Search Results (379)

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

The addition of 3-isocyanatopropyltriethoxysilane and 2-aminonaphthalene in THF affords the title compound 1-(naphthalen-2-yl)-3-(3-(triethoxysilyl)propyl)urea 1. A determination of the crystal structure of this naphthyl urea reveals the occurrence of strong intermolecular N-H···O hydrogen bonds, giving rise to a 1D supramolecular ribbon, whose interactions have also been assessed by a Hirshfeld surface analysis. The propensity of 1 to sense halide ions by intramolecular trapping through N-H···Hal bonding was also investigated by UV-vis spectroscopy and fluorescence measurements. Full article

Fulgides are a class of organic compounds that exhibit photochromic behavior in both the solid state and in solution. These compounds have attracted considerable research interest due to their wide range of potential applications, including photochromic eyewear, smart windows, optical switches, data storage, and chemical and biological sensors. Here, we report the synthesis and crystal structures of fulgides bearing four different para-substituents on the phenyl moiety. All four molecules crystallize in space groups containing an inversion center. The distances between the two carbon atoms that would form the single C–C bond in the cyclized products fall within the range of 3.301–3.475 Å. The observed structural variations are attributed to intermolecular interactions based on Hirshfeld surface analysis. The fulgides exhibit photochromism, but they are not expected to display ferroelectric behavior due to their crystallization in centrosymmetric space groups. Full article

2,3,5-triphenyl-2H-tetrazol-3-ium (TPT) chloride was studied through a combination of theoretical methods and experimental data, revealing structural and physical-chemical properties of the hydrate salt, [TPT]Cl·H₂O. The previously reported crystal structure was confirmed, but our study at lower T (100 K vs. 220 K) showed different positions for the two H₂O molecules in the unit cell around the chlorides. One of them (Cl1) is found surrounded by the tetrazole units, which we call the “dry pocket”, in contrast to the other, Cl2, which is involved in a hydrogen bonding cluster that consists of chloride and two water molecules, referred to as the “wet pocket”. Hirshfeld surface analyses showed predominant H⋯H interactions, followed by C⋯H interactions (including C–H⋯Cl/O interactions), and H⋯Cl contacts, which represent the C–H⋯Cl2 hydrogen bonds. Density functional theory (DFT) and (time-dependent) TD-DFT calculations on a molecular model of the compound, benchmarking the three functionals B3LYP, CAM-B3LYP, and PBE1PBE, found excellent agreement with experimental solution data when using the CAM-B3LYP function. UV-Vis absorptions observed at 320 nm, 245 nm, and 204 nm (in MeOH solution) were quite accurately reproduced and assigned. The observed bands were assigned to mixed HOMO–n⟶LUMO+m transitions, involving in all cases the LUMO+1 for the most intense band at 245 nm. Solid-state calculations on the GGA (PBE) level of theory using the CASTEP code and including the Tkatchenko–Scheffler (TS) scheme for the description of long-range interactions gave a good match for the calculated electronic band gap in the solid-state of 3.54 eV compared with the experimental value of 3.12 eV obtained through the Tauc plot method. Full article

The rhenium(I) tricarbonyl complex fac-[Re(CO)₃(5,6-epoxy-5,6-dihydro-1,10-phenanthroline)Br] (ReL) has previously demonstrated promising luminescent properties, enabling its direct application as a probe for walled cells such as Candida albicans and Salmonella enterica. In this new study, we present a significantly expanded and comprehensive characterization of ReL, incorporating a wide range of experimental and computational techniques not previously reported. These include variable-temperature ¹H and ¹³C NMR spectroscopy, CH-COSY, single-crystal X-ray diffraction, Hirshfeld surface analysis, DFT calculations, Fukui functions, non-covalent interaction (NCI) indices, and electrochemical profiling. Structural analysis confirmed a pseudo-octahedral geometry with the bromide ligand positioned cis to the epoxy group. NMR data revealed the coexistence of cis and trans isomers in solution, with the trans form being slightly more stable. DFT calculations and aromaticity descriptors indicated minimal electronic differences between isomers, supporting their unified treatment in subsequent analyses. Electrochemical studies revealed two oxidation and two reduction events, consistent with ECE and EEC mechanisms, including a Re(I) → Re(0) transition at −1.50 V vs. SCE. Theoretical redox potentials showed strong agreement with experimental data. Biological assays revealed a dose-dependent cytotoxic effect on HeLa cells, contrasting with previously reported low toxicity in microbial systems. These findings, combined with ReL’s luminescent and antimicrobial properties, underscore its multifunctional nature and highlight its potential as a bioactive and imaging agent for advanced therapeutic and microbiological applications. Full article

Two crystals of N,N′-bis(phosphonomethyl)-1,4,5,8-naphthalenediimide were grown in the presence of neutral (water) and charged (imidazolium cation) species, yielding [(H₂O₃P)CH₂-(C₁₄H₄N₂O₄)-CH₂(PO₃H₂)]∙H₂O (1) and [C₃H₅N₂][(H_1.5O₃P)CH₂-(C₁₄H₄N₂O₄)-CH₂(PO₃H_1.5)] (2), respectively. The ligand N,N′-bis(phosphonomethyl)-1,4,5,8-naphthalenediimide was synthesized via the condensation of naphthalene-1,4,5,8-tetracarboxylic dianhydride with (aminomethyl)phosphonic acid in N,N′-dimethylformamide or imidazole. The flexible N-methyl phosphonic acid groups adopt a cis configuration in compound 1 and a trans configuration in compound 2. In compound 1, the phosphonate groups engage in extensive hydrogen bonding, as well as with water molecules and π–π stacking, resulting in a three-dimensional closely packed structure. Compound 2 forms a densely packed three-dimensional network stabilized by charge-assisted hydrogen bonding (anion-cation), anion–π interactions, and π–π stacking interactions. Hirshfeld surface analysis was conducted and the associated two-dimensional fingerprint plots were generated to further elucidate the nature and contributions of these noncovalent interactions. Direct bandgap measurements estimated from Tauc plots yielded values of 2.92 eV and 2.85 eV for compounds 1 and 2, respectively, highlighting their potential as promising n-type organic semiconductors. Thermal analysis reveals that compound 2 exhibits greater thermal stability than compound 1. Full article

Four benzyltrimethylammonium (BTMA) salts were successfully prepared: bis(benzyltrimethylammonium) hexachloroplatinate (1), benzyltrimethylammonium tetrachloroaurate (2), bis(benzyltrimethylammonium) tetrachlorocuprate (3), and bis(benzyltrimethylammonium) tetrabromocuprate (4) from benzyltrimethylammonium hydroxide (Triton B). Their crystal structures were determined by single-crystal X-ray diffraction, and the supramolecular architectures were characterized hierarchically. Extended Hirshfeld surface analysis, including enrichment ratio calculations, was performed to evaluate intermolecular interactions. Nonclassical hydrogen bonds, such as C–H^…Cl(Br), involving the anions, contribute to the formation of self-assembled architectures. Additional stabilization arises from π^…π and Cu–Br^…π interactions, particularly in crystals 2 and 4, respectively. Hirshfeld surface analysis showed that H^…H and C^…H/H^…C interactions are the dominant contributors in all crystals. According to enrichment ratio calculations, C^…H/H^…C interactions in 1, 3, and 4; Cl^…H/H^…Cl in 1 and 3; Cu^…H/H^…Cu in 3 and 4; and Br^…H/H^…Br and Br^…C/C^…Br in 4 are statistically favored in the crystal packing. Halogen bonding Cl^…Cl was observed in 1 but does not significantly influence packing. Energy framework calculations indicated that dispersive interactions are favorable in the analyzed crystals. A library of H-bonding supramolecular patterns, including interchangeable synthons, is provided and may guide the rational design of new derivatives with controllable features. Finally, the topology of intermolecular connections and the electronic structure of the benzyltrimethylammonium cation, investigated by quantum-chemical calculations, provide insights into its reactivity. Full article

The rapid emergence of drug-resistant bacteria demands alternative antimicrobial strategies that extend beyond conventional drugs. In this study, we present the synthesis, structural characterization, and antibacterial evaluation of two new 2-chloro-5-nitrobenzoic acid (2Cl5NBH) derivatives: a methylethanolammonium salt (compound 1) and a 2D coordination polymer (compound 2). Structural characterization by single-crystal X-ray diffraction, complemented by Hirshfeld surface analysis, revealed the supramolecular architectures and highlighted the key intermolecular interactions, providing essential insights into the potential role of these compounds in modulating their physicochemical and biological behavior. Antibacterial assays demonstrated that compound 1 exhibited a broad inhibitory profile against both Gram-positive and Gram-negative bacteria. In contrast, compound 2 exhibited selective inhibition against methicillin-resistant Staphylococcus aureus (MRSA) comparable to that of gentamicin. Full article

In this paper, quantum chemical calculations at the DFT/6-311G (d,p) level of theory have been carried out to study the supramolecular structure of dihydropyrimidin-2(1H)-ones. Theoretical studies such as Hirshfeld surface analysis, MEPS (molecular electrostatic potential surface), and HOMO–LUMO calculation were also carried out to obtain the energy gap and to determine the kinetic stability and chemical reactivity. The crystal structure of dihydropyrimidin-2(1H)-ones shows the present of N-H…O and O-H…O hydrogen bonding interactions. The N-H…O bond lengths are 2.102 Å and 2.037 Å, respectively. The theoretical hydrogen bonding interactions were also compared with the available experimental data and found to be closely related. Full article

Background/Objectives: Vector-borne diseases like malaria remain a major global health concern, worsened by insecticide resistance in mosquito populations. Quinoline-based compounds have been extensively studied for their pharmacological effects, including antimalarial and larvicidal properties. Modifying quinoline structures with hydrazone groups may enhance their biological activity and physicochemical properties. This study reports the synthesis, structural characterization, and larvicidal testing of a new series of aryl hydrazones (6a–i) derived from 8-trifluoromethyl quinoline. Methods: Compounds 6a–i were prepared via condensation reactions and characterized using ¹H NMR, ¹⁹F-NMR, ¹³C NMR, and HRMS techniques. Their larvicidal activity was tested against Anopheles arabiensis. Single-crystal X-ray diffraction (XRD) was performed on compound 6d to determine its three-dimensional structure. Hirshfeld surface analysis, fingerprint plots, and interaction energy calculations (HF/3-21G) were used to examine intermolecular interactions. Quantum chemical parameters were computed using density functional theory (DFT). Molecular docking studies were performed for the synthesized compounds 6a–i against the target acetylcholinesterase from the malaria vector (6ARY). In silico ADMET properties were also calculated to evaluate the drug-likeness of all the tested compounds. Results: Compound 6a showed the highest larvicidal activity, causing significant mortality in Anopheles arabiensis larvae. Single-crystal XRD analysis of 6d revealed a monoclinic crystal system with space group P2₁/c, stabilized by N–H···N intermolecular hydrogen bonds. Hirshfeld analysis identified H···H (22.0%) and C···H (12.1%) interactions as key contributors to molecular packing. Density functional theory results indicated a favorable HOMO–LUMO energy gap, supporting molecular stability and good electronic distribution. The most active compounds, 6a and 6d, also showed strong binding interactions with the target protein 6ARY and satisfactory ADMET properties. The BOILED-Egg model is a powerful tool for predicting both blood–brain barrier (BBB) and gastrointestinal permeation by calculating the lipophilicity and polarity of the reported compounds 6a–i. Conclusions: The synthesized arylhydrazone derivatives demonstrated promising larvicidal activity. Combined crystallographic and computational studies support their structural stability and suitability for further development as eco-friendly bioactive agents in malaria vector control. Full article

The crystal structures and vibrational spectra of 5-chloro-7-azaindole (5Cl7AI), 4,5-dichloro-7-azaindole (4,5Cl7AI), and 5-hydroxy-7-azaindole (5OH7AI) were investigated to elucidate how ring substituents modulate intermolecular hydrogen bonding and molecular packing in the solid state. Density functional theory (DFT) calculations were employed to support the interpretation of the spectroscopic data, while Hirshfeld surface analysis provided additional insight into intermolecular contacts. Single-crystal X-ray diffraction revealed that the halogenated derivatives form nearly linear N–H···N hydrogen-bonded dimers or layered arrangements, whereas 5OH7AI adopts a three-dimensional network stabilized by N–H···O and O–H···N interactions. FT-IR and FT-Raman spectra showed that variations in hydrogen-bond topology strongly affect the N–H and O–H stretching regions: the halogenated derivatives exhibit broad, red-shifted bands (3300–2500 cm⁻¹) characteristic of N–H···N hydrogen bonds, while 5OH7AI displays smaller red shifts of the N–H stretching bands accompanied by some additional features from O–H stretching vibrations. DFT calculations at the B3LYP-D3 and ωB97X-D levels reproduced the experimental geometries and vibrational spectra very well, providing detailed insight into the relationship between hydrogen-bond linearity, network dimensionality, and vibrational behavior. Full article

Background/Objectives: Dihydroquercetin, known for its broad biological activities, is a key component in dietary supplements and functional foods. This study aims to identify its novel pure solid forms, advancing understanding of its physicochemical properties and polymorphism. Methods: Systematic screening, preparation, and characterization efforts identified five solvates: dihydroquercetin monohydrate (1:1, S1 and S2), sesquihydrate (1:1.5, S3), dihydrate (1:2, S4), and ACN solvate (1:1, S5), along with one solvent-free phase (S6). Results: The crystal structures of the five solvates were successfully elucidated for the first time. A comprehensive suite of techniques, including single-crystal and powder X-ray diffraction, DSC, TG, and FT-IR, were employed to characterize the solvates and polymorphs. Hirshfeld surface analysis, void map analysis, intermolecular energy calculations, and energy framework methods were utilized to investigate the characteristics of the solvates. The crystal transformation relationships among these forms were also explored. Conclusions: Results demonstrate that O···H interactions dominate the intermolecular forces, accounting for over 35% of the total interactions. Full article

In the present study, we have developed a series of compounds [M(tcm)₂(bix)₄]_n [where M = Co (1), Ni (2), and Cu (3)] using tricyanomethanide (tcm) and 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands. The compounds were characterized by elemental analysis, PXRD, FT-IR and single-crystal X-ray crystallography. Single-crystal X-ray investigation of compounds 1, 2, and 3 shows the formation of the porous 2D structure. These 2D structures are further stacked to create a 3D network in the crystallographic space. All the compounds are thermally stable up to 300 °C, as revealed by the TGA. Hirshfeld surface analysis was carried out, and it reveals the existence of short intermolecular interactions between the layers. Full article

The reactions of UO₂(NO₃)₂·6H₂O or UO₂(O₂CMe)₂·2H₂O and 2,2′-{(1,2-ethanediyl)bis[nitrilo(phenyl)methylidene]}bisphenol (H₂L) in MeOH and DMF have provided access to complexes [UO₂(L)(MeOH)] (1) and [UO₂(L)(DMF)]·DMF (2·DMF), respectively. The molecular structures of the complexes are similar. The central U^VI atom is surrounded by five oxygen and two nitrogen atoms in a distorted pentagonal bipyramidal geometry; the two uranyl oxygen atoms are at the axial positions. Two phenolato oxygen and two imino nitrogen atoms from the tetradentate chelating (1.1111 using Harris notation) L²⁻ ligand are located at the equatorial plane, which is completed by the oxygen atom of a terminally ligated solvent (MeOH, DMF) molecule. Interestingly, the L²⁻ ligand adopts a chair (or stepped) conformation in 1 and a boat conformation in 2·DMF. The supramolecular features of 1 and 2·DMF are distinctly different due to the different H-bonding abilities of coordinated MeOH and DMF, and the presence of an extra-lattice solvent molecule in the latter. The solid complexes were studied by IR, Raman, electronic (UV/Vis), and emission spectroscopic techniques. Complex 1 decomposes in CHCl₃ and DMSO, whereas the molecular structure of 2 is retained in these solvents. A new polymorph of the free ligand, H₂L(B), has also been discovered and its crystal structure is described. Full article

This study presents the synthesis and comprehensive characterization of a novel nitroform salt, bis(2-methyl-3-amino-1,2,4-triazolyl)furoxan trinitromethanide (compound 2), derived from the molecular scaffold of bis-(2-methyl-3-amino-1,2,4-triazolyl)-furoxan (compound 1). The incorporation of the nitroform anion significantly enhances the energetic performance while maintaining moderate stability. Single-crystal X-ray diffraction analysis revealed that compound 2 crystallizes in the orthorhombic space group P2₁2₁2₁ with a density of 1.712 g·cm⁻³. Although its crystal packing adopts a less optimal zigzag-type mixed stacking mode and exhibits uneven electrostatic potential distribution, an extensive intramolecular hydrogen-bonding network contributes to its structural stability, as evidenced by a thermal decomposition temperature of 141 °C and impact sensitivity of 17 J. Detonation parameters calculated using EXPLO5 software demonstrate superior performance (detonation velocity = 8271 m·s⁻¹, detonation pressure = 26.9 GPa) compared to TNT and close proximity to RDX, coupled with markedly improved mechanical stability over both RDX and HMX. Hirshfeld surface and electrostatic potential analyses further elucidate the relationship between molecular structure and sensitivity, highlighting the critical role of hydrogen bonding in moderating mechanical sensitivity despite high energy content. These results underscore the potential of nitroform functionalization for designing advanced energetic materials with balanced performance and safety. Full article