6,8-Di-chloro-3-(pyridin-2-yl)-2-[1-(pyridin-2-yl)eth-yl]-1,2-di-hydro-quinoxaline.

The crystal structure of the racemic title compound, C20H16Cl2N4 is described, where the formation of a di-substituted 6,8-di-chloro quinoxaline, containing two stereogenic centres, is confirmed.

Exploring the in vitro anticancer activities of Re(I) picolinic acid and its fluorinated complex derivatives on lung cancer cells: a structural study.

Fifteen rhenium(I) tricarbonyl complexes of the form fac-[Re(N,O')(CO)3(X)], where N,O'-bidentate ligand = 2-picolinic acid (Pico); 3,5-difluoropyridine-2-carboxylic acid (Dfpc); 3-trifluoromethyl-pyridine-2-carboxylic acid (Tfpc) and X = H2O; pyrazole (Pz); pyridine (Py); imidazole (Im); and methanol (CH3OH) were synthesized using the '2 + 1' mixed ligand approach with an average yield of 84%. The complexes were characterized using the following spectroscopic techniques: IR, 1H and 13C NMR, UV/Vis, and single-crystal X-ray diffraction. The effect of the fluorine atoms on the backbone of the N,O'-bidentate ligand was investigated and a trend was noticed in the carbonyl stretching frequencies: with Pico < Tfpc < Dfpc. The in vitro biological screening on Vero (healthy mammalian), HeLa (cervical carcinoma) and A549 (lung cancer) cells revealed one toxic complex, fac-[Re(Pico)(CO)3(H2O)], with respective LC50 values of 9.0 ± 0.9, 15.8 ± 4.9 (SI = 0.570) and 20.9 ± 0.8 (SI = 0.430) µg/mL. As a result, it can be used as a positive control drug of toxicity.

Bis[(4-methyl-phen-yl)di-phenyl-phosphine-κP](nitrito-κ2 O,O')silver(I).

The title AgI complex, [Ag(NO2)(C19H17P)2], reveals a distorted pseudo-trigonal-planar shape around the AgI atom geometry resulting from the coordination of two phosphine ligands, as well as a nitrito-O,O' ligand coordinating to the silver(I) atom through the oxygen atoms; in this description, the two oxygen atoms are assumed to occupy one position, forming an acute O-Ag-O angle of 51.44 (9)°. The plane resulting from the NO2 coordination to Ag is nearly perpendicular to the plane from the coordination of the phosphine-P atoms to Ag [dihedral angle = 86.43 (9)°].

catena-Poly[[(benzyl-diphenyl-phosphine-κP)silver(I)]-µ-nitrato-κ2 O:O'-[(benzyl-diphenyl-phosphine-κP)silver(I)]-µ-nitrato-κ4 O,O':O',O''].

The structure of the title complex, [Ag2(NO3)2(C19H17P)2] n , reveals a chain emanating from the coordination of one phosphine ligand to each silver(I) cation, as well as the bis-monodentate coordination of a bridging nitrato ligand (per Ag atom) and the bis-bidentate coordination of another bridging nitrato ligand (per Ag atom). The distorted four-coordinate Ag atoms are characterized by bonding angles that notably deviate from the ideal tetra-hedral shape.

Rational Optimization of Dihydropyrimidinone-Quinoline Hybrids as Plasmodium falciparum Glutathione Reductase Inhibitors.

A series of dihydropyrimidinone-based antimalarial compounds were designed and synthesised based on the previously identified amide-based quinoline hybrids which showed good resistance reversal ability against the resistant strain of Plasmodium falciparum. The aromatic ring on the dihydropyrimidinone of the original hits was exchanged for a methyl group to bring the molecular weights below 500 Da and also determine the effect of the aromatic ring count on the resistance reversal ability of the hybrids. Apart from the previously used amide bond, the hybrid linker was also extended to the triazole linker. Although the triazole linker is synthetically easier to access, the use of an amide linker seems to have an activity advantage. The synthesised compounds in addition to the previously identified hits were subjected to molecular docking particularly targeting the orthosteric site of Plasmodium falciparum glutathione reductase (PfGR) protein. The ligand with the best binding interaction was rationally optimised to increase its suitability as a competitive inhibitor against the cofactor of the PfGR. Two of the optimised ligands showed better binding affinities than the cofactor while one of the two ligands displayed hydrophobically packed correlated hydrogen-bond which is very important in maintaining the ligand stability within the protein. In silico ADME predictions of the synthesised compounds indicate that these compounds possess good pharmacokinetic properties.

(Nitrito-κ2 O,O')bis-[tris-(4-methyl-phen-yl)phosphane-κP]silver(I).

The mol-ecular structure of the title compound, [Ag(NO2)(C21H21P)2], exhibits a pseudo-tetra-hedral coordination around the central AgI atom. The compound crystallizes with one mol-ecule in the asymmetric unit in the monoclinic space group P21/n with a rather long b axis [33.8752 (2) Å]. Weak C-H⋯O and C-H⋯N inter-actions consolidate the crystal packing. The nitrite-O atoms each occupy a single position in the coordination geometry.

Tris(benzyl-diphenyl-phosphane-κP)(nitrato-κO)silver(I).

The mol-ecular structure of the title complex, [Ag(NO3)(C19H17P)3], exhibits a severely distorted tetra-hedral coordination environment around the central AgI atom, comprising one O and three P atoms. Apart from a primary Ag-O coordination of the nitrato ligand of 2.667 (3) Å, a second (weaker) secondary inter-action of the nitrato ligand via the other O atom of 3.118 (4) Šis observed. The compound crystallizes with a complete mol-ecule in the asymmetric unit. Weak C-H⋯O inter-actions consolidate the packing.

Chelated Fischer carbene complexes of annulated thiophenes: synthesis, structure and electrochemistry.

Two (thieno[3,2-b]thiophene) and three annulated thiophenes (dithieno[2,3-b;3',2'-d]thiophene and dithieno[3,2-b;2',3'-d]thiophene) were employed as building blocks to synthesize linear or semi-circular chelated mononuclear biscarbene and dinuclear tetracarbene complexes. The electronic properties of the annulated thienylene chelated carbene complexes were investigated by cyclic voltammetry experiments and compared to non-chelated Fischer-type monocarbene complexes. Density functional theory (DFT) calculations were used to assign the redox events and to probe the extent of electron delocalisation as well as the possibility of electronic (intramolecular metal-metal) communication as a result of intervalence. The differences of these electronic properties in the conjugated chelated carbene complexes are compared to chelated carbene compounds without a linear conjugated pathway.

Synthesis, Spectroscopy and Electrochemistry in Relation to DFT Computed Energies of Ferrocene- and Ruthenocene-Containing -Diketonato Iridium(III) Heteroleptic Complexes. Structure of [(2-Pyridylphenyl)2Ir(RcCOCHCOCH3].

A series of new ferrocene- and ruthenocene-containing iridium(III) heteroleptic complexes of the type [(ppy)2Ir(RCOCHCOR')], with ppy = 2-pyridylphenyl, R = Fc = FeII(η5-C5H4)(η5-C5H5) and R' = CH3 (1) or Fc (2), as well as R = Rc = RuII(η5-C5H4)(η5-C5H5) and R' = CH3 (3), Rc (4) or Fc (5) was synthesized via the reaction of appropriate metallocene-containing ß-diketonato ligands with [(ppy)2(-Cl)Ir]2. The single crystal structure of 3 (monoclinic, P21/n, Z = 4) is described. Complexes 1-5 absorb light strongly in the region 280-480 nm the metallocenyl -diketonato substituents quench phosphorescence in 1-5. Cyclic and square wave voltammetric studies in CH2Cl2/[N(nBu)4][B(C6F5)4] allowed observation of a reversible IrIII/IV redox couple as well as well-resolved ferrocenyl (Fc) and ruthenocenyl (Rc) one-electron transfer steps in 1-5. The sequence of redox events is in the order Fc oxidation, then IrIII oxidation and finally ruthenocene oxidation, all in one-electron transfer steps. Generation of IrIV quenched phosphorescence in 6, [(ppy)2Ir(H3CCOCHCOCH3)]. This study made it possible to predict the IrIII/IV formal reduction potential from Gordy scale group electronegativities, χR and/or ΣχR' of -diketonato pendent side groups as well as from DFT-calculated energies of the highest occupied molecular orbital of the species involved in the IrIII/IV oxidation at a 98 % accuracy level.

trans-Bis[(2-bromo-phen-yl)diphenyl-phosphane-κP]carbonyl-chlorido-rhodium(I).

The title compound, trans-[RhCl(C(18)H(14)BrP)(2)(CO)], has a slightly disordered square-planar geometry with the Rh ion(I) situated on an inversion the centre and carbon-yl-chloride disorder observed as a result of the crystallographic inversion symmetry. Selected geometric parameters include: Rh-P = 2.3430 (8) Å, Rh-Cl = 2.434 (3) Å, Rh-C = 1.722 (8) Å, P-Rh-P = 180.00 (3)°, P-Rh-Cl = 95.40 (7)°, 84.60 (7)° and Rh-C-O = 177.9 (8)°.