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The structures and ligand binding modes of polychalcogenide anions are reviewed in this article. Participation in hypervalent 3 c-4 e bonds and/or weaker secondary np2 → nσ* bonds leads to a strikingly more diverse homopolytaomic anion chemistry for selenium and tellurium in comparison to sulfur, for which only unbranched chain anions S n2- with n = 2-9 have been reported. Trapped S2 ·- and S3 ·- radicals are responsible for the characteristic colours of the ultramarine pigments and S3 ·- is the dominant sulfur species at the high temperatures and pressures of deep metamorphic settings. Hypervalent linear TeTe24-, T-shaped TeTe34- and square-planar TeTe46- units generate a remarkable variety of structural motifs and connectivity patterns for 1 to 3D polytelluride anions. Electron-deficient polytelluride sheets are, however, prone to periodic spatial modifications of their charge density (CDWs) with a lower total free energy, whose formation is driven by nesting effects in the electronic band structure causing Fermi surface instabilities. Polychalcogenide ligands augment the typical terminal and bridging coordination modes of monoatomic chalcogenide anions through their ability to participate in chelation, side-on and combination binding modes. In addition to the electrical conductivity and thermoelectric energy conversion properties of the polytellurides, potential applications of the polychalcogenides range from the manufacture of synthetic zeolite pigments and ion-exchangeable polysulfide aerogels to NIR-emissive lanthanide polyselenides with high quantum efficiency. [ABSTRACT FROM AUTHOR]

Abstract: The DNA binding of polypyridyl (pp) (η5-pentamethylcyclopentadienyl)iridium(III) complexes of the type [(η5-C5Me5)IrCl(pp)](CF3SO3) (pp=dpq, dppz, dppn) (1–3) and [(η5-C5Me5)Ir(L)(pp)](CF3SO3)2 (L=(NH2)2CS, pp=dpq, dppz, dppn) (4–6), (L=(NMe2)2CS, pp=dpq, dppz, dppn) (7–9) has been studied by UV/Vis spectroscopy, circular dichroism and viscosity measurements. Modest increases ΔT m of 2–7°C in the thermal denaturation temperature (for r =[complex]/[DNA]=0.1) and the effectively unchanged values or decreases in viscosity observed for CT DNA after incubation with complexes 1–3 for 60min are in accordance with thermodynamically preferred coordinative Ir-N (nucleobase) binding to the biopolymer. However, kinetically favoured intercalation for 2 and 3 leads to large initial hypochromic UV/Vis shifts for the π–π∗ transitions of their polypyridyl ligands in the range 300–450nm. As indicated by the large ΔT m value of 14°C and the marked increase in viscosity for 5/CT DNA mixtures, dppz appears to present an optimum surface area for side-on intercalation for L=(NH2)2CS. Whereas lower values for these parameters suggest partial intercalation for the smaller dpq ligand of complex 4, the ΔT m value of only 2°C and a decrease in DNA viscosity are in accordance with surface binding for the dppn complex 6. In contrast, replacement of L=(NH2)2CS in 6 by L=(NMe2)2CS in 9leads to very strong intercalative binding of the larger polypyridyl ligand with a binding constant K b =1.0(6)×107 M−1 following a possible change in the DNA structure from B to A, as suggested by CD spectroscopy. Viscosity studies and ΔT m values for complexes 7 and 8 are in accordance with, respectively, partial and strong intercalative binding of these complexes into DNA. Circular dichroism measurements suggest that the presence of the bulky (NMe2)2CS ligand causes significant distortions of the DNA structure for the larger dppz and dppn ligands. [Copyright &y& Elsevier]

Abstract: The pH- and time-dependent reactions of the antitumor drug cisplatin, cis-[PtCl2(NH3)2], with the methionine- and histidine-containing pentapeptides Ac-Met-Gly-His-Gly-Gly-OH, Ac-Met-Gly-Gly-His-Gly-OH and Ac-Gly-Met-Gly-His-Gly-OH (Gly=glycyl, Met= l-methionyl, His= l-histidyl) at 313K have been investigated by high performance liquid chromatography, mass spectrometry and nuclear magnetic resonance. Cisplatin mediates a rapid “downstream” hydrolytic cleavage of the Met-Gly amide bond in weakly acid solution (pH ⩽5) for all three peptides, leading to release of H-Gly-His-Gly-Gly-OH, H-Gly-Gly-His-Gly-OH and H-Gly-His-Gly-OH, respectively, and formation of κ2 S,N M chelate complexes of the methionine-containing residuals Ac-Met-OH or Ac-Gly-Met-OH. An alternative reaction pathway affords tridentate κ3 S,N M,N(imidazole) macrochelates of the original pentapeptide following ammine loss. The downstream cleavage pathway is competitive with the likewise cisplatin-mediated upstream cleavage of the Ac-Gly linkage in the pentapeptide Ac-Gly-Met-Gly-His-Gly-OH. This leads to formation of both the κ3 S,N M,N G1 complex of H-Gly-Met-Gly-His-Gly-OH due to upstream cleavage and the analogous tridentate complex for H-Gly-Met-OH due to initial downstream loss of H-Gly-His-Gly-OH followed by upstream loss of acetic acid. As downstream cleavage is not observed for Ac-(Gly)2-Met-(Gly)2-OH under similar conditions, it may be concluded that rapid histidine imidazole substitution of the ammine ligand in trans-position to an anchoring methionine S atom must assist hydrolytic cleavage of the Met-Gly amide bond. [Copyright &y& Elsevier]

The article analyzes the crystal structure of the organic compound N,N-Diethyl-N'-[(E)-4-pyridylmethylene]benzene-1,4-diamine supported by combined X-ray and density functional theory structure optimization. It determines the presence of neutral molecules of a dipolar Schiff base chromophore in the structure and observes the crystallization of the compound in the noncentrosymmetric space group Pna21. Also observed is the stacking interactions in the crystal structure leading to herring-bone packing motif.

The title compound, [Mn(C6H15N3)2][As2Se6], contains a sandwich-like centrosymmetric complex cation with two tridentate 9-aneN3 (1,4,7-triaza­cyclo­nona­ne) ligands, which coordinate the MnII atom in an octa­hedral manner. AsSe3 pyramids are linked by two Se—Se bonds into the centrosymmetric chair-shaped six-membered ring of the [As2Se6]2− counter-anions. [ABSTRACT FROM AUTHOR]

The centrosymmetric title compound, [Mn2Sn2Se6(C6H18N4)2], contains a central ditetra­hedral edge-bridged [Sn2Se6]4− anion, which connects two [Mn(tren)]2+ fragments [tren is tris­(2-amino­ethyl)amine] through Mn—Se bonds of length 2.608 (2) Å to symmetry-related terminal Se atoms. These Se atoms also participate in additional weak Mn—Se inter­actions of length 3.122 (2) Å to the Mn atoms of symmetry-related [Mn(tren)}2+ fragments, leading to the formation of infinite chains. [ABSTRACT FROM AUTHOR]

The title compound, Cs4As4Se8, contains discrete cyclic [As4Se8]4− anions consisting of corner-sharing AsSe3 pyramids. A twist–chair conformation is observed for the eight-membered As4Se4 rings, which exhibit a crystallographic inversion centre. Both of the crystallographically independent Cs+ cations contain eight Se atoms in their coordination spheres. [ABSTRACT FROM AUTHOR]

The title compound, Cs[As(CH3)2Se2], contains discrete tetra­hedral dimethyl­diselenidoarsenate(V) anions and Cs cations, with As and Cs located on a crystallographic twofold rotation axis. A distorted octa­hedral coordination is observed for the caesium counter-cation, with Cs⋯Se distances in the range 3.706 (2)–3.762 (2) Å. [ABSTRACT FROM AUTHOR]

The title compound, Cs3AsSe4·H2O, contains discrete tetra­hedral tetra­selenidoarsenate(V) anions. The solvent water O atom participates in the coordination spheres of all three independent Cs cations, as do, in each case, seven Se atoms. [ABSTRACT FROM AUTHOR]

The title compound, [Mn(C2H8N2)3]2[Sn2Te6], contains [Mn(en)3]2+ (en is ethyl­enediamine) complex cations and crystallographically centrosymmetric [Sn2Te6]4− anions in its monoclinic crystal structure. The five-membered chelate rings of symmetry-related cations exhibit either λλλ or δδδ conformations. Two SnTe4 tetra­hedra edge-share to afford the hexa­telluridodistannate(IV) anions, whose terminal Sn—Te bonds are significantly shorter than the bridging Sn—Te bonds. [ABSTRACT FROM AUTHOR]

Solvothermal reaction of Ge and Se with Mn(CH3COO)2·4H2O in the presence of [(CH3)3NH]Cl generates the open framework quaternary selenidogerman­ate(IV) [(CH3)3NH]2[MnGe4Se10], which contains corner-linked adamantanoid Ge4Se10 cages and MnSe4 tetra­hedra. The trimethyl­ammonium counter-cations are disordered and exhibit an S4 crystallographic site symmetry. Whereas the Ge—Se distances within the Ge4Se6 core lie in the range 2.357 (1)–2.370 (1) Å, a significantly shorter Ge—Se bond length of 2.284 (1) Å is observed for the bridging Se atom to the MnSe4 units. [ABSTRACT FROM AUTHOR]

The title compound, [Cs(C12H24O6)]2[As2Se6], contains two independent centrosymmetric [As2Se6]2− counter-anions, in which AsSe3 pyramids are linked by two Se—Se bonds into a chair-shaped six-membered ring. Four of the Se atoms of the first [As2Se6]2− anion coordinate the Cs atoms of dimeric [{Cs(18-crown-6)}2(μ-As2Se6)] units that are joined by additional O⋯Cs inter­actions into polymeric sheets. In contrast, all six Se atoms of the second [As2Se6]2− anion coordinate Cs atoms within discrete [{Cs(18-crown-6)}2(μ-As2Se6)] dimers. [ABSTRACT FROM AUTHOR]

The title compound, Cs4SrSn3Se9, contains infinite `dreier' [SnSe3]2− chains consisting of corner-linked SnSe4 tetra­hedra. Whereas the larger independent caesium cations exhibit coordination numbers of 8 and 9, a distorted octa­hedral environment is observed for the smaller strontium cation. [ABSTRACT FROM AUTHOR]

The title compound, Cs6Sb4Se9·0.5H2O, contains discrete [Sb4Se9]6− chain anions consisting of corner-linked SbSe3 pyramids. Mol­ecular C2 symmetry is observed for these nona­selenidoantimonate(III) anions, which exhibit bridging Sb—Se distances in the range 2.615 (2)–2.650 (3) Å and shorter terminal Sb—Se distances between 2.507 (3) and 2.522 (3) Å. [ABSTRACT FROM AUTHOR]

Abstract: Until recently, Rh(III) and particularly Ir(III) complexes were generally considered as being unlikely candidates for anticancer agents owing to the typical kinetic inertness of their transition metal centres. Systematic studies on the cellular impact of a range of octahedral Rh(III) complexes containing polypyridyl and other aromatic chelates have now, however, demonstrated that high cytotoxicity in cancer cells and in certain cases promising relative tolerance by healthy cells can be achieved by judicious selection of the remaining ligands. Current knowledge on the biological properties of Rh(III) and Ir(III) compounds is reviewed in this article, with particular emphasis being placed on design strategies and on their solution behaviour, DNA binding preferences, structure–activity relationships and apoptosis induction in both adhesive and non-adhesive cells. [Copyright &y& Elsevier]

Abstract: A [Ni(CN)4]2−-based two-dimensional Mn(II) coordination polymer {Mn(H2O)2[NiCN]4·4H2O}, in which the coordination layers are stacked on top of each other sandwiching 2D water layer of boat-shaped hexagonal water clusters has been synthesized. The complex exhibits high thermal decomposition temperature and reversible water absorption, which were clearly demonstrated by thermal and PXRD studies on the parent and rehydrated complex after dehydration. [Copyright &y& Elsevier]

Abstract: The pH- and time-dependent reactions of the antitumor drug cisplatin, cis-[PtCl2(NH3)2], with the methionine-containing peptides Ac-Met-Gly-OH, Ac-Met-Pro-OH, Ac-Met-Pro-Gly-Gly-OH and Ac-Gly-Met-Pro-Gly-Gly-OH (Gly=glycyl, Met= d-methionyl, Pro=L-prolyl) at 313K have been investigated by high performance liquid chromatography, mass spectrometry and nuclear magnetic resonance. As a result of the strong trans influence of the methionyl SM atom, initial Pt–SM binding at pH>5 is followed by a rapid formation of tridentate machrochelates for the N-acetylated peptides. The site trans to SM is occupied by a carboxylate O atom in the case of the κ 3SM,NM,OG/P macrochelates of the dipeptides and by the C-terminal glycylamide NG2 atom for the κ 3SM,OM,NG2 macrochelate of Ac-Met-Pro-Gly-Gly-OH. Cisplatin simultaneously mediates the rapid hydrolytic cleavage of the Met-X (X=Gly, Pro) amide bond for both dipeptides over the whole range 2.8⩽pH⩽10.0. The released amino acids X react with the resulting κ 2SM, NM chelate of N-acetylmethionine to afford mixed κSM:κ 2N x ,O x complexes of the type cis-[Pt(NH3)(Ac-Met-OH-κS)(H-X-O-κ 2N x ,O x )]+ as final products at pH<5 for X=Gly and pH<8 for X=Pro. In contrast to the dipeptides, hydrolytic cleavage of the Met-Pro amide bond in Ac-Met-Pro-Gly-Gly-OH at pH>5 is significantly inhibited by the presence of high concentrations of the macrochelate [Pt(NH3)(Ac-Met-Pro-Gly-Gly)-κ 3SM,OM,NG2]+. Downstream hydrolysis of the Met-Gly amide bond is competitive with upstream Ac-Gly cleavage for Ac-Gly-Met-Pro-Gly-Gly-OH at pH<4.5. [Copyright &y& Elsevier]

Abstract: Mononuclear neutral manganese(II) and cobalt(II) complexes with the antibiotic Sodium Monensin A (Mon-Na, 1b) were synthesized and characterized. The crystal structures of M(Mon-Na)2Cl2 ·H2O (M=Mn, 2; M=Co, 3) were determined by X-ray crystallography. The complexes crystallize in monoclinic space group C2 with a tetrahedrally coordinated transition metal attached to oxygen atoms of deprotonated carboxyl groups of two Sodium Monensin molecules and two chloride ions. The sodium ion remains in the cavity of the ligand and cannot be replaced by Mn(II) or Co(II). The complexes were additionally characterized by different spectroscopic techniques (UV–Visible, EPR, FAB-MS). A preferable octahedral environment around the transition metal centers is observed in polar solvents while the complexes retain their tetrahedral structure in non-polar media. The antimicrobial activity of 1b, 2 and 3 was tested against Gram(+) and Gram(−) bacteria. [Copyright &y& Elsevier]

An automated multidimensional protein identification technology, which combines biphasic liquid chromatography with electrospray ionisation tandem mass spectrometry (MS/MS), was employed to analyse tryptic peptides from Escherichia coli cells treated with the antiproliferation agent [(η6- p-cymene)RuCl2(DMSO)], where DMSO is dimethyl sulfoxide. MS/MS spectra were recorded for molecular ions generated by neutral loss of p-cymene from intensive peptide ions coordinated by the (η6- p-cymene)RuII fragment. Matching of the MS/MS spectra of the ruthenated peptides to spectra of proteins in the E. coli database enabled the identification of five protein targets for [(η6- p-cymene)RuCl2(DMSO)]. One of these is the constitutive cold-shock protein cspC, which regulates the expression of genes encoding stress-response proteins, and three of the other targets, ppiD, osmY and sucC, are proteins of the latter type. The DNA damage-inducible helicase dinG was likewise established as a protein target. Aspartate carboxylate functions were identified as the probable Ru binding sites in cspC, ppiD and dinG, and threonine and lysine side chains in osmY and sucC, respectively. [ABSTRACT FROM AUTHOR]

Abstract: This work describes the synthesis and characterization of two Pd(II) complexes [(3,5-Hdmpz)2Pd2(μ-3,5-dmpz)2(2,6-dipic)] (1) and [Na2(H2O)4Pd(2,6-dipic)2] (2) (3,5-Hdmpz=3,5-dimethylpyrazole and 2,6-dipic=2,6-pyridinedicarboxylate). The X-ray molecular structure determination shows that 1 is a binuclear complex bridged by two 3,5-dmpz units and is completely unsymmetric since one palladium atom contains two protonated 3,5-Hdmpz ligands and the other one contains the 2,6-dipic2− unit that coordinates in a bidentate fashion. The central six-member Pd2N4 core shows a boat-like conformation where the palladium atoms are positioned at the vertices of the boat. The molecules are assembled in an extended zigzag one-dimensional network formed through 3,5-Hdmpz-carboxylate (2,6-dipic2−) hydrogen bonds. The packing of complex 2 is constructed of cationic Na+–H2O and anionic Pd-2,6-dipic2− units joined together to form an extended two dimensional network. Alternate short and long Na–Na distances are observed in the cationic layer. A detailed quantum-chemical calculation on the Na-chains in 2 has been made. Complex 1 shows a luminescence property and antimicrobial activity against Bacillus subtilis, Escherichia coli and Aspergillus niger where the MIC has been found to be 100μg/mL for all three species. [Copyright &y& Elsevier]

Abstract: Two hydrogen-bonded palladium(II) and platinum(II) complexes, [Pd(Hida)2] (1) and [Pt(Hida)2] (2) (Hida− =iminodiacetate), have been synthesized and characterized by single crystal X-ray diffraction analyses. Hida− serves as a bidentate ligand coordinating to both Pd(II) and Pt(II) through its nitrogen and oxygen atom, exhibiting a square planar geometry with a trans configuration. The uncoordinated carboxylic group and the imino group of the ligand are involved in strong intermolecular hydrogen bonding to form a two dimensional layered network in both the complexes. The network is propagated along the ac-plane and stacks orthogonally to the b-axis. The thermogravimetric analyses for complexes 1 and 2 reveal stepwise decomposition processes indicating the probable decarboxylation of the free and bonded carboxylates. As there are two types of hydrogen bonding (N–H⋯O, O–H⋯O) present in both the complexes, two endothermic peaks regarding heat change are evident from their DSC diagrams. [Copyright &y& Elsevier]

The pH- and time-dependent reaction of the anticancer drug carboplatin, [Pt(cbdca-κ2O,O′)(NH3)2] (cbdca=cyclobutane-1,1-dicarboxylate), with the tripeptides H-glyglymet-OH (glycylglycyl-l-methionine) and Ac-glyglymet-OH at 313 K was investigated by high-performance liquid chromatography, NMR and mass spectrometry. The relative stability of the initial ring-opened κS complex [Pt(cbdca-κO)(Ac-glyglymet-OH-κS)(NH3)2] leads to increased formation of the kinetically favoured κS:κS′ bis-adduct [Pt(Ac-glyglymet-OH-κS)2(NH3)2]2+ in comparison with cisplatin. As a result a second 1:2 reaction pathway κS→κS:κS′→κ2NM, S:κS′→κ3NG2,NM, S:κS′, where NM and NG2 represent, respectively, metallated methionine and glycine nitrogen atoms, competes with the 1:1 route κS→κ2NM, S→κ3NG2,NM, S also observed for cisplatin. Cleavage of N-acetylglycine at the backbone C(O)–N bond to the second gly residue (G2) is observed after 100 h for the respective tridentate complexes [Pt(Ac-glyglyH−1metH−1-OH-κ3NG2,NM, S) (Ac-glyglymet-OH-κS)] and [Pt(Ac-glyglyH−1metH−1-OH-κ3NG2,NM, S)(NH3)] at pH <5.2. The longevity of the initial κS complex leads to about an eight-fold increase in the rate of formation of the κN7:κN7′ bis-adduct [Pt(5′-GMP-κN7)2(NH3)2]2− for the reaction of carboplatin with 5′-GMP2− at pH 7 in the presence of Ac-glyglymet-OH. A mixed-ligand κS:κN7 species [Pt(5′-GMP-κN7)(Ac-glyglymet-OH-κS)(NH3)2] provides the major precursor for this 1:2 nucleotide complex and κN7 coordination of 5′-GMP2− is also observed in the κ2NM,S:κN7 complex [Pt(5′-GMP-κN7)(Ac-glyglymetH−1-OH-κ2NM,S)(NH3)2]− formed by substitution of the ammine ligand trans to the methionine sulphur. As the intermediate κS:κN7 species is formed rapidly within the first 10 h of reaction, these results suggest that the transfer reaction pathway κS→κS:κN7→κN7:κN7′ involving κS platinated peptides could play an important role in accelerating the rate of DNA binding for carboplatin. [Copyright &y& Elsevier]

Stability constants for the binary (1 : 1) complexes of CoII, NiII, CuII, ZnII, CdII, CaII, SrII and BaII with cytosine, cytidine, 5-bromocytosine, 5-azacytosine and 5-fluorocytosine were determined in aqueous solution (Ionic strength, μ = 0.1 mol dm -3 NaNO 3 ) potentiometrically at 25, 35 and 45°C. Experimental pH titration data were analyzed using the BEST computer program in order to evaluate formation constants of various intermediate species formed in the above binary systems. Enthalpy and entropy changes for the formation of binary complexes were calculated. On the basis of solution studies, efforts were made to prepare the binary complexes with 5-azacytosine ligand. Isolated solid complexes were characterized by different techniques and spectroscopic studies suggested a polymeric nature for the complexes, with OH and 5-azacytosine acting as bridging ligands. [ABSTRACT FROM AUTHOR]

Bis(η6-arene)ruthenium(II) complexes of the type [(η6-cymene)Ru(η6-L)](CF3SO3)n (2–7), n=2–3, containing catechol and 5-hydroxyindole derivatives L may be prepared by treatment of [(η6-cymene)Ru(acetone)3](CF3SO3)2 with the appropriate compound in CF3COOH. For the l-Dopa and H-dopamine complexes 2 (n=2) and 3 (n=3), η6-coordination leads to a dramatic reduction of more than 6 units in pKa to values of, respectively 3.67(3) and 3.98(7) for the first deprotonation of a phenyl hydroxo substituent. An even greater increase in acidity on η6-coordination is observed for the indole N1 and O5 donor atoms in the 5-hydroxytryptophan complex 4 (n=2). A pH potentiometric and 1H NMR study of the interaction of the 5-hydroxy-3-indolyl acetic acid and N-acetyl-tryptophan (AcTrpOH) complexes 6 and 7 (n=2) with [Pd(dien)(H2O)]2+ confirms facile metalation of the indole nitrogen N1 at pH>4, leading to predominance of dinuclear complexes such as of [(η6-cymene)Ru(η6-AcH−1TrpO-κN1)Pd(dien)]2+ in neutral and weakly alkaline solution. X-ray structural analyses are reported for complexes 3 and 4. A significant distortion towards an η5-oxohexadienyl coordination is indicated for 4 by the short C5&z.sbnd;O5 distance of 1.29(2) A˚ and the tilting of the C5 bonding plane at an angle of 12.4° to the coordination plane of the remaining five indole C-atoms. [Copyright &y& Elsevier]

The model tripeptide Boc-Leu(1)-Aib(2)-Phe(3)-OMe 1 containing a non-coded amino acid residue (Aib: α-amino isobutyric acid) forms a supramolecular helical assemblage via non-covalent interactions in single crystals. The SEM image of the peptide 1 in the solid state shows the ribbon like fibrillar morphology, a characteristic feature of highly ordered aggregated fibrils like amyloid fibrils. [Copyright &y& Elsevier]

The article presents information on the structure of the organic compound S-Phenyl 4-cyanothiobenzoate or C14H9NOS. The molecules of this compound exhibit a chiral non-planar structure in which the 4-cyanophenyl and S-phenyl rings are tilted at dihedral angles of 1.81 (2) and 72.49 (1)° with respect to the central thiocarbonate unit. The compound crystallizes in the non-centrosymmetric monoclinic space group P21 and participates in very weak intermolecular hydrogen bonds and its observed structure is in good agreement with those determined for other S-phenyl thiobenzoates.

Im Rahmen der Entwicklung neuer biologisch aktiver Organometallverbindungen mit Aspirin-Teilstruktur, deren Wirkmechanismus die Hemmung der Cyclooxygenase(COX)-Enzyme einschließt, wurden auch entsprechende Derivate des Zeise-Salzes synthetisiert. In In-vitro-Untersuchungen konnte dann gezeigt werden, dass neben den Zeise-Aspirin-Derivaten auch das Zeise-Salz selbst einen sehr potenten Hemmstoff der COX-Enzyme darstellt. Kaliumtetrachloroplatinat(II) und Cisplatin haben in vergleichbaren Konzentrationen keinen Einfluss auf die Enzymaktivität. Für die COX-1 konnte mittels LC-ESI-Tandem-Massenspektrometrie nachgewiesen werden, dass das Zeise-Salz mit den Aminosäuren Tyr385 (aktives Zentrum des Enzyms) und Ser516 (Acetylierungsstelle des Aspirins) essenzielle Zentren des Enzyms platiniert, was dessen Funktion stark beeinträchtigt. Damit konnte erstmals nachgewiesen werden, dass das Zeise-Salz selbst pharmakologisch aktiv ist und einen potenten Enzyminhibitor darstellt. [ABSTRACT FROM AUTHOR]

With the aim to design new biologically active bioinorganic drugs of aspirin, whose mode of action is based on the inhibition of the cyclooxygenase(COX) enzymes, derivatives of Zeise's salt were synthesized in this structure-activity relationship study. Surprisingly, not only these Zeise-aspirin compounds but also Zeise's salt itself showed high inhibitory potency against COX enzymes in in vitro assays. In contrast, potassium tetrachloroplatinate and cisplatin did not influence the enzyme activity at equimolar concentrations. It was demonstrated by LC-ESI tandem-mass spectrometry that Zeise's salt platinates the essential amino acids Tyr385 (active site of the enzyme) and Ser516 (will be acetylated by aspirin) of COX-1, thereby strongly impairing the function of the enzyme. This finding demonstrates for the first time that Zeise's salt is pharmacologically active and is a potent enzyme inhibitor. [ABSTRACT FROM AUTHOR]

A series of linear diimine and diamine-bridged binuclear dioxomolybdenum(VI) complexes having general formula [(MoO 2 L) 2 (B-B)] [where, B-B is a bridging linear N,N′-bidentate spacer 4,4′ bipyridine, 1,2 bis (4-pyridyl) ethene and 1,2 bis (4-pyridyl) ethane] with the tridentate binegative Schiff base ligands obtained by the condensation of salicylaldehyde/2-hydroxyacetophenone with S-benzyl/S-methyl dithiocarbazate have been synthesized. Elemental analysis, various spectroscopic (IR, UV–Vis, 1 H NMR) measurements and electrochemical studies have been used for characterization of these complexes. The complexes 2 , 2a , 9 and 10 were structurally characterized by single crystal X-ray crystallography which reveal that in these complexes the overall coordination geometry around the Mo(VI) center can be described as distorted octahedral. Complexes 2 , 2a , 9 and 10 give rise to interesting supramolecular architectures via hydrogen bonding and π - π stacking interactions. In addition, extensive hydrogen bonding interactions in complex 10 lead to the formation of cavities. DFT calculations on the ligand and complexes 2 , 2a , 9 and 10 were also carried out. [ABSTRACT FROM AUTHOR]

Abstract: Cu(II) complexes of the tridentate thiosemicarbazone ligands diacetyl monooxime thiosemicarbazone (dmoTSCH2 ) and diacetyl monooxime (4-phenyl)thiosemicarbazone (dmoPhTSCH2 ) have been synthesized. X-ray crystal structures of dmoPhTSCH2 and [Cu(dmoTSCH)Cl]2 ·H2O (1·H2O) are also reported. The Cu(II) compound 1·H2O is a dinuclear complex, where the Cu(II) centers have a square pyramidal geometry and are bridged by two thiolato ligands. A C2 axis passes through the middle of Cu2S2 rectangle. Variable temperature susceptibility measurement for 1·H2O shows that this compound exhibits a very weak antiferromagnetic behavior (in the solid state) with J 1 = −2.97cm−1, using the Heisenberg isotropic spin Hamiltonian (H =−J 1 S 1·S 2). DFT calculations show that the intramolecular magnetic interaction should be ferromagnetic, and the net antiferromagnetic behavior is due to competition with antiferromagnetic intermolecular interactions through hydrogen bonds. [Copyright &y& Elsevier]

Abstract: The cytostatic properties and cellular effects of novel diene–ruthenium(II) complexes of the types OC-6-13-[RuCl2(pp)(cod)] 1–5 (pp=2,2′-bipyridyl (bpy), phen=1,10-phenanthroline (phen), 5,6-dimethylphenanthroline (5,6-Me2phen), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq), ethylenediamine (en)) and OC-6-24-[RuCl{(Me2N)2CS}(pp)(cod)](CF3SO3) 6–8 (pp=phen, 5,6-Me2phen, dpq) have been studied for the human cancer cell lines MCF-7 and HT-29 and for Jurkat leukemia cells. CD spectra indicate that 7 causes a massive distortion of the CT DNA B double helix toward the A form. Whereas the neutral complexes 1, 2 and 5 exhibit only modest antiproliferative activity toward MCF-7 and HT-29 cells, the monocationic complexes are significantly more active, in particular the DNA-distorting complex 7 with its IC50 values of 0.73 and 0.42μM, respectively. As established by online monitoring with a cell-based sensor chip, this potent 5,6-Me2phen complex invokes dose-dependent decreases in MCF-7 cellular respiration and extracellular acidification rates and causes a time-delayed decrease in the impedance of the cell layers, that can be ascribed to cell death. Treatment of Jurkat cells with 7 leads to high concentrations of reactive oxygen species and the induction of apoptosis. The pronounced dose-dependent inhibition of oxygen consumption by isolated mice mitochondria indicates the involvement of an intrinsic mitochondrial pathway in the programmed cell death process. [Copyright &y& Elsevier]

The title compound, fac-[RhCl3(pzH)3] (pzH = pyrazole) or fac-[RhCl3(C3H4N2)3], was prepared by treating RhCl3·3H2O with three equivalents of pyrazole. It contains a central RhIII atom coordinated in a facial manner by three pyrazole N atoms and three chloride ligands. As a result of their participation in weak intramolecular N—H...Cl hydrogen bonds, the pyrazole rings adopt a propeller-like arrangement. The mean planes of the pyrazole ligands exhibit dihedral angles of 26.83 (17), 2.03 (10) and 18.83 (14)° with the planes containing their coordinating N atoms, the RhIII atom and the acceptor Cl atoms of their individual N—H...Cl interactions. [ABSTRACT FROM AUTHOR]

Cations of the dinuclear title compound, [Ir2(C10H15)2(C5H10NS2)2](ClO4)2, contain two half-sandwich (η5-C5Me5)IrIII fragments and two tridentate diethyldithiocarbamate ligands, whose S atoms coordinate individual IrIII atoms in a κ2 S, S′-fashion to afford four-membered chelate rings. The IrIII atoms are linked by the thiocarbamate ligands in a μ-S bridging manner in a central (IrS)2 ring. The (η5-C5Me5)IrIII fragments adopt a cis arrangement relative to this ring and exhibit Ir—C distances in the range 2.167 (5)–2.206 (5) Å. Ir—S bond lengths to the bridging S atoms lie between 2.3897 (11) and 2.4098 (12) Å, and are slightly longer than those of 2.3842 (12) and 2.3832 (12) Å observed for the monodentate S atoms. The ions are linked by C—H...O hydrogen bonds. [ABSTRACT FROM AUTHOR]

The title compound, [Ir(η5-C5Me5)Cl(en-κ2 N)](CF3SO3) (en is ethylenediamine) or [Ir(C10H15)Cl(C2H8N2)](CF3SO3), contains a half-sandwich (η5-C5Me5)IrIII fragment coordinated in a bidentate manner by the N atoms of an en ligand. N—H...O hydrogen bonds between the en amino groups and O atoms of the trifluoromethanesulfonate anions generate polymeric chains. The cation and anion both have C s symmetry. The C atoms of the en ligand are disordered about a mirror plane. The crystal structure involves N—H...O, C—H...O and N—H...Cl hydrogen bonds. [ABSTRACT FROM AUTHOR]

The title compound, [Ir(η5-C5Me5)(dien-κ3 N)](CF3SO3)2 (dien is diethyl­enetriamine) or [Ir(C10H15)(C4H13N3)](CF3SO3)2, contains a half-sandwich (η5-C5Me5)IrIII fragment coordinated in a facial manner by the N atoms of a dien ligand. N—H⋯O hydrogen bonds to the trifluoro­methane­sulfonate counter-anions link the organometallic cations into a chiral polymeric network. [ABSTRACT FROM AUTHOR]

Cations of the title compound, [Ir(C10H15)(C5H10NS2)(CO)](CF3O3S), contain half-sandwich (η5-C5Me5)IrIII fragments. The remaining positions in the octa­hedral IrIII coordination environment are occupied by the S atoms of the bidentate diethyl­dithio­carbamate ligand and the C atom of the carbonyl ligand. [ABSTRACT FROM AUTHOR]

The cation of the title compound, [Ir(C10H15)(C4H8NO2S)](CF3SO3)·0.5H2O, contains a half-sandwich [Ir(C5Me5)]2+ fragment, the IrIII atom of which is coordinated by the tridentate S-methyl­cysteinate ligand ( S-MecysO) in a κ3 N, O, S manner. An RIr configuration is observed for the transition metal and an SS configuration for the chiral thio­ether S atom. [ABSTRACT FROM AUTHOR]

Abstract: The antiproliferative properties and cellular impact of novel substitutionally inert rhodium(III) complexes of the types [Rh{(CH3)2 NCS2}2(pp)]Cl 3–5 (pp=5,6-Me2phen, dpq, dppz) and OC-6-23-[Rh(2-S-py)2(pp)]Cl 6 and 7 (2-S-py=pyridine-2-thiolate; pp=dpq, dppz) have been investigated for the adherent human cancer cell lines MCF-7 and HT-29 and for non-adherent Jurkat cells. Whereas CD and viscosity measurements indicate that the polypyridyl ligands of 4 and 5 intercalate into CT DNA, this is not the case for the analogous pyridine-2-thiolate complexes 6 and 7. Complexes 3–7 all exhibit a high antiproliferative activity towards MCF-7 and HT-29 cells, with IC50 values in the range 0.055–0.285μM. As established by online monitoring with a cell-based sensor chip, the highly cytostatic complex 6 (IC50 =0.059 and 0.078μM) invokes an immediate concentration-dependent reduction of MCF-7 cell respiration and a time-delayed decrease in cellular impedance, which can be ascribed to the induction of cell death. Annexin V/PI assays demonstrated that 6 also has a pronounced antiproliferative activity towards Jurkat cells and that it invokes extensive apoptosis and high concentrations of reactive oxygen species in these leukemia cells. The observation of a dose-dependent inhibition of the oxygen consumption of isolated mice mitochondria indicates the involvement of an intrinsic mitochondrial pathway in this process. [Copyright &y& Elsevier]

Abstract: Novel molecular complexes of 1,10-phenanthroline (phen) and 5-amino-1,10-phenanthroline (5-NH2-phen) [(5-NH2-phen)2(phen) (H2O)3 (1), (phen)2(imidazole) (H+) (BF4 −) (2), (phen)2(benzimidazole) (H+) (BF4 −) (3), (5-NH2-phen)4(H2O)3 (4), and (phen)3 (indole) (H+) (BF4 −) (5)] were synthesized via self-assembly processes and their in vitro anticancer activity was investigated. The structures of the compounds were confirmed by UV, FTIR, CIMS(CH4) and elemental analysis. The crystal structure of 2 was determined by X-ray diffraction. Cytotoxicity of the substances was measured using the cultivated human tumour cell lines HepG2, HEp-2, and 8-MB-GA. The tested substances showed different activity depending on the cell line and amount used. Substances 2 and 3 were not toxic to the non-tumour cells (Lep-3), but significantly toxic to all tumour ones. This is not the case with compounds 4 and 5, which are non-toxic towards carcinogenic cell lines, but even stimulate both HepG2 and HEp-2. [Copyright &y& Elsevier]

Abstract: In medicinal chemistry carbaboranes have been used almost exclusively as boron carriers for boron neutron capture therapy (BNCT). Recent developments extended the carrier approach and use carbaboranes as scaffolds for radiodiagnostic or therapeutic agents. Most recent studies, however, focus on carbaboranes as modern hydrophobic pharmacophores. This research employs preferably meta- and para-carbaborane, because these isomers are extremely hydrophobic and very stable. In this paper we therefore investigated the pharmacophoric behavior of the ortho isomer as putative phenyl mimetic by comparing aspirin to asborin, its ortho-carbaborane analogue. Special emphasis is placed on the impact of the cluster properties on the pharmacological profile. Subjects under study are the mode of cyclooxygenase (COX) inhibition, stability, and toxicity. The straightforward syntheses of the corresponding nido compounds as well as their contribution to the pharmacology of the closo precursors will be highlighted. Finally, proof will be given that the ortho-carbaborane core of asborin merits the designation “pharmacophore” by definition and is a multifunctional group rather than just a hydrophobic, bulky spectator. [Copyright &y& Elsevier]

Abstract: Half-sandwich organorhodium(III) complexes of the type [(η5-C5Me5)RhCl(pp)] (CF3SO3) containing polypyridyl ligands (pp) represent a promising class of cytostatic agents. Replacement of the polypyridyl ligands of complexes 1 (pp=phen) and 6 (pp=dppz) by methyl-substituted derivatives in 2–5 (pp=4-Mephen, 5-Mephen, 4,7-Me2phen, 5,6-Me2phen) and 7 (pp=Me2dppz) leads to a significant improvement in their antiproliferative activity towards human MCF-7 and HT-29 cancer cells. For instance, the IC50 value towards HT-29 cells decreases from 4.3±0.2μM for 6 to 0.98±0.49μM for complex 7. In contrast, no activity (IC50 >100μM) was observed for the HOOC and n-BuNHCO substituted dppz complexes 8 and 9. UV/vis, CD and NMR spectra for mixtures of complexes 7–9 with CT DNA were in accordance with intercalation of the substituted dppz ligands between the base pairs of the double helix and direct evidence for this binding mode was also provided by a 2D NOESY study for complex 7 with the hexanucleotide d(5′-CGTCGG-3′). Each of the methyl-substituted phen complexes 2–5 is significantly more active towards immortalized HEK-293 cells (IC50 values 0.40±0.02 to 0.94±0.02μM) than towards the cancer cells. Flow cytometric measurements of DNA fragmentation in BJAB cells following an incubation period of 72h with 1, 5 and 6 indicate that the complexes induce specific apoptotic cell death in the non-adherent lymphoma cells. [Copyright &y& Elsevier]

Abstract: Two mononuclear Cu(II) complexes, [Cu(L1H2)](ClO4)1.25Cl0.75·1.25H2O (1) and [Cu(L2H2)](ClO4)2 (2), of the pyridoxal Schiff base ligands N,N′-dipyridoxylethylenediimine (L1H2) and N,N′-dipyridoxyl-1,3-propanediimine (L2H2) are reported. X-ray crystal structures of both complexes are also reported. In both complexes the pyridoxal nitrogen atoms remain protonated. In the solid state, the tetradentate Schiff base ligand is virtually planar in 1, while in 2 the ligand conformation is like an inverted umbrella. In cyclic voltammetry experiments it is found that in these complexes the Cu(III) and Cu(I) states are more easily accessible than in their salen type analogs. The pyridoxal Schiff base complexes are also found to be resistant to oxidative electro-polymerization, unlike their corresponding salicyl aldehyde Schiff base complexes. [Copyright &y& Elsevier]

Cations and anions of the title compound {systematic name: 1-[4-(amino­carbonyl)butyl]guanidinium bis­(hydrogen­squarate)}, C6H17N5O2+·2C4HO4−, are connected into a three-dimensional network by inter­molecular N—H⋯O hydrogen bonds between thel-argininamidium ammonium, amide and guanidinium functions and the hydrogensquarate carbonyl O atoms. The independent hydrogensquarate monoanions are linked into dimers by pairs of O—H⋯O′ hydrogen bonds. [ABSTRACT FROM AUTHOR]

Mol­ecules of the title compound, C9H11NO, are connected into infinite chains by inter­molecular N—H⋯O hydrogen bonds of length 2.893 (3) Å between the N-methyl­amino and carbonyl functions. [ABSTRACT FROM AUTHOR]

Gold(I) complexes such as auranofin have been used for decades to treat symptoms of rheumatoid arthritis and have also demonstrated a considerable potential as new anticancer drugs. The enzyme thioredoxin reductase (TrxR) is considered as the most relevant molecular target for these species. The here investigated gold(I) complexes with benzimidazole derived N-heterocyclic carbene (NHC) ligands 1a−4a represent a promising class of gold coordination compounds with a good stability against the thiol glutathione. TrxR was selectively inhibited by 1a−4a in comparison to the closely related enzyme glutathione reductase, and all complexes triggered significant antiproliferative effects in cultured tumor cells. More detailed studies on a selected complex (2a) revealed a distinct pharmacodynamic profile including the high increase of reactive oxygen species formation, apoptosis induction, strong effects on cellular metabolism (related to cell surface properties, respiration, and glycolysis), inhibition of mitochondrial respiration and activity against resistant cell lines. [ABSTRACT FROM AUTHOR]

Abstract: The dodecanuclear rhenium anionic complex with terminal hydroxo ligands [Re12CS17(OH)6]6− was obtained by the reaction of K6[Re12CS17(CN)6]·20H2O with molten KOH at 300°C. The cluster complex was crystallized as a potassium salt from aqueous solution. The reaction between K6[Re12CS17(OH)6]·4H2O and Na2S2O4 in water under reflux results in the formation of the complex Na12[Re12CS17(SO3)6]·48.5H2O. Both new compounds were characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The electronic structure of [Re12CS17(OH)6]6− was also elucidated by DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: Mononuclear transition metal complexes of the polyether ionophorous antibiotic monensin (monensic acid, MonH) with nickel(II) and zinc(II) were prepared and characterized using single crystal X-ray diffraction and spectral methods. Monensin complexes crystallize as [Ni(Mon)2(H2O)2]·H2O·5MeCN (1) and [Zn(Mon)2(H2O)2]·H2O·4.5MeCN (2), respectively, in the monoclinic space group P21. Compounds 1 and 2 consist of two monoanionic monensic acid ligands (monensinates) bound in a bidentate coordination mode to the transition metal ion. The metal center is placed in an octahedral environment with monensin anions occupying the equatorial plane of complexes via oxygens of carboxylate and hydroxyl groups located at the both ends of ionophore molecule. The strongly folded antibiotic anions are supported by intramolecular H-bonds, most of them originating from the two aqua ligands attached to the metal(II) ions in axial positions and completing their 6-fold coordination. The bioactivity assay reveals that the presence of divalent metal ion in the monensin complexes influences the biological properties of the ligand and should be taken into account when discussing its mode of action. [Copyright &y& Elsevier]

Abstract: Two mononuclear zinc(II) complexes, [ZnL1H2Cl]Cl·2H2O (1·Cl·2H2O) and [ZnL2HCl]·H2O (2·H2O) (L1H2 and L2H2 are N,N′-bis(pyridoxylidene)ethylenediamine and N,N′-bis(pyridoxylidene)1,3-propanediamine, respectively) have been synthesized and characterized by elemental analysis, FT-IR, fluorescence spectroscopy, TG–DTA and single crystal X-ray diffraction studies. The Zn(II) ion in complex 1 have a square pyramidal geometry with appreciable distortion towards trigonal bipyramid, whereas in 2 it has a geometry which is near the midpoint of square pyramid and trigonal bipyramid. The zinc atom is coordinated by two imine nitrogens, two phenolic oxygens and one chloride ion. The Zn(II) complexes show emission at 462nm when excited at their lowest energy absorption at 372nm. [Copyright &y& Elsevier]