ray crystallography. Ethylene polymerization at 2 MPa using a catalyst of the [Me₂Si(Ph₂C)(^tBuN)]ZrCl₂(thf) and modified methylaluminoxane (MMAO) as a cocatalyst yielded a linear polyethylene (PE) with a high melting point (124°C–134°C); moreover, the polymerization activity of the catalyst was found to be up to 445 g (PE) mmol (Zr)⁻¹ h⁻¹. The polymerization of styrene using the zirconium complex and MAOs did not proceed, but the polymerization of 1,3-butadiene produced a small amount of polybutadiene with ~60% cis-1,4-structure. These results indicate that non-Cp-type CGCs, which can be defined as metal complexes bearing an ancillary ligand in which non-Cp moieties (benzyl moiety in this study) and an amido group are bridged by an organic linker, can become a new family of homogeneous olefin polymerization catalysts.

In our work, we have successfully synthesized twelve diorganotin(IV) complexes (4–15) from different hydrazone ligands and diorganotin(IV) dichlorides. The complexes have a general formula [R₂SnL^1–3], where R = Et, Me, Bu, and Ph groups. The hydrazone ligands (1–3) were synthesized through a condensation reaction involving 3-ethoxysalicylaldehyde with different benzhydrazide derivatives. All the synthesized hydrazone ligands and their complexes underwent screening by employing numerous spectroscopic and physicochemical techniques, such as molar conductance measurements, mass spectrometry, (¹H, ¹¹⁹Sn, and ¹³C) NMR, SEM-EDAX, and FT-IR. Spectroscopic analysis revealed that the hydrazone ligands were attached to tin atoms in a tridentate fashion via ONO donor atoms, suggesting a pentacoordinated geometry for the complexes. Furthermore, the X-ray crystallography analysis for Complex 6 revealed the distorted square pyramidal geometry around the tin atom. Moreover, a DFT study was also carried out for Ligand 3 and its complexes (12–15) by employing B3LYP/LanL2DZ theory level (Gaussian 9 software package) to obtain the optimized geometry and global reactivity descriptors, structural behavior, and their efficacy against different microbes. To assess the biological efficacy of synthesized compounds, an in vitro antimicrobial assay was conducted against different fungal (Aspergillus niger and Candida albicans) and bacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa) strains. The results of the antimicrobial assay demonstrated that Complexes 7, 11, and 15 depicted better results against E. coli strain and C. albicans strain, implying that the higher lipophilic character of these complexes facilitates their easy passage through the cell membrane of microbes. Furthermore, an ADMET study was carried out to evaluate the toxicity score of synthesized compounds.

A series of novel asymmetric alkyl P-substituted bis(phosphanyl)amine (PNP) Ph₂PN (cyclopentyl) PR₁R₂-type L1–L5 ligands and these corresponding Ni(II) precatalysts C1–C5 were synthesized and characterized. The structures of these complexes were confirmed by using ¹H-, ³¹P-, ¹³C-NMR, FT-IR, and elemental analysis. Using ethylaluminum dichloride (EADC) as a cocatalyst, nickel complexes exhibited high activity in elective ethylene oligomerization, with the main products being dimers and a small number of trimers. Under optimized conditions of 60°C and 1.0 MPa ethylene pressure, C4, bearing a diisopropylphosphoryl group, exhibited highest catalytic activity of 1342.9 kg·g Ni⁻¹·h⁻¹ with 85.2% C₄ and 14.8% C₆ products selectivity, while C2, bearing a diethylphosphonyl group, showed catalytic activity of 596.4 kg·g Ni⁻¹·h⁻¹ with 88.2% C₄ and 11.8% C₆ product selectivity. Single crystal analysis offered a more comprehensive insight into the subtle effects of alkyl P-substituted in the scaffold of C2 and C4 ligands on catalytic activity. Density functional theory (DFT) calculations indicated that lower energy of the LUMO in the C4A intermediate enhances the activity of ethylene oligomerization. It provides a new method for purposefully designing ligands for ethylene oligomerization with high catalytic activity.