An Efficient Synthesis of Novel Aminothiazolylacetamido-Substituted 3,5-Bis(arylidene)-4-piperidone Derivatives and Their Cytotoxicity Studies.

The expansion of 3,5-bis(arylidene)-4-piperidone derivatives with heterocyclic compounds such as 1,3-thiazole should take into account this correlation. The synthesized aminothiazolylacetamido-substituted 3,5-bis(arylidene)-4-piperidone derivatives 3a-j were found to have GI50 values in the range of 0.15-0.28 µM against HeLa and HCT116 cancer cell lines. In silico docking studies confirmed that the proteasome inhibition mechanism involves a nucleophilic attack from the N-terminal threonine residue of the ß-subunits to the C=O group of compounds. A C=O group of amide was able to interact with the NH group of the alanine residue and the 5g NH group of amino thiazole, along with an OH group of the serine residue. These results strongly suggest that the synthesized compounds could be a potential candidate inhibitor of the 20S proteasome. These molecules have the potential to be developed as cytotoxic and anticancer agents, as revealed by this study.

Synthesis and structures of dinuclear palladium complexes with 1,3-benzimidazolidine-2-thione and 1,3-imidazoline-2-thione.

The synthesis and structures of dinuclear palladium complexes with 1,3-benz-imidazolidine-2-thione (bzimtH) and 1,3-imidazoline-2-thione (imtH) are reported, namely, bis-(µ-1H-benzimidazole-2-thiol-ato)-κ2 N 3:S;κ2 S:N 3-bis-[cyanido(tri-phenyl-phosphine-κP)palladium(II)], [Pd2(C7H5N2S)2(CN)2(C18H15P)2] or [Pd2(µ-N,S-bzimtH)2(CN)2(PPh3)2] (1), and bis-(µ-1H-imidazole-2-thiol-ato)-κ2 N 3:S;κ2 S:N 3-bis-[cyanido(tri-phenyl-phosphine-κP)palladium(II)] aceto-nitrile 0.58-solvate, [Pd2(C3H3N2S)2(CN)2(C18H15P)2]·0.58C2H3N or [Pd2(µ-N,S-imtH)2(CN)2(PPh3)2]·0.58C2H3N (2). The compound [Pd2(µ-N,S-bzimtH)2(CN)2(PPh3)2] is located on a crystallographic twofold axis while [Pd2(µ-N,S-imtH)2(CN)2(PPh3)2]. 0.58(C2H3N) contains two partially occupied aceto-nitrile solvent mol-ecules with occupancies of 0.25 and 0.33. In both of these compounds, the anionic bzimtH- and imtH- ligands coordinate through N,S-donor atoms in a bridging mode, covering four coordination sites of two metal centers and other two sites are occupied by two PPh3 ligand mol-ecules. Finally, the remaining two sites of two metal centers are occupied by cyano groups, abstracted by the metals from the solvent during reaction. In the packing of the 1,3-benzimidazolidine- 2-thione and 1,3-imidazoline-2-thione complexes, there are intra-molecular π-π inter-actions involving the thione moiety as well as an N-H⋯N hydrogen bond linking the thione and cyano ligands. In addition, in 2, as well as the π-π inter-action involving the thione moieties, there is an additional π-π inter-action involving one of the thione moieties and an adjacent phenyl ring from the tri-phenyl-phosphine ligand. There are also C-H⋯N inter-actions between the imidazoline rings and the aceto-nitrile N atoms.

Three-Component [3+2] Cycloaddition for Regio- and Diastereoselective Synthesis of Spirooxindole-Pyrrolidines.

1,3-Dipolar cycloaddition of nonstabilized azomethine ylides derived from α-C-H functionalization of tetrahydroisoquinoline for regio- and diastereoselective synthesis of spirooxindole-pyrrolidines is developed. A three-component reaction of readily available cyclic amine, aryl aldehydes, and olefinic oxindoles provides a pot, atom and step economy (PASE) approach for making spiro-heterocyclic compounds with biological interest.

Incorporation of in situ generated 3,3'-(sulfane-diyl)bis-(1-methyl-1,3-imidazolidine-2-thione) into a one-dimensional CuI coordination polymer with sulfur-bridged {CuI 4S10} n central cores.

The reaction of [Cu(CH3CN)4](BF4) with 1-methyl-1,3-imidazolidine-2-thione {SC3H4(NMe)NH}, under aerobic conditions at room temperature, yielded an unusual one-dimensional coordination polymer, namely, catena-poly[[[(1-meth-yl-1,3-imidazolidine-2-thione-κS)copper(I)]-µ-(1-methyl-1,3-imidazolidine-2-thione)-κ2 S:S-copper(I)-µ-[3,3'-(sulfanedi-yl)bis-(1-methyl-1,3-imidazolidine-2-thione)]-κ5 S,S',S'':S,S''] bis-(tetra-fluorido-borate)], {[Cu2(C4H8N2S)2(C8H14N4S3)](BF4)2} n or [Cu4(κ5:L 1-N-S-N-L 1)2(κ1:L 1-NH)2(κ2:L 1-NH)2] n (BF4)4n 1 [L 1 = SC3 H4(NMe)NH] with sulfur-bridged {CuI 4S10} n central cores. The in situ generated bis-(1-methyl-1,3-imidazolidinyl-2-thione) sulfide [{SC3H4(NMe)NSN(NMe)C3H4S; abbrev. L 1-N-S-N-L 1] ligand, in combin-ation with 1-methyl-1,3-imidazolidine-2-thione (L 1-NH) ligands, construct this coordination polymer. Each CuI ion is bonded to four sulfur donor atoms in a distorted tetra-hedral geometry and the formation of this polymer solely by sulfur donor atoms with {CuI 4S10} n central cores, is the first such example in copper-heterocyclic-2-thione chemistry.

Synthesis, characterization and antitubercular activities of heterocyclic selenosemicarbazones.

Reaction of cyclohexanoneselenosemicarbazone with aldehydes and ketones containing heterocyclic rings (2-oxindole, 6-cholro-2-oxindole, 3-methyl-2-oxindole, isatin, 1-methyl isatin, furfural, pyrrole-2-carboxldehyde) in ethanol yielded, respective, selenosemicarbazones {2-oxindoleselenosemicarbazone (2-HOxsesc,H1L), 6-chloro-2-oxindole selenosemicarbazone (6-ClHOxsesc, H2L), 3-methyl-2-oxindole selenosemicarbazone (3-MeHOxses, H3L), isatinselenosemicarbazone (HIstsesc, H4L), 1-methyl isatinselenosemicarbazone (1-MeHIstsesc, H5L), 2-thiopheneselenosemicarbazone (2-Hthiosesc, H6L), 2-furfuralselenosemicarbazone (2-Hfursesc, H7L) and 2-pyrrole selenosemicarbazone (2-Hpysesc, H8L)}. However the similar reaction with aldehyde containing single aromatic ring (3-chlorobenzaldehyde and 4-chlorobenzaldehyde) formed 1, 2-bis(3-chlorobenzylidiene) hydrazine (A) and 1, 2-bis(4-chlorobenzylidiene) hydrazine (B) rather than selenosemicarbazone. All the synthesized compounds were characterized using IR and NMR (1H, 13C) spectroscopy. Structure of A and B were confirmed by single crystal X-ray crystallography. The synthesized selenosemicarbazones were tested for their anti-tubercular activities and H1L, H3L, H5L and H6L are found to exhibit excellent anti-TB activity. The experimental data will give an opportunity to examine their anti-tubercular activities and identify the lead molecule.

Chloro-cobalt complexes with pyridyl-ethyl-derived di-aza-cyclo-alkanes.

Syntheses are described for the blue/purple complexes of cobalt(II) chloride with the tetra-dentate ligands 1,4-bis-[2-(pyridin-2-yl)eth-yl]piperazine (Ppz), 1,4-bis-[2-(pyridin-2-yl)eth-yl]homopiperazine (Phpz), trans-2,5-dimethyl-1,4-bis-[2-(pyridin-2-yl)eth-yl]piperazine (Pdmpz) and tridentate 4-methyl-1-[2-(pyridin-2-yl)eth-yl]homopiperazine (Pmhpz). The CoCl2 complexes with Ppz, namely, {µ-1,4-bis-[2-(pyridin-2-yl)eth-yl]piperazine}bis-[di-chlorido-cobalt(II)], [Co2Cl4(C18H24N4)] or Co2(Ppz)Cl4, and Pdmpz (structure not reported as X-ray quality crystals were not obtained), are shown to be dinuclear, with the ligands bridging the two tetra-hedrally coordinated CoCl2 units. Co2(Ppz)Cl4 and {di-chlorido-{4-methyl-1-[2-(pyridin-2-yl)eth-yl]-1,4-di-aza-cyclo-hepta-ne}cobalt(II) [CoCl2(C13H21N3)] or Co(Pmhpz)Cl2, crystallize in the monoclinic space group P21/n, while crystals of the penta-coordinate mono-chloro chelate 1,4-bis-[2-(pyr-id-in-2-yl)eth-yl]piperazine}chlorido-cobalt(II) perchlorate, [CoCl(C18H24N4)]ClO4 or [Co(Ppz)Cl]ClO4, are also monoclinic (P21). The complex {1,4-bis-[2-(pyridin-2-yl)eth-yl]-1,4-di-aza-cyclo-hepta-ne}di-chlorido-cobalt(II) [CoCl2(C19H26N4)] or Co(Phpz)Cl2 (P ) is mononuclear, with a penta-coordinated CoII ion, and entails a Phpz ligand acting in a tridentate fashion, with one of the pyridyl moieties dangling and non-coordinated; its displacement by Cl- is attributed to the solvophobicity of Cl- toward MeOH. The penta-coordinate Co atoms in Co(Phpz)Cl2, [Co(Ppz)Cl]+ and Co(Pmhpz)Cl2 have substantial trigonal-bipyramidal character in their stereochemistry. Visible- and near-infrared-region electronic spectra are used to differentiate the two types of coordination spheres. TDDFT calculations suggest that the visible/NIR region transitions contain contributions from MLCT and LMCT character, as well as their expected d-d nature. For Co(Pmhpz)Cl2 and Co(Phpz)Cl2, variable-temperature magnetic susceptibility data were obtained, and the observed decreases in moment with decreasing temperature were modelled with a zero-field-splitting approach, the D values being +28 and +39 cm-1, respectively, with the S = 1/2 state at lower energy.

Antioxidant and Antivenom Potential of an Essential Oil, 4-(2-Oxo-propyl)-cyclopentane-1,3-dione, and Allantoin Derived from the Polyherbal Combination of Aristolochia indica L. and Piper nigrum L.

The goal of this study was to identify new compounds from a methanol extract of a polyherbal combination of Aristolochia indica L. and Piper nigrum L. (MECAIPN), two traditional medicinal plants used to cure envenomation, as well as to assess their antioxidant and antivenom properties. MECAIPN yielded EA1 (an essential oil), AA2 (4-(2-oxo-propyl)-cyclopentane-1,3-dione), and W3 ((2,5-dioxo-imidazolidin-4-yl)-urea) (Allantoin). Although EA1 had stronger radical scavenging activity, AA2 had higher DPPH and ferric ion radical scavenging activity, and W3 had higher molybdenum ion radical scavenging activity due to being a single molecule, the binding investigation revealed that EA1 has a greater Stern-Volmer quenching constant (Ksv) than AA2 and W3. Synchronous measurements indicated that EA1, AA2, and W3 bind to tryptophan and tyrosine residues in venom, causing denaturation of the secondary structure of the residue. Finally, the current study concludes that EA1 has more therapeutic antivenom potential, which could be related to the synergism of chemicals found in it. When it came to single compounds, AA2 had stronger antioxidant and antivenom capabilities than W3. To understand the mechanism of action and manufacture the green antivenom medication, more testing of the EA1 and compounds remains required.

Bis[3-(anthracen-9-yl)pentane-2,4-dionato-κ2 O,O'](N,N-di-methyl-formamide-κO)[tris-(pyrazol-1-yl-κN 2)hydroborato]europium(III).

The title compound, [Eu(C9H10BN6)(C19H15O2)2(C3H7NO)] or [TpEu(Anthracac)2(DMF)], was synthesized by reaction of a tris-(pyrazol-yl)borate (Tp-) Eu3+ complex with 3-(anthracen-9-yl)pentane-2,4-dione (HAnthracac) in the presence of tri-ethyl-amine. In the title compound, Eu3+ is located in an octa-vertex square-pyramidal coordination environment. In the two Anthracac- ligands, the anthracene and nearly planar acetyl-acetonate fragments are almost orthogonal. Neighboring mol-ecules of TpEu(Anthracac)2(DMF) are connected in the crystal by inter-molecular van der Waals inter-actions, while π-stacking inter-actions are limited to the edges of two anthracene rings.

Role of Coordination Geometry on the Magnetic Relaxation Dynamics of Isomeric Five-Coordinate Low-Spin Co(II) Complexes.

To investigate the influence of the coordination geometry on the magnetization relaxation dynamics, two geometric isomers of a five-coordinate low-spin Co(II) complex with the general molecular formula [Co(DPPE)2Cl]SnCl3 (DPPE = diphenylphosphinoethane) were synthesized and structurally characterized. While one isomer has a square pyramidal geometry (Co-SP (1)), the other isomer figures a trigonal bipyramidal geometry (Co-TBP (2)). Both complexes were already reported elsewhere. The spin state of these complexes is unambiguously determined by detailed direct current (dc) magnetic data, X-band, and high-frequency EPR measurements. Slow relaxation of magnetization is commonly observed for systems with S > 1/2. However, both 1 and 2 show field-induced slow relaxation of magnetization. Especially 1 shows relaxation times up to τ = 35 ms at T = 1.8 K, which is much longer than the reported values for undiluted Co(II) low-spin monomers. In 2, the maximal field-induced relaxation time is suppressed to τ = 5 ms. We attribute this to the change in g-anisotropy, which is, in turn, correlated to the spatial arrangement of ligands (i.e., coordination geometry) around the Co(II) ions. Besides the detailed electronic structure of these complexes, the experimental observations are further corroborated by theoretical calculations.

Pseudo-Five-Component Reaction for Diastereoselective Synthesis of Butterfly Shaped Bispiro[Oxindole-Pyrrolidine]s.

A pseudo-five-component reaction involving double decarboxylative 1,3-dipolar cycloaddition of azomethine ylides with olefinic oxindoles for the diastereoselective synthesis of bispiro[oxindole-pyrrolidine]s is developed. The major diastereomers are unique butterfly shaped compounds with a plane of symmetry. Recyclable zeolite HY acid catalyst is used to promote the reaction, and only CO2 and H2O are generated as byproducts.

Geometrical variations of two manganese(II) complexes with closely related quinoline-based tripodal ligands.

Structural analyses of the compounds di-µ-acetato-κ4 O:O'-bis-{[2-meth-oxy-N,N-bis-(quinolin-2-ylmeth-yl)ethanamine-κ4 N,N',N'',O]manganese(II)} bis-(tetra-phen-yl-borate) di-chloro-methane 1.45-solvate, [Mn2(C23O2)2(C23H23N3O)2](C24H20B)·1.45CH2Cl2 or [Mn(DQMEA)(µ-OAc)2Mn(DQMEA)](BPh4)2·1.45CH2Cl2 or [1](BPh4)2·1.45CH2Cl2, and (acetato-κO)[2-hy-droxy-N,N-bis(quinolin-2-ylmeth-yl)ethanamine-κ4 N,N',N'',O](methanol-κO)manganese(II) tetra-phenyl-borate methanol monosolvate, [Mn(CH3COO)(C22H21N3O)(CH3OH)](C24H20B)·CH3OH or [Mn(DQEA)(OAc)(CH3OH)]BPh4·CH3OH or [2]BPh4·CH3OH, by single-crystal X-ray diffraction reveal distinct differences in the geometry of coordination of the tripodal DQEA and DQMEA ligands to MnII ions. In the asymmetric unit, compound [1](BPh4)2·(CH2Cl2)1.45 crystallizes as a dimer in which each manganese(II) center is coordinated by the central amine nitro-gen, the nitro-gen atom of each quinoline group, and the meth-oxy-oxygen of the tetra-dentate DQMEA ligand, and two bridging-acetate oxygen atoms. The symmetric MnII centers have a distorted, octa-hedral geometry in which the quinoline nitro-gen atoms are trans to each other resulting in co-planarity of the quinoline rings. For each MnII center, a coordinated acetate oxygen participates in C-H⋯O hydrogen-bonding inter-actions with the two quinolyl moieties, further stabilizing the trans structure. Within the crystal, weak π-π stacking inter-actions and inter-molecular cation-anion inter-actions stabilize the crystal packing. In the asymmetric unit, compound [2]BPh4·CH3OH crystallizes as a monomer in which the manganese(II) ion is coordinated to the central nitro-gen, the nitro-gen atom of each quinoline group, and the alcohol oxygen of the tetra-dentate DQEA ligand, an oxygen atom of OAc, and the oxygen atom of a methanol ligand. The geometry of the MnII center in [2]BPh4·CH3OH is also a distorted octa-hedron, but the quinoline nitro-gen atoms are cis to each other in this structure. Hydrogen bonding between the acetate oxygen atoms and hydroxyl (O-H⋯O) and quinolyl (C-H⋯O and N-H⋯O) moieties of the DQEA ligand stabilize the complex in this cis configuration. Within the crystal, dimerization of complexes occurs by the formation of a pair of inter-molecular O3-H3⋯O2 hydrogen bonds between the coordinated hydroxyl oxygen of the DQEA ligand of one complex and an acetate oxygen of another. Additional hydrogen-bonding and inter-molecular cation-anion inter-actions contribute to the crystal packing.

Crystal structure and Hirshfeld surface analysis of ethyl 2-[9-(2-hy-droxy-phen-yl)-3,3,6,6-tetra-methyl-1,8-dioxo-2,3,4,4a,5,6,7,8a,9,9a,10,10a-dodeca-hydro-acridin-10-yl]acetate.

In the title compound, C27H33NO5, a 3,3,6,6-tetra-methyl-tetra-hydro-acridine-1,8-dione ring system carries an ethyl acetate substituent on the acridine N atom and an o-hy-droxy-phenyl ring on the central methine C atom of the di-hydro-pyridine ring. The benzene ring is inclined to the acridine ring system at an angle of 80.45 (7)° and this conformation is stabilized by an intra-molecular O-H⋯O hydrogen bond between the hy-droxy substituent on the benzene ring and one of the carbonyl groups of the acridinedione unit. The ester C=O oxygen atom is disordered over major and minor orientations in a 0.777 (9):0.223 (9) ratio and the terminal -CH3 unit of the ethyl side chain is disordered over two sets of sites in a 0.725 (5): 0.275 (5) ratio. In the crystal, C-H⋯O hydrogen bonds combine to link the mol-ecules into a three-dimensional network. van der Waals H⋯H contacts contribute the most to the Hirshfeld surface (66.9%) followed by O⋯H/H⋯O (22.1%) contacts associated with weak hydrogen bonds.

Crystal structures of 1-(4-chloro-phen-yl)-4-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carb-oxy-lic acid and 4-(4-meth-oxy-phen-yl)-1-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carbo-nitrile.

In the title compounds C23H21ClN2O3 [I, namely 1-(4-chloro-phen-yl)-4-(4-methyl-phen-yl)-3,8-dioxo-1,2,5,6,7,8-hexa-hydro-quine-3-carb-oxy-lic acid] and C24H22N2O3 [II, namely 4-(4-meth-oxy-phen-yl)-1-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carbo-nitrile], each of the cyclo-hexene and di-hydro-pyridine rings of the 1,2,5,6,7,8-hexa-hydro-quinoline moieties adopts a twisted-boat conformation. The asymmetric units of both compounds I and II consist of two independent mol-ecules (A and B). In II A, three carbon atoms of the cyclo-hexene ring are disordered over two sets of sites in a 0.670 (11):0.330 (11) occupancy ratio. In the crystal of I, mol-ecules are linked through classical N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif and with their mol-ecular planes parallel to the crystallographic (020) plane. Non-classical C-H⋯O hydrogen-bonding inter-actions connect the dimers, resulting in a three-dimensional network. In the crystal of II, mol-ecules are linked by C-H⋯N, C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.

Synthesis of (3-nitro-2-oxo-benzaldehyde thiosemicarbazonato)-zinc(II) complexes: the position of nitro group in phenyl ring alters antimicrobial activity against K. pneumoniae 1, S. typhimurium 2, MRSA and C. albicans.

The basic purpose of this investigation was to explore the effect on antimicrobial activity of a nitro group at an ortho- versus para-position in the 2-hydroxy-phenyl ring of nitro-salicylaldehyde-N-substituted thiosemicarbazone (X-NO2-stscH2-N1HR, X = 3 or 5; stsc-stands for salicyladehyde thiosemicarbazone) complexes with zinc. Reactions of zinc(ii) acetate with 3-nitro-salicylaldehyde-N-substituted thiosemicarbazones (3-NO2-stscH2-N1HR) and 2,2-bipyridine, or 1,10-phenanthroline as co-ligands, yielded complexes of stoichiometry, [Zn(3-NO2-stsc-N1HR)(N,N-L)] {L, R: bipy, H, 1; Me, 2; Et, 3; Ph, 4; phen, H, 5; Me, 6; Et, 7; Ph, 8}. The thio-ligands coordinate to the metal as dianions (deprotonation of -OH and -N2H moieties) through O, N3 and S donor atoms in distorted trigonal bipyramid geometry (4, 5, 7: τ = 0.718-0.576) or in distorted square pyramid geometry (8: τ = 0.349). ESI-mass spectrometry supported the formation of molecular ion peaks. Complexes displayed fluorescence with λmax = 438-473 nm. It was found that these five-coordinated [Zn(3-NO2-stsc-N1HR)(N,N-L)] complexes showed high antimicrobial activity against methicillin resistant S. aureus (MRSA), Klebsiella pneumoniae 1, Salmonella typhimurium 2 and C. albicans vis-à-vis that of 5-NO2-stscH2-N1HR zinc complexes reported earlier. However, in comparison, the antimicrobial activity of 5-nitro complexes against S. aureus was high relative to 3-nitro complexes in the present case.

Crystal structure and spectroscopic properties of aqua-dichlorido-{1,1'-[(pyridine-2,6-diyl-κN)bis(methyl-ene)]bis-(4-butyl-4,5-di-hydro-1H-1,2,4-triazole-5-thione-κN 2)}cobalt(II).

The structure of the title compound, [CoCl2(C19H27N7S2)(H2O)], at 173 K has monoclinic (C2/c) symmetry. We report here the synthesis, single-crystal structure, electrospray mass spectrum and NMR spectroscopy of a new six-coordinate cobalt(II) pincer complex. The pincer ligand, in this complex, which is novel, coordinates via three nitro-gen atoms (two triazole and one pyridine). The ligand is ambidentate and can coordinate via three nitro-gen atoms or two sulfur and one nitro-gen atoms. The cobalt(II) metal center has pseudo-octa-hedral geometry and based on the single-crystal structure, the pincer ligand coordinates in a meridional fashion with the metal and adjacent six-membered ring ligands all in a similar plane and forming two slightly distorted boat configurations. The other two coordinated monodentate ligands are one water mol-ecule and two chloride ions with four cobalt(II) complexes in the unit cell. The asymmetric unit of the complex is comprised of half the pyridine ring and water mol-ecule with the CoII atom at the center of the pincer situated about a twofold axis. The Co-N, Co-O, and Co-Cl bond lengths are consistent with single bonds. In the crystal, the complex forms a three-centre bifurcated weak hydrogen-bonding inter-action with a chlorine ion, forming one inter-molecular inter-action with the pincer group and a water mol-ecule and a second intra-molecular inter-action with a C-H group within the pincer group. Crystal packing is also highlighted with C 2 2(6)>aa>a ring motifs, forming a three-dimensional supra-molecular network structure. While some stacking of the pyridine rings in the unit cell is observed, there are no relevant π-π inter-actions in the crystal packing. The 1H and 13C{1H} NMR spectra of the complex are consistent with a plane of symmetry being present. The electrospray mass spectrum, which was collected in positive ion mode, showed the loss of one water mol-ecule and one chloride ligand from the complex. In the future, we plan to screen this cobalt(II) complex for electrocatalysis reactivity.

Copper(I) and silver(I) complexes of anthraldehyde thiosemicarbazone: synthesis, structure elucidation, in vitro anti-tuberculosis/cytotoxic activity and interactions with DNA/HSA.

A reaction of copper(i) halides (X = I, Br, Cl) and silver(i) halides with 9-anthraldehyde thiosemicarbazone (9-Hanttsc, H1L) and triphenylphosphine produced halogen-bridged dinuclear complexes, [M2(µ2-X)2(η1-S-9-Hanttsc)2(Ph3P)2] (M = Cu, X = Cl, 1; Br, 2; I, 3; M = Ag, X = Cl, 4; Br, 5). A similar reaction of 9-anthraldehyde-N1-methyl thiosemicarbazone (9-Hanttsc-N1-Me, H2L) with Ph3P and silver(i) halides yielded sulfur-bridged dimers, [Ag2X2(µ2-S-9-Hanttsc-N1-Me)2(Ph3P)2] (X = Cl, 9; Br, 10), however with copper(i) halides insoluble compounds were formed, which upon the addition of one extra mole of Ph3P gave mononuclear complexes of the formula [CuX(η1-S-9-Hanttsc-N1-Me)(Ph3P)2] (X = Cl, 6; Br, 7; I, 8). All of the complexes have been characterized by elemental analysis, NMR (1H, 13C) spectroscopy and single crystal X-ray crystallography (2, 5, 6, and 9). Both the ligands (H1L and H2L) and their complexes (1-10) were tested for their anti-tubercular and anticancer activities. The interactions of the ligands and their complexes (copper and silver) with calf thymus DNA (ct-DNA) and human serum albumin (HSA) were examined through UV-visible and fluorescence spectroscopy. Results showed that copper complex 2 displayed strong interactions with ct-DNA and HSA having binding constant values of 6.66 × 104 M-1 and 3.28 × 104 M-1, respectively, followed by silver complex 10 which gave binding constant values of 4.60 × 104 M-1 and 3.06 × 104 M-1, respectively. All of the complexes also showed good interactions with DNA in docking studies.

Di-2-pyridylketone-N1-substituted thiosemicarbazone derivatives of copper(II): Biosafe antimicrobial potential and high anticancer activity against immortalized L6 rat skeletal muscle cells.

The basic aim of this study pertains to developing antimicrobial or anticancer agents based on N, S-donor organic ligands bonded to metals. In the present investigation, di-2-pyridylketone-N1-substituted thiosemicarbazone (py2tscH-N1HR2, Chart 2) thio-ligands were reacted with copper(I) halides in organic solvents yielding copper(II) complexes of stoichiometry, [Cu(N,N,S-py2tsc-N1HR2)X] (X = I, R2 = H, 1; Me, 2; Et, 3; Ph, 4; X = Br, R2 = H, 5; Me, 6; Et, 7; Ph, 8; X = Cl, R2 = H, 9; Me, 10; Et, 11; Ph, 12); the formation of CuII probably occurs through a proton coupled electron transfer (PCET) process. Electron spin resonance, ultraviolet-visible spectroscopy and X-ray crystallography (2, 3, 5, 7, 11) supported a distorted square planar geometry of these complexes. Moderate to high antimicrobial activities of these complexes against methicillin resistant Staphylococcus aureus, Gram positive bacteria, Staphylococcus aureus and Gram negative bacteria, Klebsiella pneumoniae 1, Salmonella typhimurium 2 and one yeast Candida albicans were recorded. Complexes were found to be biosafe with 88-91% cellular viability. All complexes have shown high anticancer activity against the immortalized L6 rat skeletal muscle cell line with very low IC50 values.

Synthesis, crystal structure, DFT calculations and Hirshfeld surface analysis of 3-butyl-2,6-bis-(4-fluoro-phen-yl)piperidin-4-one.

The title compound, C21H23F2NO, consists of two fluoro-phenyl groups and one butyl group equatorially oriented on a piperidine ring, which adopts a chair conformation. The dihedral angle between the mean planes of the phenyl rings is 72.1 (1)°. In the crystal, N-H⋯O and weak C-H⋯F inter-actions, which form R 2 2[14] motifs, link the mol-ecules into infinite C(6) chains propagating along [001]. A weak C-H⋯π inter-action is also observed. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H⋯H (53.3%), H⋯C/C⋯H (19.1%), H⋯F/F⋯H (15.7%) and H⋯O/O⋯H (7.7%) contacts. Density functional theory geometry-optimized calculations were compared to the experimentally determined structure in the solid state and used to determine the HOMO-LUMO energy gap and compare it to the UV-vis experimental spectrum.

Combination of single-molecule magnet behaviour and luminescence properties in a new series of lanthanide complexes with tris(pyrazolyl)borate and oligo(ß-diketonate) ligands.

A series of tris(pyrazolyl)borate mono-, di- and trinuclear complexes, [Tp2Ln]nX (Ln = Eu, Tb, Gd, Dy, Xn- = various mono-, bis- and tris(ß-diketonates) has been prepared. The Tb3+ and Dy3+ complexes are luminescent single molecular magnets (SMM) and exhibit luminescence quantum efficiencies up to 73% for the Tb3+ and 4.4% for the Dy3+ compounds. Similar Eu3+ complexes display bright emission only at lower temperatures. The Dy3+ and Tb3+ complexes possess SMM behavior in a non-zero dc field at low temperatures, while the polynuclear Dy3+ complexes also show slow magnetic relaxation even in zero dc field up to 8 K. Ueff-values determined from dynamic magnetic measurements were up to 31 and 6 cm-1 for the Dy3+ and Tb3+ complexes, respectively. It was found that within a series of Dy3+ and Tb3+ compounds, Ueff and luminescence quantum yields decreased with increasing nuclearity of the compounds and a shortening of the intramolecular Ln-Ln distance. ΔOrbach-values estimated from low-temperature luminescence spectra were significantly higher than those obtained from ac magnetic data, which may be due to involvement of additional processes in the relaxation mechanism (quantum tunneling, Raman, direct) reducing the energy barrier. Some of the Tb3+-compounds also display metal-centred electroluminescence, giving them potential as emitting layers in LEDs.

Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase.

Chemical model complexes are prepared to represent the active site of an enzyme. In this protocol, a family of tridentate pincer ligand precursors (each possessing two sulfur and one nitrogen donor atom functionalities (SNS) and based on bis-imidazole or bis-triazole compounds) are metallated with CoCl2·6H2O to afford tridentate SNS pincer cobalt(II) complexes. Preparation of the cobalt(II) model complexes for liver alcohol dehydrogenase is facile. Based on a quick color change upon adding the CoCl2·6H2O to acetonitrile solution that contains the ligand precursor, the complex forms rapidly. Formation of the metal complex is complete after allowing the solution to reflux overnight. These cobalt(II) complexes serve as models for the zinc active site in liver alcohol dehydrogenase (LADH). The complexes are characterized using single crystal X-ray diffraction, electrospray mass spectrometry, ultra-violet visible spectroscopy, and elemental analysis. To accurately determine the structure of the complex, its single crystal structure must be determined. Single crystals of the complexes that are suitable for X-ray diffraction are then grown via slow vapor diffusion of diethyl ether into an acetonitrile solution that contains the cobalt(II) complex. For high quality crystals, recrystallization typically takes place over a 1 week period, or longer. The method can be applied to the preparation of other model coordination complexes and can be used in undergraduate teaching laboratories. Finally, it is believed that others may find this recrystallization method to obtain single crystals beneficial to their research.