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.

Design, synthesis, and in silico-in vitro antimalarial evaluation of 1,2,3-triazole-linked dihydropyrimidinone quinoline hybrids

In response to the malaria parasite’s resistance towards quinoline-based antimalarial drugs, we have employed quinoline-containing compounds in combination with dihydropyrimidinone (DHPM) analogues as resistance reversal agents (RAs) and investigated their antimalarial activities based on DHPM’s resistance reversal abilities. The present study employed click chemistry to link DHPM and quinoline compounds which offered several synthetic advantages over the previously used amide coupling for the same hybrids. Among the synthesised compounds, 4 hybrids with the 7-chloroquinoline moiety showed antimalarial activity below 1 µM while compounds with the mefloquine moiety showed lower antimalarial activity than chloroquine (CQ) and the 7-chloroquinoline hybrids. Among the tested hybrids for the IC50 determination, four compounds displayed good antimalarial activity with increased sensitivity against the CQ-resistant K1 strain between 421 and 567 nM and showed higher activity between 138 and 245 nM against the NF54 CQ-sensitive strain, while three compounds have IC50 values greater than 5 µM. Additionally, in silico molecular docking and molecular dynamics studies were conducted to investigate the binding affinities of all the synthesised compounds as glutathione reductase protein competitive inhibitors. Further optimisation of the compound with the highest binding affinity generated 16 compounds with higher binding affinities than the flavine adenine dinucleotide (FAD) cofactor.

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.

(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 Ag^I 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 Ag^I 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) Å is observed. The compound crystallizes with a complete mol-ecule in the asymmetric unit. Weak C-H⋯O inter-actions consolidate the packing.

Bis[(4-methylphenyl)diphenylphosphane-κP](nitrato-κ2 O,O′)silver(I)

The molecular structure of the title AgI complex, [Ag(NO3)(C19H17P)2] or [Ag{(p-CH3C6H4)(C6H5)2P-κP}2-NO3-κ2 O:O′], is described, where a distorted trigonal–planar coordination environment is exhibited about the central AgI atom; in this description, the two O atoms are assumed to occupy one position in the coordination sphere. The compound crystallized with half a molecule in the asymmetric unit having the AgI atom lying on a twofold axis.

catena-Poly[[(benzyldiphenylphosphine-κP)silver(I)]-μ-nitrato-κ2 O:O′-[(benzyldiphenylphosphine-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 tetrahedral shape.

Bis[(4-methylphenyl)diphenylphosphine-κP](nitrito-κ2 O,O′)silver(I)

The title silver(I) diphenyl-p-tolyl­phosphine complex crystallizes with one complete mol­ecule in the asymmetric unit that features a bidentate nitrito, as well as two diphenyl-p-tolyl­phosphine ligands coordinated to a Ag^I center.

The title Ag^I complex, [Ag(NO₂)(C₁₉H₁₇P)₂], reveals a distorted pseudo-trigonal–planar shape around the Ag^I 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)°].

Rational Optimization of Dihydropyrimidoinone-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 ( Pf GR) protein. The ligand with the best binding interaction was rationally optimised to increase its suitability as a competitive inhibitor against the cofactor of the Pf GR. 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.

Photo-and thermoresponsive N-salicylideneaniline derivatives: solid-state studies and structural aspects

Eight photo-and/or thermoresponsive salicylideneanilines were obtained by mechanosynthesis under solvent-free conditions and stabilized by external stimuli for their isolations in solid-state. Switching properties of these materials were investigated by various analytical techniques and spectroscopic data.

Exploring steric and electronic parameters of biaryl phosphacycles

Steric and electronic parameters of the newly developed biaryl phosphacycles derived from the phobane[3.3.1] (Phob) and phosphatrioxa-adamantane (Cg) moieties were quantified from various experimental and theoretical methods.

Synthesis and structure of thienyl Fischer carbene complexes of PtII for application in alkyne hydrosilylation

Efficient alkyne hydrosilylation mediated by well-defined platinum(ii) bis(ethoxycarbene) complexes of the Fischer-type prepared by facile transmetallation.

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 β-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.

Crystal structure of (2,4-dimethoxybenzyl)triphenylphosphonium trifluoroacetate — trifluoroacetic acid (1/1), C31H27F6O6P

C31H27F6O6P, triclinic, P1̄ (no. 2), a = 8.0017(2) Å, b = 11.1702(3) Å, c = 17.8353(4) Å, α = 104.9000(10)°, β = 96.5360(10)°, γ = 97.7380(10)°, V = 1508.05(7) Å3, Z = 2, R gt(F) = 0.0354, wR ref(F 2) = 0.0896, T = 150(2) K.

Crystal structure of 3-(4-methoxyphenyl)-1-phenylprop-2-yn-1-one, C16H12O2

C16H12O2, monoclinic, P21/c (no. 14), a = 15.7947(10) Å, b = 6.2958(4) Å, c = 12.2787(8) Å, β = 94.216(2)°, V = 1217.69(14) Å3, Z = 4, R gt(F) = 0.0398, wR ref(F 2) = 0.1336, T = 150(2) K.

Tandem transfer hydrogenation–epoxidation of ketone substrates catalysed by alkene-tethered Ru(ii)–NHC complexes

Eight novel alkene-tethered Ru(ii)–NHC complexes were employed as catalysts in tandem transfer hydrogenation–epoxidation reactions using phenacyl bromide derivatives as substrates.

Base-free glucose dehydration catalysed by NHC-stabilised heterohalo cyclopentadienyl Cr(iii) complexes

Synthesis of Cr(iii) NHC complexes for application as catalysts in the dehydration of glucose to form 5-hydroxymethylfurfural.

Crystal structure of bis(phenylethynyl)tetrakis(dimethylphenylphosphine) ruthenium(II), C48H54P4Ru

C

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)°.