Organometallic Research Articles

Patterns of electrical properties change of heavy metal-organic compound contaminated media in soil-groundwater systems: From laboratory experiments to site application

Differences in electrical properties of media are the basis for determining the type and extent of contamination using geophysical methods. However, differences in heavy metals and organic matter complicate the electrical properties of compound-contaminated media, and existing geophysical methods cannot independently identify compound contamination. Therefore, this study proposes a geophysical detection system that combines electrical resistance tomography (ERT) and induced polarization methods and establishes a solid theory as the basis for the system application through laboratory experiments, model analysis, and site applications. The study reveals that as the organics volume proportion increases, the resistivity and normalized chargeability of contaminated media increased slowly, followed by a rapid increase, and finally reached a stable state. The specific type of compound significantly influences the electrical properties, while the resistivity of different kinds of compound-contaminated media reaches the same maximum value as the organics volume proportion increases. The medium type determines the contaminated media's lower resistivity limit and upper normalized chargeability limit. Additionally, the interplay between heavy metal type, content, and medium complicates the electrical properties of the media, with the compound type exerting a significant impact on resistivity. Archie's law and random forest modeling reveal that the inflection point for resistivity change occurs at 40 % and 80 % organics volume proportions, while the inflection point for normalized chargeability change occurs at 30 % and 70 % organics volume proportions in compound-contaminated media. These inflection points depend on the types of compounds, compositions, proportions, and media, and their importance for the electrical properties of the media changes with the increasing organics volume proportion. Based on the changing patterns of resistivity and normalized chargeability in heavy metal-organic compound contaminated media, the modified geophysical detection system can effectively identify the pollution type and intensity, which provides accurate pollution information to develop effective treatment strategies.

4‐Methyltetrahydropyran: A Versatile Alternative Solvent for the Preparation of Chiral BINOL Catalysts and the Asymmetric Alkylation of Aldehydes

AbstractWe herein report that the highly hydrophobic ether 4‐MeTHP constitutes a promising resource for the development of sustainable synthetic methodologies grounded on the use of organometallic reagents. The beneficial effects of 4‐MeTHP as reaction medium are illustrated in the organolithium‐promoted anionic ortho‐Fries rearrangement of 1,1’‐bi‐2‐naphthol (BINOL)‐based carbamates under bench‐type conditions. The use of 4‐MeTHP induces a remarkable and unexpected stability of the organolithiums species, enabling the efficient preparation of chiral (bis)carboxamide catalysts. Furthermore, superior performances of 4‐MeTHP than other environmentally responsible solvents are observed using the synthesized BINOL catalysts in the asymmetric addition of organozinc reagents to aldehydes. Spectroscopic studies in solution suggest that 4‐MeTHP plays a key role in these reactions by inducing the preferential formation of a reactive monomeric dinuclear complex. This methodology allows for the asymmetric assembly of enantioenriched secondary alcohols in good yields and high stereoselectivity, working at 0 °C and under air.

Simple thiazole-based ligands for palladium(II) Suzuki-Miyaura aryl cross-coupling catalysts

Two new palladium(II) catalysts, each containing a phenylthiazole ligand (2-methyl- (1a) and 2-amino-4-phenyl-1,3-thiazole (1b)) are prepared and characterized. The crystal structure of one, 2-methyl-4-phenyl)palladium(II) acetate (3a), is presented; it crystallizes as a dimer, with the ligand attached through the nitrogen on the thiazole and the ortho-carbon on the phenyl ring. The organometallic compounds can be used as catalysts in Suzuki-Miyaura aryl cross-coupling reactions. They are compatible with a wide range of functional groups, including carbonyls, amines, and phenols.

Synthesis, Characterization, and Cytotoxicity Evaluation of Novel Water-Soluble Cationic Platinum(II) Organometallic Complexes with Phenanthroline and Imidazolic Ligands.

Platinum-based chemotherapeutic agents are widely used in the treatment of cancer. However, their effectiveness is limited by severe adverse reactions, drug resistance, and poor water solubility. This study focuses on the synthesis and characterization of new water-soluble cationic monofunctional platinum(II) complexes starting from the [PtCl(η1-C2H4OEt)(phen)] (1, phen=1,10-phenanthroline) precursor, specifically [Pt(NH3)(η1-C2H4OEt)(phen)]Cl (2), [Pt(1-hexyl-1H-imidazole)(η1-C2H4OEt)(phen)]Cl (3), and [Pt(1-hexyl-1H-benzo[d]imidazole)(η1-C2H4OEt)(phen)]Cl (4), which deviate from traditional requirements for antitumor activity. These complexes were evaluated for their cytotoxic effects in comparison to cisplatin, using immortalized cervical adenocarcinoma cells (HeLa), human renal carcinoma cells (Caki-1), and normal human renal cells (HK-2). While complex 2 showed minimal effects on the cell lines, complexes 3 and 4 demonstrated higher cytotoxicity than cisplatin. Notably, complex 4 displayed the highest cytotoxicity in both cancer and normal cell lines. However, complex 3 exhibited the highest selectivity for renal tumor cells (Caki-1) among the tested complexes, compared to healthy cells (HK-2). This resulted in a significantly higher selectivity than that of cisplatin and complex 4. Therefore, complex 3 shows potential as a leading candidate for the development of a new generation of platinum-based anticancer drugs, utilizing biocompatible imidazole ligands while demonstrating promising anticancer properties.

Biochar derived from animal and plant facilitates synergistic transformation of heavy metals and phosphorus in sewage sludge composting

This study investigated the influence of plant-derived biochar (PB) and animal-derived biochar (AB) on behavior of heavy metals and phosphorus fractions during sewage sludge composting. PB was highly effective in reducing the bioavailability of Zn and Cu by 39% and 50%, respectively, while AB decreased the bioavailability of Pb (30%) and Cd (12%). Both biochar increased available phosphorus by over 38%. Acid extractable and bioavailable Pb in AB, and water-soluble, oxidizable and total Zn, acid extractable and oxidizable Cu in PB were positively correlated with moderately resistant organic phosphorus (MROP). Besides, in AB, Cd had strong and positive correlation with highly resistant organic phosphorus (HROP). This suggested biochar facilitated the formation of stable organometallic complexes through binding metal ions to phosphorus fractions, with notable differences based on biochar source. FT-IR showed biochar promoted humification, with PB enhancing carboxyl and polysaccharide formation, while AB encouraged quinone and aryl ether structures. These surface functional groups on the biochar likely contributed to heavy metals and phosphorus binding through chelation, adsorption, and electron shuttling.

Deciphering the frontier: Structural, bonding, and electronic insights into of M5C6 (M = Cu, Ag, and Au) metal-carbide clusters with theoretical calculations

This study investigates the structural, bonding, and electronic properties of M5C6 clusters (M = Cu, Ag, Au) and their anions, revealing their potential in organometallic chemistry. Using DFT calculations, it provides insights into the stability and bonding of these clusters, particularly highlighting the exceptional properties of Au5C6−. The anions are identified as superhalogens, with significant C − C π bonding and a VDE of 4.04 eV for Au5C6−, indicating its usefulness in chemical reactions. ELF and AdNDP analyses further elucidate the covalent bonding and σ-aromaticity within Au5C6−.

Nitrogen Fixation by Manganese Complexes - Waiting for the Rush?

Manganese is currently experiencing a great deal of attention in homogeneous catalysis as a sustainable alternative to platinum group metals due to its abundance, affordable price and low toxicity. While homogeneous nitrogen fixation employing well-defined transition metal complexes has been an important part of coordination chemistry, manganese derivatives have been only sporadically used in this research area. In this contribution, the authors systematically cover manganese organometallic chemistry related to N2 activation spanning almost 60 years, identify apparent pitfalls and outline encouraging perspectives for its future development.

Mitochondrion-specific organometallic sonosensitizer boosts synergistic sonodynamic therapy for augmented ferroptosis to trigger systemic immunity

Drug design and mechanisms are essential for advancing our understanding of sonosensitizer development, the biological processes underlying anti-tumor responses, and guiding optimal treatment strategies. This article highlighted a remarkably efficient organometallic compound (IRCur-Pt), which has shown remarkable efficiency in reducing toxicity and increasing sono-sensitivity. Our research offers a theoretical framework to explain the superior performance of IRCur-Pt, highlighting its precise targeting of mitochondria and its ability to generate a substantial amount of 1O2 upon ultrasound stimulation, directly killing cancer cells. Notably, IRCur-Pt disrupted mitochondrial structure, resulting reduced ATP capacity, interference with NADPH, depletion of GSH, inhibition of GPX4 activity, accumulation of lipid peroxidation, and subsequent occurrence of ferroptosis. Furthermore, proteomic analysis strongly supported IRCur-Pt’s anti-tumor mechanisms in vivo, confirming the activation of reactive oxygen species (ROS) ferroptosis signaling pathways, along with T cell receptor signaling pathways. Consistent anti-tumor effects were observed in animal models. In systemic immune assessments, IRCur-Pt+US effectively activated adaptive T cells while suppressing the proliferation of Treg cells, highlighting its substantial therapeutic potential. Through a multifaceted approach, IRCur-Pt demonstrated outstanding anti-tumor performance under US irradiation. This study comprehensively introduced novel perspectives for drug design, inducing cancer cell apoptosis, amplifying ferroptosis, triggering systemic immunity, and providing an innovative avenue for cancer treatment.

De Novo Synthesis of 2,2'-Bipyridines and Related Bis-azines via Cascade Coupling and Double Pyridannulation of Isocyanides.

Herein, we present a new and general protocol for the assembly of 2,2'-bipyridyls from nonpyridine substrates without using any metal catalysts or organometallic reagents. The process starts from the coupling of two 1,3-dienyl isocyanides followed by a 6π-electrocyclization/aromatization cascade featuring the simultaneous formation of two pyridine rings in a single operation. Notably, this strategy is also applicable to the construction of nonsymmetrical 2-(2-pyridyl)-quinolines/-quinoxalines. Furthermore, the aggregation-induced emission (AIE) characteristics endow our approach with great potential in biorelevant fields.

Coumarin-modified ruthenium complexes: Synthesis, characterization, and antiproliferative activity against human cancer cells.

Among ruthenium complexes studied as anticancer metallodrugs, NKP-1339, NAMI-A, RM175, and RAPTA-C have already entered clinical trials due to their potent antitumor activity demonstrated in preclinical studies and reduced toxicity in comparison with platinum drugs. Considering the advantages of ruthenium-based anticancer drugs and the cytostatic activity of organometallic complexes with triazole- and coumarin-derived ligands, we set out to synthesize Ru(II) complexes of coumarin-1,2,3,-triazole hybrids (L) with the general formula [Ru(L)(p-cymene)(Cl)]ClO4. The molecular structure of the complex [Ru(2a)(p-cymene)(Cl)]ClO4 (2aRu) was determined by single-crystal X-ray diffraction, which confirmed the coordination of the ligand to the central ruthenium(II) cation by bidentate mode of coordination. Coordination with Ru(II) resulted in the enhancement of cytostatic activity in HepG2 hepatocellular carcinoma cells and PANC-1 pancreatic cancer cells. Coumarin derivative 2a positively regulated the expression and activity of c-Myc and NPM1 in RKO colon carcinoma cells, while the Ru(II) half-sandwich complex 2cRu induced downregulation of AKT and ERK signaling in PANC-1 cells concomitant with reduced intracellular levels of reactive oxygen species. Altogether, our findings indicated that coumarin-modified half-sandwich Ru(II) complexes held potential as anticancer agents against gastrointestinal malignancies.

Synthesis, characterization and biological applications of substituted indolo[2,1-b]quinazolin-12(6H)-one based rhenium(I) organometallic compounds.

The Re(I) organometallic compounds [(Re(CO)3L1-6 )Cl], where Ligand(L) = Tryptanthrin derivatives were prepared and characterized by various spectroscopic techniques. To assess the binding capacities and binding manner, tests of Calf thymus DNA under the impact of organometallic complexes were conducted using absorption titration and viscosity measuring techniques. Data from the research mentioned above point to an intercalation type of binding, which was verified by the docking study. Swiss ADME tools carried out an ADME study. The work focuses on computing the molecular orbital energies for the synthesized compounds using the density functional theory (DFT). The compounds were tested against the MCF-7 cell line to determine their anticancer effects. It was observed that their IC50 values were equivalent to those of the standard medication, indicating that they had a similar antiproliferative impact.

Metal‐Mediated Synthesis of a Mixed Arduengo‐Fischer Carbodicarbene Ligand

Carbodicarbenes are strong C‐donor ligands, which have found numerous applications in organometallic and main group element chemistry. Herein, we report a structurally distinct carbodicarbene ligand, which is formed by dinitrogenative coupling of a Fischer carbene complex with an N‐heterocyclic diazoolefin. The resulting carbonyl complex serves as a stable source for the mixed Arduengo‐Fischer carbodicarbene ligand. Facile ligand transfer reactions were demonstrated to occur with gold(I), copper(I), palladium(II), and rhodium(I) complexes.

Metal-Mediated Synthesis of a Mixed Arduengo-Fischer Carbodicarbene Ligand.

Carbodicarbenes are strong C-donor ligands, which have found numerous applications in organometallic and main group element chemistry. Herein, we report a structurally distinct carbodicarbene ligand, which is formed by dinitrogenative coupling of a Fischer carbene complex with an N-heterocyclic diazoolefin. The resulting carbonyl complex serves as a stable source for the mixed Arduengo-Fischer carbodicarbene ligand. Facile ligand transfer reactions were demonstrated to occur with gold(I), copper(I), palladium(II), and rhodium(I) complexes.

Computed versus experimental energy barriers in solution: Influence of the type of the density functional approximation.

Mechanistic investigations at the density functional theory level of organic and organometallic reactions in solution are now broadly accessible and routinely implemented to complement experimental investigations. The selection of an appropriate functional among the plethora of developed ones is the first challenge on the way to reliable energy barrier calculations. To provide guidelines for the choice of an initial and reliable computational level, the performances of commonly used non-empirical (PBE, PBE0, PBE0-DH) and empirical density functionals (BLYP, B3LYP, B2PLYP) were evaluated relative to experimental activation enthalpies. Most reactivity databases to assess density functional performances are primarily based on high level calculations, here a set of experimental activation enthalpies of organic and organometallic reactions performed in solution were selected from the literature. As a general trend, the non-empirical functionals outperform the empirical ones. The most accurate energy barriers are obtained with hybrid PBE0 and double-hybrid PBE0-DH density functionals, both providing similar performance. Regardless of the functional under consideration, the addition of the GD3-BJ empirical dispersion correction does not enhance the accuracy of computed energy barriers.

Trajectory-Based Time-Resolved Mechanism for Benzene Reductive Elimination from Cyclopentadienyl Mo/W Phenyl Hydride Complexes.

Calculated potential energy structures and landscapes are very often used to define the sequence of reaction steps in an organometallic reaction mechanism and interpret kinetic isotope effect (KIE) measurements. Underlying most of this structure-to-mechanism translation is the use of statistical rate theories without consideration of atomic/molecular motion. Here we report direct dynamics simulations for an organometallic benzene reductive elimination reaction, where nonstatistical intermediates and dynamic-controlled pathways were identified. Specifically, we report single spin state as well as mixed spin state quasiclassical direct dynamics trajectories in the gas phase and explicit solvent for benzene reductive elimination from Mo and W bridged cyclopentadienyl phenyl hydride complexes ([Me2Si(C5Me4)2]M(H)(Ph), M = Mo and W). Different from the energy landscape mechanistic sequence, the dynamics trajectories revealed that after the benzene C-H bond forming transition state (often called reductive coupling), σ-coordination and π-coordination intermediates are either skipped or circumvented and that there is a direct pathway to forming a spin flipped solvent caged intermediate, which occurs in just a few hundred femtoseconds. Classical molecular dynamics simulations were then used to estimate the lifetime of the caged intermediate, which is between 200 and 400 picoseconds. This indicates that when the η2-π-coordination intermediate is formed, it occurs only after the first formation of the solvent-caged intermediate. This dynamic mechanism intriguingly suggests the possibility that the solvent-caged intermediate rather than a coordination intermediate is responsible (or partially responsible) for the inverse KIE value experimentally measured for W. Additionally, this dynamic mechanism prompted us to calculate the kH/kD KIE value for the C-H bonding forming transition states of Mo and W. Surprisingly, Mo gave a normal value, while W gave an inverse value, albeit small, due to a much later transition state position.

Explore the feasibility of electrospray ionization high-resolution mass spectrometry in elemental analysis

As a representative soft ionization technique, electrospray ionization (ESI) is commonly applied for the analysis of organic and biological compounds and is less used in inorganic applications. This study introduces the performance of ESI high-resolution mass spectrometry (HRMS) in the detection of elements. The HRMS instrument was equipped with a sub-atmospheric pressure (SAP) ESI source to reduce sample consumption and simplify the sampling operations. In addition, in-source collision-induced dissociation (IS-CID) was introduced into the analysis to generate simple metallic ion species such as atomic ions and charged oxides and reduce organic peak interferences. Various solutions containing metal salts and organometallic compounds were analyzed, demonstrating a picogram-level absolute detection limit and accurate multi-element identification capability of the instrument. Furthermore, SAP-ESI-HRMS exhibits diverse analytical performances, enabling both elemental and organic analyses by simply regulating the IS-CID energy in the measurement.

A light-detecting Ru(II)/Si heterojunction system involving a binuclear Ru (II) complex with pyridine-2,6-diimine (pydim) ligand

A meticulously detailed chemical procedure was employed to synthesize the Ru (II)-containing pyridine-2,6-diimine (pydim) organometallic complex. The resulting complex was then applied to Al-coated Si wafers using the spin-coating technique, leading to the production of Al/Ru(II) organometallic complex/n-Si/Al photodiodes. The light responsiveness of these photodiodes was demonstrated through the acquisition of I-V and I-t characteristics. Subsequently, essential parameters such as ideality factor, photosensitivity, barrier height, and photoresponse values were evaluated based on the obtained I-V and I-t plots. The calculations yielded ideality factors and barrier heights, resulting in average values of 6.41 and 0.552 eV, respectively. Furthermore, an in-depth analysis of the electrical properties of the diodes was conducted using G-V and C-V assessments, revealing a strong dependence on AC signal frequency. This investigation underscored that the observed frequency-related electrical behaviour is rooted in series resistance and interface states.

Competitive adsorption of quinary heavy metal ions onto chestnut shell activated carbon

For several decades, heavy metals have been a source of environmental pollution and the scientific community is continually asked for facing this threat. This study investigated the performance of an activated carbon made from chestnut shell (CNS-AC) in adsorbing Cd(II), Cr(VI), Ni(II), Cu(II), and Zn(II) in single and quinary-metal systems. The CNS-AC was characterized using FT-IR, TGA/DTG, FEG-SEM, EDX, and BET. Experimental results revealed that the adsorption follows the pseudo-second order kinetics, both in single and quinary systems. The equilibrium results reflect the Langmuir equilibrium model, with maximum adsorption capacities (mg.g−1) varying from 21.34 for Cd(II) to 73.16 for Zn(II); in single-metal systems, and from 9.80 for Cd(II) to 33.33 for Cu(II); in the quinary-metal systems. The overall maximum adsorption capacity in quinary-metal solution was of 113.22 mg g−1, higher than qm for each single-metal system. Furthermore, it was found that Cd(II) and Zn(II) pollution abatement to the standard limits was achieved in only one stage while two stages were enough to achieve the related pollution abatement for the other metals. A computational investigation was conducted using the Gaussian 09 and Density Functional Theory (DFT) methods, assuming the generation of organometallic complexes between the functionalized activated carbon and the metal ions. CNS-AC's carboxyl and amine functional groups seemed to be involved in the metal ions adsorption. The calculated bonding energies between the adsorbent and metal ions decreased in the following order Cu(II) < Cr(VI) < Ni(II) < Zn(II) < Cd(II). Correspondingly, experimental results revealed an actual competition between heavy metals for adsorption sites where Zn(II), Ni(II), and Cd(II) removal was hindered by the other metal ions occurrence while Cr(VI) and Cu(II) removal rates have remained broadly unchanged. The new insights brought by the theoretical study combined to the experimental investigation highlights the CNS-AC efficacy as adsorbent for Cd(II), Cr(VI), Ni(II), Cu(II), and Zn(II) removal.

Influence of Co(II) and Cd(II) metal ions on structural, electronic and nonlinear optical properties of 4-methoxypyridine-2-carboxylic acid complexes: An experimental and computational study

Molecular engineering of metal-organic frameworks has attracted increasing attention due to their potential technological applications in the fields of optics and photonics. Therefore, a number of organometallic complexes are investigated for nonlinear optical applications. The current research aimed to synthesize and investigate spectroscopic and nonlinear optical properties of two metal-organic coordination compounds, namely Co(MeOPic)2∙(H2O)2 and Cd(MeOPic)2∙(H2O)2. The FT-IR and UV-Vis spectra for the distorted octahedral Co(II) and Cd(II) complexes were recorded. In order to provide a deep understanding about the relation between structure and nonlinear optical properties, density functional theory studies were also applied to both of the complexes by using B3LYP/6–311++G(d,p)/LanL2DZ level. TG-DTA analysis demonstrated that Cd(II) complex is approximately stable up to 134 °C, and the same complex only loss the aqua ligands between 134 and 189 °C. Therefore, the main skeleton part continues to remain stable up to 208 °C. Static NLO studies also demonstrated that both complexes have weak responses due to centrosymmetric structures, while Co(II) complex is appropriate to third-order NLO applications (γ (0;0,0,0) = 148.70×10−36 esu and γ (-2w;w,w,0)=-1521.4×10−36 esu).

2-Aryl-1H-imidazo[4,5-f][1,10]phenanthroline-Based Binuclear Ru(II)/Ir(III)/Re(I) Complexes as Mitochondria Targeting Cancer Stem Cell Therapeutic Agents.

A series of novel Ru(II)/Ir(III)/Re(I)-based organometallic complexes [Ru2L1, Ru2L2, Ir2L1, Ir2L2, Re2L1, and Re2L2] have been synthesized to assess their potency and selectivity against multiple cancer cells A549, HCT-116, and HCT-116 colon CSCs. The cytotoxic screening of the synthesized complexes has revealed that complex Ru2L1 and Ir2L2 are two proficient complexes among all, but Ru2L1 is the most potent complex. A significant binding constant value was observed for DNA and BSA in all complexes. Significant lipophilic properties allow them to penetrate cancer cell membranes, and substantial quantum yield (ϕf) values support bioimaging potential. Again, these complexes are particular for mitochondrial localization and produce a profuse amount of ROS to damage the mitochondrial DNA and then G1 phase cell-cycle arrest. Protein expression analysis unveiled that pro-apoptotic Bax protein overexpressed in Ru2L1-treated cells, whereas antiapoptotic Bcl-2 protein was expressed twofold in Ir2L2-treated cells, which correlated with autophagy reticence.