Search Results (455)

1-Phenyl-4-p-tolyl-[1,2,3]triazole was obtained via a CuAAC reaction involving phenyl azide and 1-ethynyl-4-methylbenzene. The NMR spectra of the compound are discussed, and its crystal structure was studied by X-ray analysis. According to the latter analysis and a Hirshfeld surface analysis, the predominant intermolecular C-H⋅⋅⋅N and C-H⋅⋅⋅π interactions in this molecule are responsible for crystal packing. 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

We present a modular building block strategy for synthesizing phosphonated polyaromatic systems as an alternative to the conventional late-stage phosphonation of prefabricated aromatic scaffolds, which often requires harsh conditions and has limited tolerance for functional groups. A monophosphonated biphenyl building block was obtained via nickel-catalyzed phosphonation of dibromobiphenyl at 170 °C for three hours. This synthesis is more economical and milder than typical high-temperature palladium systems. In parallel, a borated pyrene derivative was prepared by Suzuki–Miyaura borylation. The final palladium-catalyzed Suzuki cross-coupling reaction produced the target compound, octaethyl(pyrene-tetrakis(biphenyl))tetrakis(phosphonate), Et₈-PyTPPE. Single-crystal X-ray diffraction reveals a centrosymmetric molecule that crystallizes in the triclinic space group P–1, with the inversion center located at the central C–C bond of the pyrene core. The pyrene unit is essentially planar, while the biphenylphosphonate arms are highly twisted relative to the core and to each other. The crystal packing is dominated by weak intermolecular interactions, and no significant π–π stacking is observed. Hirshfeld surface analysis shows that H···H (60.5%) and C···H (22.5%) contacts predominate, while O···H interactions (14.4%) with phosphoryl oxygen atoms represent the most relevant directed contacts. From photophysical investigations, Et₈-PyTPPE exhibits blue fluorescence (λ_em. = 452 nm) in solution and aggregation-induced red-shifted emission with nanosecond lifetimes in the solid state, confirming purely fluorescent behavior. 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

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