Ligand Exchange Research Articles

Speciation of Cr(III) and Cr(VI) in aqueous solution and their removal by oyster mushroom biomass

This study investigates the effectiveness of oyster mushroom (Pleurotus platypus) for the removal of Cr(III) and Cr(VI) from aqueous solutions by conducting a series of batch adsorption experiments. Results from the adsorption pH envelope experiments show that while the adsorption of Cr(III) increases with increasing pH, the adsorption of Cr(VI) decreases as the pH rises. These two distinct pH envelope patterns for Cr(III) and Cr(VI) suggest that the adsorption processes are primarily driven by the electrostatic force of attractions followed by the ligand exchange process. Findings from the adsorption isotherm experiments demonstrate that chromium binding to the adsorbent surface is better described by the Freundlich model than the Langmuir model, underscoring the presence of multiple surface binding sites. The study highlights the significance of identifying dominant chromium species before they are subjected to adsorptive removal from contaminated waters. J. Bangladesh Acad. Sci. 47(2); 267-275: December 2023

NaH2PO4 synergizes with organic matter to stabilize chromium in tannery sludge

Heavy metal stabilization is an effective method to treat chromium in tannery sludge. Here we show that mainly investigated NaH2PO4 (MSP) and organic matter (OM) to stabilize chromium in tannery sludge. The experimental investigation revealed that the addition of montmorillonite (MMT) and MSP samples showed a significant increase in the percentage of reducible and oxidizable Cr in the former compared to the samples with the addition of MMT. This is attributed to the formation of Cr–O bond, which allows the MSP to undergo an inner-sphere complexation reaction with the metal oxide of Cr via ligand exchange. Significantly, the MSP moiety adsorbs on the surface of OM through monodentate, which increases the adsorption sites of OM for Cr6+ and promotes the reduction of Cr6+ to Cr3+. Moreover, PO43− reacts with Cr3+ to produce CrPO4 precipitation, thus reducing the free Cr3+ content. Finally, DFT calculations confirmed that a ternary system is formed between PO43−, OM, and Cr, and the binding energy is negative, which indicated that PO43− could co-stabilize Cr with OM.

Air- and Water-Stable Heteroleptic Copper (I) Complexes Bearing Bis(indazol-1-yl)methane Ligands: Synthesis, Characterisation, and Computational Studies.

A series of four novel heteroleptic Cu(I) complexes, bearing bis(1H-indazol-1-yl)methane analogues as N,N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N,N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH2Cl2 at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1H-indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.

An Isolable Phosphinogermylyne as a Synthon of One‐Coordinate GeI Radical

Comprehensive SummaryReduction of chlorogermylene MsFluindtBu‐GeCl 1 with potassium graphite (KC8) afforded putative germylyne radical MsFluindtBu‐Ge 2 as confirmed by electron paramagnetic resonance (EPR) spectroscopy. However, it slowly decayed via C—H bond activation at the fluorenyl moiety to yield a bis(germylene) 3 at room temperature. By using a Lewis base to stabilize the unoccupied p orbital at the GeI radical center, acyclic two‐coordinate GeI radicals MsFluindtBu‐Ge(IMe4) 4 (IMe4 = 1,3,4,5‐tetramethyl‐imidazolin‐2‐ylidene), MsFluindtBu‐Ge(IiPr) 5 (IiPr = 1,3‐diisopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene), MsFluindtBu‐Ge(PMe3) 6 were isolated in crystalline forms. The unpaired electron in 4—6 mainly resides at the Ge 4p orbital as revealed by EPR spectroscopic studies and theoretical calculations. Interestingly, facile ligand exchange of PMe3 in 6 with IMe4 and IiPr was observed to afford 4 and 5, respectively. Moreover, phosphinogermylyne 6 reacted with PhEEPh (E = S, Se), 4‐tetrabutylphenylacetylene (Ar'CCH), [CpMo(CO)3]2 and nBu3SnH to furnish germylenes MsFluindtBu‐GeEPh (E = S 7, Se 8), MsFluindtBu‐GeCH=CHAr’ 9, a germylyne complex MsFluindtBu‐Ge≡Mo(CO)2Cp 10 and a Ge(IV) compound MsFluindtBu‐GeH2SnnBu3 11, respectively. The reactivity studies demonstrate that 6 can act as a synthon of one‐coordinate germylyne radical attributing to labile coordination of trimethylphosphine.

Highly efficient and selective extraction of Au(I) from thiosulfate gold-leaching solution using diphenylphosphine

Solvent extraction has the advantages of continuous operation mode and high loading capacity, which has received some attention in the field of thiosulfate gold leaching, but current research results are not satisfactory. In this study, diphenylphosphine (DPP) diluted in benzene was used to extract gold from thiosulfate solution, and its extraction behavior and properties were investigated. The effects of the DPP concentration, pH value, contact time, and sodium thiosulfate concentration on the extraction performance were evaluated. Under the optimal conditions, 0.7 mmol/L DPP showed high gold-extraction efficiency (99%) from 0.2 mol/L S2O32− solution embracing 10 mg/L Au(I) at pH = 10.0 with an aqueous/organic (A/O) ratio of 2. A high A/O ratio (A/O = 15) can be used in the extraction stage to achieve complete recovery of gold ions from solution. In addition, DPP showed high selectivity and recovery ability in Cu–NH3–thiosulfate gold-leaching solution, and the recovery rate was higher than 99%. The mechanism of gold-ion extraction by DPP involving ligand exchange between DPP− and [Au(S2O3)2]3− was confirmed by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy. The P atom in Ph2–P− plays an important role in complexation of gold ions, which was confirmed by density functional theory calculation. The extraction method with low reagent consumption and high recovery rate developed in this study will greatly promote the development of gold leaching with thiosulfate.

A robust bendable IrOx thin film via mild alkaline solution process for neuron stimulating electrodes

We demonstrate a unique chemical formula to deposit hydrous iridium oxide thin film on a platinum-coated polyimide substrate. In a mild alkaline solution, the iridium (III) precursor undergoes the ligand exchange and hydrolysis reaction to become the iridium (III) dimers that are physically adsorbed on the substrate for subsequent heterogeneous condensation and growth of amorphous hydrous iridium oxide thin film. Both UV–Vis and X-ray absorption spectroscopy (XAS) are employed to determine the reaction steps involved. The chemical nature and crystallinity of the hydrous iridium oxide thin film are investigated by XAS, X-ray photon spectroscopy, and X-ray diffraction. The hydrous iridium oxide thin film reveals an impressive normalized charge storage capacity (CSC) of 0.3 mC/cm2-nm and a low impedance (80.5 Ω) at 1k Hz. In addition, in bending test of 3,000 cycles, the hydrous iridium oxide thin film retains 91.2 % of its initial normalized CSC without any physical crack and delamination. The cell viability test suggests negligible bio-toxicity. Our results provide a solid evidence of fabricating a robust flexible electrode for neural interfaces for potential use in implantable electronic devices.

Development of comprehensive approaches to characterizing CuII complexes: structures in solution and solid‐state, dynamic behavior, and bioactivity

AbstractCuII ternary systems with aromatic N‐donors (1,10‐phenanthroline, dipyrido‐[3,2‐f:2’,3’‐h]‐quinoxaline, and 2‐methyldipyrido‐[3,2‐f:2’,3’‐h]‐quinoxaline) and amino acids have been extensively studied in water solution under closely physiological conditions using several techniques, including potentiometric pH titration, mathematical modeling, nuclear magnetic relaxation, EPR, and DFT calculations. Based on the distribution diagrams of the complex species, single crystal syntheses of the ternary systems CuII‐aromatic N‐donor‐L‐amino acid were carried out. As a result, several crystal structures of the complexes with the desired copper‐to‐ligand ratio were established by X‐ray diffraction analysis. The most successful synthetic attempts were with L‐proline and L‐serine, resulting in the crystals with the desired copper(II) to ligand ratio. The developed approach made it possible to thoroughly describe systems with major proteinogenic amino acids in the L‐configuration. Numerous non‐covalent interactions such as H‐bonds, π‐π stacking, d‐π interactions, lone electron pair‐π interactions between CuII atom, conjugated aromatic ligand system, counterions, and water molecules were found to affect the stability and structure of the resulting complex particles. It has been found that in the CuII–N‐donor–amino acid systems there is an acceleration of ligand exchange by a factor of 2–25 compared to CuII‐amino acid systems, which is explained by taking into account steric effects, d‐π interactions, and the pseudo Jahn‐Teller effect. The investigated systems were tested for antitumor activity against MCF‐7, PC‐3, OVCAR‐4, SNB‐19, and M‐14 cell lines, and most samples, in particular, CuII–Phen–L‐His, CuII–MeDPQ−L‐Val and CuII–MeDPQ−L‐Ser, showed a therapeutic activity index greater than 2 for all selected cell types, which opens up prospects for their medical application.

Enhanced Electrochemiluminescence of Rod‐Shape 25‐Atom AuAg Nanoclusters through Ligand Engineering

AbstractThe pursuit of highly emissive electrochemiluminescence (ECL) luminophores has long been a goal for both understanding mechanism and advancing detection applications. In this study, we employ ligand engineering to boost the ECL performance of bimetallic Au12Ag13 nanoclusters, substituting the PPh3 ligand with P(Ph‐OMe)3. The results demonstrate a 3.6‐fold enhancement in ECL efficiency following ligand exchange when compared to Au12Ag13‐PPh3, particularly in the presence of 1 mM tri‐n‐propylamine (TPrA) as a coreactant – surpassing the performance of the conventional Ru(bpy)32+ luminophore. Voltammetric analysis reveals the presence of both oxidative and reductive ECL signals under sweeping potentials, with corresponding ECL spectra collected. Proposed ECL mechanisms are rooted in the anodic and cathodic activities of Au12Ag13‐P(Ph‐OMe)3 nanoclusters. Notably, this work captures extremely high and transient ECL signals, sequentially activating LUMO and HOMO states, reminiscent of the behavior observed in Au12Ag13‐PPh3. Our findings present a promising strategy to enhance the ECL of metal nanoclusters, holding potential for further applications in sensing and detection.

Using wafer scale ferroelectric domains of LiNbO3 to form permanent planar p–n junction in narrow band gap nanocrystals

p–n junctions based on nanocrystals now serve as fundamental components in optoelectronics. However, the process of designing these p–n junctions has largely relied on empirical choices, either for ligand exchange or for the selection of charge transport layers. Therefore, a systematic strategy is still lacking. In this study, we explore the utilization of ferroelectric domains as a general method for remotely inducing the formation of a p–n junction. To ensure compatibility with devices of various designs, we employ a commercially available periodically poled LiNbO3 (PPLN) substrate commonly used in nonlinear optics. We engineer a PPLN/graphene/HgTe heterostructure and demonstrate its planar photodiode behavior. Through x-ray photoemission microscopy, we confirm that the rectifying behavior stems from the influence of the ferroelectric domains, by ruling out the possibility of the formation of non-ohmic contacts at the electrode/semiconductor interfaces. This approach proves to be quite general and holds promise for the future design of high-speed nanocrystal-based photodiodes.

Exploring Bismuth Coordination Complexes as Visible-Light Absorbers: Synthesis, Characterization, and Photophysical Properties.

Bismuth-based coordination complexes are advantageous over other metal complexes, as bismuth is the heaviest nontoxic element with high spin-orbit coupling and potential optoelectronics applications. Herein, four bismuth halide-based coordination complexes [Bi2Cl6(phen-thio)2] (1), [Bi2Br6(phen-thio)2] (2), [Bi2I6(phen-thio)2] (3), and [Bi2I6(phen-Me)2] (4) were synthesized, characterized, and subjected to detailed photophysical studies. The complexes were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and NMR studies. Spectroscopic analyses of 1-4 in solutions of different polarities were performed to understand the role of the organic and inorganic components in determining the ground- and excited-state properties of the complexes. The photophysical properties of the complexes were characterized by ground-state absorption, steady-state photoluminescence, microsecond time-resolved photoluminescence, and absorption spectroscopy. Periodic density functional theory (DFT) calculations were performed on the solid-state structures to understand the role of the organic and inorganic parts of the complexes. The studies showed that changing the ancillary ligand from chlorine (Cl) and bromine (Br) to iodine (I) bathochromically shifts the absorption band along with enhancing the absorption coefficient. Also, changing the halides (Cl, Br to I) affects the photoluminescent quantum yields of the ligand-centered (LC) emissive state without markedly affecting the lifetimes. The combined results confirmed that ground-state properties are strongly influenced by the inorganic part, and the lower-energy excited state is LC. This study paves the way to design novel bismuth coordination complexes for optoelectronic applications by rigorously choosing the ligands and bismuth salt.

Influence on the release of arsenic and tungsten from sediment, and effect on other heavy metals and microorganisms by ceria nanoparticle capping

In this study, ceria nanoparticle (CNP) was used as a capping agent to investigate the efficiency and mechanism of simultaneously controlling the release of sediment internal Arsenic (As) and tungsten (W). The results of incubation experiment demonstrated that CNP capping reduced soluble As and W by 81.80% and 97.97% in overlying water, respectively; soluble As and W by 65.64% and 60.13% in pore water, respectively; and labile As and W in sediment by 45.20% and 53.20%, respectively. The main mechanism of CNP controlling sediment internal As and W was through adsorption via ligand exchange and inner-sphere complexation, as determined through adsorption experiments, XPS and FIRT spectra analysis. Besides, CNP also acted as an oxidant, facilitating the oxidation of AsⅢ to AsV and thereby enhancing the adsorption of soluble As. Additionally, sediment As and W fractions experiments demonstrated that the immobilization of As and W with CNP treatment via transforming mobile to stable fractions was another mechanism inhibiting sediment As and W release. The obtained significant positive correlation between soluble As/W and Fe/Mn, labile As/W and Fe/Mn indicated that iron (Fe) and manganese (Mn) oxidation, influenced by CNP, serve as additional mechanisms. Moreover, Fe redox plays a crucial role in controlling internal As and W, while Mn redox plays a more significant role in controlling As compared to W. Meanwhile, CNP capping effectively prevented the release of As and W by reducing the activity of microorganisms that degrade Fe-bound As and W and reduced the release risk of V, Cr, Co, Ni, and Zn from sediments. Overall, this study proved that CNP was a suitable capping agent for simultaneously controlling the release of As and W from sediment.

Copper-Catalyzed C-H (Phenylsulfonyl)difluoromethylation of Acrylamides: Scope, Mechanism, and Critical Role of Additives.

Herein, we report the Cu-complex catalyzed, native functional group-assisted, and TFA/NMF additives promoted (phenylsulfonyl)difluoromethylation of vinylic C(sp2 )-H bond of acrylamides. Using our in-home designed reagent, this reaction enables the construction of the C(sp2 )-CF2 SO2 Ph bond from simple C-H bond activation by copper catalysis under mild reaction conditions with total Z-selectivity. The versatility of utilized fluorinated group was illustrated by its conversion into value-added CF2 moieties as well as the remarkable =CHF residue. The performed experimental and computational mechanistic studies enabled to identify the true nature of active catalyst and substrate, as well as establish critical roles of TFA and NMF additives. In this reaction, the TFA acts as a promoter of the much-needed CuII /CuII →CuIII /CuI disproportionation, while the NMF facilitates the following ligand exchange and C-C coupling processes. We ruled out the generation of radical intermediates and established the C-H activation to be irreversible and the rate-determining step of the entire process.

Assembly of Six Types of Heteroleptic Pd2L4 Cages under Kinetic Control.

Heteroleptic assemblies composed of several kinds of building blocks have been seen in nature. It is still unclear how natural systems design and create such complicated assemblies selectively. Past efforts on multicomponent self-assembly of artificial metal-organic cages have mainly focused on finding a suitable combination of building blocks to lead to a single multicomponent self-assembly as the thermodynamically most stable product. Here, we present another approach to selectively produce multicomponent Pd(II)-based self-assemblies under kinetic control based on the selective ligand exchanges of weak Pd-L coordination bonds retaining the original orientation of the metal centers in a kinetically stabilized cyclic structure and on local reversibility given in certain areas of the energy landscape in the presence of the assist molecule that facilitates error correction of coordination bonds. The kinetic approach enabled us to build all six types of Pd2L4 cages and heteroleptic tetranuclear cages composed of three kinds of ditopic ligands. Although the cage complexes thus obtained are metastable, they are stable for 1 month or more at room temperature.

Efficient adsorption of phosphorus by macroscopic MOF/chitosan composites and preliminary investigation of subsequent phosphorus recovery through electrochemically-driven struvite precipitation

The proper management of phosphorus (P) from wastewater is crucial for sustainable development consideration. Herein, we developed a strategy which combines adsorption via tailored adsorbents and electrochemically-driven struvite precipitation (ESP) for P recovery. Novel polydopamine-modified Ce-MOF/chitosan composite beads (PDA@Ce-MOF-CS) were prepared by a facile in situ growth of Ce-MOF crystals incorporated natural polymers and PDA coating. The physicochemical properties of PDA@Ce-MOF-CS were characterized. Both batch and fixed-bed column experiments were conducted to evaluate its adsorption performances. Representatively, PDA@Ce-MOF-CS performed good selectivity for P removal and exhibited a maximum adsorption capacity of 161.13 mg P/g at pH 3 and 318 K. Meanwhile, the developed adsorbent showed great reusability after ten regeneration cycles as well as good adsorption stability. The dominant mechanism for efficient P adsorption included electrostatic attraction, surface precipitation and ligand exchange. Interestingly, PDA@Ce-MOF-CS exhibited a remarkable adsorption capacity of 92.86 mg P/g by treating real P-rich electroplating wastewater, and the desorbed P in the eluate could be effectively recovered and converted into a solid fertilizer as struvite via ESP. Overall, this work provided a new research direction for P recovery from wastewater as struvite by combined technologies with the help of macroscopic MOF architectures.

Atomic layer deposition mechanism of hafnium dioxide using hafnium precursor with amino ligands and water

As a unique nanofabrication technology, atomic layer deposition (ALD) has been widely used for the preparation of various materials in the fields of microelectronics, energy and catalysis. Hafnium dioxide (HfO2), as an excellent high-κ oxide, is widely used as a substitute gate dielectric for conventional SiO2 in field effect transistor devices. Currently, HfO2 high-κ gate dielectric in MOSFET devices was prepared via ALD technology using tetrakis(dimethylamino)hafnium(IV) (Hf(NMe2)4, TDMAHf) and water (H2O) as the precursors. In this work, the complicated surface reaction mechanism of HfO2 H2O-based ALD using Hf(NMe2)4 was investigated using density functional theory calculations. In the TDMAHf reaction, the dimethylamino group of the precursor was eliminated by ligand exchange reaction with the hydroxyl group on the surface. Subsequently, a second dimethylamino group of TDMAHf could further be eliminated by another hydroxyl group on the surface. In the H2O reaction, ligand exchange reactions and coupling reactions could both occur. By the ligand exchange reactions, water molecule could react with the dimethylamino group on the surface. Simultaneously, the hydroxyl and amino groups could also react with neighboring hydroxyl groups to eliminate dimethylamine and water molecules via the coupling reactions. All these insights into the complicated surface reaction mechanism of H2O-based ALD could promote the further development of ALD chemistry and materials.

A computational insight on the aromatic amino acids conjugation with [Cp*Rh(H2O)3]2+ by using the meta-dynamics/FMO3 approach

ContextRh(III) complexes demonstrated to exert promising pharmacological effects with potential applications as anti-cancer, anti-bacterial, and antimicrobial agents. One important Rh(III)-ligand is the pentamethylcyclopentadienyl (Cp*) group forming in water the [Cp*Rh(H2O)3]2+ complex. Among of its attractive chemical properties is the ability to react specifically with Tyr amino acid side chain of G-protein–coupled receptor (GPCR) peptides by means of highly chemoselective bioconjugation reaction, at room temperature and at pH 5–6. In this computational work, in order to deepen the mechanism of this chemoselective conjugation, we study the ligand exchange reaction between [Cp*Rh(H2O)3]2+ and three small molecules, namely p-cresol, 3-methylimidazole, and toluene, selected as mimetic of aromatic side chains of tyrosine (Tyr), tryptophan (Trp) and phenylalanine (Phe), respectively. Our outcomes suggest that the high selectivity for Tyr side chain might be related to OH group able to affect both thermodynamic and kinetic of ligand exchange reaction, due to its ability to act as both H bond acceptor and donor. These mechanistic aspects can be used to design new metal drugs containing the [Cp*Rh]2+ scaffold targeting specifically Tyr residues involved in biological/pathological processes such as phosphorylation by means of Tyr-kinase enzyme and protein–protein interactions.MethodsThe geometry of three encounter complexes and product adducts were optimized at the B3LYP//CPCM/ωB97X-D level of theory, adopting the 6-311+G(d,p) basis set for all non-metal atoms and the LANL2DZ pseudopotential for the Rh atom. Meta-dynamics RMSD (MTD(RMSD)) calculations at GFN2-xTB level of theory were performed in NVT conditions at 298.15 K to investigate the bioconjugation reactions (simulation time: 100 ps; integration step 2.0; implicit solvent model: GBSA). The MTD(RMSD) simulation was performed in two replicates for each encounter complex. Final representative subsets of 100 structures for each run were gained with a sampling rate of 1 ps and analyzed by performing single point calculations using the FMO3 method at RI-MP2/6-311G//PCM[1] level of theory, adopting the MCP-TZP core potential for Rh atom.

Transient Measurements and Simulations Correlate Exchange Ligand Concentration and Trap States in Colloidal Quantum Dot Photodetectors.

Colloidal quantum dot (CQD) photodetectors (PDs) can detect wavelengths longer than the 1100 nm limit of silicon because of their highly tunable bandgaps. CQD PDs are acutely affected by the ligands that separate adjacent dots in a CQD-solid. Optimizing the exchange solution ligand concentration in the processing steps is crucial to achieving high photodetector performance. However, the complex mix of chemistry and optoelectronics involved in CQD PDs means that the effects of the exchange solution ligand concentration on device physics are poorly understood. Here we report direct correspondence between simulated and experimental transient photocurrent responses in CQD PDs. For both deficient and excess conditions, our model demonstrated the experimental changes to the transient photocurrent aligned with changes in trap state density. Combining transient photoluminescence, absorption, and photocurrent with this simulation model, we revealed that different mechanisms are responsible for the increased trap density induced by excess and deficient active layer ligand concentrations.

Electroreductive Synthesis of Nickel(0) Complexes**

AbstractOver the last fifty years, the use of nickel catalysts for facilitating organic transformations has skyrocketed. Nickel(0) sources act as useful precatalysts because they can enter a catalytic cycle through ligand exchange, without needing to undergo additional elementary steps. However, most Ni(0) precatalysts are synthesized with stoichiometric aluminum–hydride reductants, pyrophoric reagents that are not atom‐economical and must be used at cryogenic temperatures. Here, we demonstrate that Ni(II) salts can be reduced on preparative scale using electrolysis to yield a variety of Ni(0) and Ni(II) complexes that are widely used as precatalysts in organic synthesis, including bis(1,5‐cyclooctadiene)nickel(0) [Ni(COD)2]. This method overcomes the reproducibility issues of previously reported methods by standardizing the procedure, such that it can be performed anywhere in a robust manner. It can be transitioned to large scale through an electrochemical recirculating flow process and extended to an in situ reduction protocol to generate catalytic amounts of Ni(0) for organic transformations. We anticipate that this work will accelerate adoption of preparative electrochemistry for the synthesis of low‐valent organometallic complexes in academia and industry.

Cigarette Butts as Water Emerging Contaminants: Possible Method for Their Remediation

Nano-sized particles derived from cigarette butts (CBs) are extremely small particles, typically less than 100 nanometers in size, generated by the degradation or breakdown of CB materials. The potential impact of nano-sized particles derived from CBs on irrigation water is a topic of concern. Despite the lack of research focusing specifically on these aspects, it is essential to consider the potential risks associated with these particles. The presence of toxic compounds in CBs, such as nicotine, heavy metals, and polycyclic aromatic hydrocarbons (PAHs), raises concerns about the potential health risks of consuming water contaminated with nano-sized particles from CBs and the potential for these particles to accumulate in the soil, affecting nutrient availability and overall crop growth. Nano-sized particles can travel through water systems and may reach irrigation channels and sources through various pathways, and if CB nano-litter is present in nearby surface water bodies or infiltrates into groundwater, it can introduce these particles and associated contaminants into water sources and the agricultural environment. To ensure the safety and limited entry into water sources used for irrigation it is crucial to implement effective water treatment processes capable of removing or reducing nano-sized particles, as well as the associated chemicals, from the water supply. To mitigate potential risks, various water purification methods can be considered, such as the use of magnetic biochar. Magnetic biochar is a type of biochar that is enriched with magnetic materials. It has been explored as a potential tool for wastewater treatment due to its ability to attract and adsorb contaminants. The hybridized properties of both organic and inorganic materials in magnetic biochar promote its adsorptive ability for a wide range of contaminants. Also, it has unique properties such as solar responsiveness, reusability, magnetic recovery, magnetic recovery, and surface functionalization which are desirable in the design of recyclable adsorbent for industrial wastewater treatment. Therefore, by incorporating magnetic biochar in water treatment systems, it may be possible to effectively remove nano-sized particles derived from CBs, along with other pollutants and contaminants, from water. For example, metal ions can be adsorbed via ligand exchange and complexation, while nicotine and PAHs are primarily via π-π interaction, hydrogen bonding, and electrostatic interactions. Therefore, the present study will assess the potential capacity of magnetic biochar to adsorb these particles, considering its impact on water remediation, soil health, and crop growth, and evaluate the overall cost-effectiveness and practicality of its implementation.

Electroreductive Synthesis of Nickel(0) Complexes.

Over the last fifty years, the use of nickel catalysts for facilitating organic transformations has skyrocketed. Nickel(0) sources act as useful precatalysts because they can enter a catalytic cycle through ligand exchange, without needing to undergo additional elementary steps. However, most Ni(0) precatalysts are synthesized with stoichiometric aluminum-hydride reductants, pyrophoric reagents that are not atom-economical and must be used at cryogenic temperatures. Here, we demonstrate that Ni(II) salts can be reduced on preparative scale using electrolysis to yield a variety of Ni(0) and Ni(II) complexes that are widely used as precatalysts in organic synthesis, including bis(1,5-cyclooctadiene)nickel(0) [Ni(COD)2 ]. This method overcomes the reproducibility issues of previously reported methods by standardizing the procedure, such that it can be performed anywhere in a robust manner. It can be transitioned to large scale through an electrochemical recirculating flow process and extended to an in situ reduction protocol to generate catalytic amounts of Ni(0) for organic transformations. We anticipate that this work will accelerate adoption of preparative electrochemistry for the synthesis of low-valent organometallic complexes in academia and industry.