The role of π–π, C–H⋯halogen, and halogen⋯π interactions in the crystal packing of 9-aminoacridinium 3-halobenzoate salts: an experimental and theoretical investigation

The title compound, C 23 H 16 O 2 S 2 , is a benzo[ b ]thiophene-2-carboxylate derivative and consists of naphthothiophene and benzothiophene moieties bridged by a methylene group. The dihedral angle between the two aromatic ring systems is 88.5 (2)°. Intramolecular C—H...O interactions generate an S (6) ring motif. The acetate group assumes an extended conformation. Weak C—H...π and π–π stacking interactions are present in the crystal structure, together with a short S...S interaction of 3.77 (8) Å. A Hirshfeld surface analysis indicates that H...H interactions contribute the most to the crystal packing (34.9%).Please give email addresses for all authors

Synthesis-controlled polymorphism in bis(Benzylammonium) Tetrathiocyanatocobaltate(II): Distinct crystal packing (C2/c vs. P21) dictates band gap energy and superior antimicrobial performance with computational investigation

A synergistic investigation on halogen driven piperidine derivatives as caix inhibitors: From crystal packing to docking analysis

The rational design of stimuli-responsive organic room-temperature phosphorescence (RTP) materials is often hindered by an incomplete understanding of the intricate interplay between molecular structure, crystal packing, and excited-state dynamics, particularly in polymorphic systems. Clarifying how subtle structural variations govern photophysical properties is crucial for advancing tunable luminescent materials. Herein, we systematically investigate the dual-emission mechanism and pressure-responsive behavior of a polymorphic RTP material, BrTA-F, in its two crystalline phases (Cry-A and Cry-B), using density functional theory (DFT) and time-dependent density functional theory (TDDFT) combined with quantum mechanics and molecular mechanics methods (QM/MM) and thermal vibration correlation function (TVCF) methods. The results reveal that the distinct spatial distribution of fluorine (F) atoms modulates intermolecular interactions and molecular planarity, leading to different hydrogen bond strengths and excited-state characteristics between the two polymorphs. The dual-RTP emission in Cry-B is attributed to competitive radiative decay from the monomeric first (T1) and second (T2) triplet excited state, which is facilitated by enhanced spin orbit coupling (SOC) resulting from variations in n-π*/ππ* transition proportions. Furthermore, Cry-A demonstrates high sensitivity to hydrostatic pressure, which tunes the emission wavelength and decay rates by compressing the lattice and altering intermolecular force balances. This work provides fundamental insights into the structure-property relationships in polymorphic RTP systems and offers guidance for designing stimuli-responsive luminescent materials.

The reaction of 1,1-bis-(carboxymethylthio)-1-phenylethane with piperidine was conducted in an acetone solution at a molar ratio of the initial components of 1:2. As a result, a new compound was obtained: piperidinium-1,1-bis-(carboxymethylthio)-1-phenylethane, characterized by FT-IR. The crystal structure of the synthesized compound is structurally elucidated via single crystal XRD technique, indicating that a H-atom is transferred from half of the piperidinium-1,1-bis-(carboxymethylthio)-1-phenylethane part to the piperidine ring and the structure is a salt in nature. N–H ⋯ O and C–H ⋯ O bondings contribute to the stability and enforcement of crystal packing; further assessment is supported via Hirshfeld surface analysis, considering interatomic contacts. We employed density functional theory (DFT)-based computations along with molecular dynamics (MD) simulations in a systematic manner, aiming for the investigation of the stabilizing interactions and electronic characteristics of the molecular ionic compound. The structural framework is notably stabilized by dual N–H···O hydrogen bonding, originating from piperidine rings positioned on either side of the central fragment. Electronic structure analysis revealed intermolecular charge transfer characteristics through HOMO–LUMO orbital distributions, complemented by TD-DFT studies of excited state behavior. Furthermore, ab initio MD simulations at 300 K conclusively demonstrated the ionic compound's robust kinetic and dynamic stability.

The title compound, (C3H5N2)4[Co(C3H4N2)6](C9H3O6)2·2H2O (1), was synthesized by slow evaporation of mixed ethano-lic solutions of CoCl2, benzene-1,3,5-tri-carb-oxy-lic acid (H3btc) and imidazole (Im) at room temperature. The crystal structure comprises [Co(Im)6]2+ cations, btc3- anions, Im+ cations and water mol-ecules in a 1:2:4:2 ratio. The crystal packing shows alternating layers stacked along the c-axis direction, linked primarily by hydrogen bonds of the types N-H⋯O (between cations and anions) and O-H⋯O (between anions and water mol-ecules).

Abstract Three novel phosphor/thiophosphor-amides, [(5-CH 3 )- 2 Py-NH] 2 [C 6 H 11 (CH 3 )N]P(X) (X = O ( 1 ) and S ( 2 )) and [(5-CH 3 )- 2 Py-NH]P(O)[OCH 2 C(CH 3 ) 2 CH 2 O] ( 3 ), were synthesized and characterized by FT-IR and 1 H/ 13 C/ 31 P-NMR spectroscopy. The structures of 1 and 3 were determined by using single-crystal X-ray diffraction (SC-XRD) crystallography which reveals both compounds to crystallize in monoclinic space groups ( P 2 1 / c and P 2 1 / n , respectively). A crystal packing analysis shows that neighbouring molecules are connected together via N–H⋯O═P hydrogen bonds forming one-dimensional chains. A Hirshfeld surface analysis indicates that crystal packing is dominated by H⋯H, H⋯O/O⋯H, H⋯C/C⋯H, and H⋯N/N⋯H contacts, with O⋯H/H⋯O interactions including the classical N–H⋯O═P hydrogen bonds being particularly favored. Phosphor/thiophosphor-amide derivatives are emerging as promising scaffolds for targeting key enzymes of acetylcholinesterase (1EEA, 5FPP) and urease (2UBP, 4GY7). Molecular docking revealed favorable binding affinities (up to −10.3 kcal/mol for 1 with 1EEA), with compounds 1 and 2 generally exhibiting stronger predicted interactions than compound 3 . Key stabilizing interactions involve phosphoryl/thiophosphoryl groups and pyridine rings. Redocking of co-crystallized ligands with RMSD assessment confirmed the reliability of the docking protocol. While these results do not provide definitive evidence of inhibitory potency, they support further computational refinement and experimental evaluation, highlighting the potential of these derivatives as enzyme-interacting agents with biomedical relevance.

Copper-based hybrid halides have attracted growing interest as tunable luminescent materials with diverse coordination architectures. Herein, a series of copper bromide-based hybrids were synthesized featuring distinct architectures: (MEP)(Cu2Br4)0.5 (M1), (MEP)(Cu4Br6)0.5 (M2), and (MEP)8(Cu4Br6)4 (M3, MEP = Methyltriphenylphosphonium). All compounds exhibit broad-band emissions at room temperature, spanning green to orange. Systematic structural and photophysical analyses demonstrate that variations in Cu-Br coordination geometry, cluster distortion, and crystal packing critically regulate electron-phonon coupling, exciton localization, and metallophilic interactions, thereby leading to markedly different photoluminescence quantum efficiencies (PLQYs) and environmental stabilities. Among them, M2 possesses the highest PLQY and superior stability, which is attributed to its higher lattice rigidity, symmetric cluster geometry, and compact organic-inorganic framework. In addition, in situ high-pressure measurements suggest M2 is highly sensitive to pressure. As the pressure increased to 4.1 GPa, M2 shows a three-stage fluorescence response, and no phase transition was observed, demonstrating its excellent structural stability and high-pressure tunable optical response. Moreover, M2 was further applied in multifunctional demonstrations, including latent fingerprint visualization, fluorescent writing, and white light-emitting diode (WLED). This study uncovers the correlation between structure and photophysical behavior, providing a basis for developing efficient, lead-free, and multifunctional luminescent materials.

The luminescent and magnetic properties of trivalent lanthanides (Ln3+) are indispensable for many emerging technologies, but exacting fine control over these properties requires an understanding of how to purposefully engineer the coordination geometry and site symmetry of Ln3+ centres. Here, we use the Cambridge Structural Database to extract the structures of 12,670 eight-coordinate Ln3+ centres and use Continuous Shape Measures, Continuous Symmetry Operation Measures, and a new structural similarity-based network analysis to survey geometry and structure trends. This survey is then leveraged to deliver concrete strategies for controlling the coordination geometry of eight-coordinate Ln3+ centres using familiar concepts like Ln3+ metal size and ligand denticity, bite angle, flexibility, shape, symmetry, and size. Ultimately, we present a roadmap for targeting each of the six common eight-coordinate geometries - hexagonal bipyramidal, cubic, square antiprismatic, dodecahedral, bicapped trigonal prismatic, and snub disphenoid - which are each demonstrated to have unique use-cases in diverse research areas. The effects of crystal packing and non-covalent interactions are also illustrated, allowing fine-grained control over the geometry and symmetry of Ln3+ centres. This work ultimately serves to inform the deliberate design of Ln3+ coordination complexes and materials for applications including data-storage, quantum information processing, lighting, thermometry, and medical bioimaging.

Noncovalent Interactions and Crystal Packing Chromono-3-carboxylic Acid Esters and Their Triazole Derivatives: A Combined Experimental and Theoretical Study

In the title compound, [Eu(C13H12F3O3)3(C2H5OH)(H2O)], the tris-[4,4,4-tri-fluoro-1-(4-propoxyphen-yl)butane-1,3-dionato(1-)]europium(III) complex is augmented by ethanol and water mol-ecules as neutral co-ligands, leading to a coordination number of 8 of the central EuIII ion. In the crystal structure, O-H⋯O hydrogen bonding involving ethanol and water as donor and meth-oxy O atoms as acceptor groups consolidates the crystal packing. The complex has been characterized by positive ion FAB-MS and luminescence spectroscopy.

In the title salt, (C2H4N3S)2[MnCl2(C3H2O4)(H2O)2], the central MnII atom of the complex anion adopts a distorted octa-hedral coordination environment, defined by two aqua, two chlorido, and one bidentate malonato ligands. The anion is charge balanced by two thia-diazole moieties protonated at one of the heterocyclic N atoms. In the crystal, the cations and anions engage in extensive hydrogen-bonding inter-actions and short S⋯Cl contacts; additional π-π stacking inter-actions are present between adjacent cations. Hirshfeld surface analysis was used to qu-antify the inter-molecular inter-actions of the complex anion, revealing that H⋯O, H⋯Cl, and H⋯H inter-actions contribute most to the crystal packing.

ABSTRACT Dynamic polymers represent a versatile class of materials that reversibly change their structure and properties in response to external stimuli. These materials offer unique functionalities for applications in sensors, actuators, coatings, and recyclable systems. Topochemical polymerization, a solid‐state reaction governed by molecular alignment within a crystal lattice, enables regio‐ and stereo‐selective formation of polymers. However, few examples of dynamic linear polymers exist, and coumarin derivatives have not yet been explored under topochemical conditions. In this study, a series of n ‐alkyl bis‐coumarin monomers is synthesized and investigated for their ability to undergo reversible [2π + 2π] cycloaddition. Monomers with butyl and hexyl spacers form photoactive crystals capable of reversible polymerization and depolymerization under 365 nm and 254 nm irradiation, respectively, while the octyl analogue remains inactive due to excessive olefinic spacing. Structural analysis reveals that crystal packing and solvent‐dependent recrystallization critically influence photoreactivity.

We report the single-crystal X-ray diffraction structures of the azo-benzene-bridged aza-18-crown-6 cryptand 7,16-[3,3'-(diazene-1,2-di-yl)bis-(1,3-phenyl-enecarbon-yl)]-1,4,10,13-tetra-oxa-7,16-di-aza-cyclo-octa-decane, C26H32N4O6, 1, and its sodium complex poly[[{μ-7,16-[3,3'-(diazene-1,2-di-yl)bis-(1,3-phenyl-enecarbon-yl)]-1,4,10,13-tetra-oxa-7,16-di-aza-cyclo-octa-deca-ne}bis-{tetra-kis-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]borato}disodium] benzene disolvate], {[Na2(C32H12F24B)2(C26H32N4O6)]·2C6H6} n . The free ligand 1 crystallizes in space group P21/n and adopts an elongated strain-distorted crown conformation with a slightly twisted azo-benzene unit. In contrast, 2 [obtained with sodium tetra-kis-3,5-bis-(tri-fluoro-meth-yl)phenyl borate (NaBArF)] crystallizes in space group P1 and features multiple Na+ centers that assemble into a three-dimensional network in the solid state. Hirshfeld surface analysis was used to provide a complementary, qu-anti-tative description of the dominant inter-molecular contacts governing the crystal packing.

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.

This study offers a comprehensive structure-property correlation of a novel olefin E-1-(4'-pyridyl)-2-(4″-quinolinyl) ethylene (PQE) and its N-methylated derivative (MPQE) and demonstrates how crystal packing, hydration, and conjugation collectively dictate their solid-state photoreactivity and photochromic, thermosalient, photophysical, and electrochemical properties. PQE exhibited a quantitative [2 + 2] photocycloaddition reaction forming its head-to-tail dimer, which further exhibited a reversible cleavage of the cyclobutane ring. Crystals of PQE exhibited a color change under UV light, indicating photochromic behavior. Two different crystal forms, namely, MPQE and hydrated MPQE·2.25H2O, were obtained by tuning the crystallization medium. Despite having suitable stacking of MPQE cations, MPQE·2.25H2O remained photoinert; however, it exhibited a thermosalient behavior due to dehydration-induced lattice strain. MPQE displayed bathochromic spectral shifts in comparison to neutral PQE, indicating the effect of N-quaternization. The dimer, BPBQCB, displayed hypsochromic and hypochromic spectral shifts compared to PQE, for loss of conjugation. Their redox characteristics have been explored. Such observation of multifunctional behavior is rare and offers potentials for various applications.

Crystal structures of three bioactive adamantane-linked 1,2,4-triazoles depicting the influence of sulfur and fluorine atoms in the crystal packing

DNA-stabilized silver nanoclusters (DNA-AgNCs) can be finely tuned through DNA sequence design. Here, we present mutations in a DNA strand that stabilize an [Ag28Cl2]14+ cluster, which remains largely unaltered, as confirmed by spectroscopy and mass spectrometry. The crystal structure of one mutant further reveals previously unseen packing interactions among DNA-AgNCs.

The title compound, C21H15N3O2, contains a nitro-aniline ring and an anthracene ring system bridged over the methyl-ene amino group. The anthracene ring system is essentially planar with an r.m.s. deviation of 0.03 (2) Å and it is oriented at a dihedral angle of 79.70 (5)° with respect to nitro-aniline ring. There is an intra-molecular N-H⋯N hydrogen bond between N atoms of nitro-aniline ring and amino group. In the crystal, N-H-O hydrogen bonds link the mol-ecules into infinite chains along the b-axis direction. π-π stacking inter-actions between the nitro-aniline rings of adjacent mol-ecules with centroid-to-centroid distance of 3.7682 (2) Å and C-H⋯π(ring) inter-actions may help to consolidate the three-dimensional architecture. A Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (35.5%), H⋯C/C⋯H (33.7%) and H⋯O/O⋯H (18.3%) inter-actions.