Search Results (147)

Application of organic ligand 2-(3-ethyl-pyrazin-2-yl)quinoline-4-carboxylate with N/O donor atoms enabled solvothermal synthesis of a 2D Cu(II) coordination polymer, {Cu(L)BF₄}_n (L = deprotonated 2-(3-ethyl-pyrazin-2-yl)quinoline-4-carboxylate). Both the ligand and its coordination polymer have been characterized. The condensed ring system of the applied ligand promotes the formation of coordination polymers rather than mononuclear species. The obtained 2D coordination polymer is photoluminescent with bathochromic/hypsochromic shifts in ligand absorption bands leading to a single absorption band at 465 nm. Density Functional Theory was employed to provide a theoretical description of the possible conformational changes within the ligand, with emphasis on the difference between the ligand conformation in its hydrochloride salt and in the polymer. Two models of polymer fragments were constructed to describe the electronic structure and non-covalent interactions. The Quantum Theory of Atoms in Molecules (QTAIM) was applied for this purpose. Using the obtained results, we were able to develop potential energy profiles for various conformations of the ligand. For the set of the studied systems, we detected non-covalent interactions, which are responsible for the spatial conformation. Concerning the models of polymers, electron spin density distribution has been visualized and discussed. Full article

The development of novel platinum-based anticancer agents remains a critical objective in medicinal inorganic chemistry, particularly in light of resistance and toxicity limitations associated with cisplatin. In this study, the synthesis, structural characterization, quantum chemical analysis, and cytotoxic evaluation of four new acetylplatinum(II) complexes (cis-[Pt(COMe)₂(PASO₂)₂], cis-[Pt(COMe)₂(DAPTA)₂], trans-[Pt(COMe)Cl(DAPTA)₂], and trans-[Pt(COMe)Cl(PASO₂)]: 1–4, respectively) bearing cage phosphine ligands PASO₂ (2-thia-1,3,5-triaza-phosphaadamantane 2,2-dioxide) and DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) are presented. The coordination geometries and NMR spectral features of the cis/trans isomers were elucidated through multinuclear NMR and DFT calculations at the B3LYP/6-311++G(d,p)/LanL2DZ level, with strong agreement between experimental and theoretical data. Quantum Theory of Atoms in Molecules (QTAIM) analysis was applied to investigate bonding interactions and assess the covalent character of Pt–ligand bonds. Cytotoxicity was evaluated against five human cancer cell lines. The PASO₂-containing complex in cis-configuration, 1, demonstrated superior activity against thyroid (8505C) and head and neck (A253) cancer cells, with potency surpassing that of cisplatin. The DAPTA complex 2 showed enhanced activity toward ovarian (A2780) cancer cells. These findings highlight the influence of ligand structure and isomerism on biological activity, supporting the rational design of phosphine-based Pt(II) anticancer drugs. Full article

The one-dimensional (1D) Sb(III)-based organic–inorganic hybrid perovskite (AImd)₂¹_∞[SbI₅] (AImd = 1-allylimidazolium) crystallizes in the orthorhombic, centrosymmetric space group Pnma. The structure consists of corner-sharing [SbI₆] octahedra forming 1D chains separated by allylimidazolium cations. Void analysis through Mercury CSD software confirmed a densely packed lattice with a calculated void volume of 1.1%. Integrated quantum theory of atoms in molecules (QTAIM) and non-covalent interactions index (NCI) analyses showed that C–H···I interactions between the cations and the ¹_∞[SbI₅]²⁻ network predominantly stabilize the supramolecular assembly followed by N–H···I hydrogen bonds. The calculated growth morphology (GM) model fits very well to the experimental morphology. UV–Vis diffuse reflectance spectroscopy allowed us to determine the optical band gap to 3.15 eV. Density functional theory (DFT) calculations employing the B3LYP, CAM-B3LYP, and PBE0 functionals were benchmarked against experimental data. CAM-B3LYP best reproduced Sb–I bond lengths, while PBE0 more accurately captured the HOMO–LUMO gap and the associated electronic descriptors. These results support the assignment of an inorganic-to-organic [Sb–I] → π* charge-transfer excitation, and clarify how structural dimensionality and cation identity shape the material’s optoelectronic properties. Full article

A series of novel N-Mannich bases derived from a dimethylpyridine–1,2,4-triazole hybrid was synthesized and evaluated in vitro for cytotoxic activity on several human gastrointestinal cancer cells (EPG, Caco-2, LoVo, LoVo/Dx, and HT-29). Compound 6 bearing a phenyl group at the N-4 position and a 4-methylphenyl piperazine moiety at the N-2 position of the 1,2,4-triazole-3-thione scaffold exerted good cytotoxic activities on EPG and Caco-2 cell lines, along with pronounced selectivity, showing lower cytotoxicity against normal colonic epithelial cells (CCD 841 CoTr). Further evaluation revealed the good ability of compound 6 to inhibit the efflux function of P-glycoprotein in P-gp-expressing cell lines (HT-29, LoVo, and LoVo/Dx). Moreover, compound 6 induced apoptotic cell death through a significant increase in the caspase-3 and p53 protein levels in HT-29 cells. Finally, the molecular docking method was applied to explain our experimental findings. The molecular modeling study based on Density Functional Theory (DFT) and the Quantum Theory of Atoms in Molecules (QTAIM) analysis provided insight into the geometric and electronic structure properties of the compounds. Full article

Cancer has a threatening impact on human health, and it is one of the primary causes of fatalities worldwide. Different conventional treatments have been employed to treat cancer, but their non-specific nature reduces their therapeutic efficacy. This study employs a C₅N₂-based targeted drug carrier to study the delivery mechanism of anticancer drugs, particularly cisplatin, carmustine, and mechlorethamine, using density functional theory (DFT). The geometries of the drugs, the C₅N₂ substrate, and the drug@C₅N₂ complexes were optimized at the PBE0-D3BJ/def2SVP level of theory. Interaction energy was computed for the complexes which follow the trend, i.e., cisplatin@C₅N₂ (−27.60 kcal mol⁻¹) > carmustine@C₅N₂ (−19.69 kcal mol⁻¹) > mechlorethamine@C₅N₂ (−17.79 kcal mol⁻¹). The non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses confirmed the presence of van der Waals forces between the carmustine@C₅N₂ and mechlorethamine@C₅N₂ complexes, while weak hydrogen bonding has also been observed between the cisplatin@C₅N₂ complex. Electron localization function (ELF) analysis was performed to analyze the degree of delocalization of electrons within the complexes. The electronic properties of the analytes and the C₅N₂ substrate confirmed the enhanced reactivity of the complexes and illustrated electron density shift between the drugs and the C₅N₂ sheet. Recovery time was determined to assess the biocompatibility and the desorption behavior of the drugs. Moreover, negative solvation energies and increased dipole moments in a solvent phase manifested enhanced solubility and easy circulation of the drugs in biological media. Subsequently, this study illustrates that cisplatin@C₅N₂, carmustine@C₅N₂, and mechlorethamine@C₅N₂ complexes can be utilized as efficient drug delivery systems. Full article

A comprehensive investigation of the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type Pb₂SO₅ (PSO) structure was conducted, for the first time, using density functional theory simulations. Thus, different functionals, PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP, and B3LYP, were used, and their results were compared to predict their fundamental properties accurately. All DFT calculations were performed using a triple-zeta valence plus polarization basis set. Among all the DFT functionals, PBE0 showed the best agreement with the experimental and theoretical data available in the literature. Our results also reveal that the [PbO₅] clusters were formed with five Pb–O bond lengths, with values of 2.29, 2.35, 2.57, 2.60, and 2.79 Å. Meanwhile, the [SO₄] clusters exhibited uniform S–O bond lengths of 1.54 Å. Also, a complete topological analysis based on Bader’s Quantum Theory of Atoms in Molecules (QTAIM) was applied to identify atom–atom interactions in the covalent and non-covalent interactions of the PSO structure. Additionally, PSO has an indirect band gap energy of 4.83 eV and an effective mass ratio ($m_h^{*}$/$m_e^{*}$) of about 0.192 (PBE0) which may, in principle, indicate a low degree of recombination of electron–hole pairs in the lanarkite structure. This study represents the first comprehensive DFT investigation of Pb₂SO₅ reported in the literature, providing fundamental insights into its electronic and structural properties. Full article

The coordination chemistry, structural characterization, and biomolecular interactions of europium(III) and iron(III) complexes with the pyridoxal-semicarbazone (PLSC) ligand were thoroughly examined using experimental and computational approaches. Single-crystal X-ray diffraction revealed that the europium complex exhibits a nine-coordinate geometry with one protonated and one deprotonated PLSC ligand and nitrato and aqua ligands. In contrast, the iron complex adopts a six-coordinate structure featuring a monoprotonated PLSC, two chlorido, and an aqua ligand. Hirshfeld surface analysis confirmed the significance of intermolecular contacts in stabilizing the crystal lattice. Theoretical geometry optimizations using DFT methods demonstrated excellent agreement with experimental bond lengths and angles, thereby validating the reliability of the chosen computational levels for subsequent quantum chemical analyses. Quantum Theory of Atoms in Molecules (QTAIM) analysis was employed to investigate the nature of metal–ligand interactions, with variations based on the identity of the donor atom and the ligand’s protonation state. The biological potential of the complexes was evaluated through spectrofluorimetric titration and molecular docking. Eu-PLSC displayed stronger binding to human serum albumin (HSA), while Fe-PLSC showed higher affinity for calf thymus DNA (CT-DNA), driven by intercalation. Thermodynamic data confirmed spontaneous and enthalpy-driven interactions. These findings support using PLSC-based metal complexes as promising candidates for future biomedical applications, particularly in drug delivery and DNA targeting. Full article

This study employs Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations to investigate interactions between water molecules and Poly(N-isopropylacrylamide) (PNIPAM). DFT reveals preferential water binding sites, with enhanced binding energy observed in the linker zone. Quantum Theory of Atoms in Molecules (QTAIM) and electron localization function (ELF) analyses highlight the roles of hydrogen bonding and steric hindrance. MD simulations unveil temperature-dependent hydration dynamics, with structural transitions marked by changes in the radius of gyration (Rg) and the radial distribution function (RDF), aligning with DFT findings. Our work goes beyond prior studies by combining a DFT, QTAIM and MD simulations approach across different PNIPAM monomer-to-30mer structures. It introduces a systematic quantification of pseudo-saturation thresholds and explores water clustering dynamics with structural specificity, which have not been previously reported in the literature. These novel insights establish a more complete molecular-level picture of PNIPAM hydration behavior and temperature responsiveness, emphasizing the importance of amide hydrogen and carbonyl oxygen sites in hydrogen bonding, which weakens above the lower critical solution temperature (LCST), resulting in increased hydrophobicity and paving the way for understanding water sorption mechanisms, offering guidance for future applications such as dehumidification and atmospheric water harvesting. Full article

Three diaryliodonium dicyanoargentates(I), [MesIAr][Ag(CN)₂] (Ar = Ph 1, Mes 2, 4-MeC₆H₄ 3; Mes = 2,4,6-Me₃C₆H₂), were prepared by anion metathesis. The X-ray structural analyses for these crystals revealed C–I^III∙∙∙N≡C halogen bonds (abbreviated as XB) between I atoms of diaryliodonium cations and N atoms of cyano groups, which provide different supramolecular organization. The noncovalent nature of these interactions was studied by density functional theory (DFT) calculations and topological analysis of the electron density distribution in the framework of the quantum theory of atoms in molecules (QTAIM) at the PBE-D3/jorge-DZP-DKH level of theory both in gas phase and crystal models. The philicities of partners in these contacts were confirmed by electron localization function (ELF) projections, electron density/electrostatic potential (ED/ESP) profiles, and Hirshfeld surfaces analysis. An analysis of the available crystallographic data from the literature allows us to find other examples of σ-hole interactions including the dicyanoargentate(I) anion, and the C–X∙∙∙N≡C (X = Br, I, Te) bonding were also confirmed theoretically. Full article

A detailed characterization of metal clusters bound at the surface of crystalline metal oxide supports is crucial for identifying their structure–property relationships relevant to practical applications. Theoretical investigations based on first-principles calculations have proven to be helpful in characterizing supported metal clusters. In this work, the adsorption of an Sn dimer on the regular and defective (100) surfaces of MgO crystal was studied by means of density functional theory (DFT) calculations. The investigated defects included ${\mathrm{F}}_{\mathrm{s}}^0$, ${\mathrm{F}}_{\mathrm{s}}^{+}$, and ${\mathrm{F}}_{\mathrm{s}}^{2+}$ oxygen vacancies on MgO(100). From the results of the calculations, it is clear that the adsorption of Sn₂ at the ${\mathrm{F}}_{\mathrm{s}}^0$ and ${\mathrm{F}}_{\mathrm{s}}^{+}$ centers is stronger than that occurring on the defect-free MgO(100) surface. While the triplet spin multiplicity of a free Sn dimer tends to be preserved upon its adsorption at the ${\mathrm{F}}_{\mathrm{s}}^{2+}$ center, spin quenching is favored for the dimer adsorbed at the regular O²⁻ and defective ${\mathrm{F}}_{\mathrm{s}}^0$ and ${\mathrm{F}}_{\mathrm{s}}^{+}$ centers. The topological analysis of the electron density for the adsorbed dimer was carried out within the quantum theory of atoms in molecules (QTAIM). The calculated values of QTAIM parameters for the Sn-Sn bond of the adsorbed dimer do not differ radically from the corresponding values for the dimer in the gas phase. Full article

2-Hydroxy-3-methoxybenzaldehyde semicarbazone (HMBS) is a multidentate ligand with interesting coordination behavior that depends on the central metal ion and the overall complex geometry. In this contribution, the structural characteristics of five HMBS-containing complexes with different metal ions (Dy, Er, Ni, and V) were investigated. Four binuclear and one mononuclear complex were selected from the Cambridge Structural Database. The crystallographic structures and intermolecular interactions in the solid state were analyzed, and the effect of central metal ions was elucidated. The different contributions of the most numerous contacts were explained by examining additional ligands in the structure. Density functional theory (DFT) optimizations were performed for the selected complexes, and the applicability of different computational methods was discussed. The Quantum Theory of Atoms in Molecules (QTAIMs) approach was employed to identify and quantify interactions in nickel and vanadium complexes, highlighting the role of weak intermolecular interactions between ligands in stabilizing the overall structure. Molecular docking studies of the interaction between these complexes and Human Serum Albumin (HSA) demonstrated that all compounds bind within the active pocket of the protein. The overall size and presence of aromatic rings emerged as key factors in the formation of stabilizing interactions. Full article

We investigated Im-3m H₃S at 200 GPa, a pressure regime where crystalline H₃S is widely considered to be a superconductor. Simulated circularly polarized 10 femtosecond (fs) laser pulses were applied and we quantified the effects on the electron dynamics both during the application of the ultra-fast laser pulse and 5.0 fs after the pulse was switched off. In addition, the carrier-envelope phase (CEP) angle ϕ, which quantifies the relationship between the time-varying direction of electric (E)-field and the amplitude envelope, is employed to control the time evolution of the wavefunction ψ(r). This is undertaken for the first application of Next Generation Quantum Theory of Atoms in Molecules (NG-QTAIM) to the solid state. Ultra-fast phenomena related to superconductivity are discovered in the form of a geometric Berry phase angle associated with the H--H bonding in addition to very high values of the chirality–helicity function that correspond to values normally found in chiral molecules. Future applications are discussed, including chiral spin selective phenomena in addition to high-temperature superconductivity and organic superconductors where phonons do not play a significant role. Full article

The present work deals with the computational study of HC₃N$··$HCN$··$H₂C₂-, (HC₃N)₂$··$H₂C₂-, and HC₃N$··$(H₂C₂)₂-mixed trimers. The different equilibrium structures of the different low-lying minima on the corresponding potential energy surface (PES) were accurately determined, and the relative stabilities were computed by extrapolation procedures to the complete basis set limit. For each mixed trimer, the non-covalent interactions ruling the structure of the most stable isomer were analyzed using the QTAIM (Quantum Theory of Atoms in Molecules) approach. Additional insights into these interactions were provided by the Natural Bond Orbital (NBO) and Symmetry-Adapted Perturbation Theory (SAPT) methods. These results can be used to assist further theoretical investigations and experimental studies on the formation of larger molecules potentially relevant in astrochemistry. Full article

Synthetic mimics of the active site of [FeFe]-hydrogenase enzymes are important in the context of catalytic hydrogen production for future energetic applications. Providing a detailed quantum chemical description of the catalytic center of such mimics contributes to a better understanding of their behavior in hydrogen production processes. In this work, the analysis of bonds in the butterfly [2Fe2S] core in a series of complexes based on recently synthesized [FeFe]-hydrogenase mimics has been carried out using a wide range of quantum chemical topological methods. This series includes hexacarbonyl diiron dithiolate-bridged complexes with the bridging ligand bearing a five-membered carbon ring functionalized with diverse groups. The quantum theory of atoms in molecules (QTAIM) and the electron localization function (ELF) provided detailed characteristics of Fe–Fe and Fe–S bonds in the [2Fe2S] core of the complexes. A relatively small amount of strongly delocalized electron charge is attributed to the Fe–Fe bond. It was established how the topological parameters of the Fe–Fe and Fe–S bonds are affected by the five-membered carbon ring and its functionalization in the bridging dithiolate ligand. Next, one of the first applications of the interacting quantum atoms (IQA) method to [FeFe]-hydrogenase mimics was presented. The pairwise interaction between the metal centers in the [2Fe2S] core turns out to be destabilizing in contrast to the Fe–S interactions responsible for the stabilization of the entire core. Full article

The alkoxycarbonylation of styrene by palladium chloride is studied employing the density functional theory (DFT). Initially, [PdCl₃]^– reacts with methanol to form the methoxy-bound intermediate, which undergoes β-hydride elimination to form the key intermediate [PdCl₂H]^–. Then, a 1,2-insertion reaction to styrene takes place to form linear and branched alkyl coordinated with the Pd^II. Then, CO coordination followed by a 1,1-insertion reaction leads to the formation of acyl intermediate. Next, the methanolysis leads to the formation of esters. Previous reports with other catalysts suggested the intermolecular/intramolecular transition state (TS) formation with a high activation barrier, and this step was the bottleneck. To the best of our knowledge, this is the first time we have considered a two-step mechanism for the alcoholysis of the ester formation mechanism. After coordination with the metal, the methanol undergoes oxidative addition to form the Pd^IV square pyramidal intermediate, followed by reductive elimination to form the ester with regeneration of the metal hydride active intermediate. Deeper insight into the nature of bonding at the TSs is obtained through energy decomposition with natural orbital for chemical valence (EDA-NOCV) and quantum theory of atoms in molecules (QTAIM). Full article