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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]

The rich π-electrons region of graphene enables it to be a good material which can interact with many organic molecules. As a low-sensitivity and high-energy explosive, 1,1-diamino-2,2-dinitroethene and its dimer possess unique characters including hydrogen bonds and π bond which can adsorb on graphene through physisorption. The results suggest that the adsorption energies have a very small difference on the different adsorption sites. Due to the physisorption, the geometrical and electronic properties of 1,1-diamino-2,2-dinitroethene and its dimer vary significantly. The intramolecular as well as intermolecular hydrogen bond strengths are considerably affected due to the π···π interaction of 1,1-diamino-2,2-dinitroethene or its dimer with graphene. The cooperativity between intermolecular hydrogen bonds and π···π interactions is observed which causes wax of intermolecular hydrogen bonds and wane of π···π interactions. The physisorption of 1,1-diamino-2,2-dinitroethene or its dimer also leads to the variation of electronic property of graphene. The physisorptions of 1,1-diamino-2,2-dinitroethene and its dimer on graphene have been investigated theoretically. Image 1 • The physisorptions of 1,1-diamino-2,2-dinitroethene and its dimer on graphene have been investigated theoretically. • The geometrical and electronic properties of 1,1-diamino-2,2-dinitroethene and its dimer vary significantly. • The cooperativity between intermolecular hydrogen bonds and π···π interactions is observed. • The physisorption of 1,1-diamino-2,2-dinitroethene or its dimer modulates the electronic property of graphene. [ABSTRACT FROM AUTHOR]