European Journal of Inorganic Chemistry最新文献

Metal ions play a key role in regulating antimicrobial peptides (AMPs), either inducing or enhancing their effects against pathogens. In human saliva, AMPs, including fragments of the glycoprotein MUC7, form a natural defense against oral and systemic infections. This study investigates a 20-residue MUC7-derived peptide containing three histidine residues as potential coordination sites for divalent metal ions. Complexes are analyzed using electrospray ionization mass spectrometry, potentiometry, and spectroscopic methods: ultraviolet–visible spectroscopy, circular dichroism, and electron paramagnetic resonance, together with antimicrobial assays. Cu(II) coordination did not significantly alter secondary structure or improve antimicrobial properties. In contrast, Zn(II) induced conformational changes under alkaline conditions, correlating with slightly enhanced antimicrobial performance. Proline, tyrosine, and phenylalanine residues likely modulate metal coordination through steric hindrance and conformational effects. These findings highlight the role of metal coordination in modulating AMP function. Although this particular MUC7-derived fragment exhibits only modest antimicrobial activity compared to other known fragments of this protein, its distinct metal-binding behavior suggests that it may serve an alternative biological role in the oral environment beyond direct pathogen inhibition.

A nonequilibrium atomic-scale simulation for time-evolutional spin dynamics on molecular magnets is important to develop quantum electronic devices based on spin clusters and single molecule magnets. Spin dynamic calculations of individual spins in a radical-bridged trinuclear Ni(II) complex are presented using the stochastic Landau–Lifshitz–Gilbert model. The model involving superexchange interactions (J_ij) of spins between Ni (S = 1) cations (Ni1, Ni2, Ni3) and a hexahydroxytriphenylene (HHTP) radical (S = 1/2), and single-ion magnetic anisotropy (D_i) of Ni. The time-evolution simulation reveals that the spin directions show a damping oscillation within ≈10 ps. At equilibrium, the spins are almost in the aromatic HHTP radical plane (xy-plane). The angles of the spins on Ni1, Ni2, Ni3, and the radical relative to the x-axis are 23.6°, 86.0°, 30.1°, and 31.4°, respectively, mainly due to the negative D_Ni1 value. The oscillation frequencies of 120 GHz and 210 GHz correspond to the zero-field magnetic resonance. Temperature-evolution simulations reveal that the directions of the spins gradually fluctuate with increasing temperature, and finally, the spins are almost randomly oriented above 5 K, reflecting the energy barrier of the total magnetic anisotropy. Such nonequilibrium atomic-scale simulations of time- and temperature-evolution dynamics would be useful for predicting the qubit or coherence state of single molecule magnets.

The reduction of transition metal oxides with hydrogen is currently used in the production of various transition metals, e.g., molybdenum, tungsten, rhenium, and may potentially be applied to others, especially iron, in the future. The gas–solid reduction process is well suited for investigations using in situ X-ray powder diffraction. This method allows for the study of influences such as temperature, heating rate, reaction time, impurities, or water partial pressure on crystal structures, reaction pathways, intermediates, crystallite sizes, or phase transitions with high time resolution. For some transition metals, extensive investigations have already been conducted while others have not been subject of in situ studies so far. Herein, the production processes for transition metals of groups 6–8 have been summarized, including how well the production method has been studied, whether in situ methods are employed and what results the use of such methods promises.

The crystal structures of three compounds derived from the reduction of Mn₂(CO)₁₀ with potassium in liquid ammonia solution with and without the presence of [2.2.2]crypt ([2.2.2]crypt = 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]-hexacosane) is reported. For the formation of [K([2.2.2]crypt)]₂[HMn(CO)₄] 2 NH₃ and K₃[Mn(CO)₄] 2 NH₃, liquid ammonia plays a crucial role as a solvent providing solvated electrons used for the reduction as well as for the stabilization of highly charged manganese carbonylates in ammoniate crystals. The isolation of [K([2.2.2]crypt)][Mn(CO)₄(NH₃)] 3 NH₃ offers an insight into a possible intermediate during the reduction from [Mn(CO)₅]⁻ to [Mn(CO)₄]³⁻ via the ammonia alkali metal route.

Porphyrin derivatives have been widely studied as models for (bacterio)chlorophyll pigments, and various dimeric architectures have been constructed through covalent or noncovalent bonds to mimic the special pairs found in photosynthetic reaction centers. Herein, novel cyclic porphyrin dimers are reported that are formed through the coordination between meso-substituted porphyrins bearing two phosphine oxide groups and lanthanide complexes, Ln(hfa)₃ (Ln = Yb, Lu; hfa = hexafluoroacetylacetonate). Single-crystal X-ray analysis of the Yb(III) complex revealed a slipped cofacial arrangement, in which two porphyrin units are bridged by Yb(III) centers via phosphine oxide coordination, closely resembling natural special pairs. The resulting dimers are stable in toluene and exhibit broadened Soret bands and redshifted Q bands compared to the monomeric porphyrin ligand. Upon porphyrin photoexcitation, the Yb(III) complex shows near-infrared luminescence from the Yb(III) center, while the porphyrin fluorescence intensity is essentially unaffected, demonstrating potential for oxygen sensing (Φ_Yb(Ar)/Φ_Yb(air) = 4.8). Transient absorption measurements confirmed the extended T₁ lifetime of the porphyrin units within the dimer structure. The dimers also show enhanced photostability under blue-light irradiation compared to the monomer. This study presents the first example of the Yb(III)-coordinated slipped cofacial porphyrin dimer with ratiometric oxygen-sensing capability and high photostability.

The Front Cover shows eight uranyl phosphonate and arsonate nanotubules and nanospheres. These materials represent a diverse family of self-assembling nanoscale structures, whose topological variety, intricate architectures, and functional properties arise from continued advances in synthetic chemistry. The Review by P. O. Adelani (DOI: 10.1002/ejic.202500222) highlights three decades of research aimed at understanding actinide materials for nuclear waste disposal and advanced nuclear fuel cycles.

The energetics and mechanisms of cyclocondensation reactions between SeCl₂ and ^tBuNH₂ in 1:3 molar ratio are examined using density functional theory with implicit solvation in tetrahydrofuran at 193 K. The results give strong support for the proposed stepwise pathway consisting of three key steps: 1) formation of an acyclic building block ^tBuN(H)SeCl, 2) chain growth to ClSe[N(^tBu)Se]_nCl (n = 1–3, 7–9), and 3) ring closure to 1,3,5-Se₃(N^tBu)₃ (1), 1,3,5,7-Se₄(N^tBu)₄ (2), 1,3-Se₃(N^tBu)₂ (3), or 1,3,5-Se₄(N^tBu)₃ (4). The paths leading to 3 and 4 include additional redox steps and diradical intermediates to generate SeSe bonds. The proposed paths share common intermediates, which allows the rationalization of the experimental product distribution as well as changes to it upon altering the stoichiometry or the total SeCl₂ concentration. The results further show that the successive addition of [N(^tBu)Se] units quickly becomes energy neutral, decreasing the likelihood for the formation of molecules with more than eight atoms by cyclocondensation. Plausible mechanisms explaining the formation of the 15-membered ring 1,3,6,8,11,13-Se₉(N^tBu)₆ (5) involve the coupling of diradical intermediates or redox processes converting SeCl₂ to Se₂Cl₂, both of which might also play a role in the generation of SeSeSe functionalities in 1,5-Se₆(N^tBu)₂ (6).

The Front Cover shows a ruthenium arene-based compound, a new metal-based cancer drug that shows promise due to unique mechanisms and better targeting of cancer cells than early treatments like cisplatin. Ruthenium(II) arene scaffolds have emerged as suitable candidates due to their ligand substitution ability, selectivity, lower toxicity, and stability compared to traditional platinum-based drugs like cisplatin. More information can be found in the Research Article by S. Maji and co-workers (DOI: 10.1002/ejic.202500300).

The catalytic dehydrocoupling of amine boranes produces well-defined BN compounds and polymers that are isovalent electronic to hydrocarbon analogs. In this study, the synthesis and characterization of a set of Rh, Ir, and Ru complexes with tridentate imidazolylphosphine PN(H)N ligands of the type (imidazolyl)CH₂N(H)CH₂CH₂PR₂ (R = iPr, tBu) are presented. These complexes potentially engage in metal–ligand cooperative dehydrogenation of amine boranes, followed by BN coupling. All complexes show facial coordination of the PN(H)N ligands to the metal centers with pronounced hydrogen bonding to an outer-sphere chloride ligand. All Rh and Ir complexes are active catalysts for the dehydrogenation of H₃B·NMeH₂ and H₃B·NMe₂H, producing mainly linear and cyclic BN oligomers. Only the Ru complex [Ru(PN(H)N)(PPh₃)(CO)(H)]Cl (8) produces low-molecular-weight poly(aminoboranes) from H₃B·NMeH₂ with high activity after activation with KOtBu, supporting metal-ligand cooperativity during activation of the amine borane substrates.

The conversion and utilization of carbon dioxide (CO₂) is a challenging contemporary issue in the present day, and the first step is the CO₂ fixation. Recently, the main group metal compounds have been found that have the analogous reactivity to transition metals and are capable of activating inert small molecules. In this work, the reaction mechanisms of [Al-M] (M = Zn, Be, Mg, and Ca) heterobimetallic compounds with CO₂ are investigated by density functional theory calculations. The calculated results indicate that the bimetallic main group compounds [AlAe] (Ae = Be, Mg, Ca) show similar activities near to that of [AlZn] and they can activate CO₂ at low temperature due to the low energy barriers. For both [AlAe] and [AlZn], AlC bond mode is the thermodynamic control and AlO bond mode is kinetic control pathway. At experimental conditions, AlC bond mode is the main reaction pathway for [AlAe], whereas for [Al-Zn], AlO bond mode is preferred. The reactivity is depended on AlM bond strength, the weaker AlM bond, the more reactivity of [Al-M] is.