P. Sugumar

Unprecedented formation of organo-ruthenium(II) complexes containing 2-hydroxy-1-naphthaldehyde S-benzyldithiocarbazate: synthesis, X-ray crystal structure, DFT study and their biological activities in vitro

As a contribution to the development of new ruthenium complexes with pharmacologically interesting properties, two new mononuclear ruthenium(II) complexes of the general formula [Ru(H-Nap-sbdtc)Cl(CO)(EPh3)2] (1 & 2) [H-(Nap-sbdtc) = 2-hydroxy-1-naphthaldehyde-S-benzyl-dithiocarbazate; E = P or As] were synthesized. The new ruthenium(II) carbonyl complexes are remarkably stable and were obtained in good yields. Their identities have been established by satisfactory elemental analyses and various spectroscopic techniques (IR, UV/visible, (1H, 13C, and 31P) NMR, and ESI-MS). For a better definition, the molecular structure of complexes 1 and 2 has been determined by X-ray crystallography, which confirms the coordination mode of the ligand and reveals a distorted octahedral geometry around the ruthenium ion. The molecular structure of complexes 1 and 2 has been optimized by DFT calculations. The binding affinity and binding mode of the ligand and their ruthenium(II) complexes toward calf thymus CT-DNA were determined by the emission spectral method, the fluorescent indicator displacement (FID) assay and viscosity measurements. Further, the interactions of the ligand and their complexes 1 and 2 with bovine serum albumin (BSA) were investigated using UV-Vis and fluorescence spectroscopic methods. Absorption and emission spectral studies indicate that complexes 1 and 2 interact with CT-DNA and BSA protein more strongly than their parent ligand. In addition, the interactions of the complexes with DNA/BSA were followed by electrophoretic mobility spectrometry studies and the results show that these complexes exhibited good cleavage properties. In vitro anticancer activity has been scrutinized by the MTT assay, acridine orange/ethidium bromide (AO/EB) and diamidino-2-phenylindole (DAPI) staining against the human cervical cancer (HeLa) cell line.

2-Amino-6-methyl­pyridinium 4-hy­droxy­benzoate

In the title molecular salt, C6H9N2 +·C7H5O3 −, the dihedral angle between the benzene ring and the CO2 group in the anion is 6.1 (2)°. In the crystal, the cation and anion are linked by N—H⋯O and C—H⋯O hydrogen bonds, and the anions are connected by O—H⋯O hydrogen bonds, forming a three-dimensional network.

Ethyl 3-(4-chloro-phen-yl)-2-phenyl-3-(4-phenyl-1,2,3-selena-diazol-5-yl)propano-ate.

In the title compound, C25H21ClN2O2Se, the selenadiazole ring is almost planar [maximum deviation = 0.004 (2) Å], and the adjacent benzene ring is twisted by 50.6 (1)° with respect to this ring.

1-Dichloro­acetyl-t-3,t-5-dimethyl-r-2,c-6-diphenyl­piperidin-4-one

In the title compound, C21H21Cl2NO2, the piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring subtend angles of 87.9 (7) and 70.8 (9)°, respectively, with the best plane through the piperidine ring. In the crystal, molecules are connected by C—H⋯O and C—H⋯Cl interactions into layers in the ab plane.

2-Amino-5-chloro­pyridinium 4-amino­benzoate

In the title molecular salt, C5H6ClN2 +·C7H6NO2 −, the cations and anions are connected by cation-to-anion and anion-to-anion N—H⋯O hydrogen bonds into a three-dimensional network. The dihedral angle between the ring and the CO2 group in the anion is 7.14 (7)°.

Ethyl 2-phenyl-3-(4-phenyl-1,2,3-selenadiazol-5-yl)-3-p-tolyl-propano-ate.

In the title compound, C26H24N2O2Se, the selenadiazole ring is essentially planar [maximum deviation = 0.004 (3) Å]. The dihedral angle between the selenadiazole ring and the attached benzene ring is 50.17 (1)°. The crystal packing is stabilized by intermolecular C—H⋯N interactions.

5,7-Bis(1-benzothio-phen-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]dioxine.

In the title compound, C22H14O2S3, the dioxane ring is disordered over two sites [site occupancies = 0.623 (3) and 0.377 (3)]; both components adopt half-chair conformations. The two benzothiophene ring systems are asymmetrically twisted away from the attached thiophene ring [dihedral angles = 20.57 (3) and 6.70 (3)°] and are oriented at an angle of 26.83 (3)°. No significant hydrogen bonding or π–π interactions are observed in the crystal structure.

1-(2,2-Di­chloro­acet­yl)-3-ethyl-2,6-di­phenyl­piperidin-4-one

The asymmetric unit of the title compound, C21H21Cl2NO2, contains two independent molecules that show similar geometrical features. The piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring are oriented at angles of 65.4 (1) [64.7 (2)°] and 89.2 (1)° [86.3 (2)°] with respect to the least-squares plane of the piperidine ring. In the crystal, adjacent molecules are linked by a network of C—H⋯O interactions, forming a C(6) chain along the c-axis direction.

4-(5-Chloro­thio­phen-2-yl)-1,2,3-selenadiazole

In the title compound, C6H3ClN2SSe, the selenadiazole and chlorothiophene rings are almost coplanar [dihedral angle = 5.24 (15)°]. In the crystal, C—H⋯N interactions link the molecules into chains extending along the b-axis direction. C—H⋯π interactions also occur.

3-Isopropyl-1-{2-[(1-methyl-1H-tetra­zol-5-yl)sulfan­yl]acet­yl}-2,6-di­phenyl­piperidin-4-one hemihydrate

In the title compound, C24H27N5O2S·0.5H2O, the piperidine ring adopts a distorted boat conformation. The phenyl rings subtend dihedral angles of 69.7 (1) and 88.7 (1)° with the best plane through the piperidine moiety. In the crystal, symmetry-related molecules are linked through a network of C—H⋯O and C—H⋯N interactions, the former connecting them into zigzag chains along the c-axis direction and the latter forming an R 2 2(4)motif. The dimer formation (C—H⋯N) and the repetition of symmetry-related molecules (C—H⋯O) along the b-axis direction stabilize the packing mode. The water molecule is located on a twofold rotation axis.