Packing Interactions Research Articles

Intrinsically Microporous Polyimides Based on a Rigid-Soft Structure for Hydrogen Separation.

Polyimide (PI)-based gas separation membranes are of great interest in the field of H2 purification owing to their good thermal stability, chemical stability, and mechanical properties. Among polyimide-based membranes, intrinsically microporous polyimides are easily soluble in common organic solvents, showing great potential for fabricating hollow fiber gas separation membranes. However, based on the solution-diffusion model, improving the free volume or the movability of polymer chains can improve gas permeability, but would result in poor thermal stability. Herein, we develop a carbazole-alkyl-based diamine monomer that endows PI chains with a "rigid-soft" structure to balance the trade-off between them. Soft units enhance the movability of polymer chains during the film-forming process, ensuring that rigid units achieve tight chain packing and strong intermolecular interactions. Meanwhile, bulky carbazole groups could further restrict the motion of soft units in the solid state. On the one hand, it restricts the movability of the polymer chains below Tg, enhancing the small gas selectivity for H2 and He. On the other hand, it ensures good thermal stability. Moreover, extending the length of the alkyl chains helps improve the free volume and intermolecular interactions simultaneously, thereby further optimizing the gas permeability/selectivity trade-off. As a result, the as-prepared PI shows H2 permeability of 89.61 Barrer, H2/CH4 selectivity of 87.85, and H2/N2 selectivity of 45.03 in contrast to the reference FPI TFMB-6FDA exhibiting H2 permeability of 92.95 Barrer, H2/CH4 selectivity of 72.62, and H2/N2 selectivity of 38.57. Meanwhile, a high Tg value of 334 °C is also achieved.

Morphological Control of Y6 Thin Films Reveals Charge Transfer Is Facilitated by Co-facial Interactions.

The organic semiconductor Y6 has been extensively used as an acceptor in organic photovoltaic devices, yielding high efficiencies. Its unique properties include a high refractive index, intrinsic exciton dissociation, and barrierless charge generation in bulk heterojunctions. However, the direct impact of the crystal packing morphology on the photophysics of Y6 has remained elusive, hindering further development of heterojunction and homojunction devices. Herein, we study the photogenerated species in multiple distinct Y6 crystal packing geometries via transient absorption spectroscopy and photovoltaic measurements of the corresponding single-component devices. Our results reveal that "co-facial" interactions drive the generation of charge-transfer states in neat films of Y6 and that exciton dissociation can be switched on and off by controlling these interactions. Additionally, we find that a combination of long-range order and more co-facial packing interactions accelerates the charge-transfer generation process and increases the exciton to charge-transfer conversion efficiency. These insights provide valuable structure-property relationships for optimizing device performance.

Crystal structure and Hirshfeld surface analysis of supra-molecular aggregate of 2,2,6,6-tetra-methyl-piperidin-1-ium bromide with 1,2,3,4-tetra-fluoro-5,6-di-iodo-benzene.

The asymmetric unit of the title compound, C9H20N+·Br-·C6F4I2, contains one 2,2,6,6 tetra-methyl-piperidine-1-ium cation, one 1,2,3,4-tetra-fluoro-5,6-di-iodo-benzene mol-ecule, and one uncoordinated bromide anion. In the crystal, the bromide anions link the 2,2,6,6-tetra-methyl-piperidine mol-ecules by inter-molecular C-H⋯Br and N-H⋯Br hydrogen bonds, leading to dimers, with the coplanar 1,2,3,4-tetra-fluoro-5,6-di-iodo-benzene mol-ecules filling the space between them. There is a π-π interaction between the almost parallel benzene rings [dihedral angle = 10.5 (2)°] with a centroid-to-centroid distance of 3.838 (3) Å and slippage of 1.468 Å. No C-H⋯π(ring) inter-actions are observed. A Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯F/F⋯H (23.8%), H⋯H (22.6%), H⋯Br/Br⋯H (17.3%) and H⋯I/I⋯H (13.8%) inter-actions. Hydrogen bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing.

Two Isomeric Thienoacenes in Thin Films: Unveiling the Influence of Molecular Structure and Intermolecular Packing on Electronic Properties.

Isomerism of molecular structures is often encountered in the field of organic semiconductors, but little is known about how it can impact electronic and charge transport properties in thin films. This study reveals the molecular orientation, electronic structure, and intermolecular interactions of two isomeric thienoacenes (DN4T and isoDN4T) in thin films, in relation to their charge transport properties. Utilizing scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARUPS), and near-edge X-ray absorption fine structure measurements (NEXAFS), we systematically analyze the behavior of these isomers from submonolayer to multilayer coverage on highly ordered pyrolytic graphite (HOPG) as substrates. We find that at submonolayer coverage both DN4T and isoDN4T molecules predominantly adopt a nearly flat-lying orientation on the surface, minimizing intermolecular interactions. The distinct emission features of the highest occupied molecular orbital (HOMO) level in ARUPS enables the determination of molecular reorganization energies. These are found to be in good agreement with theoretical predictions, suggesting superior charge transport in DN4T compared to isoDN4T. Notably, thickness-dependent photoemission measurements reveal a significant splitting (approximately 450 meV) of the HOMO level of isoDN4T, attributed to polarization-induced effects rather than wave function overlap, indicating a nuanced interplay between molecular packing and electronic properties. Our results underscore the importance of molecular packing and substrate interactions in determining the electronic structure and transport properties of organic semiconductor thin films. Substrate-induced polymorphism and the crucial role of polarization-induced effects influencing charge transport are highlighted. These insights are pivotal for future engineering of molecular and thin film structures, aiming to enhance the performance of organic semiconductor-based devices.

Theoretical investigations, Molecular Docking, ADMET analysis, Molecular Dynamic Simulation, and Drug-Likeness Scoring of (E)-1-[2-(3,4-Dimethylphenyl) Diazen-2-Ium-1-Yl] Naphthalen-2-Olate as a Corticosteroid Side-Chain-Isomerase Inhibitor

In this article, the optimized structure and their associated properties of the (E)-1-[2-(3,4-Dimethylphenyl)diazen-2-ium-1-yl]naphthalen-2-olate compound (EDNO) were obtained and evaluated using The density functional theory DFT at the (B3LYP/6-311G++(d,p)) level in the gas phase, To quantify the intermolecular interactions, Hirshfeld surface(HS) analysis was used, HS and 2D fingerprints indicate H⋅⋅⋅H (52%) and C− H⋅⋅⋅C (26.7%) as the most relevant intermolecular interactions in the crystal packing of EDNO. the reduced density gradient (RDG) method was used to reveal and distinguish between attractive interactions such hydrogen bonds, repulsive interactions and van der Waals interactions. Further, molecular docking, binding free energy calculations, and ADMET prole of the title compound was carried out to determine the binding affinity and toxicity. A 100 ns molecular dynamics (MD) simulation was performed to evaluate the binding stability of the compound EDNO/2WV2 complex using Desmond. Binding free energy of the complex was computed for 100 trajectory frames using the MM-GBSA approach

Ferrocene Appended Linear Chromophores for Aggregation‐Induced Emission (AIE) and Nonlinear Optics (NLO): Combined Experimental and Theoretical Studies

AbstractNew nonlinear optical (NLO)‐active chromophores, featuring phenyl and methoxy phenyl substitutions at the D‐π‐A motif [(Fc‐C(C6H4‐R) = CH‐CH = C(CN)‐C6H4‐Br)] [R = H (1), OCH3 (2)] are synthesized and structurally analyzed. Chromophore 2 crystallized in a triclinic system (P‐1), consistent with DFT‐optimized structures. Non‐covalent interactions in the crystal packing suppress antiparallel alignment, enhancing SHG efficiencies. Molecular electrostatic potential (MEP) maps reveal structure‐property relationship and electronic communication between donor–acceptor moieties. Both chromophores exhibit suppressed emission in solution due to twisted intramolecular charge transfer (TICT) facilitated by the cyano vinylene group. However, Upon aggregation‐induced emission in a THF/H2O mixture, fluorescence significantly increases, attributed to restricted intramolecular rotation (RIR). Second Harmonic Generation (SHG) efficiencies, measured using the Kurtz–Perry powder technique with potassium dihydrogen phosphate (KDP) as a reference, show chromophore 2 is 1.1 times higher efficiency than chromophore 1. Density functional theory (DFT) derived hyperpolarizability values follow this trend, with chromophore 2 (β0 = 40.39 × 10−30 esu in B3LYP functional) surpassing chromophore 1. DFT and time‐dependent density functional theory (TD‐DFT) calculations employing B3LYP, CAM‐B3LYP, and LC‐BLYP functionals determined second‐order nonlinear optical parameters, B3LYP and CAM‐B3LYP produced values with minimal differences and a close correlation with the experimental results.

Synthesis, crystal structure, Hirshfeld surface analysis, NCI-RDG, molecular docking, molecular dynamic simulations, and toxicity assessment of 2-((2, 4-dimethoxybenzylidene) hydrazono) -1, 2-diphenylethanone

This study reports the synthesis of a hydrazone-like compound with the chemical formula C23H20N2O3. The synthesis involved reacting benzilmonohydrazone with 2,4-dimethoxybenzaldehyde at 85°C for 3 hours. The mixture was cooled, filtered, and washed with ethanol. The resultant solid was then recrystallized in a suitable solvent to isolate the desired product. To investigate the molecular geometrical properties of the 2-(2, 4-dimethoxybenzylidene) hydrazone)-1, 2-diphenylethanone (DBHDE) molecule, both theoretical and experimental methods were employed. Density functional theory (DFT) calculations using the B3LYP functional and a 6-311G (d, p) basis set were performed, and the calculated geometric parameters showed good agreement with the experimental data. In addition, Hirshfeld surface analysis and 2D fingerprint plots indicated that the most significant intermolecular interactions in the crystal packing of DBHDE are H...H (48.8%) and C...H/H...C (28.4%). According to NCI-RDG analysis, the centers of the three benzene rings represent the highest repulsive interaction regions in the molecule. Finally, the biological potential of the synthesized compound was thoroughly evaluated using molecular docking studies, molecular dynamics simulations, in silico ADME-T investigation, and biochemical analyses (cholesterol, creatinine and transaminases) in wistar rats.

A 3D nitrogen-rich heat-resistant supramolecular MOF with superior energetic performances assembled from Zn(II) and 5-aminotetrazole

Heat-resistant explosives are pivotal for specialized applications demanding high thermal stability, essential in both civil and military sectors, especially in extreme environments. Our study focuses on the synthesis of a 3D nitrogen-rich supramolecular energetic metal-organic framework (MOF), Zn(ATZ)2 (1), using the 5-aminotetrazole (HATZ) ligand and Zn(II) ion. Structural analysis indicates that compound 1 adopts the orthorhombic CmCm space group and possesses a robust 2D network, characterized by strong π-π packing interactions between 2D layers, offering exceptional thermal stability up to 322 °C with minimal mechanical sensitivity. The standard molar enthalpy of formation (ΔfHo) and heat of detonation (ΔHdet) for compound 1 are calculated to be 7.08 kJ/g and 7.34 kJ/g, respectively. Remarkably, the ΔfHo of compound 1 significantly exceeds those of traditional heat-resistant explosives like RDX (0.32 kJ/g), HNS (0.17 kJ/g), TNT (–0.295 kJ/g), and TATB (–0.54 kJ/g), and is also higher than those of most reported energetic MOF materials. Similarly, its ΔHdet value surpasses those of common explosives such as TNT (4.144 kJ/g), HMX (5.525 kJ/g) and RDX (5.71 kJ/g), as well as the majority of reported energetic MOFs. Compound 1 also demonstrates impressive detonation properties with a velocity (D) of 7.22 km s-1 and a pressure (P) of 21.95 GPa, outperforming many other energetic MOF materials. These superior energetic characteristics position compound 1 as a strong candidate for heat-resistant explosives, showcasing its potential for future applications in demanding environments.

Discovery of a Series of Macrocycles as Potent Inhibitors of Leishmania Infantum.

Macrocycles are prominent among drugs for treatment of infectious disease, with many originating from natural products. Herein we report on the discovery of a series of macrocycles structurally related to the natural product hymenocardine. Members of this series were found to inhibit the growth of Plasmodium falciparum, the parasite responsible for most malaria cases, and of four kinetoplastid parasites. Notably, macrocycles more potent than miltefosine, the only oral drug used for the treatment of the neglected tropical disease visceral leishmaniasis, were identified in a phenotypic screen of Leishmania infantum. In vitro profiling highlighted that potent inhibitors had satisfactory cell permeability with a low efflux ratio, indicating their potential for oral administration, but low solubility and metabolic stability. Analysis of predicted crystal structures suggests that optimization should focus on the reduction of π-π crystal packing interactions to reduce the strong crystalline interactions and improve the solubility of the most potent lead.

Synthesis, structure and non-covalent interactions of trans-[2-(HCF2(CF2)3CH2OCH2)2-py-PdCl2] complex: Rare C−F⋯F−C halogen bonds and blue-shifting C−H⋯X hydrogen bonds

The sp3-based C−F⋯F − C halogen bonds (XBs) and blue-shifting C−H⋯X (X = F, Cl) hydrogen bonds (HBs) are a relatively unusual phenomenon in chemistry, due to their uncommonness and the challenges associated with their direct observations. To investigate these interactions, a novel fluorinated trans-[2-(HCF2(CF2)3CH2OCH2)2-py-PdCl2], abbreviated as 2-(8FH-py)2PdCl2 complex, has been synthesized and structurally characterized. The incorporation of a fluorinated ponytail on the pyridyl ring in the 2-(8FH-py)2PdCl2 complex allows us to explore rare sp3-based type II C9−F4⋯F6−C10 and C8−F2⋯F6−C10 XBs dimers. These findings suggest, for the first time, the formation of halogen bonding dimers through C−F⋯F−C interactions, to our knowledge. Additionally, the 2-(8FH-py)2PdCl2 reveals interesting blue-shifting C−H⋯X hydrogen bonding interactions in the crystal packing. These C−H⋯F interactions connect adjacent molecules in a head-to-tail manner, resulting in the continuation of R22(9) synthons along the crystallographic a-axis. These hydrophobic interactions, which are expected to be very different from the typical hydrophilic interactions, play a crucial role in enhancing the self-assembly and stability of the crystal structure. In addition, the presence of blue-shifting C−H⋯X hydrogen bonding interactions affirmed by the FT-IR studies. Furthermore, the high positive values of electron density (ρ) and Laplacian density (∇2ρ) from quantum theory of atoms in molecule (QTAIM) analyses suggest the presence of electrostatic and weak interactions between atoms. We believe that this discovery will open up new opportunities for exploring and utilizing fluorinated complexes in various scientific fields, fluoro-pharmaceuticals and crystal engineering.

Investigation of synthesis, spectroscopic characterization, crystal structure, and computational studies of 3-(4-(dimethylamino)phenyl)-1,5-di(thiophen-2- yl)pentane-1,5-dione as potent against Cathepsin S

The chief purpose of this work was to synthesize and characterize 3-(4-(dimethylamino)phenyl)-1,5-di(thiophen-2-yl)pentane-1,5-dione (4) whose structure was subsequently confirmed by single-crystal X-ray analysis. This molecule adopts a conformation approximating a three-bladed fan. In the crystal, C–H···O and C–H···S hydrogen bonds, together with C–H···π(ring) interactions form corrugated layers parallel to the bc plane. Electronic structure calculations were performed at the ωB97xd/def2tzvp level to explore the reactivity and topology of the molecule. Quantum theory of atoms in molecule (QTAIM) and NBO studies provide bonding characteristics and the extent of charge transfer with orbital energies computed from FMO theory together with optical and nonlinear optical (NLO) properties. A Hirschfeld surface analysis was performed to explore the nature of interactions in the crystal packing and the dispersion interactions were found to have a significant role in stabilizing the crystal structure. The H···H interactions are the most significant among the intermolecular interactions. Compound 4 was subjected to structural activity relationship analysis and exhibited potency against Cathepsin S. Molecular docking and molecular dynamics analysis were carried out to understand the binding interaction mechanism and stability of 4 in its complex with Cathepsin S.

Cobalt(II) Complex Constructed from Pyrazinecarboxamide and Aromatic Carboxylic Acid: Synthesis, Single Crystal XRD Along with Computational Study

A cobalt (II) mononuclear complex was synthesized by two-nitrobenzoic acid and pyrazine-two-carboxamide ligands in the presence of sodium bicarbonate and aqueous solution of cobalt acetate tetrahydrate. The synthesized cobalt(II) complex was characterized by single crystal X-rays diffraction. The coordination geometry of the cobalt complex was octahedral with water molecules occupying the axial sites. A lot of intermolecular interactions were in response to stabilize the supramolecular assembly which were inspected by Hirshfeld surface analysis. Enrichment ratios were calculated to find the pair of atoms having the highest propensity to form crystal packing interactions. Void analysis was conducted to forecast how the crystal would respond to applied stress. Interaction energy calculations were carried out using the B3LYP/6-31G(d,p) electron density model to identify which energy types most significantly contributed to the supramolecular assembly. Moreover, the energy data obtained from DFT calculations showed an average level of stability of the molecule. The moderate HOMO-LUMO energy gap suggested reactivity, while a high electrophilicity index indicates a strong tendency for electron-accepting reactions.

Structural Investigation and Hirshfeld Surface Analysis of 2-6-Dimethoxy-4-((2-Nitrophenylimin)Methyl)Phenol

Introduction: The reaction between 4-hydroxy-3,5-dimethoxyenzaldehyde and 2-ni-troaniline has been discovered, and the final product has been identified such as 2-6-dimethoxy-4-((2-nitrophenylimin)methyl)phenol (C1). METHOD: X-ray diffraction examination per-formed on a single crystal provided conclusive evidence regarding the structure. Crystallography reveals that the two molecules A and B that were enclosed within the asymmetric unit are struc-turally distinct from one another. C-H···O, N-H···O, and O-H···O bonding is primarily respon-sible for the crystal packing stability. H-O and off-set stacking interactions also contribute to the crystal packing's overall stability. Results: To do further research into the intermolecular interactions, the Hirshfeld surface analy-sis technique is utilized. It is possible to determine the partiality of the interatomic contacts to create crystal packing interactions by computing the improvement ratio for those contacts. In addition, computational research is carried out with the B3LYP/6-31G(d,p) model to determine the amount of energy that is required for molecular pairs to interact. Conclusion: The study concluded the roles those different kinds of interaction energy play in maintaining the stability of the molecular pair.

Effect of multi-donor and extended π-conjugation in ferrocene appended indanedione chromophores for aggregation induced emission enhancement (AIEE) and nonlinear optics†

A new (D-D’π-A) type ferrocene and methoxyphenyl (D-D′) conjugated indanedione (A) based linear and π-extended multi-donor-π-acceptor chromophores 1–4 were synthesized and characterized. The chromophores 2–4 were further investigated by single-crystal analysis through X-ray diffraction, revealing centrosymmetric space groups with non-covalent interactions (inter, intramolecular hydrogen bonding, and C–H…π interactions) and these molecular packing interactions favor SHG efficiencies. Electrochemical studies show the one-electron charge transfer (Fe2+⇌Fe3+) and observed greater redox potential of chromophore 4 than the parent ferrocene due to the substitution effect. The solvatochromic studies in emission spectra resulted in redshift (56–109 nm) for the chromophores 1–4 by increasing the solvent polarities, which indicates higher excited state stabilization relative to the ground state, results effective intramolecular charge transfer process within the chromophores. The occurrence of ferrocene moieties lowers the fluorescence intensities of the chromophores 1–4, which was overcome through aggregation induced emission enhancement (AIEE) studies at 60 % (THF/H2O). The AIEE state also shows 23 times higher quantum yield than the THF solution for chromophore 4. In addition, a thin film using polymethyl methacrylate as a binder shows a significant blue shift with higher emission intensity than those obtained in the solution due to the intermolecular interactions and enhancement of viscosity. The SHG efficiency studied using the Kurtz and Perry powder technique results in a higher value for chromophore 4 (2 times higher than the reference KDP) attribute to the multi donors, acceptor, and extended π conjugation reducing the anti-parallel alignment in the solid state. The computational calculations were done to validate the experimental results using B3LYP/6-31+G** level of theory.

Using the pH sensitivity of switchable surfactants to understand the role of the alkyl tail conformation and hydrogen bonding at a molecular level in elucidating emulsion stability

HypothesisThe monoalkyl diamine surfactant, N-dodecylpropane-1,3-diamine (DPDA), is expected to exhibit a pH-dependent charge switchability. In response to pH changes, the interfacial self-assembly of DPDA becomes an intermediary constituent that can potentially modify the interfacial interactions and structural assembly of both the oil and water phases. Hence, we hypothesize that as we change the pH, DPDA will respond to it by changing its charge and alkyl tail conformation as well as the conformation of adjacent phases at the molecular level, consequently affecting emulsion formation and stability. A neutral pH, resulting in a mono-cationic dialkyl amine, affects the conformation, driving an ordered self-assembly and stable emulsion. ExperimentsThe pH-sensitivity and interfacial activity of DPDA were evaluated through pH titration and interfacial tension measurements. Subsequently, a molecular-level study of DPDA, as a pH-sensitive switchable surfactant, was performed at the dodecane-water interface using SFG spectroscopy. The interpretation of the vibrational spectra was further reinforced by determining the gauche defects in the interfacial alkyl chain organization and the extent of hydrogen (H) bonding between the interfacial water molecules. FindingsBy adjusting the pH of water, the charge of the adsorbed DPDA molecules, their self-assembly, the organization of interfacial molecules, and ultimately the stability of the emulsion were tuned. At pH 7.0, the SFG spectra of DPDA showed that the interfacial alkyl chains were relatively well-ordered, while water molecules also had stronger H-bonding interactions. As a result, the oil–water emulsion showed improved stability. When water was at a high pH, the water molecules had fewer H-bonding interactions and relatively disordered alkyl chains at the interface, providing desirable conditions for demulsification. These observations were compatible with the observation in bulk emulsion preparation, confirming that alkyl chain packing and water H-bonding interactions at the interface contribute to overall emulsion stability.

2D hydrogen bonded organic framework (2D-HOF) in benzodioxane-coupled-pyridine as a charge carrier: Synthesis, structural, quantum computational investigation

This research presents a comprehensive investigation into the synthesis, structural features, and charge carrier properties of a novel 2D Hydrogen-Bonded Organic Framework (2D-HOF) formed by Benzodioxane-Coupled-Pyridine. The synthesis involves the reaction of 2,3-dihydrobenzo[b][1,4]dioxin-6-carbaldehyde with pyridine-2-carbohydrazide in the presence of acetic acid and ethanol solvent, leading to the formation of (E)-2-(2-((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methylene)hydrazinyl)pyridine (DDMP). Single crystal X-ray diffraction analysis reveals the monoclinic crystal system with the P21/n space group, showcasing a non-planar structure due to a distinctive twisting motion in the dioxane ring. The crystal packing is governed by a complex network of intermolecular interactions, including hydrogen bonds, short contacts, and π-stacking, ultimately forming a stable 2D-HOF. Hirshfeld Surface (HS) analysis provides insights into key interactions, emphasizing the significance of hydrogen bonding, short contacts, and stacking interactions in molecular packing. The 2D fingerprint (FP) plots quantitatively highlight crucial interatomic contacts, with hydrogen bonding, CH…H, and O…H interactions dominating. Molecular Electrostatic Potential (MEP) analysis reveals potential sites for electrophilic and nucleophilic attacks, aiding in predicting reactive sites and charge carrier behavior. Energy framework analysis sheds light on the pairwise interaction energies within the crystal structure, emphasizing the role of dispersive forces in stabilizing the crystal lattice. Density functional theory calculations indicate the molecule's charge transfer capabilities, suggesting its suitability for applications such as batteries, supercapacitors, and solar cells. Additionally, global reactivity parameters suggest that the 2D HOF material has electron and proton conduction capabilities, making it versatile for various applications. Atoms-in-molecules (AIM) topology analysis, particularly non-covalent interaction (NCI) analysis, provides a detailed understanding of intra and intermolecular interactions, highlighting hydrogen bonding and π…π interactions. H-bond binding energy analysis confirms the non-covalent nature of identified interactions, emphasizing their strength and significance.

Synthesis and crystal structures of disubstituted ferrocenes carrying bromo and N-heteroaryl substituents

Noncovalent interactions in crystal packing play significant roles in the formation of extended network structures. Thus, this study aims to investigate the influence of noncovalent bonds, particularly halogen bonds, on the crystal packing of ferrocene derivatives. For this purpose, disubstituted ferrocene derivatives carrying both bromo and N-heteroaryl substituents, 1‑bromo-1ʹ-(Het)ferrocene [Het = 5-pyrimidyl (1), 2-pyridyl (2), and 4-pyridyl (3)] and 1‑bromo-2-(Het)ferrocene [Het = 5-pyrimidyl (4) and 4-pyridyl (6)], were synthesized. Here, we discuss a comparison of their molecular and crystal structures, with those of a related compound, 1‑bromo-2-(2-pyridyl)ferrocene (5). Although the crystal packings of 1–5 are classified into quasi-one-dimensional chain structures, their intermolecular interactions are different. Compounds 1–3 exhibit Br⋅⋅⋅cyclopentadienyl halogen bonds to form extended structures. In contrast, 4 shows the π–π stacking interactions between the pyrimidine rings of adjacent molecules, and 5 exhibits the Br⋅⋅⋅N halogen bonds between adjacent molecules. The crystal structures contained chiral molecules of opposing handedness.

Molecular Packing Topology and Interactions to Decipher Mechanical Compliances in Dicyano-Distyrylbenzene Derivatives.

Flexible optoelectronics is the need of the hour as the market moves toward wearable and conformable devices. Crystalline π-conjugated materials offer high performance as active materials compared to their amorphous counterpart, but they are typically brittle. This poses a significant challenge that needs to be overcome to unfold their potential in optoelectronic devices. Unveiling the molecular packing topology and identifying interaction descriptors that can accommodate strain offers essential guiding principles for developing conjugated materials as active components in flexible optoelectronics. The molecular packing and interaction topology of eight crystal systems of dicyano-distyrylbenzene derivatives are investigated. Face-to-face π-stacks in an inclined orientation relative to the bending surface can accommodate expansion and compression with minimal molecular motion from their equilibrium positions. This configuration exhibits good compliance towards mechanical strain, while a similar structure with a criss-cross arrangement capable of distributing applied strain equally in opposite directions enhances the flexibility. Molecular arrangements that cannot reversibly undergo expansion and compression exhibit brittleness. In the isometric CT crystals, the disproportionate strength of the interactions along the bending plane and orthogonal directions makes these materials sustain a moderate bending strain. These results provide an updated explanation for the elastic bending in semiconducting π-conjugated crystals.

One-step synthesis of 2-Methyl-2,4-Diphenyl-2,3-Dihydro-1H-Benzo[b][1,4]diazepine: Investigating crystal structure, hirshfeld surface analysis and supercapacitor applications

This study reports the synthesis, spectroscopic characterization and detailed crystal structure analysis of a benzodiazepine compound, 2-methyl-2,4-diphenyl-2,3-dihydro-1H-benzo[b][1,4]diazepine, synthesized from 1,2-phenylenediamine and acetophenone. The crystal structure, determined via single crystal X-ray analysis, reveals the compound's placement within the monoclinic system with the P 21/c space group. The asymmetric unit comprises the main molecule and an uncoordinated water molecule linked through an intramolecular O–H···N hydrogen bond. The crystal packing is influenced by centrosymmetric dimers formed by uncoordinated water molecules through O–H···N hydrogen bonds, along with weak C–H···π interactions. Hirshfeld surface analysis highlights the significance of H … H and H … C/C … H interactions in the crystal packing, providing insight into the intermolecular forces at play. Supercapacitance performance of the GCPE/LDABA electrode was assessed and specific capacitance value of 17.89 mF g−1 was achieved in a 0.1 M Na2SO4 electrolyte. Long-term stability of the GCPE/LDABA electrode was maintained up to 2000 cycles. This study not only elucidates the structural features of the title compound but also sheds light on its potential utility through an investigation into its electrochemical performance via supercapacitor application.

Exploring the nonlinear optical properties of hypoxanthinium salts: a structural and computational analysis.

In this study, we detail the synthesis and crystallographic characterization of an unprecedented structure, specifically hypoxanthinium chloride monohydrate ((I) hereafter), which crystallizes in the monoclinic P21/c space group. A comparative analysis was conducted with four related hypoxanthinium salts: hypoxanthinium bromide monohydrate (II), 9-methylhypoxanthinium chloride monohydrate (III), hypoxanthinium nitrate monohydrate (IV), and hypoxanthinium perchlorate monohydrate (V). This analysis has focused mainly on their crystal packing, hydrogen-bonding networks, and non-classical intermolecular interactions, as elucidated by comprehensive Hirshfeld surface and topological analyses. Theoretical investigation of the nonlinear optical (NLO) properties of the hypoxanthinium derivatives (I-V) was performed using the Density Functional Theory (DFT). The crystalline environment was simulated using the iterative Supermolecule method (SM), and the static and dynamics linear refractive index, linear polarizability, second-order hyperpolarizability, and the third-order nonlinear susceptibility at the DFT/CAM-B3LYP/6-311++G(d,p) level were computed. The results for the macroscopic third-order nonlinear susceptibility of (II) was found to equal . By replacing the bromine atom in (II) with a chlorine atom as in (III), the value will be multiplied by 2.16, and therefore these results are large enough to suggest the potential application of these crystals as NLO materials.