SYNTHESIS AND CRYSTAL STRUCTURE ANALYSIS OF THE SUPERMOLECULAR COMPOUND OF QUINAZOLINE-4-ON WITH NITRIC ACID

ABSTRACT

The study focuses on the supramolecular structure of quinazolin-4-one complex with nitric acid, synthesized and characterized using X-ray crystallography. The crystal structure belongs to the monoclinic system, space group P 21/c, with significant N–H...O and C–H...O hydrogen bonds stabilizing the structure. Hirshfeld surface analysis reveals areas of high-density bonding interactions, notably strong N–H...O bonds, which are integral to structural stability. The analysis of fingerprint plots further highlights prominent intermolecular contacts, such as O⋯H/H⋯O, H⋯H, and C⋯H/H⋯C, contributing to the understanding of molecular interactions within the structure.

АННОТАЦИЯ

Исследование посвящено супрамолекулярной структуре комплекса хиназолин-4-она с азотной кислотой, синтезированного и охарактеризованного методом рентгеновской кристаллографии. Кристаллическая структура относится к моноклинной системе, пространственная группа P 21/c, в которой структура стабилизируется водородными связями N–H...O и C–H...O. Анализ поверхности Хиршфельда выявляет области высокой плотности межмолекулярных взаимодействий, особенно прочные связи N–H...O, что важно для устойчивости структуры. Анализ двухмерных отпечатков дополнительно подчеркивает важные межмолекулярные контакты, такие как O⋯H/H⋯O, H⋯H и C⋯H/H⋯C, что способствует лучшему пониманию молекулярных взаимодействий.

Keywords: Quinazolin-4-one, nitric acid complex, hydrogen bonds, Hirshfeld surface, supramolecular chemistry, X-ray crystallography.

Ключевые слова: Хиназолин-4-он, комплекс с азотной кислотой, водородные связи, поверхность Хиршфельда, супрамолекулярная химия, рентгеновская кристаллография.

Introduction

Today, scientific research in the fields of chemistry and physical chemistry is developing very rapidly, and new achievements are being made with the help of modern technologies. Research conducted in these fields is contributing to the creation of many new materials, medicines, and technological solutions. To develop a deeper understanding of complex chemical compounds and the interactions between them through the integration of chemistry and physical chemistry. Of particular interest is the presence of heteroatoms in heteroatom-containing organic compounds and supramolecular substances based on them. Similarly, quinazoline is a class of heteroatom chemical compounds containing two nitrogen atoms and is of great importance in the field of organic chemistry. Quinazolines are particularly distinguished by the complexity of their crystal structures and their multifunctionality. These compounds play an important role in various chemical reactions and their physicochemical properties have been extensively studied. This research focuses on the assembly and study of complex structures of quinazoline compounds through supramolecular chemistry. In this field, complex structures are formed based on weak interactions between molecules - for example, hydrogen bonds, van der Waals forces and π-π interactions. Quinazoline 4-one nitric acid supramolecular complex salts have complex crystal structures, which facilitates their physical and chemical analysis (I).

A semimolecular compound formed by I-quinazolin-4-one with nitric acid

Method

0.16 g (0.001 mol) of Xinazolone-4-one was dissolved in ethanol, and to the resulting solution, 2 ml of 60% nitric acid solution was added dropwise. The mixture was heated at 40°C using a magnetic stirrer until a clear solution was obtained. The clear solution was then treated in a 30 kHz ultrasonic bath at 40°C for 40–60 minutes. Afterward, single crystals were grown by leaving the solution in a dark place at room temperature for one week.

Result and Discussion

Based on these data, it can be seen that the crystal structure is complex and has multifunctional properties. In this space group (P 21/c), the molecules are arranged symmetrically, which has a positive effect on the physicochemical properties of the crystal.

According to the results of X-ray structural analysis, in the asymmetric cell of the crystal, quinazoline cations are bonded to nitrate anions (I) by forming hydrogen bonds. The hydrogen bonds are mainly of the N-H...O and C-H...O type (Table 1).

Table 1.

 Hydrogen bonds (Å, °)

N-H⋯O bonds are stronger, with large angles and short distances. C-H⋯O bonds are relatively weaker and often have a twisted structure. These properties affect the internal and external bonding of the structure, as well as its stability.

In addition, the molecule contains a chain bond with the structure (8),  (2) with a group set structure.

Graph-set notations stabilize molecules by showing structural motifs that hold multiple molecules together within a crystal. For example, the (8) va (2) motifs bind molecules tightly, reinforcing the crystal structure.

The crystal molecule contains Cg•••Cg type π‧π bonds. They are shown by the strong distances between the Cg1‧‧Cg1 (4.8644 A°), Cg1‧‧Cg2 (4.8991 A°) and Cg2‧‧Cg3 (4.934 A°) rings, where the Cg1 ring is formed by N1/C2/N3/C4/C9/C10, the Cg2 ring by C5/C6/C7/C8/C9/C10 and the Cg3 ring by N1/C2/N3/C4/C9/C5/C6/C7/C8/C9/C10 atoms (Figure 3).

Figure 3. Connection of molecules through Cg..Cg bonds (green lines Cg3, red lines Cg2 and Cg1 bonds)

Hirshfeld surface analysis was performed using CrystalExplorer 17.5 (Spackman et al., 2021 [Spackman, P. R., Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Jayatilaka, D. & Spackman, M. A. (2021). J. Appl. Cryst. 54, 1006–1011.]) to analyze intermolecular interactions. The three-dimensional Hirshfeld surface is shown mapped to the normalized contact distance (dnorm). The bright red dots represent the shortened (resurrected) contacts and correspond to N—H⋯O and C—H‧‧‧O intermolecular hydrogen bonds (Figure 4).

The Hirshfeld surface clearly shows the N–H...O and C–H...O bonds of the structure, with the N–H...O bonds providing stronger bonds due to their short distances and large angles. The C–H...O bonds are relatively weaker and often have a twisted structure. The areas of high bond density are highlighted in red on the Hirshfeld surface, which is especially noticeable at the sites of the N–H...O bonds, indicating their important role in stabilizing the structure (Figure 4).

In the two-dimensional fingerprint patterns, O⋯H/H⋯O contacts are the most common (44.6%), followed by H⋯H/H⋯H (16.2%), H⋯C/C⋯H (14.6%), and O⋯C/C⋯O (11.4%) (Fig. 6e). N⋯H/H⋯N (4.8%), O⋯N/N⋯O (2.9%), O⋯O/O⋯O (2.8%), C⋯N/N⋯C (1.5%), and C⋯C/C⋯C (0.5%) contacts have little effect on molecular packing.

Conclusion

In conclusion, in the experiment, the compound of quinazolon-4-one and nitric acid was prepared in an alcoholic medium and obtained in the form of a single crystal. The monoclinic system of the crystal and the arrangement based on the P 21/c space group help in studying its physicochemical properties. The results of X-ray structural analysis confirm the molecular symmetry and bonds within the crystal. N–H...O and C–H...O hydrogen bonds increase the structural stability and affect the molecular stability.

The stiffness and different angles of hydrogen bonds in the structure affect the internal and external bonds of the molecule. N–H...O bonds are stronger due to their large angles and short distances, and play an important role in stabilizing the crystal structure. C–H...O bonds are relatively weaker and have a twisted structure, which provides multifunctionality of the structure.

In Hirshfeld surface analysis, short bonds within the normalized contact distance are shown in red, which mainly helps in N–H...O and CH...O bonds. Graph-set notations serve to stabilize the structure internally. Motifs such as (8) av  (2) bind molecules tightly, restoring the integrity of the crystal structure. π‧π bonds of the Cg‧‧Cg type, on the other hand, cause molecules to pack more tightly.

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