European Journal of Inorganic Chemistry最新文献

A crystalline dihydroxy substituted Schiff base ligand [LH] was involved in the synthesis of three copper(II) complexes viz [Cu(LH)₂] (Cu1), [Cu(LH)(bpy)] (Cu2) and [Cu(LH)(phen)] (Cu3) (bpy=2,2’-bipyridine and phen=1,10-phenanthroline). FTIR, ESI-MS, elemental analysis, ESR studies and NMR techniques were employed to characterize all the newly synthesized compounds. Monoclinic structure with space group P2₁/n of ligand (LH) was confirmed by single crystal XRD analysis. The molecular structure of ligand and complexes were optimized using density functional theory (DFT) at B3LYP/LanL2DZ levels in the gas phase. According to DFT investigations Cu1 exhibits tetragonally distorted octahedral geometry around Cu(II) while Cu2 and Cu3 appeared in penta-coordination as distorted trigonal bipyramidal geometry. UV-Vis, fluorescence and viscosity titrations were used to examine the metal complex interactions with CT-DNA and BSA protein. The binding results suggest that the complexes bind to DNA via groove binding mode. Molecular docking was performed to analyse the binding interaction of complexes with BSA and DNA. Antioxidant investigation indicates that the Cu1 possesses remarkable ability to scavenge radicals against DPPH due to the lowest IC₅₀ value 211.20 μg/mL. In-vitro cytotoxicity was assessed against MCF-7 breast cancer cells where Cu1 was found to have superiority in cytotoxicity with IC₅₀ value 52.35 μm over other analogues. Acridine orange/ethidium bromide staining analysis of Cu1 were used to determine apoptosis as the cause of cell death.

The combination of spin crossover (SCO) with chirality has caught increasing research interest owing to its potential applications in the fields of multifunctional magnetic molecular materials and devices. In this work, we synthesized a pair of homochiral Co(II) SCO complexes and their racemic complex by applying chiral Schiff base terimine ligands modified by naphthyl group. Single-crystal X-ray diffraction results showed that the chiral ligands retained chirality after coordination with Co(II) ion, giving rise to a pair of enantiomeric Co(II) complexes in the RR and SS configurations, respectively. The circular dichroism spectroscopy demonstrated the enantiomeric nature of the homochiral complexes. The enantiomers exhibited similar thermally induced SCO, while the racemate was trapped in the high spin state. The differences in SCO behavior between the homochiral and racemic complexes are attributed to different supramolecular interactions. This work provides a feasible approach to constructing new chiral SCO materials and offers perspectives in developing switchable nonlinear optical magnetic materials.

Thermally stable trans-bis(chelate)-type Ru(II) complexes are challenging to prepare owing to steric hindrance between the two chelate ligands. Herein, we investigated the isomerization of a heteroleptic cis-bis(chelate) complex to obtain its trans form. cis-[Ru(acac)(bpy)(dmso-S)₂](OTf)⋅0.5H₂O (1⋅(OTf)⋅0.5H₂O; acac⁻=acetylacetonato; bpy=2,2’-bipyridine; dmso=dimethyl sulfoxide; OTf⁻=CF₃SO₃⁻) was prepared by reacting trans(O,S)-[Ru(bpy)(dmso-S)₂(dmso-O)₂](OTf)₂ (P0) with Li(acac) in acetone at 298 K. In 1⋅(OTf)⋅0.5H₂O, the two labile dmso-O ligands of P0 were replaced by an acac⁻ ligand. The dihedral angle between the chelate rings of bpy and acac⁻ in 1⁺ was 76.7°, suggesting steric hindrance between ligands owing to the two bulky dmso-S ligands at the cis position. 1⋅(OTf)⋅0.5H₂O was thermally stable in DMSO and acetone; however, in methanol and water, a dmso-S ligand was dissociated from 1⁺, and the complex isomerized to trans-[Ru(acac)(bpy)(dmso-S)(solvent)]⁺. Refluxing of 1⋅(OTf)⋅0.5H₂O in methanol for 18 h, evaporation to dryness under vacuum, and treatment with water yielded trans-[Ru(acac)(bpy)(dmso-S)(OH₂)](OTf) (2⋅(OTf)) with excellent purity. 2⋅(OTf) was characterized by X-ray crystallography, elemental analysis, and ¹H NMR spectroscopy. As expected, steric hindrance was not observed between the trans-arranged bpy and acac⁻, and the two chelates laid flat on the equatorial plane in 2⁺.

Posttranslational modifications (PTMs) and metal ions are integral players in the complex regulatory orchestra governing protein function. Several metal ions, including zinc, iron, copper, and others, intricately influence protein structure and activity as cofactors. Concurrently, PTMs, such as phosphorylation, acetylation, and ubiquitination, add an additional layer of complexity to the proteome, dynamically shaping cellular responses. Understanding this bidirectional relationship is crucial for unraveling the complex web of cellular regulation. This review explores the reciprocal impact of metal ions on PTMs and vice versa and provides examples and insights into how metal ions modulate PTMs and, conversely, how PTMs influence metal-binding proteins, shedding light on the complex crosstalk between these two crucial facets of cellular biology. This interplay is not only central to cellular homeostasis but also holds implications for diseases associated with dysregulated metal-ion and PTM processes.

The complexes [RuCl(Cy)(NH₂Ph)₂]Cl (1), [RuCl₂(Cy)(NH₂Bz)] (2), and [RuCl₂(Cy)(NHBz₂)] (3) were synthesized under identical conditions from [RuCl₂(Cy)]₂, where Cy=η⁶-p-cymene, Ph=phenyl, and Bz=benzyl. X-ray crystallography revealed an additional NH₂Ph ligand in 1, distinguishing it from the neutral mono-amine complexes 2 and 3. The number of amines in these complexes did not correlate clearly with the σ-donor character or steric hindrance of the amines. Different reactivities were observed for the ROMP of norbornene (NBE), as measured by batch reactions and kinetic studies using Raman and ¹H NMR spectroscopy. Semiquantitative conversions reached up to 90 % with complex 1 and around 40 % with complexes 2 and 3. DFT calculations supported the hypothesis that the reaction for complex 1 involves the release of an amine through a dissociative mechanism, whereas complexes 2 and 3 react through an associative mechanism involving amine loss. The presence of an amine in the propagation species of complex 1 suggests the participation of the amine as an ancillary ligand. All carbene species are of the η²-p-cymene type, and the catalytic cycle follows a 14–16-14 electron counting mechanism.

N-Heterocyclic carbenes (NHCs) play an important role in metal complex catalysis and stabilisation, providing stability under non-inert conditions and a high σ-donor capacity. They are crucial ligands for the synthesis of organometallic compounds like Ru^II-complexes, which can operate as very active catalysts for a variety of chemical transformations and functionalizations. RA(Ruthenium-arene)NHC complexes, known for their piano-stool structure, stabilise Ru(II) oxidation state by occupying three ruthenium coordination sites with a η⁶-coordinated arene ligand. The development of dual-acting Ru^II-arene complexes has sparked increased interest in their catalytic and biological properties. Because of their broad spectrum, metal complexes can give distinct mechanisms of pharmacological action from organic drugs. This study aimed to explore the impact of ligand amphiphilicity and counterion on bioactivity, designing a family of compounds with the NHC ligand bearing an ester moiety and switching the wingtip substituent from methyl to benzyl units. All synthesized compounds were tested in norbornene ROMP, a benchmark reaction for Ru^II potential catalysts and as anticancer and antioxidant compounds.

Bis(macrocyclic) complexes are investigated as artificial analogues of natural dinuclear metalloenzymes. Two ligands containing two cyclam rings connected through a p-cresol or 4-nitrophenol spacer were synthesized and their complexing properties were investigated. Cu^II complexes were prepared and their properties were studied by a combination of spectral, diffraction and electrochemical methods. The phenolate group is not or only weakly coordinated to the central Cu^II ion and the two macrocycles behave mostly as two independent complexing units. All the determined solid-state structures showed cyclam adopting trans-III geometry, however, solution study indicated the presence of more isomers in the solution whose abundance changes with pH. Electrochemical reduction of the complexes is irreversible and results in the reductive decomplexation to amalgamated Cu metal. The amalgamated metal is re-oxidized to Cu^II during the anodic scan of CV and the metal ion is re-coordinated. The ligand containing the nitro group shows an irreversible four-electron reduction of the nitro group. The ligands and the complexes undergo also a slow degradation when incubated in the aqueous solutions for a prolonged time. The degradation relies on the “retro-Mannich” cleavage of the methylene bridge connecting the cyclam ring with the phenol moiety.

Reactions of trans-(C₆F₅)(p-tol₃P)₂Pt(C≡C)_nSiEt₃ (PtC_2nSi; n=5, 7, 9) and excess PtCl in the presence of wet n-Bu₄N⁺ F⁻ (to effect protodesilylation) under Sonogashira-type conditions (CuCl, base, other additives) afford the title compounds PtC₁₀Pt, PtC₁₄Pt, and PtC₁₈Pt in 42–32 % yields. A four-fold substitution of the phosphine ligands in PtC₁₀Pt by PEt₃ affords Pt'C₁₀Pt’ (78 %), and a Sonogashira reaction of Pt'C₂H and Pt'Cl affords Pt'C₂Pt’ (68 %). The analogous reaction with PtC₂Si and PtCl is unsuccessful, presumably for steric reasons. The crystal structures of PtC₁₀Pt, PtC₁₄Pt, Pt'C₁₀Pt′, and Pt'C₂Pt’ exhibit a number of interesting trends and features. Certain sp chain extension reactions that lead to or employ the precursors PtC₁₀Si, PtC₁₂Si, PtC₁₄Si, and PtC₁₈Si sometimes give byproducts derived from C₂ loss, and possible origins are discussed. Related phenomena have been reported by others in the course of synthesizing extended conjugated polyynes.

To better understand the stability of isolable primary phosphine oxides, new members of this family were synthesized through the oxidation of the corresponding phosphines. Specifically, the previously reported air-stable primary phosphines (R)-2-phosphanyl-2’-methoxy-1,1’-binaphthyl, 9,10-dihydro-9,10-etheno-anthracen-9-yl phosphine, and 3-phosphino-2-naphthol were treated with hydrogen peroxide or meta-chloroperoxybenzoic acid to yield the new primary phosphine oxides. The compounds were characterized using NMR, MS, EA, and X-ray crystallography. The oxides were further investigated in thermal disproportionation, and studied as ligands in half-sandwich Ru(II) complexes bearing an auxiliary η⁶-p-cymene ligand.

Self-assembled reactions of 2,6-dipicolinoylbis(N,N-diethylthiourea) (H₂L) with Mn(CH₃COO)₂ ⋅ 4H₂O and LnCl₃, where Ln = La, Nd, Sm, Gd, Dy, Er in MeOH lead to formation of stable trinuclear complexes of the composition [LnMn₂(L)₂(μ_1,3-CH₃COO)₂X] (Mn^IILn^IIIMn^II), where X⁻ can be κ²-CH₃COO⁻ or κ¹-CH₃COO⁻. Single crystal X-ray studies reveal their symmetric structures comprising one central Ln(III) ion, two terminal Mn(II) ions sandwiched by two doubly deprotonated ligands {L²⁻}. The magnetic properties of Mn^IILa^IIIMn^II and Mn^IIGd^IIIMn^II complexes are successfully simulated using symmetrical magnetic interaction models, giving the best fitted parameters: J_Mn-Mn=−0.120(1) cm⁻¹, g_Mn=1.99(1), TIP=4.45(7) ⋅ 10⁻⁴ cm³ mol⁻¹ K for Mn^IILa^IIIMn^II and J_Gd-Mn=0.042(1) cm⁻¹, J_Mn-Mn=−0.076(1) cm⁻¹, g_Mn=1.96(1), g_Gd=2.01(1) and TIP=3.59(14) ⋅ 10⁻⁴ cm³ mol⁻¹ K for Mn^IIGd^IIIMn^II complex. The magnetic interactions between the Mn(II) and Ln(III) ions in the other Mn^IILn^IIIMn^II complexes are studied by comparing their χ_M values to the sum of χ_M values of the Mn^IILa^IIIMn^II and the analogous Zn^IILn^IIIZn^II complexes. The Mn^IIEr^IIIMn^II complex reveals a strong ferromagnetic interaction, while the Sm, Nd, Gd and Dy complexes show weak ferromagnetic interactions.