Introduction. Quinazolines belong to the class of synthetic organic compounds exhibiting remarkably high pharmaceutical activity. Quinazoline and its derivatives are generally soluble in alcohols or organic solvents; however, this property limits their administration into the body. In contrast, the compounds formed with the chloride anion demonstrate solubility in water and isotonic solutions, which makes them suitable for parenteral (injectable) administration.

Experimental Section. 3-Ethylquinazolin-4(3H)-one was dissolved in acetone, and hydrogen chloride gas was passed through the solution, resulting in the formation of 3-ethylquinazolin-4(3H)-one hydrochloride. Rf = 0.67 (system: water : methanol, 1:1), melting point 175–177 °C.

Results and Discussion. The crystal belongs to the triclinic crystal system and crystallizes in the P-1 (No. 2) space group. The crystal lattice is of the primitive type. An inversion center is present in the structure, with the number of formula units per unit cell Z = 2. ADDSYM analysis revealed the presence of pseudotranslational symmetry (1/2, 0, 0).

In the compound, intermolecular N–H···Cl and C–H···Cl hydrogen bonds were identified. In addition, intramolecular N···C and C···Cl interactions were observed. Furthermore, Hirshfeld surface analysis and fingerprint plot analysis were performed, showing that the largest contribution arises from H···H/H···H contacts.

Conclusion. In this study, we reported the synthesis, structural characterization, and Hirshfeld surface analysis of a new quinazoline-based compound, (compound name). Based on the obtained results, the newly synthesized compound was found to exhibit confirmed biological activity.

Introduction

One of the key tasks of modern chemistry is the targeted synthesis of new highly efficient biologically active compounds and their use in agriculture and medicine to combat diseases. In recent years, biologically active substances have been identified among substituted derivatives of quinazolin-4(3H)-one. Therefore, developing effective and environmentally safe preparations based on inexpensive raw materials and improving their physicochemical and biological properties remains an important scientific direction.

Experimental. 3-Butylquinazolin-4(3H)-one was dissolved in acetone with thorough stirring using a magnetic stirrer. When hydrogen chloride (HCl) gas was introduced into the solution through a tube, a white precipitate formed. The resulting solid was filtered, and the filtrate was washed 2–3 times with acetone. As a result, pure 3-butylquinazolin-4(3H)-one hydrochloride was obtained with an 88% yield. R_f = 0.66 (system: water : methanol, 1:1); melting point 179–181 °C.

Results

The crystal structure crystallizes in the monoclinic system with the P-1 space group. The asymmetric unit contains one molecule. The crystal structure exhibits three types of intermolecular hydrogen bonds: Cl–H···N, N–H···Cl, and C–H···N. The N–H···Cl hydrogen bonds connect the molecules in the crystal and form a chain-like network along the [110] direction. This indicates that the chlorine atom of the molecule and the inversion center link the quinazoline molecules together. In addition, π···π interactions between the molecules contribute to the formation of a three-dimensional structure. The crystal structure was further analyzed using Hirshfeld surface analysis.

Conclusion

In this study, we examined not only the synthesis and structure of 3-Butylquinazolin-4(3H)-one hydrochloride, but also its Hirshfeld surface. Biological tests of the synthesized 3-Butylquinazolin-4(3H)-one hydrochloride confirmed its insecticidal activity.

This paper presents a comprehensive review of the current state of knowledge regarding the crystalline architecture and solid-state behavior of Mansorin A, a key bioactive secondary metabolite isolated from the heartwood of Mansonia gagei. Despite its recognized pharmacological potential, including its antifungal and cytotoxic effects, the physical chemistry of its crystalline form is often overlooked. This paper systematically categorizes the existing crystallographic data to provide a holistic understanding of how molecular structure dictates the material properties of this natural product. The analysis focuses on the supramolecular assembly of Mansorin A, highlighting the role of the planar naphtofurane-type skeleton in promoting specific molecular arrangements. The reported unit cell parameters and the hierarchy of non-covalent interactions are examined, specifically emphasizing the π- π stacking motifs and the complex networks of C-H···O hydrogen bonds that stabilize the lattice. Furthermore, this review evaluates the impact of polymorphism and solvate formation on the solubility and thermodynamic stability of the compound. By synthesizing data from chemical, structural, and pharmacological studies, this review identifies critical gaps in the current research, particularly concerning the structure–property relationships that affect the bioavailability of Mansorin A. It is concluded that a deeper understanding of its crystal engineering aspects is essential for developing effective delivery systems. This work serves as a foundational resource for researchers aiming to optimize the formulation of Mansorin-based compounds for future therapeutic applications.

Understanding intermolecular interactions in molecular crystals is fundamental for interpreting crystal packing, supramolecular organization, and the resulting physical or chemical properties of materials. Quantum crystallography provides a powerful tool for investigating these interactions directly from experimentally derived electron density distributions. In this presentation, I will discuss a series of studies on organic and metal–organic molecular crystals where experimental crystallography is integrated with electron-density-based analysis to obtain a deeper understanding of intermolecular interactions in the solid state.

Single-crystal X-ray diffraction experiments were used to determine accurate molecular geometries and crystal structures. To improve the description of hydrogen atoms and the underlying electron density distribution, Hirshfeld Atom Refinement (HAR) was employed, allowing the incorporation of quantum mechanical information into the crystallographic refinement process. The resulting electron density models were analyzed using the Quantum Theory of Atoms in Molecules (QTAIM), which provides a detailed topological framework for identifying bond critical points and characterizing the nature and strength of both covalent and non-covalent interactions.

To complement this analysis, non-covalent interaction (NCI) analysis and Hirshfeld surface approaches were used to visualize and quantify weak intermolecular contacts within the crystal lattice. These methods enable the identification of hydrogen bonding, π–π interactions, and dispersive contacts that collectively govern crystal packing and structural stability. By combining HAR refinement with QTAIM topology and NCI visualization, a consistent picture of intermolecular interactions emerges at both the electronic and structural levels.

Overall, this integrated crystallographic strategy demonstrates how modern electron-density analysis can provide detailed insight into supramolecular organization and structure–property relationships in molecular crystals, highlighting the growing role of quantum crystallography in contemporary structural chemistry.

Macrocyclic compounds are a versatile group of ligands that can be used for selective complexation of cationic, anionic, and neutral chemical species. Macrocyclic compounds containing an acylhydrazone functional group can be prepared by the reaction of polyhydrazine and polyaldehyde precursors. To investigate the structural features of acylhydrazone macrocycles, we have prepared and crystallized two novel macrocyclic compounds (achyM5 and achyM6). The prepared compounds are ring analogs containing 22 (achyM5) and 23 (achyM6) atoms in the inner macrocyclic ring. Both compounds are N₅O₄-donor macrocycles composed of pyridine and dibenzaldehyde moieties connected by acylhydrazone groups. Although rather similar, the compounds differ in the subtle geometrical parameters such as dihedral angles, puckering amplitude, and inner macrocyclic hole size. These parameters show that the larger macrocycle (achyM6) is more deformed (puckering amplitude of 2.721(3)). In the crystal structure of achyM5, the adjacent macrocycles are connected via N-H∙∙∙O hydrogen bonds between NH groups and carbonyl oxygen along the a-axis. Interestingly, there is a short contact between the imine and pyridine N atoms (3.045 Å) of adjacent macrocycles that can be regarded as a weak N∙∙∙N pnictogen bond. The final 3D arrangement is achieved via weak C-H∙∙∙C and π∙∙∙π interactions. The achyM6 crystallizes as a water solvate, with two symmetry-independent molecules in the asymmetric unit. The water molecule is located approximately in the center of the macrocyclic ring and connected via N-H∙∙∙O hydrogen bonds. In the crystal, the adjacent macrocyclic molecules are primarily connected through O-H∙∙∙O hydrogen bonds that involve a water molecule and carbonyl oxygen, and N-H∙∙∙O hydrogen bonds between NH groups and carbonyl oxygen. A short N∙∙∙N contact between the imine and pyridine N atoms (3.007 Å) of adjacent macrocycles is also present, implying the importance of these interactions in the overall crystal stability of these systems.

The application of styrylium dyes as organic nonlinear optical materials in several photonics fields has been studied for many years. Recently, the biological activity of styrylium dyes has also been examined, namely their antibacterial effects. Therefore, our primary objective was to synthesize a styrylium compound with an antibacterial effect. Knoevenagel condensation was used to obtain a new styrylquinolinium derivative. To verify its structure, spectroscopic methods such as IR, NMR (¹H, ¹³C, COSY, HSQC, and HMBC), HRMS spectra, and X-ray studies were employed.

The compound's antibacterial and anti-inflammatory properties were also evaluated. It was found that the stytylium derivative had excellent antibacterial action against fungi, three Gram-negative strains, and five Gram-positive strains. The compound's most noticeable effects were against Pseudomonas aeruginosa and Escherichia coli. In addition, ex vivo immunohistochemistry was used to assess the compound's anti-inflammatory properties. The substance showed promising immunomodulatory and antimicrobial properties. It can be regarded as a regulated modification of the immune response, particularly in situations requiring local immunological activation, because of its capacity to both stimulate IL-1β and moderately decrease NOS3.

Furthermore, the biological activity was verified using molecular docking modeling. The compound's successful binding to the bacterial protein's active site was demonstrated by docking simulation, which corroborated the compound's antibacterial activity as reported in experiments.

Carboranes are noted for their three-dimensional aromaticity and exceptional stability. Their partially deboronated derivative, the nido-dicarbollide anion, serves as an analog of the cyclopentadienyl ligand, forming metallacarboranes with potential in catalysis and materials science. However, the application of such complexes in homogeneous catalysis remains largely underexplored. This work reports the synthesis and crystal structure of a novel binaphthylene-bridged closo-rhodacarborane complex, μ-1,2-[(CH₂)₂C₂₀H₁₂]-3-(η³-C₈H₁₃)-3,1,2-closo-RhC₂B₉H₉ (6), and its ligand precursor μ-1,2-C₂₀H₁₂(CH₂)₂-1,2-closo-C₂B₁₀H₁₀ (4).
The structures of compounds 4 and 6 were fully characterized by single-crystal X-ray diffraction, high-resolution mass spectrometry, infrared spectroscopy, and NMR. Crystallographic analysis of 6 reveals a unique exo-polyhedral agostic C–H···Rh interaction, along with a network of intra- and intermolecular noncovalent interactions, including intramolecular C–H···π, and intermolecular C–Cl···π, C–H···π, C–H···H–B, and C–H···H–C contacts. In the crystal lattice of compound 4, significant intermolecular B–H···π and C–H···H–B interactions are observed. These weak interactions are crucial for understanding the solid-state packing and stability of these molecules.
Preliminary catalytic studies demonstrate that complex 6 acts as a well-defined Rh(III) catalyst. It exhibits high activity at low loadings in selective cyclopropanation, epoxidation, C–H insertion, and Curtius-type rearrangement reactions under mild conditions. This work provides a new molecular prototype for crystal engineering and the design of catalytic materials based on metallacarboranes.

The valorization of marine biogenic waste represents an important direction in the development of sustainable functional materials. In this study, geopolymer composites incorporating biogenic particles derived from marine shell waste were synthesized and structurally characterized. The biogenic particles consist of calcium-rich crystalline powders (primarily CaCO₃ and CaO phases) obtained through cleaning, thermal treatment, and mechanical size reduction of shell materials. These particles were introduced as functional additives into metakaolin-based geopolymers synthesized from calcined kaolinite (Al₂Si₂O₅(OH)₄) and activated using alkaline solutions (NaOH, KOH and Na₂SiO₃), leading to the formation of a three-dimensional aluminosilicate network. The geopolymerization process resulted in hybrid inorganic composites in which the biogenic calcium-based particles are dispersed within an amorphous aluminosilicate matrix. Structural and morphological investigations were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to evaluate phase composition, crystallinity and particle dispersion. The results indicate that the incorporation of shell-derived particles influences the microstructure of the geopolymer matrix and contributes to the development of hybrid inorganic composites combining amorphous geopolymeric phases with crystalline calcium-based particles. The results demonstrate that marine shell waste can be successfully transformed into functional additives for geopolymer materials. This approach contributes to waste valorization while enabling the development of sustainable geopolymer composites with potential applications in environmentally friendly construction materials and environmental remediation technologies.

Conductive polymers have emerged as promising materials for flexible electrodes in wearable biomedical devices. Among them, polypyrrole (PPy) is particularly attractive due to its intrinsic electrical conductivity, chemical stability, and compatibility with soft substrates. However, pure PPy films may exhibit limited mechanical robustness and reduced stability under repeated deformation. To address these limitations, the incorporation of functional fillers represents an effective strategy to tailor the structural, electrical, and mechanical properties of the polymer matrix.

In this study, composite thin films based on p-toluenesulfonic acid-doped polypyrrole (PPy-TSA) incorporating both organic and inorganic fillers, such as polyethylene glycol (PEG), poly(vinyl alcohol) (PVA), graphene (GR), carbon nanotubes (CNTs), and zeolite (ZE), were developed and investigated. The films were obtained by electrochemical polymerization using a galvanostatic method, where pyrrole was polymerized in the presence of fillers dispersed in the electrolyte. The fillers were commercially available, while the PPy matrix was synthesized in situ.

The morphology and structural organization of the films were analyzed by scanning electron microscopy (SEM), while Fourier-transform infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopy were used to investigate the chemical structure and interactions within the composites. Electrical properties were evaluated through conductivity and sheet resistance measurements, including temperature-dependent analysis and bending tests to assess stability under deformation.

The results show that the combined incorporation of organic and inorganic fillers enables tuning of both electrical response and mechanical integrity. These properties are relevant for the development of flexible electrodes capable of detecting low-amplitude bioelectrical signals. The investigated PPy composite films demonstrate promising potential for electrocardiographic (ECG) sensing in wearable health monitoring systems.

Conductive polymers such as polypyrrole (PPy) have attracted significant interest for flexible electronic applications due to their electrical conductivity, chemical stability, and ease of synthesis. However, pure PPy films often exhibit limited mechanical robustness, which can restrict their long-term performance in flexible devices. Incorporating inorganic fillers into the polymer matrix represents a promising strategy to improve the mechanical stability of conductive polymer films while maintaining their functional properties.

In this work, composite thin films based on p-toluenesulfonic acid-doped polypyrrole (PPy-TSA) incorporating inorganic fillers such as graphene (GR), carbon nanotubes (CNTs), and zeolite (ZE) were investigated. The composite films were obtained by electrochemical polymerization using a galvanostatic method, in which pyrrole was polymerized in the presence of the inorganic components dispersed in the electrolyte solution. The inorganic fillers were used as commercially available materials, while the PPy matrix was synthesized in situ during the electrochemical process.

The morphology of the films was analyzed by scanning electron microscopy (SEM), highlighting the dispersion of the inorganic components within the polymer matrix and their effect on the structural organization of the films. Mechanical performance was evaluated through flexibility and repeated bending tests in order to assess the structural integrity of the composite films under deformation.

The results indicate that the incorporation of inorganic fillers contributes to improved mechanical stability and resistance to structural damage during bending, suggesting a reinforcing effect within the PPy matrix. These findings highlight the potential of inorganic filler-reinforced polypyrrole films for flexible electronic applications where both electrical functionality and mechanical durability are required.