2D-3D supramolecular assemblies containing 2-amino-4,6-dimethoxypyrimidine and carboxylic acids: Preparation, crystallographic characterization, and Hirshfeld surface analysis

• Published in: Journal of molecular structure 2024-01, Vol.1295, p.136662, Article 136662
• Main Authors: Ma, Xiaodan, Zhen, Yaoqi, Jin, Shouwen, Zhou, Jingxuan, Shi, Linfang, Xu, Weiqiang, Wang, Daqi
• Format: Article
• Language: English
• Subjects: 2-amino-4,6-dimethoxypyrimidine; Carboxylic acids; Crystal structure; Hirshfeld surface; Hydrogen bonding; Synthons
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2023.136662

•One salt (1) and 7 cocrystals (2–8) were prepared.•All the assemblies possess excessive classical hydrogen bonds.•The non-covalent interactions CH···O/CH2···O/CH3···O, CH3···C, CH···CH, CH···N/CH3···N, O···O, CH3···π, C···π, O···π, and π···π have been ascertained.•The graph-set descriptors were also analyzed.•Distinct motifs of chain (6), sheet (for 2) and 3D net (for 1, 3–5 and 7–8) were set up. Eight crystals (1–8) derived from various substituted carboxylic acids of 2-pyrazinecarboxylic acid, 3,4-methylenedioxybenzoic acid, 4‑hydroxy-3-nitrobenzoic acid, 4‑chloro-2-nitrobenzoic acid, mandelic acid, 4-nitrophenylacetic acid, 3,4,5-trimethoxycinnamic acid, and itaconic acid and 2-amino-4,6-dimethoxypyrimidine (admpm) were prepared and identified, and further characterized thoroughly with single crystal X-ray diffraction (SCXRD), and elemental analysis techniques. The melting points were also measured. Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis. Among the eight crystals, proton transfer from the carboxylic acid to ring N of the pyrimidine has occurred only at 1, while the remaining ones 2–8 were co-crystals. It is obvious that the R22(8) ring motif occurs in all cases when a carboxyl unit interacts with a pyrimidine base. The present work surely indicates that there are two main associate modes between the 2-amino-4,6-dimethoxypyrimidine and the carboxylic acids, which regularly occur, linear heterotetramer (LHT), and cyclic heterotetramer (CHT). Here, LHT is dominant as it occurs in 5/8 frequency (at 3–4 and 6–8), CHT in 2/8 (at 1–2), with the remaining one structure (5) forming a heterodimer. The heterotrimer (HT) was not established in this test. Thus LHT is more stable than CHT and other synthons. [Display omitted]