Vladimir B Arion

University of Vienna, Wien, Vienna, Austria

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Publications (230)730.88 Total impact


  • No preview · Article · Feb 2016
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    ABSTRACT: endo-Tricyclo[3.2.1.0(2,4)]oct-8-ylidene is a foiled carbene reaction intermediate. It was generated by thermolyzing Δ(3)-1,3,4-oxadiazoline precursors dissolved in benzaldehyde and in acetophenone. The products appear to stem from direct insertion of the carbene's divalent C atom into the α-bonds of the carbonyl compounds, however this is only superficial. The strict stereochemistry observed is due to the topologies of the reaction intermediates of the proposed two-step mechanism. Bimolecular nucleophilic addition generates bent 1,3-zwitterions. The neutral reaction intermediates undergo pinacolic rearrangements to form the observed adducts. Product ratios reflect the migratory aptitudes of the carbonyl compounds' α-substituents. The carbene reaction was modeled using DFT. The singlet carbene's bicoordinate C atom bends 31° toward the endo-fused cyclopropane bond elongating it to r = 1.69 Å. The resulting trishomocyclopropyl HOMO{-1} is a three-center two-electron bond responsible for the electron-deficient carbene's nucleophilicity. Its calculated properties are consistent with this assertion: (1) singlet-triplet (ΔES-T) energy gap of -25 kcal/mol, (2) gas-phase proton affinity (PA) value of 272 kcal/mol, (3) hard and soft acid and base (HSAB) ΔN value of -0.2 in its initial reaction with the carbonyl compounds, and (4) negative frontier orbital interaction values ΔΔE(PhC(O)H) = -4.38 eV and ΔΔE(PhC(O)Me) = -3.97 eV.
    No preview · Article · Oct 2015 · The Journal of Organic Chemistry
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    ABSTRACT: A series of heteropentanuclear oxalate-bridged Ru(NO)-Ln (4d-4f) metal complexes of the general formula (nBu4 N)5 [Ln{RuCl3 (μ-ox)(NO)}4 ], where Ln=Y (2), Gd (3), Tb (4), Dy (5) and ox=oxalate anion, were obtained by treatment of (nBu4 N)2 [RuCl3 (ox)(NO)] (1) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1, 2, and 5 were in addition analyzed by X-ray crystallography, 1 by Ru K-edge XAS and 1 and 2 by (13) C NMR spectroscopy. X-ray diffraction showed that in 2 and 5 four complex anions [RuCl3 (ox)(NO)](2-) are coordinated to Y(III) and Dy(III) , respectively, with formation of [Ln{RuCl3 (μ-ox)(NO)}4 ](5-) (Ln=Y, Dy). While Y(III) is eight-coordinate in 2, Dy(III) is nine-coordinate in 5, with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4 N(+) ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium-lanthanide complexes 2-5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC-5) and compared with those obtained for the previously reported Os(NO)-Ln (5d-4f) analogues (nBu4 N)5 [Ln{OsCl3 (ox)(NO)}4 ] (Ln=Y (6), Gd (7), Tb (8), Dy (9)). Complexes 2-5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d-4f metal complexes 6-9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP-MS data, indicating five- to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Full-text · Article · Aug 2015 · Chemistry - A European Journal
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    ABSTRACT: The magnetic field induced circular polarization of near infrared photoluminescence in Bi-doped pure silica glass was studied in the spectral range of 660 - 1600 nm covering three excited state levels. The highest degree of magnetic circular polarization of luminescence was observed in the lasing, first excited state (peak emission at 1440 nm). The results of variable temperature and variable magnetic field measurements allows to conclude that the near infrared luminescence originates from an isolated non-Kramers doublet of the even-electron system.
    Full-text · Article · Jul 2015 · Optica

  • No preview · Conference Paper · Jun 2015
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    ABSTRACT: The interest in Bismuth-activated optical materials is associated with many possible applications, especially in fiber lasers and amplifiers [1]. The lasing was demonstrated only in a few types of Bi-doped silica fibers: germanosilicate, aluminosilicate, aluminogermanosilicate and phosphosilicate [2]. Also, it was recognized that the lasing wavelength (or even lasing spectral region) is strongly affected by the co-dopant, namely, aluminium or phosphorus. Unfortunately, up to now there is no clear understanding of the mechanisms of the PL in Bi-doped silica glasses [1, 3] and even the assignment of some PL bands remains controversial in our opinion. Recently [4], we have shown that Ga/Bi co-doped silica glass exhibits the PL which is quite similar to that found in Bi-doped aluminosilicate glass [5]. In the present work we report on unusual temperature dependence of ASPL at 734 nm which was found in Ga/Bi co-doped sol-gel silica glass. While in the temperature range of 450 - 873K the behavior of ASPL is completely determined by the thermal population of the excited state levels, its intensity is continuously increasing with decreasing temperature in the range of 77 - 430 K, as it is seen in Fig. 1(a) and (b). By measuring the pump power dependence of ASPL at 300K we show that the latter can be described via the two-step intracenter excitation process and subsequent relaxation. Based on the measurements of temperature dependence of the excitation spectra of near infrared band (at 1140 nm) and that corresponding to the ASPL (at 734 nm) we propose a simple rate equation model to explain the unusual behavior of ASPL.
    No preview · Conference Paper · Jun 2015
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    ABSTRACT: Mononuclear nickel(II), copper(II), and manganese(III) complexes with a noninnocent tetradentate Schiff base ligand containing a disiloxane unit were prepared in situ by reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane followed by addition of the appropriate metal(II) salt. The ligand H2L resulting from these reactions is a 2:1 condensation product of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The resulting metal complexes, NiL·0.5CH2Cl2, CuL·1.5H2O, and MnL(OAc)·0.15H2O, were characterized by elemental analysis, spectroscopic methods (IR, UV-vis, X-band EPR, HFEPR, (1)H NMR), ESI mass spectrometry, and single crystal X-ray diffraction. Taking into account the well-known strong stabilizing effects of tert-butyl groups in positions 3 and 5 of the aromatic ring on phenoxyl radicals, we studied the one-electron and two-electron oxidation of the compounds using both experimental (chiefly spectroelectrochemistry) and computational (DFT) techniques. The calculated spin-density distribution and localized orbitals analysis revealed the oxidation locus and the effect of the electrochemical electron transfer on the molecular structure of the complexes, while time-dependent DFT calculations helped to explain the absorption spectra of the electrochemically generated species. Hyperfine coupling constants, g-tensors, and zero-field splitting parameters have been calculated at the DFT level of theory. Finally, the CASSCF approach has been employed to theoretically explore the zero-field splitting of the S = 2 MnL(OAc) complex for comparison purposes with the DFT and experimental HFEPR results. It is found that the D parameter sign strongly depends on the metal coordination geometry.
    No preview · Article · Jun 2015 · Inorganic Chemistry
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    ABSTRACT: ”Kramers pairs symmetry breaking” is evaluated at the 2-component (2c) Kramers unrestricted and/or general complex Hartree-Fock (GCHF) level of theory, and its analogy with ”spin contamination” at the 1-component (1c) unrestricted Hartree-Fock (UHF) level of theory is emphasized. The GCHF ”Kramers pairs symmetry breaking” evaluation is using the square of overlaps between the set of occupied spinorbitals with the projected set of Kramers pairs. In the same fashion, overlaps between and orbitals are used in the evaluation of ”spin contamination” at the UHF level of theory. In this manner, UHF expectation value is made formally extended to the GCHF case. The directly evaluated GCHF expectation value of the operator is considered for completeness. It is found that the 2c GCHF Kramers pairs symmetry breaking has a very similar extent in comparison to the 1c UHF spin contamination. Thus higher excited states contributions to the 1c so 2c unrestricted wave functions of open shell systems have almost the same extent and physical consequences. Moreover, it is formally shown that a single determinant wave function in the restricted open shell Kramers case has the expectation value of operator equal to the negative number of open shell electrons, while the eigenvalue of for the series of simple systems (H, He, He*-triplet, Li and Li*-quartet) are found to be equal to minus the square of the number of open shell electrons. The concept of unpaired electron density is extended to the GCHF regime and compared to UHF and restricted open shell Hartree-Fock spin density. The ”collinear” and ”noncollinear” analogs of spin density at the GCHF level of theory are considered as well. Spin contamination and/or Kramers pairs symmetry breaking, spin populations and spin densities are considered for H2O+, Cl, HCl+, phenoxyl radical (C6H5O·) as well as for Cu, Cu2+, Fe and the [OsCl5(1H-pyrazole)]- anion. The 1c and 2c unpaired electron density representation is found useful for visualization and/or representation of spin density.
    Full-text · Article · May 2015 · Computational and Theoretical Chemistry
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    ABSTRACT: In this study, 2-formylpyridine thiosemicarbazones and three different heterocyclic pharmacophores were combined to prepare thiosemicarbazone-piperazine mPip-FTSC (HL1) and mPip-dm-FTSC (HL2), thiosemicarbazone-morpholine Morph-FTSC (HL3) and Morph-dm-FTSC (HL4), thiosemicarbazone-methylpyrrole-2-carboxylate hybrids mPyrr-FTSC (HL5) and mPyrr-dm-FTSC (HL6) as well as their copper(II) complexes [CuCl(mPipH-FTSC-H)]Cl (1+H)Cl, [CuCl(mPipH-dm-FTSC-H)]Cl (2+H)Cl, [CuCl(Morph-FTSC-H)] (3), [CuCl(Morph-dm-FTSC-H)] (4), [CuCl(mPyrr-FTSC-H)(H2O)] (5) and [CuCl(mPyrr-dm-FTSC-H)(H2O)] (6). The substances were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy (HL1-HL6), ESI mass spectrometry, IR and UV-vis spectroscopy and single crystal X-ray diffraction (1-5). All compounds were prepared in an effort to generate potential antitumor agents with an improved therapeutic index. In addition, the effect of structural alterations with organic hybrids on aqueous solubility and copper(II) coordination ability was investigated. Complexation of ligands HL2 and HL4 with copper(II) was studied in aqueous solution by pH-potentiometry, UV−vis spectrophotometry and EPR spectroscopy. Proton dissociation processes of HL2 and HL4 were also characterized in detail and microscopic constants for the Z/E isomers were determined. While the hybrids HL5, HL6 and their copper(II) complexes 5 and 6 proved to be insoluble in aqueous solution, precluding antiproliferative activity studies, the thiosemicarbazone-piperazine and thiosemicarbazone-morpholine hybrids HL1-HL4, as well as copper(II) complexes 1−4 were soluble in water enabling cytotoxicity assays. Interestingly, the metal-free hybrids showed very low or even a lack of cytotoxicity (IC50 values > 300 µM) in two human cancer cell lines HeLa (cervical carcinoma) and A549 (alveolar basal adenocarcinoma), whereas their copper(II) complexes were cytotoxic showing IC50 values from 25.5 to 65.1 µM and 42.8 to 208.0 µM, respectively in the same human cancer cell lines after 48 h of incubation. However, the most sensitive for HL4 and complexes 1-4 proved to be the human cancer cell line LS174 (colon carcinoma) as indicated by the calculated IC50 values varying from 13.1 to 17.5 µM.
    No preview · Article · Apr 2015 · Dalton Transactions
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    ABSTRACT: Unusual temperature dependence of the anti-Stokes photoluminescence (ASPL) at 734 nm was found in Ga/Bi co-doped sol-gel silica glass. While in the temperature range of 450–873 K, the behavior of ASPL is completely determined by the thermal population of the excited state levels, its intensity is continuously increasing with decreasing temperature in the range of 77–430 K. By measuring the pump power dependence of ASPL at 300 K, we show that the latter can be described via the two-step intracenter excitation process and subsequent relaxation. Based on the measurements of temperature dependence of the excitation spectra of near infrared band (at 1140 nm) and that corresponding to the ASPL (at 734 nm), we propose a simple rate equation model to explain the unusual behavior of ASPL.
    Full-text · Article · Apr 2015 · Optics Letters

  • No preview · Article · Mar 2015
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    ABSTRACT: A series of pentanuclear heterometallic coordination compounds of the general formula (Bu4N)5[Ln{Os(NO)(μ-ox)Cl3}4(H2O)n] [Ln = Y (for 2) and Dy (for 3′) when n = 0; Ln = Dy (for 3), Tb (for 4), and Gd (for 5) when n = 1] were synthesized by the reaction of the precursor (Bu4N)2[Os(NO)(ox)Cl3] (1) with the respective lanthanide(III) (Gd, Tb, Dy) or yttrium(III) chloride. For the five new complexes, the coordination numbers eight or nine are found for the central metal ion. The compounds were fully characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, magnetic susceptibility measurements, and ESI mass spectrometry. In addition, compound 1 was studied by UV/Vis spectroscopy and cyclic voltammetry. The X-ray diffraction analyses revealed that the anionic complexes consist of a lanthanide or yttrium core bridged through oxalato ligands to four octahedral osmium–nitrosyl moieties. This picture, in which the central ion is eight-coordinate, holds for lanthanide ions with an ionic radius smaller than that of the dysprosium(III) ion. For larger ionic radii, the central metal ion is nine-coordinate, as the coordination sphere is completed by one molecule of water. Only in the case of dysprosium(III), it was possible to obtain complexes with both coordination numbers 8 and 9. This implies that dysprosium(III) is the tilt limit between the two coordination numbers in this series. The bond length Ln–O decreases from Dy to Gd. The nine-coordinate complexes are energetically more favored for lanthanide ions with a radius larger than that of the dysprosium(III) ion, and the eight-coordinate complexes are favored for smaller ions. Magnetic studies of the series of compounds showed that the osmium precursor 1 as well as the yttrium compound 2 are diamagnetic, whereas the magnetism of the gadolinium, terbium, and dysprosium complexes is due to isolated lanthanide ions.
    Full-text · Article · Feb 2015 · Berichte der deutschen chemischen Gesellschaft
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    ABSTRACT: 3-Aminomethylation of salicylalkylamides afforded hybrids with a Mannich base. In addition, it triggered the rotation of the amide bond. The observed conformational switch is driven by strong intramolecular hydrogen bonding between the Mannich base and phenolic group. Crystal structure analysis reveals the stabilization of the hybrid molecules by double hydrogen bonding of the phenolic OH, which acts as an acceptor and donor simultaneously. The molecules contain an amide site and a Mannich base site in an orthogonal spatial arrangement. The intramolecular hydrogen bonds are persistent in a nonpolar solvent (e.g., chloroform). The conformational change can be reversed upon protection or protonation of the Mannich base nitrogen.
    Full-text · Article · Jan 2015 · Molecules
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    ABSTRACT: The nickel(II), copper(II), and zinc(II) complexes of the proline-thiosemicarbazone hybrids 3-methyl-(S)-pyrrolidine-2-carboxylate-2-formylpyridine thiosemicarbazone (l-Pro-FTSC or (S)-H2L(1)) and 3-methyl-(R)-pyrrolidine-2-carboxylate-2-formylpyridine thiosemicarbazone (d-Pro-FTSC or (R)-H2L(1)), as well as 3-methyl-(S)-pyrrolidine-2-carboxylate-2-formylpyridine 4,4-dimethyl-thiosemicarbazone (dm-l-Pro-FTSC or (S)-H2L(2)), namely, [Ni(l-Pro-FTSC-2H)]2 (1), [Ni(d-Pro-FTSC-2H)]2 (2), [Ni(dm-l-Pro-FTSC-2H)]2 (3), [Cu(dm-l-Pro-FTSC-2H)] (6), [Zn(l-Pro-FTSC-2H)] (7), and [Zn(d-Pro-FTSC-2H)] (8), in addition to two previously reported, [Cu(l-Pro-FTSC-2H)] (4), [Cu(d-Pro-FTSC-2H)] (5), were synthesized and characterized by elemental analysis, one- and two-dimensional (1)H and (13)C NMR spectroscopy, circular dichroism, UV-vis, and electrospray ionization mass spectrometry. Compounds 1-3, 6, and 7 were also studied by single-crystal X-ray diffraction. Magnetic properties and solid-state high-field electron paramagnetic resonance spectra of 2 over the range of 50-420 GHz were investigated. The complex formation processes of l-Pro-FTSC with nickel(II) and zinc(II) were studied in aqueous solution due to the excellent water solubility of the complexes via pH potentiometry, UV-vis, and (1)H NMR spectroscopy. The results of the antiproliferative activity in vitro showed that dimethylation improves the cytotoxicity and hR2 RNR inhibition. Therefore, introduction of more lipophilic groups into thiosemicarbazone-proline backbone becomes an option for the synthesis of more efficient cytotoxic agents of this family of compounds.
    Full-text · Article · Nov 2014 · Inorganic Chemistry
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    ABSTRACT: A one-electron reduction of osmium(IV) complexes trans-[Os(IV)Cl4(Hazole)2], where Hazole = 1H-pyrazole ([1](0)), 2H-indazole ([2](0)), 1H-imidazole ([3](0)), and 1H-benzimidazole ([4](0)), afforded a series of eight new complexes as osmium analogues of KP1019, a lead anticancer drug in clinical trials, with the general formula (cation)[trans-Os(III)Cl4(Hazole)2], where cation = H2pz(+) (H2pz[1]), H2ind(+) (H2ind[2]), H2im(+) (H2im[3]), Ph4P(+) (Ph4P[3]), nBu4N(+) (nBu4N[3]), H2bzim(+) (H2bzim[4]), Ph4P(+) (Ph4P[4]), and nBu4N(+) (nBu4N[4]). All complexes were characterized by elemental analysis, (1)H NMR spectroscopy, electrospray ionization mass spectrometry, UV-vis spectroscopy, cyclic voltammetry, while H2pz[1], H2ind[2], and nBu4[3], in addition, by X-ray diffraction. The reduced species [1](-) and [4](-) are stable in aqueous media in the absence of air oxygen and do not react with small biomolecules such as amino acids and the nucleotide 5'-dGMP. Cell culture experiments in five different human cancer cell lines (HeLa, A549, FemX, MDA-MB-453, and LS-174) and one noncancerous cell line (MRC-5) were performed, and the results were discussed and compared to those for KP1019 and cisplatin. Benzannulation in complexes with similar structure enhances antitumor activity by several orders of magnitude, implicating different mechanisms of action of the tested compounds. In particular, complexes H2ind[2] and H2bzim[4] exhibited significant antiproliferative activity in vitro when compared to H2pz[1] and H2im[3].
    Full-text · Article · Oct 2014 · Inorganic Chemistry
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    ABSTRACT: Bi-doped silica glasses have attracted much attention due to promising applications in the field of fibre lasers and amplifiers. Unfortunately, since the first demonstration of the near infrared photoluminescence (NIR PL) in Al/Bi co-doped silica glass, its nature remains unclear. Recently, we have demonstrated that the novel Bi/Ga co-doped silica glass exhibits analogous luminescent properties. To explain the observed features we have also proposed the model of the complex centre, which consists of Bi+ ion interacting with the defect, the latter bing responsible for the amplification and lasing in the optical fibres. In the present talk we report the results of the experiments on PL in magnetic field, and the temperature dependent excitation spectra. The latter clearly indicate that (i) NIR PL bands at 1130 and 735 nm belong to different centres; (ii) there exists the temperature dependent energy transfer between these centres. We discuss the possible energy structure of the complex centre.
    No preview · Conference Paper · Oct 2014
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    ABSTRACT: Two new tetranuclear copper(II) complexes [Cu4(μ4-O)(L1)Cl4] (1) and [Cu4(μ4-O)(L2)2Cl4] (2), where H2L1 is a macrocyclic ligand resulting from [2+2] condensation of 2,6-diformyl-4-methylphenol (DFF) and 1,3-bis(aminopropyl)tetramethyldisiloxane, and HL2 is a 1:2 condensation product of DFF with trimethylsilyl p-aminobenzoate, have been prepared. The structures of the products were established by X-ray diffraction. The complexes have been characterised by FTIR, UV/Vis spectroscopy, ESI mass-spectrometry and magnetic susceptibility measurements. The latter revealed that the tetranuclear complexes can be described as two ferromagnetically coupled dinuclear units, in which the two copper(II) ions interact antiferromagnetically. The compounds act as homogeneous catalyst precursors for a number of single-pot reactions, including (i) hydrocarboxylation, with CO, H2O and K2S2O8, of a variety of linear and cyclic(n = 5–8) alkanes into the corresponding Cn+1 carboxylic acids, (ii) peroxidative oxidation of cyclohexane, and (iii) solvent-free microwave-assisted oxidation of 1-phenylethanol.
    Full-text · Article · Oct 2014 · Berichte der deutschen chemischen Gesellschaft
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    ABSTRACT: The acid-base properties of 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone (H4L) and its thioanalogue 1,5-bis(2-hydroxybenzaldehyde)thiocarbohydrazone (H4LS) have been studied experimentally by pH-potentiometry and UV-Vis spectrophotometry and theoretically by using DFT methods. Copper(II) complexes [Cu-2(HL)(DMSO)(2)(H2O)]NO3 center dot H2O (1), [{Cu-2(HL)(DMF)(H2O)}(n)][{Cu-2(HL)(DMF)NO3}(n)](NO3)(n) (2), [Cu-2(HL)(DMF)(2)(H2O)]HSO4 center dot H2O (3), [Cu-2(HL)(DMF)(2)(H2O)][Cu-2(HL)(SO4)(H2O)(DMF)(2)]center dot 2H(2)O (4) and [Cu-4(HL)(2)(HSO4)(DMF)(2)]HSO4 (5), where H4L = 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone, have been synthesised. Complexes 1-3 have been characterised by elemental analysis, IR spectroscopy, ESI mass spectrometry, cyclic voltammetry, magnetic susceptibility measurements and X-ray diffraction, while 4 and 5 only by X-ray crystallography. X-ray diffraction revealed that the ditopic triply deprotonated ligand possesses two binding sites able to accommodate transition metal ions, namely ONN and ONO. Magnetic measurements showed antiferromagnetic interactions between copper(II) centres.
    Full-text · Article · Sep 2014 · Polyhedron
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    ABSTRACT: Three new dinuclear arene ruthenium metalla-clips of the general formula [(p-cymene)2Ru2Cl2(μ-L)] have been prepared from [(p-cymene)2Ru2Cl2(μ-Cl)2] and H2L organic linkers (H2La = diethyl-1,2-diazenedicarboxylate, H2Lb = N,N′-bis(2-hydroxyethyl)oxamide, H2Lc = N,N′-bis{2-(2-hydroxyethoxy)ethyl}ethanediamide). The bis-chelating bridging-linkers possess two functional groups that can be synthetically modified for physico-chemical optimizations. Reaction of these three dinuclear metalla-clips with 4,4′-bipyridine, 1,2-bis(4-pyridyl)ethylene, and 4,4′-azopyridine affords, in the presence of AgCF3SO3, nine tetracationic tetranuclear metalla-rectangles. Similarly, the tridentate ligands 2,4,6-tris(4-pyridyl)-1,3,5-triazine and 1,3,5-tris{2-(4-pyridyl)vinyl}benzene were used to generate six hexacationic hexanuclear metalla-prisms. All metalla-assemblies and the dinuclear complexes were evaluated as anticancer agents against cancerous (A2780) and noncancerous (HEK293) cell lines, showing an excellent selectivity for cancer cells. The IC50 values of the cationic metalla-assemblies were typically <1 μM, whereas, for the neutral dinuclear metalla-clips, the IC50 values were >100 μM.
    Full-text · Article · Jul 2014 · Organometallics
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    ABSTRACT: In this study, the indoloquinoline backbone and piperazine were combined to prepare indoloquinoline-piperazine hybrids and their ruthenium- and osmium-arene complexes in an effort to generate novel antitumor agents with improved aqueous solubility. In addition, the position of the metal-binding unit was varied, and the effect of these structural alterations on the aqueous solubility and antiproliferative activity of their ruthenium- and osmium-arene complexes was studied. The indoloquinoline-piperazine hybrids L(1-3) were prepared in situ and isolated as six ruthenium and osmium complexes [(η(6)-p-cymene)M(L(1-3))Cl]Cl, where L(1) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-2-N-amine, M = Ru ([1a]Cl), Os ([1b]Cl), L(2) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-4-N-amine, M = Ru ([2a]Cl), Os ([2b]Cl), L(3) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-8-N-amine, M = Ru ([3a]Cl), Os ([3b]Cl). The compounds were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy, ESI mass spectrometry, IR and UV-vis spectroscopy, and single-crystal X-ray diffraction. The antiproliferative activity of the isomeric ruthenium and osmium complexes [1a,b]Cl-[3a,b]Cl was examined in vitro and showed the importance of the position of the metal-binding site for their cytotoxicity. Those complexes containing the metal-binding site located at the position 4 of the indoloquinoline scaffold ([2a]Cl and [2b]Cl) demonstrated the most potent antiproliferative activity. The results provide important insight into the structure-activity relationships of ruthenium- and osmium-arene complexes with indoloquinoline-piperazine hybrid ligands. These studies can be further utilized for the design and development of more potent chemotherapeutic agents.
    Preview · Article · Jun 2014 · Inorganic Chemistry

Publication Stats

5k Citations
730.88 Total Impact Points

Institutions

  • 2002-2015
    • University of Vienna
      • • X-ray Structure Analysis Centre
      • • Institut für Anorganische Chemie
      • • Fakultät für Chemie
      Wien, Vienna, Austria
    • Laboratoire de Chimie de Coordination.
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1992-2010
    • Academy of Sciences of Moldova
      • Institute of Chemistry
      Kischinew, Chişinău, Moldova
  • 1995
    • Max Planck Institute for Coal Research
      Mülheim-on-Ruhr, North Rhine-Westphalia, Germany
  • 1993
    • Institute of Physical Chemistry
      București, Bucureşti, Romania
  • 1989
    • Russian Academy of Sciences
      • Institute of Organoelement Compounds
      Moskva, Moscow, Russia