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The quantitative visualizations and comparisons between the four pyrazinamide (PZA) polymorphs (α, β, γ and δ) have been investigated by graphical tools based on three-dimensional Hirshfeld surfaces and two-dimensional fingerprint plots. The comparisons were performed in terms of crystal structure, d, Shape index, Curvedness and d surfaces, and fingerprint plots. The results revealed that the α and γ forms featured with 1D chains and the π···π stacking motifs belong to γ-motif, rich in π···π interactions and form infinite face-to-face stacks, β and δ forms featured with dimer unit and the π···π stacking motifs belong to γ- and herringbone-motif, respectively, the herringbone motif of δ form rich in C-H···π and edge-to-face interactions. We also correlated the phase transformation points of α, β, and δ PZA forms with the ratio of the percentage surface coverage of the N-H···O hydrogen bonds over that of the N-H···N hydrogen bonds, and found a negative correlation. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three methoxy- and methyl-substituted indole-3-acetonitriles (IAN) (4-OCH-IAN, 5-OCH-IAN and 7-CH-IAN) are reported in this work. Their structures were characterized by infrared spectra, elemental analyses, NMR spectra, differential scanning calorimetry, thermogravimetric analyses, and hot stage microscopy. The Hirshfeld surface analysis in terms of intermolecular interactions and π···π stacking motifs of the three substituted IANs was investigated in detail, and the results revealed that the different kinds of substituent groups as well as different substituted positions have a significant effect on the crystal structures, molecular π···π stacking motifs, melting points, and the types of intermolecular interactions. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three halogen atoms (4-Cl, 6-Cl and 4-Br) substituted indole-3-acetonitrile (IAN) were reported in this work. The structures of the present three compounds were characterized by Infrared spectra, Elemental analyses, NMR spectra, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and hot stage microscopy (HSM). The Hirshfeld surfaces analysis in terms of crystal structure, intermolecular interactions and π⋯π stacking motifs were performed. We found that the different kinds of halogen atoms and the different substituted positions have a significant effect on the crystal structures, molecular π⋯π stacking motifs, melting points, and the nature of intermolecular interactions for IANs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two copper complexes derived from polypyridine and salicylide ligands have been prepared. [•] Intermolecular interactions in them have been investigated by using Hirshfeld surfaces. [•] These two complexes can intercalation with DNA. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new copper (II) complex with hetero N- and O-donor ligands has been prepared. [•] The coordinated water molecules play a key role in the construction of crystal structures. [•] The intermolecular interactions and solid state luminescent properties have been investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three new co-crystals of pyridine-2-carboxamide have been synthesized and characterized. [•] It is the length of carbon chain of co-crystal formers that control the co-crystal structure. [•] We investigated detailed the interactions by Hirshfeld surface solid-state vibrational spectroscopy. [ABSTRACT FROM AUTHOR]

A new complex of the title system ([2(H 3 O + )·18-crown-6]·2[BF 4 − ]), which was induced by external magnetic field, has been prepared and characterized. When compared with other two members of the same system, the proton transfer induced by magnetic field from HBF 4 to H 2 O has leads to the co-plane of six oxygen atoms in the crown and stronger H F and O F intermolecular interactions, which can be attributed to the closer contacts between 18-crown-6, oxonium ion H 3 O + and counterion BF 4 − . In addition, a compression effect of crystals stacking has been observed. These results are of importance for the evaluation the effect of magnetic field on the host–guest systems. [ABSTRACT FROM AUTHOR]

2,3-Dimethylpyrazine and 1,2-bis(4-pyridyl)ethane are both N-containing aromatic heterocyclics with two N atoms approximately in the para position. We here report two compounds derived from these heterocyclics (compounds 1 and 2). Compounds 1 and 2 both form a 1:1 2,3-dimethylpyrazine:perchloric acid (PA) and 1,2-bis(4-pyridyl)ethane:PA cocrystal, respectively. Their crystal structures were characterized by single-crystal X-ray diffraction, which revealed that the C-H⋯O and N-H⋯O hydrogen bonding interactions were found to stabilize the crystal structure in compounds 1 and 2. However, PA plays a necessary role for the one-dimensional structure in 1 and the three-dimensional structure in 2. Hirshfeld surfaces and fingerprint plots were applied to get the same conclusion. [ABSTRACT FROM AUTHOR]