Single-crystal X-ray Diffraction Research Articles

A “Bridged” Fused-ring Energetic Compound (TNBTP) with Super Heat-resistance and One-pot Synthesis

This study presents a novel C-C bonded 5,6-fused-ring energetic compound named 6,6’,8,8’-tetranitro-2,2’-bi[1,2,4]triazolo[1,5-a]pyridine (TNBTP), along with its facile one-pot synthesis. Its solvent-free crystal structure was confirmed by single crystal X-ray diffraction at room temperature. TNBTP exhibits a ultra high decomposition temperature of 397°C. Furthermore, its detonation velocity (vD) and detonation pressure (P) are determined as 7617 m·s-1 and 27.0 GPa respectively using LASEM measurements. Notably, TNBTP displays low impact sensitivity (IS: 15 J) and friction sensitivity (FS: >360 N).

Optimizing and Analysing the Anti-cancer Potential of Novel Quinoline Acetohydrazide (QAH): A Comprehensive Study Involving Synthesis, Structural Evaluation, 3D energy Frameworks, DFT Calculations, In vitro and In silico Evaluation

The compound, 2-(4-Chlorophenyl)-N'-(2-(quinoline-8-yloxy)acetyl acetohydrazide (QAH3), was synthezised in good yield from 2-(Quinoline-8-yloxy)acetohydrazide (1), with 2-(4-Chlorophenyl)acetic acid (2). The crude product obtained was recrystallized and elucidated by spectroscopic techniques (IR, HNMR and LC-MS), the 3D structure was confirmed by single crystal X-ray diffraction (XRD) studies. The XRD analysis shows that the compound crystallizes in the monoclinic crystal system with the space group Cc. Supramolecular architecture revealed the stability of molecules and crystal packing upon N-H...O, C-H...O, and C-H...π interactions. The three-dimensional Hirshfeld surfaces associated with two-dimensional fingerprint plots have confirmed the N-H...O, C-H...O intermolecular interactions. An energy framework calculation is used to estimate the different intermolecular interactions where dispersion energy dominates over all others. The Egap found to be 4.478 eV and related reactivity parameters of the compound were studied. In vitro studies confirmed that QAH3 significantly inhibited vascular endothelial growth factor receptor II (VEGFR-2) with an IC50 value of 10.54 ± 0.12 µM, compared to quercetin, the pharmaceutical reference standard, which demonstrated an IC50 of 4.50 ± 0.05 µM. Furthermore, the anti-cancer activity was confirmed by an in silico modelling study that targeted the angiogenesis of the VEGFR-2 receptor with good a binding affinity of -9.43 kcal/mol. This research not only propels molecular science forward but also offers potential for diverse applications, especially in drug design. The study's significance lies in its comprehensive exploration of the pharmacological potential of Quinoline Acetohydrazide using a multidisciplinary approach. We have extensively investigated the structural and biological properties of these molecules by combining synthesis, quantum theory, molecular electrostatics, and density functional theory (DFT) computations. This investigation has provided valuable insights that could lead to significant advancements in molecular science and drug development. Noncovalent interactions study shows the steric and van der Waals interactions exist between chlorobenzene and quinoline rings. MEP analysis shows that the chemical reactive sites are observed around oxygen and hydrogen atoms. Moreover, the molecular docking investigations elucidate the compound's interaction with several biological targets. The significant binding affinities observed for these targets highlight the potential therapeutic relevance of the synthesized compound in treating diverse diseases.

Ionic Liquid Assisted Green Synthesis of Quinoxaline Based Bisspirooxindoles: Anticancer Evaluation and Molecular Dynamics

AbstractIn this study, we have synthesized a series of novel quinoxaline based bisspirooxindoles through green protocol using ionic liquid [Bmim]BF4. All the compounds were well characterized by spectroscopic methods like FT‐IR, 1H NMR, 13C NMR, mass and finally the structures were authenticated by single crystal X‐ray diffraction (SCXRD) (4e). The target compounds were evaluated for their anticancer activity with different cancer cell lines like MDAMB‐231, MCF‐7, MCF‐10A, HCC‐1395, Molt‐4, and FaDU. The compounds 4d, 4g, 4m, and 4n showed 42.0%, 43.3%, 52.7%, and 56.0 percentage of growth inhibition respectively with the T cell acute lymphoblastic Molt‐4 cell line. The compounds 4b, 4c, 4 h, 4k, and 4m have shown 30%–39% of growth inhibition against FaDU cell line. Further, anticancer activity was validated with in silico molecular docking and molecular dynamics simulations. The outcomes of dynamics simulations exclusively emphasize that the compounds bind to HIS862 and TYR896 residues which are among the catalytic triad of PARP1. Finally, the results of ADME is also used to assess the drug likeness, which clearly shows that our target compounds are adaptable as potential drug pathways for medicinal chemists.

Synthesis, crystal structure, supramolecular assembly inspection via hirshfeld surface analysis and computational investigation of the pyrimethamine-based salts

In current research work, two salts abbreviated as 5DECA and 2DECA derived from pyrimethamine and aceclofenac are synthesized by using a simple method of reflux in methanol. The crystal structures of salts are investigated by the single-crystal X-ray diffraction (SC-XRD) technique. The supramolecular architecture of both compounds contained N-H⋯O, N-H⋯N, C-H⋯O, off-set π⋯π stacking, and C-O⋯π interactions. The difference in supramolecular architecture is that in 5DECA, O-H⋯O and C-H⋯π interactions are present, whereas in 2DECA, N-H⋯Cl, C-H⋯Cl, and C-Cl⋯π interactions are present. The presence of water molecule in 5DECA is the main reason for the difference between the supramolecular architecture of compounds. The intermolecular interactions in terms of interatomic contacts are probed by Hirshfeld surface analysis (HSA). Void analysis is performed to understand the mechanical response of crystals. Computational studies, conducted at the DFT/B3LYP//ma-def2-SVP level of theory, confirmed that the supramolecular assemblies in these systems are governed by π-π and N-H⋯O interactions. These calculations also determined several key factors, comprising structural features, molecular electrostatic potential (MEP), the HOMO-LUMO energy gap (ΔE), and Infrared spectroscopic absorption peaks.

Five novel Pb/Zn/Co metal-organic frameworks using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and carboxylate ligands: Synthesis, characterization, DFT calculation and catalytic PMS degradation of RhB

Five new metal-organic frameworks (MOFs), namely {Pb(atpt)(3-bpd)0.5}n (1); {Co(cbz)2(3-bpd)(H2O)2·2H2O}n (2); {Co(imdc)(3-bpd)(H2O)·H2O}n (3); {Co(tdca)(3-bpd)(H2O)2·DMF}n (4); {Zn(tdca)(3-bpd)(H2O)2·DMF}n (5), were assembled with metal ions Pb²⁺, Zn²⁺, and Co²⁺ using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpd) as the main ligand, combined with 2-aminoterephthalic acid (H2atpt), 4-cyanobenzoic acid (Hcbz), 4,5-imidazoledicarboxylic acid (H2imdc), and thiophene-2,5-dicarboxylic acid (H2tdca) as auxiliary ligands via hydro/solvothermal methods. Their molecular structures were analyzed by single-crystal X-ray diffraction and characterized by FT-IR and PXRD. Complex 1 has a three-dimensional structure with a hepta-coordinated, semi-directed {PbNO6} metal center. The central metal ions in complexes 2–5 exhibit a six-coordinated {MN2O4} (M = Co or Zn) octahedral geometry. In complex 2, the carboxylate ligand does not function as a bridging ligand, resulting in a 1D chain structure, while complexes 3- 5 extend into 2D layered structures. Thermogravimetric analysis indicates good thermal stability for complexes 1–5. Then, the prepared complexes were used as catalysts to degrade Rhodamine B (RhB) during the monopersulfate (PMS) activation. Complexes 3 and 4 demonstrated significant efficiency, achieving degradation rates of 93.61 % and 98.56 % within 10 min. Radical scavenging experiments and EPR analysis identified that the activation of PMS for dye degradation by the two catalysts occurs through both radical and non-radical pathways, with SO4•− and •OH radicals being the dominant species. Density functional theory (DFT) calculations explained the superior catalytic performance of complex 4 compared to complex 3.

The role of Li⋯F interactions in lithium and heterobimetallic lithium–magnesium complexes of the hexafluoroisopropoxide anion

As part of ongoing investigations of battery electrolytes and additives based on derivatives of 1,1,1,3,3,3-hexafluoroisopropanol, the solvent-free hexameric precursor [Li(μ3-OCH(CF3)2)]6 (1) was isolated and characterised by single-crystal X-ray diffraction and found to possess a ring-stacked hexagonal prismatic Li6 arrangement supported by Li⋯F interactions. To explore the behaviour of this fluoroalkoxide ligand further, the lithium magnesiate complexes [Li2(thf)4Mg(μ2-OCH(CF3)2)4] (2) and [Li3(thf)2(nBuMg)(μ3-OCH(CF3)2)4] (3) were also obtained; 2 from the reaction of the fluorinated alcohol with a 2:1 mixture of nBuLi:nBu2Mg, and 3 from the reaction of the alcohol with a 1:1 mixture of nBuLi:nBu2Mg. The structure of 3 is of particular interest, being based on a Li3MgO4 heterocubane arrangement which possesses a highly unusual 3:1 Li:Mg stoichiometry. The solid-state structures of 1–3 illustrate some of the range of vastly different geometries possible for s-block metal alkoxides and highlight the potential importance of Li⋯F interactions in molecular stabilisation.

Bioactivity-guided isolation of potent inflammasome and mitochondria damage inhibitory diterpenoids from Orthosiphon wulfenioides.

Orthosiphon wulfenioides is a medicinal plant to treat arthritis, vascular inflammation, edema, and dyspepsia. To explore the anti-inflammatory components and their mechanism of action, 12 previously undescribed highly oxidized diterpenes, wulfenioidones L-W (1-12), were isolated from O. wulfenioides by bioactivity orientation. Their structures were elucidated using HRESIMS, NMR, specific rotation, single-crystal X-ray diffraction, and ECD spectra analysis. Compounds 1-4 exhibited significant inhibition on LDH release by preventing macrophage J774A.1 pyroptosis. Compound 1 showed the most potent inhibitory effect with an IC50 value of 5.81 μM. It was revealed in the western blot experiment that compound 1 not only significantly and dose-dependently decreased the activation of CASP1 and IL-1β, but also prevented GSDMD-FL from splitting into GSDMD-NT, the membrane pore-forming protein to release inflammatory factors, thus blocking the extracellular release of IL-1β. More interestingly, compound 1 not only blocked the activation of NLRP3 inflammasome, but also strikingly enhanced the orange fluorescence of JC-1 aggregates, thus showing the activity of maintaining mitochondrial membrane potential and reversing mitochondria damage.

A study on complexation of Zn(II) salts with 4-aryl-2-(pyridin-2-yl)quinolines: The influence of anions on the complex structures and their luminescent properties

A novel ligand, 6‑methoxy-4-(4-methoxyphenyl)-2-(pyridin-2-yl)quinoline (PQ) was synthesized and studied for its interaction with ZnX2.nH2O (X: Cl-, OAc-,NO3−) to form three complexes of the type [Zn(X2)(PQ)(H2O)n] (Zn1-Zn3) with high yields, ranging from 75 to 94 %. The structures of Zn1–Zn3 were fully characterized using ESI mass spectrometry, IR and 1H NMR spectroscopy, and single-crystal X-ray diffraction (for Zn1 and Zn3). Spectroscopic analyses revealed that Spectroscopic analyses revealed that the central atom Zn(II) in Zn1, Zn2, and Zn3 has the coordination numbers of 4, 5, and 6, respectively. In these complexes, Zn(II) coordinates with the PQ ligand through its two nitrogen atoms, while the remaining coordination sites are occupied by anions such as Cl-, OAc, NO3−, or by H₂O. The results also indicate that the optical properties of the Zn(II) complexes depend not only on the primary organic ligand QP but also on the secondary inorganic ligands. In THF, the complexes Zn1 and Zn3, which contain chlorido and nitrato ligands exhibit intense fluorescence blue emissions at 443 and 462 nm with quantum yields of 0.66 and 0.70, respectively. Although the complex Zn2 has the weakest emission in THF, it exhibited the strongest blue emission intensity in solid state. In addition, computational studies provided insights into the structural and electronic properties, showing a strong correlation with experimental data. The calculated absorption and emission spectra were promarily based on the transition between HOMO and LUMO (π-π*) with high oscillator strength.

Synthesis and crystal structure of a novel metal cyanide halide complex (NH4)6Fe(CN)6Cl2·0.4H2O

Hexacyanidometallates possess unique physical properties, which has been extensively studied. However, there are still a number of its derivatives that may be considered which remains unknown, such as metal cyanide halide hexacyanidometallates, especially those of transition-metal elements, but preparing such complex is hampered by the preference of the formation of compounds without halogens. Here, we report synthesis of a novel transition metal cyanide halide hexacyanidometallates derivate (NH4)6Fe(CN)6Cl2·0.4H2O through reactant ratio control. The crystal structure was studied via single-crystal X-ray diffraction, supported by elemental analysis and IR spectra. The crystal structure of (NH4)6Fe(CN)6Cl2·0.4H2O crystallizes in space group R3¯ with rhombohedral stacking behavior. Moreover, the crystal structure of (NH4)6Fe(CN)6Cl2·0.4H2O features rich hydrogen bonds, contributing to the crystal stability.

Synthesis, characterization and photophysical properties of three novel lanthanide materials

Three new lanthanide compounds with different structures, i.e. [Tb(2,6-naphthalenedisulfonic acid)(OH)(H2O)2]n (1), [Nd(HIA)2(NO3)(H2O)3]n2n(NO3)·nH2O (2; HIA = isonicotinic acid) and [Er6(H2O)12(NO3)6(OH)8(O)]2NO3·2H2O (3), were obtained from hydrothermal reactions. Their crystal structures were characterized with single-crystal X-ray diffraction. Compound 1 is characteristic of a two-dimensional (2-D) layer-like structure, compound 2 features a one-dimensional (1-D) chain-like structure, while compound 3 shows an isolated (0-D) Er6 hexanuclear structure. The solid-state UV/Vis diffuse reflectance spectra show that the semiconductor bandgaps are 2.89 eV, 3.12 eV and 4.64 eV for compounds 1, 2 and 3, respectively. The solid-state photoluminescent measurements exhibit that they can show green, red and blue emissions. These photoluminescence emissions are originated from the characteristic emissions of the 4f electron intrashell transitions of the 5D4 → 7F6 of the Tb3+ ions in compound 1, the 4F7/2 → 4S3/2 of the Nd3+ ions in compound 2 and the 4F9/2 (4F5/2) → 4I15/2 of the Er3+ ions in compound 3. Their CIE (Commission Internationale de I'Éclairage) chromaticity coordinates are (0.2451, 0.4041), (0.7334, 0.2666) and (0.1391, 0.0483). Their CCT (Correlated Color Temperature) are 8937 K, 400,100 K and 2654 K.

Crystallochemistry, thermodynamic and physical properties of the intermetallic compound Cu3−x(As,Sb)

During the investigation of the Cu-As-Sb ternary system, we identified the ternary intermetallic Cu3−x(As,Sb) compound. Its crystal structure was solved and refined by single crystal and powder X-ray diffraction. While the binary Cu3−xAs and Cu3−xSb phases crystallize in the hexagonal Cu3P-type (hP24, P63cm) and cubic anti-BiF3-type (cF16, Fm3¯m), respectively, Cu3−x(As,Sb) adopts the cubic Cu6AsSb prototype (cP32, Pm3‾n). Crystallochemical reasons lead to the exclusion that its structure could be of the UH3-type. Cu3−x(As,Sb) is isotypic with Cu12−xTeSb3; their crystal structure is a stuffed ternary derivative of the Cr3Si-type. SEM-EDX analyses reveal very large compositional ranges for this compound, mostly concerning the Sb/As ratio: 71.1−73.9 at.% Cu, 4.0−24.5 at.% As and 2.5−23.5 at.% Sb, corresponding to about Cu2.5-2.8As0.23-0.98Sb0.23-0.92 (x = 0.2−0.5). The lattice parameter and, consequently, the unit cell volume regularly expand while increasing the Sb/As compositional ratio: a ≈ 7.47 Å for Cu3−xAs0.75Sb0.25, a ≈ 7.65 Å for Cu3−xAs0.25Sb0.75 (averaged values).Cu3−x(As,Sb) forms either by a peritectic reaction for As-rich compositions, or congruently for the equiatomic Sb/As and Sb-rich compositions. The decomposition- or melting-temperature values decrease as a function of the Sb/As compositional ratio [e.g. peritectic at 710 °C for Cu3−xAs0.75Sb0.25 (Cu72As21Sb7), congruent melting at 690 °C for Cu3−xAs0.50Sb0.50 (Cu72As14Sb14), and at 675 °C for Cu3−xAs0.25Sb0.75 (Cu72As7Sb21)].Physical properties (electrical resistivity and magnetic susceptibility) indicate that Cu3−x(As,Sb) behaves as a good metal with electrical resistivity decreasing as the Sb/As compositional ratio increases; a peculiar anomaly in the electrical resistivity behavior (heavy-fermions like) was observed at low temperature, the origin of which needs further investigation. The compound is a standard diamagnet.

Potential COX-2 inhibitors modulating NF-κB/MAPK signaling pathways: Design, synthesis and evaluation of anti-inflammatory activity of Pterostilbene-carboxylic acid derivatives with an oxime ether moiety

In this work, a series of novel Pterostilbene–oxime ether–carboxylic acid (POC) derivatives (d1–d10, e1–e10 and 1–13) were designed, synthesized, and characterized by spectroscopic techniques. In order to further determine the absolute configuration of these compounds, one of them, compound d3, was investigated by X-ray single crystal diffraction method. d3 had a triclinic crystal with P-1 space group, and its CHCH and CHN was confirmed as E configuration. A strong hydrogen bond was formed between the hydrogen atom in CHCH moiety and the nitrogen atom in CHN moiety, which was a vital factor in the formation and stability of E configuration in the CHCH and CHN. The safety and anti-inflammatory activities of compounds (d1–d10, e1–e10 and 1–13) in vitro were evaluated. At 20 μM, compounds (d1–d10, e1–e10 and 1–13 were non-toxic and exhibited weak to strong inhibitory effects on the LPS-induced NO release. Among them, five compounds (1, 2, 7, 8 and 9) showed excellent anti-inflammatory effects with IC50 (NO) values ranging from 9.87 to 19.78 μM, as well as strong COX-2 inhibitory abilities with IC50 (COX-2) values ranging from 85.44 to 140.88 nM. Moreover, there was a rough positive correlation between their anti-inflammatory properties and the COX-2 inhibitory abilities. Compounds (1, 2, 7, 8 and 9) smoothly docked with COX-2 protein (PDB ID: 5KIR) to form stable complexes with strong hydrogen bonds, with an affinity range of −8.3 to −9.9 kcal/mol. SAR indicated that the amidation of POC at R2 position was more favorable for enhancing the compound’s biological actives than esterification. In addition, the 4-fluobenzyl substitution at R2 position of the oxime ether moiety can obviously enhance the activity of above amide derivates. Introducing acyl groups (CO(CH2)nCH3, n = 2, 4 and 6) into NH(CH2)3OH group to form ester chain is disadvantageous for activity enhancing, moreover, the longer the carbon chain, the poorer the activity. The strongest COX-2 inhibitor (IC50 (COX-2) = 85.44 ± 3.88 nM), compound 7, exerted as anti-inflammatory activities (IC50 (NO) = 9.87 ± 1.38 μM) by down-regulating the expression of COX-2 and iNOS, and modulating NF-κB/MAPK signaling pathways.

Synthesis, Structure And Thermogravimetric Analysis Of Copper(II) Complex Derived From N1 ,N3 -Bis(1-(Pyridin2-Yl)Ethylidene)Propane-1,3-Diamine

Cu(II) complex derived from ligand, (N 1 ,N3 -bis(1-(pyridin-2-yl)ethylidene)propane-1,3-diamine (L) which was synthetized in situ, is reported. The isolated Cu(II) complex was characterized by elemental analyses, IR, and UV-Vis spectroscopies, and Thermogravimetric analyze (TGA). Additionally, the structure of the complex was determined by single crystal X-ray diffraction study. The diimine ligand was coordinated to Cu(II) ion through two azomethine nitrogen atoms and two pyridine nitrogen atom. One bromide ion complete the coordination sphere yielding a distorted square pyramidal geometry. The structure of the copper(II) complex is confirmed by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 8.3433 (3) Å, b = 13.2605 (3) Å, c = 18.838 (6) Å,  = 97.522 (16)°, V = 2066.2 (6) Å3 , Z = 4, R1 = 0.048 and wR2 = 0.081. The Cu(II)cation in N4Br inner is situated in a distorted square pyramidal environment. Thermogravimetric analyze of the complex were carried out at 20–800 °C and showed that the complex were decomposed into three steps.

Synthesis, spectroscopical and DFT studies on third order NLO crystal: Sodium bis(malonato)borate monohydrate (SBMBM)

The single crystal of sodium bis(malonato)borate monohydrate (SBMBM) was grown using the Slow Evaporation Solution Technique(SEST). To analyze the crystal lattice parameters of the grown SBMBM crystal, Single Crystal X-Ray Diffraction analysis were used. The results shows that the crystal belongs to Triclinic crystal system with space group P21/n with lattice parameters A = 7.9058 (4) Å, B = 8.2979 (5) Å, and C = 14.6473 (9) Å, where α = 90°, β = 101.565 (2)°, and γ = 90° The theoretical calculation utilizing HF/LANL2DZ and the experimental results agree rather well. The molecular optimized geometry, FT-IR, and the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated using the HF/LANL2DZ basis set. The several functional groups in the SBMBM crystal are investigated by FT-IR spectrum. Studies of UV–visible NIR transmittance indicate that the crystal has a high transmittance throughout the whole visible spectrum. Using the Z-scan technique, third-order nonlinear optical (NLO) property of SBMBM crystal is analysed, and the linear and nonlinear refractive index are computed. χ3 = 4.49 × 10−6esu is the third-order nonlinear optical susceptibility.

Investigation on Growth, Structural, Spectral, DFT, MEP Computational Studies of Novel Methyl Triphenylphosphonium Bromide HydrateSingle Crystal for Third-Order Nonlinear Optical Limiting Applications

A novel organic nonlinear optical (NLO) single crystal, Methyl Triphenylphosphonium Bromide Hydrate (MTPB), grown for the first time using the slow evaporation solution technique at room temperature. Comprehensive structural analysis by single crystal X-ray diffraction reveals that MTPB crystallizes in the monoclinic system with space group P2₁/n, and its lattice parameters have been accurately determined. Structural refinement was performed using the full matrix least squares technique with the SHELXL-97 program. To characterize the molecular structure and interactions, FT-IR and FT-Raman spectra provided functional group identification, and 2D fingerprint and Hirshfeld surface analyses offered insights into hydrogen bonding interactions within the crystal. The novelty extends to computational analysis, where the molecule's geometry was optimized using DFT-B3LYP with a 6-31++G(d,p) basis set, allowing comparison between theoretical vibrational frequencies and experimental data. Additionally, the third-order NLO properties were assessed via the Z-scan technique, marking the first use of MTPB in optical limiting applications. This work's innovation lies in the successful synthesis, comprehensive characterization, and demonstration of MTPB's significant potential as an optical limiter, paving the way for new NLO applications.

A new chalcone derivative: Synthesis, crystal structure, Hirshfeld surface, quantum chemical investigations, Druggability and human Cathepsin D inhibitory activity

This paper presents the synthesis of a novel chalcone derivative, and its molecular structure has been determined by NMR and single-crystal X-ray diffraction analysis. The molecules are connected via OH⋅⋅⋅O, CH⋅⋅⋅O, and CH⋅⋅⋅S hydrogen bonds along with CH⋅⋅⋅π and π⋅⋅⋅π interactions. Hirshfeld surface studies have been conducted to comprehensively quantify the patterns of intermolecular interactions. DFT calculations provided insights into the nature of the molecule, including frontier molecular orbital, ADCH charge, Molecular Electrostatic Potential and Natural Bond Orbitals analysis using the optimized structure by B3LYP/6–311 G (d, p) level. The calculated HOMO-LUMO gap (3.23 eV) indicates decent softness and reactivity of the target molecule. The molecular docking studies reveal that the target compound exhibits a high binding affinity with Human Cathepsin D (CatD), with a docking score of -7.58 kcal/mol. The assessment of drug-likeness properties and ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiles further support its potential as a potent CatD inhibitor candidate for medication development.

The paddlewheel complex of 1,8-naphthyridine and palladium(II)

This work presents the synthesis of the tetracationic paddlewheel complex of 1,8-naphthyridine and palladium(II), [Pd2(µ-napy)4]X4, (X = BF4− or PF6−). Single-crystal X-ray diffraction confirms a D4h symmetric paddlewheel structure encompassing the two Pd units in the metal core coordinated by four ditopic 1,8-naphthyridine ligands, featuring a relatively short Pd–Pd distance. Spectroscopic analyses combined with density-functional theory (DFT) provide insights into the nature of the Pd–Pd and Pd–Napy interactions as well as observed optical absorption frequencies.

Half-Sandwich Cerium and Lanthanum Dialkyl Complexes: Synthesis, Structure, and Reactivity Studies.

Cerium and lanthanum dialkyl complexes [η5-1,2,4-(Me3C)3C5H2]Ln(CH2C6H4-o-NMe2)2 (Ln = Ce 1 and La 2), supported by a tri-tert-butylcyclopentadienyl ligand, have been successfully synthesized. Studies demonstrate that these complexes possess diverse reactivity toward various small molecules. For example, the reaction of complexes 1 and 2 with diphenyl dichalcogenides PhEEPh (E = S, Se) results in the formation of lanthanide thiolates [(η5-1,2,4-(Me3C)3C5H2)Ln(SPh)(μ-SPh)]2 (Ln = Ce 3 and La 4) and selenolates [(η5-1,2,4-(Me3C)3C5H2)Ln(SePh)(μ-SePh)]2 (Ln = Ce 5 and La 6), concomitantly releasing PhE(CH2C6H4-o-NMe2). Furthermore, complexes 1 and 2, upon reaction with dibenzyl disulfide, yield tetranuclear rare-earth metallomacrocyclic compounds {[(η5-1,2,4-(Me3C)3C5H2)Ln(μ-SCH2C6H5)]2(μ-η3:η3-SCHC6H5)}2 (Ln = Ce 7 and La 8). This reaction may involve a process of σ-bond metathesis and C-H activation. While the reaction of 1 and 2 with dibenzyl diselenide in the presence of LiCH2C6H4-o-NMe2 leads to the formation of lanthanide-lithium selenido clusters [(η5-1,2,4-(Me3C)3C5H2)La(μ-SeCH2C6H5)]3(μ3-Se)[μ3-SeLi(THF)3] (Ln = Ce 9 and La 10). Meanwhile, lanthanide selenido clusters [(η5-1,2,4-(Me3C)3C5H2)La(μ-SeCH2C6H4-o-NMe2)]4(μ3-Se)2 (Ln = Ce 11 and La 12) can be obtained by treating 1 and 2 with elemental selenium in a 1:2 molar ratio. Additionally, the treatment of 1 and 2 with benzoxazole generates ring-opening/C-C coupling/C-N coupling products {(η5-1,2,4-(Me3C)3C5H2)La[μ-OC6H4-o-N═CHN(CH(CH2C6H4-o-NMe2)2C6H4-o-O]}2 (Ln = Ce 13 and La 14). All new compounds were characterized by various spectroscopic methods, and their solid-state structures were confirmed by single-crystal X-ray diffraction analyses.

Engineering the Coordination Environment in the Silver(I)- and Ruthenium(II)-N-Heterocyclic Carbene Complexes in Instigating the Electrocatalytic Hydrogen Evolution Reaction.

The quest for cost-efficient and high-performance electrocatalysts towards electrocatalytic water splitting is a key and an interdisciplinary area of study. Considerable progress is being driven by developments in the field of energy research. In a fundamental study, we have synthesized NHC precursors (6 and 7) and corresponding metal-NHC complexes of silver(I)- (8 and 9) and ruthenium(II)- (10 and 11) of a N-heterocyclic carbene-based ligand type incorporating coumarins. These NHC precursors and metal-NHC complexes were characterized through various analytical and spectral techniques. The silver(I)-NHC complexes 8 and 9 displayed a linear coordination geometry with a center of inversion, which is evidenced by the single-crystal X-ray diffraction technique. Both the series of complexes were assessed for their efficacies in the hydrogen evolution reaction (HER). The results demonstrated that attributed to its peculiar coordination geometry, high electrical conductivity the silver(I)- and ruthenium(II)-NHC complexes exhibited exemplary electrocatalytic activity. Activities of the hydrogen evolution reaction on two differently modified electrode substrates with metal-NHC complexes have been studied. To attain the benchmark HER current density of 10 mA cm-2, in 1.0 M KOH, an overpotential of -375 to -527 mV vs RHE was required for the metal-NHC complexes. Based on the analysis of the Tafel slope values, the rate-determining step was the adsorption of hydrogen as investigated in the potential window. The molecular electrocatalyst 10 presented a superior stability and maintained the electrocatalytic activity for a duration of 18 h with complex 8 and 24 h with respect to complex 10 in 1.0 M KOH. Apace with these studies, hydrogen oxidation studies were examined in 0.5 M H2SO4 by a substantial current density at the platinum ring electrode. This research offers feasible guidance for developing organometallic-based molecular electrocatalysts with good electrocatalytic performance.

Structural and Biological Evaluation of Manganese(II) and Copper(II) Complexes with 2,5-Pyridinedicarboxylate Ligands: Experimental and Theoretical Insights into Antibacterial Potential and Antibiofilm Property

Two novel coordination complexes, [Mn(HPDC)2(H2O)2] (YS-Mn) and [Cu(HPDC)2][NH(CH3)2]2 (YS-Cu), were successfully synthesized utilizing 2,5-pyridinedicarboxylic acid as the ligand. These complexes were comprehensively characterized using a variety of spectroscopic and analytical techniques, including single-crystal X-ray diffraction, infrared spectroscopy, and elemental analysis. The structural analysis revealed that YS-Mn crystallizes in a monoclinic system with a C2/c space group, while YS-Cu adopts a triclinic system with a P-1 space group. The biological activities of these complexes were evaluated against a panel of microbial strains to assess their potential as antimicrobial agents. The Mn(II) complex demonstrated significant antibacterial activity, with the lowest minimum inhibitory concentration (MIC) of 128 µg/mL observed against S. aureus 3160, followed by B. cereus and E. coli at 256 µg/mL. Against K. pneumoniae 1705 and S. marcescens 97, the MIC was determined to be 512 µg/mL. Furthermore, the Mn(II) complex exhibited potent biofilm inhibitory effects, particularly against S. aureus 3160, at sub-MIC concentrations. Molecular docking studies suggested that the Mn(II) complex interacts with MetAPs in E. coli, interfering with protein and DNA synthesis, thus contributing to its antimicrobial activity. The promising biological activity exhibited by the Mn(II) and Cu(II) complexes, particularly the Mn(II) complex, highlights their potential as promising candidates for further development as therapeutic agents to combat drug-resistant pathogens.