Search

The crystallization of 3‐chloroisonicotinic acid (3‐CINA) can lead to three crystal forms (I, II and III), but 3‐CINA in each form has different conformation. The three crystal forms have different lattice energies. The intermolecular interactions in the molecular pairs involving the conformer in each crystal were evaluated, it is found that the sum of these intermolecular interaction energies in each crystal has a linear relationship with the corresponding lattice energy. QTAIM analyses for the intermolecular interactions of molecular pairs correspond to Hirshfeld surface analyses for the crystal form, illustrating that the stability of the crystal is closely associated with the intermolecular interactions involving the conformer in the asymmetric unit of the crystal. 3‐chloroisonicotinic acid (3‐CINA) has three crystal forms (I, II and III), first principles investigation and Hirshfeld surface analysis have been employed to explore them. [ABSTRACT FROM AUTHOR]

The high-energetic and low-sensitive explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was theoretically investigated by first principles calculations and Hirshfeld surface analysis. The experimental and partly optimized LLM-105 crystals were compared which indicated that it is important to correct the hydrogen positions. Hirshfeld surface analyses of the experimental and partly optimized LLM-105 crystals were also compared, which showed that the intermolecular H⋯O interactions significantly contribute to the stability of the LLM-105 crystal, while the contributions of other intermolecular interactions in the experimental and partly optimized LLM-105 crystals are quite different. The geometrical and electronic structures of LLM-105 molecules in the experimental and partly optimized crystals as well as that in the gas phase were compared. QTAIM analysis was employed to illustrate the existences of intermolecular interactions in the molecular pairs taken from partly optimized LLM-105 crystal, and the types of intermolecular interactions from QTAIM analysis are in agreement with the results of Hirshfeld surface analysis. The reason why the LLM-105 molecule in the partly optimized crystal adopts a non-coplanar structure in which the NO 2 and NH 2 groups is not coplanar with the six-membered ring is elaborated. The existence of cooperativity among different intermolecular interactions were verified by analysing the trimeric complexes formed among three LLM-105 molecules in the partly optimized crystal. The non-coplanar of the NO 2 and NH 2 groups with the six-membered ring in LLM-105 molecule is favorable in forming more intermolecular interactions which cooperate and stabilize the crystal. [Display omitted] • The explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) crystal was investigated theoretically. • The single LLM-105 molecule, the dimeric and trimeric complexes were analyzed. • The non-coplanar LLM-105 molecule favors the formation of more intermolecular interactions which stabilize the crystal. • The cooperativity among the intermolecular interactions was verified. [ABSTRACT FROM AUTHOR]