In the molecular structure of the title compound, C16H13Cl2N5, the 1,4-dihydropyridine ring of the 1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrimidine ring system adopts a screw-boat conformation, while the 1,3-diazinane ring is puckered. In the crystal, intermolecular N—H...N and C—H...N hydrogen bonds form molecular sheets parallel to the (110) and (\overline{1}10) planes, crossing each other. Adjacent molecules are further linked by C—H...π interactions, which form zigzag chains propagating parallel to [100]. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from N...H/H...N (28.4%), H...H (24.5%), C...H/H...C (21.4%) and Cl...H/H...Cl (16.1%) contacts.
Two osmium complexes of common formula [H(dmso)2][OsIVХ5(dmso‐κO)] 1 (Х=Cl) and 2 (Х=Br) are synthesized via the reaction of H2OsX6 (Х=Cl, Br) with DMSO. The complex 1 crystallized in the orthorhombic space group Pca21. For 2, two orthorhombic polymorphs are found, namely, 2 a in space group Cmcm and 2 b in space group Pbca. Within the [H(dmso)2]+ cations of 1 and 2 a, the cis‐configuration of the DMSO moieties has been observed for the first time. The complexes are characterized by a set of spectroscopic (NMR, IR, UV‐Vis, EXAFS/XANES) and diffraction (single crystal and powder) techniques. Both complexes 1 and 2 retain their molecular structures in DMSO and acetone solutions, as evidenced by Os L3‐edge EXAFS/XANES. 1H NMR spectra of 1 and 2 in DMSO solutions reveal signals of coordinated DMSO. In acetone solutions, signals of the [H(dmso)2]+ cations are observed in addition to those of coordinated neutral DMSO.
The title compound, 2C16H27NO·H2O, crystallizes in the monoclinic P21/c space group with two independent molecules (A and B) in the asymmetric unit. In the crystal, molecules A and B are linked through the water molecules by intermolecular O—H...O and O—H...N hydrogen bonds, producing chains along the b-axis direction. These chains are linked with neighboring chains parallel to the (103) plane via C—H...π interactions, generating ribbons along the b-axis direction. The stability of the molecular packaging is ensured by van der Waals interactions between the ribbons. According to the Hirshfeld surface study, H...H interactions are the most significant contributors to the crystal packing (80.3% for molecule A and 84.8% for molecule B).
The interaction of chitosan with 3-(chloromethyl)-[1,2,4]selendiazole[4,5-a]pyridin-4 bromide results in water-soluble, selenium-containing, cationic chitosan derivatives. Derivatives of chitosan with degrees of substitution of 0.15, 0.45, and 0.65 were obtained. These derivatives are characterized by a pronounced in vitro antibacterial activity against Staphylococcus aureus and Escherichia coli, and the antibacterial activity of the derivatives increases with an increase in their degree of substitution. The antibacterial activity of the highly substituted derivative is comparable to that of the conventional antibiotics ampicillin and gentamicin.
Complex [H(dmso)] 2 [Os IV Cl 6 ] ⋅ 2H 2 O (1) was synthesized by refluxing of [H(dmso) 2 ] 2 [OsCl 6 ] in concentrated HCl and characterized by the IR and UV/Vis spectroscopy and X-ray powder and single-crystal diffraction studies. In this complex, rare highly electrophilic [Me 2 S=O⋅⋅⋅H] + cation is stabilized by multiple chalcogen bonds including bifurcated S⋅⋅⋅(Cl) 3 and S⋅⋅⋅Cl non-covalent interactions. DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method) support the presence of intermolecular non-covalent interactions S⋅⋅⋅Cl and O⋅⋅⋅Cl in the solid state.
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