Search Results (515)

In this study, the applicability of achiral column chromatography—including both medium-pressure liquid chromatography (MPLC) and classical gravity-driven techniques—was evaluated as a laboratory method for enantiomeric enrichment of scalemic (non-racemic) samples of axially chiral compounds. As model substrates, 3-(ortho-substituted-phenyl)quinazolin-4-one derivatives were employed. The results confirmed that self-disproportionation of enantiomers (SDE), occurring during column chromatography (SDEvCC), enabled the efficient isolation of enantiomerically pure fractions, with MPLC demonstrating particularly high effectiveness. Additionally, the parameters governing gravity-driven column chromatography were systematically optimized, with particular attention to variables such as eluent type and concentration, stationary phase composition, sample preparation protocol, and solvent purity. Furthermore, leveraging known crystallographic data and quantum chemical calculations based on Density Functional Theory (DFT), a molecular association mechanism was proposed to elucidate the physicochemical basis of the SDE phenomenon. Full article

A series of Group 10 metal dithiocarbonate complexes [M(S₂COⁱPr)₂] (M = Ni 1, Pd 2, Pt 3) was prepared following procedures from the literature and cocrystallized with the ditopic σ/π-hole donor 1,4-diiodotetrafluorobenzene. Single-crystal X-ray diffraction revealed a consistent I···S halogen bonding motif alongside a remarkable diversity in metal-involving interactions across the Ni–Pd–Pt triad. While nickel(II) exhibits strong electrophilic M···S semicoordination, the palladium(II) center displays ambiphilic behavior, and platinum(II) acts exclusively as a nucleophile via π-hole···M bonding. Comprehensive density functional theory studies, including molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules/noncovalent interaction plot analyses, and energy decomposition analysis, were used to quantify this competitive balance. The results demonstrate that the increasing nucleophilicity from Ni to Pt, supported by shifting MEP minima and stronger π-hole stabilization energies, dictates the preference for nucleophilic over electrophilic metal-centered contact. Full article

To investigate the potential of halogen-containing building blocks in the development of artificial carbohydrate receptors, the 1,3,5-trisubstituted 2,4,6-triethylbenzene scaffold with halogenated subunits and classical hydrogen bonding sites was used as a model system. In the first studies, the influence of the presence of halogens on the binding properties of compounds bearing benzamidomethyl units was investigated, whereby the type of halogen and its ring position were varied. The question was whether the presence of halogens could lead to an increase in binding effectivity and whether this increase can be attributed to the formation of halogen bonds (especially for X = Br and I in ortho position) with the sugar substrate or to other effects. The binding studies revealed some interesting relationships between structure and binding affinity for the tested compounds 1–9. For those bearing the halogen substituent in the ortho position to the amide functionality, the binding affinity increases in the expected order 4 (o-F) < 3 (o-Cl) < 2 (o-Br) < 1 (o-I). In the presence of small amounts of water in CDCl₃, an increase in binding strength was observed in comparison to experiments conducted in dry CDCl₃. The present studies aim to provide impulses for the use of halogenated building blocks in the design of artificial carbohydrate receptors. Optimizing the type of halogenated units and the receptor architecture should result in more effective carbohydrate receptors capable of functioning effectively in aqueous media through a combination of different noncovalent interactions. Full article

The molecular electrostatic surface potential (MESP) has become a key theoretical tool for probing reactivity in chemical systems. It reveals electrophilic and nucleophilic regions on molecular surfaces, underpinning the understanding of noncovalent interactions such as hydrogen, triel, tetrel, pnictogen, chalcogen, halogen, matere, and aerogen bonding, among many others. These interactions, driven by Coulombic attraction, govern aggregation in molecular and supramolecular systems across solid, liquid, and gas phases. MESP applications span crystal engineering, polymers, biology, catalysis, photovoltaics, and drug discovery. While limitations exist—such as the arbitrariness in defining isodensity surfaces—its impact on advancing both theoretical and applied chemical research is substantial. This review outlines the conceptual foundations of MESP and highlights its broad relevance across the chemical sciences. Full article

One-dimensional hybrid organic–inorganic semiconductors enable band-edge engineering through reduced dimensionality and interfacial orbital hybridization. Nevertheless, the electronic physics of Cu/Ag-based systems has received limited attention. Here, we perform high-throughput first-principles calculations on 90 Cu/Ag halide HOISs derived from experimentally reported parent structures to elucidate bonding-dependent electronic behavior. We uncover a clear transition from electronically isolated inorganic chains in ionic hybrids to strongly hybridized band edges in covalent and mixed-bonding hybrid frameworks, where ligand p orbitals cooperatively couple with Cu-derived states and halogen p orbitals. This hybridization produces p-orbital-dominated band edges, enhanced dispersion, and light-hole effective masses along the 1D chains. Guided by this bonding-driven mechanism, we further identify four Cu-based compounds, which are helpful for tuning light-harvesting properties in low-dimensional hybrid semiconductors. Full article

Highly polar M-mol-X (M = alkali metal, mol = molecule, X = halogen) insertion complexes have been predicted to offer potential practical applications, including molecular interactions with light, ion-pair induced isomerization, etc. In the present work, the insertion complexes of the seven-membered, fused bicyclic norcaradiene and its monocyclic isomer trapped in Li-I, Na-I, and K-I counterion pairs were investigated using ab initio methods. The structures, stability, polarities, and simulated infrared spectra are analyzed and the effects of the insertion on the norcaradiene to cycloheptatriene isomerization process are examined. Furthermore, an uncommon bond between iodine and a fully substituted carbon atom is reported upon and hypothesized to be catalyzed by the presence of the cation in the insertion complexes. Full article

Two novel cocrystals of zwitterionic trimethylglycine (TMG) with 2,6-dichlorophenol [TMG•2,6-dichlorophenol] (1:1) and 2,6-dibromophenol [TMG•2,6-dibromophenol] (1:2) are synthesized and structurally characterized using single crystal X-ray diffraction. To estimate the energy of various intermolecular interactions, periodic DFT calculations were performed followed by Bader analysis of the crystalline electron density. TMG molecules form dimers in [TMG•2,6-dichlorophenol] (1:1). Its supramolecular structure is governed by the primary charge-assisted H-bonds (~60 kJ/mol) and supported by C–H∙∙∙O contacts (~12 kJ/mol). Cl/Br substitution introduces a more potent halogen-bonding donor. The Br∙∙∙O⁻ interaction (~10 kJ/mol) is strong enough to reorganize the packing into a catemeric motif. As a result, TMG molecules form infinite chains in [TMG•2,6-dibromophenol] (1:2). This illustrates that “fine tuning” is not merely about changing distances, but about shifting the entire energy hierarchy of the crystal. Two-dimensional fingerprint diagrams (2D diagrams) obtained from the Hirshfeld surface and Bader’s analysis of the crystalline electron density give significantly different values of the contributions of the H∙∙∙H contacts, 28% vs. 5% respectively. The main reason for this discrepancy is the large number of relatively short intermolecular H∙∙∙H contacts without a critical bond point in trimethylglycine cocrystals. Full article

This paper systematically studied the structural, mechanical, electronic, and optical characteristics of cubic KZnX₃ (X = F, Cl, Br, and I) perovskites through the density functional theory (DFT) in the Quantum Espresso framework. Structural optimization and stability analyses confirm that all compounds crystallize in the cubic Pm-3m phase and are thermodynamically, mechanically, and dynamically stable. Elastic constants indicate that the materials are anisotropic and ductile in nature. Calculations of Debye temperatures show a systematic decrease of 402 K (KZnF₃) to 158 K (KZnI₃), which is related to the increasing mass of halogen and its impact on the rigidity of the lattice. Electronic structure calculations show that all compounds are indirect bandgap semiconductors, with bandgaps systematically decreasing from 4.24 eV (KZnF₃) to 0.86 eV (KZnI₃) at the HSE06 level, enabling tunable semiconducting characteristics for optoelectronic applications. The analysis of the density of states and charge density indicates that the bonding between Zn and X is mixed ionic and covalent and that the bonding between K and X is mostly ionic. Calculations of optical properties show an increase in polarizability, absorption, refractive index and plasmonic response when heavier halogen is used, highlighting the potential of KZnX₃ perovskites for photovoltaic and optoelectronic devices. Overall, halogen substitution in KZnX₃ provides an effective strategy for tailoring electronic and optical properties. Full article

Phenothiazine is a heteroaromatic molecule capable of various noncovalent interactions, including halogen bonding and π-stacked association. Despite its broad use in functional materials and pharmaceutical ingredients, a systematic comparison of these interaction modes has been lacking. Here, we report a combined experimental and computational study of intermolecular interactions of phenothiazine with a prototypical halogen-bond (HaB) donor (tetrabromomethane), planar π-electron acceptors (tetracyanopyrazine and tetrafluoro-p-benzoquinone), and multifunctional species capable of both interaction types (iodo- and bromo-3,5-dinitrobenzenes). X-ray structural analysis revealed that CBr₄ forms exclusively C–Br···π halogen bonds with the aromatic rings of phenothiazine, whereas all π-acceptors yield alternating donor–acceptor stacks characterized by multiple short contacts indicative of multicenter interactions. Notably, co-crystals of iodo- and bromodinitrobenzenes with phenothiazine display only π-stacked architectures. Density-functional calculations showed that isolated HaB complexes involving N, S, or π sites of phenothiazine possess comparable binding energies (≈−3 kcal mol⁻¹), whereas π-stacked complexes are substantially stronger (≈−9–12 kcal mol⁻¹). QTAIM, NCI, NBO, and energy-decomposition analyses indicated that while amounts of charge transfer in halogen-bonded and π-stacked complexes are comparable, the enhanced stability of the latter originates primarily from a large dispersion contribution. These results rationalize the solid-state preference for π-stacking over halogen bonding in systems where both motifs are accessible and clarify the hierarchy and physical origin of noncovalent interactions involving phenothiazine, providing guidance for the design of supramolecular assemblies and functional materials based on this versatile electron donor. Full article

This study investigates the rational design of a dinuclear zinc(II) coordination polymer, (C₃₆H₃₄Br₂N₈O₄S₂Zn₂), to explore how halogen substitution and ligand choice modulate structural architecture, contributing to the development of functional coordination polymers with tailored properties. The complex was synthesized from a bromo-substituted semicarbazone Schiff base ligand (L1) and a rigid bipyridine linker (L2) under solvothermal conditions, and its structure was elucidated using single-crystal X-ray diffraction (SCXRD), complemented by characterization via powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. Crystallographic analysis reveals that the complex crystallizes in the triclinic space group P-1, forming discrete dinuclear units where each Zn(II) center adopts a distorted square–pyramidal geometry; these units are extended into one-dimensional chains by bridging L2 ligands and further assembled into a three-dimensional supramolecular network through hydrogen-bonding interactions. PXRD confirms the high phase purity of the bulk material, TGA indicates notable thermal stability up to 130 °C, and IR spectroscopy validates the coordination modes and hydrogen-bonding network. This work elucidates the critical role of the bromo substituent and rigid ancillary ligands in modulating the solid-state structure of the zinc(II) complex. The revealed structure-directing principles provide a valuable reference for the rational design of functional coordination polymers. Full article

Pirimicarb is a carbamate insecticide, widely used due to its specific control effect on aphid populations. However, the European Food Safety Authority conducted a risk assessment and proposed regulatory endpoints for it in October 2024. Therefore, there is an urgent need to develop rapid, sensitive, and convenient rapid detection technologies for pirimicarb. Thus, this study proposes an enzyme-free rapid detection method: using 4,5,6,7-tetrabromo-2′,4′,5′,7′-tetraiodofluorescein (RB2) as a detection probe, since the synergistic effect of halogen and hydrogen bonding between RB2 and pirimicarb (PIB) in acidic aqueous solution induces charge transfer and leads to a distinct color change in RB2, thereby enabling the rapid detection of PIB. This method has good selectivity, and a limit of detection (LOD) of 0.0321 mg·L⁻¹ in aqueous solution is achieved with a visual detection time of less than 60 s for PIB. And the LODs for PIB in cucumber and tomato peel samples are 0.0536 mg·L⁻¹ and 0.0243 mg·L⁻¹, respectively. Importantly, this method does not require enzymes as a vehicle in the detection process; it solely relies on the synergistic effect of halogen and hydrogen bonding between RB2 and PIB to achieve visual identification and detection of PIB, providing a reference method for the rapid detection of PIB. Full article

Water pollution from phenols remains a critical concern due to their persistence, toxicity, and industrial prevalence. Graphene oxide (GOx), with its functional groups and large surface area, offers strong adsorption potential. Using density functional theory (DFT), reduced density gradient (RDG), and quantitative structure–activity relationship (QSAR), we examined how protonation and substituents influence phenol adsorption. Deprotonated phenolates bind more strongly to GO than neutral species via electrostatics and H-bonding. Substituents alter affinity: halogens enhance it, bulky alkyls hinder it, and nitro groups show electron-withdrawing effects. Bisphenolate A displayed multidentate binding. QSAR models reproduced DFT energies with R² > 0.99, enabling fast prediction. These results highlight how pH speciation and substituents govern adsorption on GO, guiding the design of efficient water treatment materials. Full article

The title compound 2-iodopyridin-3-yl acetate was obtained by acetylation of the OH group of 2-iodo-3-hydroxypyridine. Knowing that the hydroxyl group, as a strong H-bond donor in halogenated hydroxypyridines, usually directs supramolecular packing and might enforce possible halogen–halogen contacts, we crystallized 2-iodo-3-acetoxypyridine with the aim of disrupting the most important H-bond donor and assessing the propensity of the iodine for halogen bond formation. Indeed, in the compound 2-iodopyridin-3-yl acetate, the crystal packing is characterized by infinite 3D chains bonded through I···O=C and C-H···I contacts between adjacent molecules. These chains are interconnected by weak C-H···O contacts, implying the presence of oxygen in the ester. The I···H contact with the C-H axis perpendicular to the electron belt of the iodine atom can enhance the σ-hole of the iodine and act cooperatively in crystal cohesion. No halogen–halogen contacts were present. Full article

Objective: Based on our previous findings, we designed new molecules by extending functionalized pyrazole derivatives containing iodine atoms, which are linked via an amino bond to halogen-substituted phenyl groups. In addition, these newly developed pyrazole compounds exhibit anti-tumor, antibacterial, and anti-biofilm activities. Methods: Three new series of pyrazole compounds were designed. Fifteen novel pyrazole derivatives, distributed across three series (4a–d, 5a–d, and 6a–g), were synthesized and structurally characterized by ¹H-NMR, ¹³C-NMR, FTIR, UV-Vis spectroscopy, and elemental analysis. Results: Among them, compound 4c, which exhibited notable anti-tumor activity, crystallized in a monoclinic system and was further analyzed via single-crystal X-ray diffraction. All synthesized compounds were evaluated in vitro on NCTC normal fibroblast cells and HEp-2 tumor epithelial cells. Compound 4c demonstrated significant anti-tumor activity while displaying no cytotoxic effects on normal cells. The antibacterial and anti-biofilm activities of the compounds were also assessed against four bacterial strains. Compounds 5a and 5c exhibited the highest antibacterial activity against Staphylococcus aureus ATCC 25923, both with a minimum inhibitory concentration (MIC) of 0.023 μg/mL. Additionally, compounds 4a, 5a, 6a, 6e, and 6f showed the strongest anti-biofilm effects, each presenting a minimum biofilm inhibition concentration (MBIC) of 0.023 μg/mL. ADME and ADMET in silico predictions indicated that all compounds exhibit generally favorable, drug-like physicochemical properties. Conclusions: The study reinforces the applicability of these compounds as promising anticancer, antibacterial, and anti-biofilm drugs. Full article

By the reaction of AgNO₃, 2-methyl-2-propanethiol (HStBu), with various-sized halogen ions as templates, three multi-nuclear silver-thiolate cluster-based chain-like coordination polymers, [Ag₆(μ-SBu)₆]_n (USC-CP-2), [Ag₆(μ-StBu)₅Br]_n (USC-CP-4) and [Ag₁₄(μ-StBu)₁₂I₂]_n (USC-CP-3) constructed by different Ag(I)-nanocages, have been synthesized and characterized by X-ray diffraction analyses. With F⁻, Cl⁻ or without template, USC-CP-2 exhibits a one-dimensional structure composed of detached Ag₆-cages, absent of fluoride or chloridion. While with Br⁻ and I⁻, USC-CP-4 and USC-CP-3, two distinct halogen-templating multi-sliver cages-based chain-like polymeric structures have been observed, which are a mono-Br⁻ encapsulated Ag₈-cage, or a dual-I⁻ embedded Ag₁₆-cage, respectively. In these three compounds, the multi-Ag(I) cages were self-assembled by Ag-S bonds through bridged μ₂-StBu ligands, and stabilized argentophilic interactions between neighboring silver atoms. This study demonstrates that the halide anions of varying sizes play a critical role in inducing the nucleation and structural evolution of the silver-thiolate clusters. Full article