Maciej Kubicki

Synthesis, structural characterization and in vitro cytotoxicity of new Au(III) and Au(I) complexes with thioamides

The reactions of tetrachloroauric(III) acid (HAuCl4) with the thioamides; 2-mercapto-benzothiazole (mbztH) and 5-ethoxy-2-mercapto-benzimidazole (EtmbzimH) lead to the desulfuration of the ligands and the formation of the ionic complexes {[AuCl4]- [bztH2]+} (1), and {[AuCl4]- [EtbzimH2]+ (H2O)} (2) (where bztH2+ and EtbzimH2+ are the desulfurated cations of the starting ligands). The reaction of HAuCl4 with 2-mercapto-nicotinic acid (mnaH2), however results in the formation of 2-sulfonate-nicotininc acid (C6H5NO5S) (3) with the simultaneous oxidation of the sulfur atom. On the other hand, the reactions of the gold(I) complex [Au(tpp)Cl] (4) (tpp = triphenylphosphine (Ph3P)) with the thioamides; 2-mercapto-thiazolidine (mtzdH), 2-mercapto-benzothiazole (mbztH) and 5-chloro-2-mercapto-benzothiazole (ClmbztH) in the presence of potassium hydroxide resulted in the formation of the gold(I) complexes of formulae [Au(tpp)(mtzd)] (5), [Au(tpp)(mbzt)] (6) and [Au(tpp)(Clmbzt)] (7) without ligand desulfuration. All complexes have been characterized by elemental analysis, FT-IR, far-FT-IR,1H-NMR, spectroscopic techniques and X-Ray crystallography. The electrochemical behavior of 1, 2 and 4-7 complexes and the ligands EtmbzimH, mbztH and mnaH2 was also studied in acetonitrile and DMF using cyclic voltammetry. The results are in support of a mechanism of desulfuration of the ligands by Au(III), involving a first oxidation of S to -SO3-, followed by a C-S bond cleavage. This is also supported by PM6 calculations of bond dissociation energies of the various compounds involved. Complexes 1, 2 and 4-7 were tested for in vitro cytotoxicity against leiomyosarcoma cells and the results are discussed in relation with the geometry of the complexes and compared with those of cisplatin and other metals. Complexes 1 and 5 showed higher activity than that of cisplatin, while HAuCl4 was inactive against sarcoma cells.

New Antimony(III) Bromide Complexes with Thioamides : Synthesis, Characterization, and Cytostatic Properties

New antimony(III) bromide complexes with the heterocyclic thioamides, thiourea (TU), 2-mercapto-1-methylimidazole (MMI), 2-mercapto-benzimidazole (MBZIM), 2-mercapto-5-methyl-benzimidazole (MMBZIM), 5-ethoxy-2-mercapto-benzimidazole (EtMBZIM), 2-mercapto-3,4,5,6-tetrahydro-pyrimidine (tHPMT), 2-mercaptopyridine (PYT), 2-mercapto-thiazolidine (MTZD), 3-methyl-2-mercaptobenzothiazole (MMBZT), and 2-mercaptopyrimidine (PMTH) of formulas [SbBr(3)(TU)(2)] (1), [SbBr(3)(MMI)(2)] (2), {[SbBr(2)(MBZIM)(4)](+) [Br](-) H(2)O} (3), {[SbBr(2)(mu(2)-Br)(MMBZIM)(2)](2)} (4), {[SbBr(2)(mu(2)-Br)(EtMBZIM)(2)](2) MeOH} (5), {[SbBr(3)(mu(2)-S-tHPMT)(tHPMT)](n)} (6), {[SbBr(2)(mu(2)-Br)(PYT)(2))(n)} (7), {[SbBr(2)(mu(2)-Br)(MTZD)(2)](n)} (8), [SbBr(3)(MMBZT)(2)] (9), and {[SbBr(5)](2-)[(PMTH(2)(+))(2)]} (10) have been synthesized and characterized by elemental analysis, conductivity measurements, FTIR spectroscopy, FT-Raman spectroscopy, TG-DTA analysis, and X-ray powder diffraction. The crystal structures of 3, 4, 5, 6, 7, 8, and 10 were also determined by X-ray diffraction. In 3, four sulfur atoms from thione ligands and two bromide ions form an octahedral (O(h)) cationic [SbS(4)Br(2)](+) species in which the two bromide anions lie at axial positions. A third bromide counteranion neutralizes the whole complex. 4 and 5 are dimers, whereas 6, 7 and 8 are polymers, built up by monomeric units of square pyramidal (SP) geometry around the metal center, which were formed by two sulfur atoms of thioamide ligands and three bromide ions. Finally, 10 is ionic salt containing 1D polymeric network of {[SbBr(5)](2-)}(n) anions and (-)[(PMTH(2)(+))2] counter cations in the lattice. The complexes showed mostly a moderate cytostatic activity against a variety of tumor cell lines.

New One-Pot Synthesis of (E)-β-Aryl Vinyl Halides from Styrenes

A new, efficient protocol for the highly stereoselective one-pot synthesis of (E)-beta-aryl vinyl iodides and (E)-beta-aryl vinyl bromides from styrenes based on sequential ruthenium-catalyzed silylative coupling-N-halosuccinimide-mediated halodesilylation reactions is reported.

Highly selective synthesis of (E)-N-aryl-N-(1-propenyl) ethanamides via isomerization of N-allyl ethanamides catalyzed by ruthenium complexes

Abstract A convenient and highly selective method of synthesis of (E)-N-aryl-N-(1-propenyl)ethanamides via isomerization of respective N-allyl-N-arylethanamides catalyzed by [RuClH(CO)(PPh3)3] has been described. N-Allyl-N-arylethanamides have been obtained by allylation of respective N-arylethanamides under PTC conditions. It is proposed that the observed selectivity of the double bond migration to (E)-enamides is due to the interaction of the arene ring with the Ru atom in the transition state.

Crystal structure, electrochemistry, and catalytic studies of a series of new oxidovanadium(IV) Schiff-base complexes derived from 1,2-diphenyl-1,2-ethylenediamine

New derivatives of N2O2 tetradentate Schiff bases, from condensation of meso-1,2-diphenyl-1,2-ethylenediamine and salicylaldehyde derivatives (X-salicylaldehyde; X = 3-OMe, 4-OMe, 5-OMe, 6-OMe, 5-Cl, 5-Me), and oxidovanadium(IV) complexes were synthesized and characterized by 1H NMR, UV-Vis, IR spectroscopy, and elemental analysis. Crystal structure of 5-OMe; H2L3 and two of the complexes (VOL2 and VOL3) were also obtained. In the crystals, the molecule of H2L3 is Ci symmetrical, as it occupies the special position on the center of symmetry; its conformation is partially determined by classical intramolecular O–H···N hydrogen bonds. The complexes have monomeric structures with a distorted square pyramid of vanadium, with the oxo ligand in the apical position. Cyclic voltammetry studies show quasi-reversible VIV/VV redox for which the presence of electron-withdrawing groups on salicylaldehyde derivatives shifts the E° to more positive values. The complexes were used as catalysts for selective epoxidation of cyclooctene with tert-butylhydroperoxide as oxidant, in various solvents and reaction conditions. High catalytic activities and excellent selectivity was found. The catalytic activity of the complexes increased increasing E°, a consequence of the presence of electronegative substituents. This epoxidation process with the new catalysts was also studied under solvent-free condition and excellent reactivity was observed.

Organotin-Drug Interactions. Organotin Adducts of Tenoxicam: Synthesis and Characterization of the First Organotin Complex of Tenoxicam

The synthesis and spectral characterization of the novel organotin complexes [SnBu2(ten)] (1) and [SnBu2(Hten)2] (2) of the potent and widely used anti-inflammatory drug tenoxicam (H2ten) are reported. A crystal-structure determination of 1 showed that, in this complex, the ligand is doubly deprotonated at the hydroxy O-atom and the amide N-atom and is coordinated to the SnBu2 fragment via four- and six-membered chelate rings. An extended network of Sn−O−Sn, C−H⋅⋅⋅O and C−H⋅⋅⋅π contacts lead to aggregation and a supramolecular assembly. Potentiometric titrations in nonaqueous solutions support the ionization of the drug by removal of the second H-atom, the amide H-atom, in the presence of the diorganotin(IV) fragment. The Ka values of the poorly H2O-soluble drug tenoxicam were obtained spectrophotometrically in aqueous solutions of constant ionic strength.

Organotin(IV) Derivatives of L-Cysteine and their in vitro Anti-Tumor Properties

The synthesis and characterization of the organotin compounds [(n-C4H9)2Sn(cys)] (1), [(C6H5)2Sn(cys)] (2), [(C6H5)3Sn(Hcys).(H2o)] (3), {[(CH3)2Sn(Kcys)2].2(H20)} (4), {[(n-C4H9)2Sn(Kcys)2].2(H20)} (5) and {[(C6H5)2Sn(Kcys)2].2(H20)} (6) (where H2cys = L-cysteine) are reported. The compounds have been characterized by elemental analysis and 1H-NMR, Uv-Vis, FT-IR and MOssbauer spectroscopic techniques. Attempted recrystallization of (2) in DMSO/methanol 2:1 solution yielded after several days unexpectedly the dimeric compound bis(tri-phenyltin)sulphide {[(C6H5)3Sn]2S} (7) which has been characterized by x-ray analysis. The structure of the parent complex (2) as well as the mechanism of the decomposition of cysteine are being further investigated. The in vitro anticancer activity of complexes (I)- (6), against human leukemia (HL60), human liver (Bel7402), human stomach (BGC823) and human cervix epithelial human carcinoma (Hela), nasopharyngeal carcinoma (KB) and lung cancer (PG) tumor cells, were evaluated.

Synthesis, characterisation and study of mercury(II) bromide complexes with triphenylphosphine and heterocyclic thiones. The crystal structures of [bis(triphenylphosphine) dibromo mercury(II)] and [dibromo (pyrimidine-2-thionato) (triphenylphosphine) mercury(II)]. Extended intra-molecular linkages via NH⋯Br and CH⋯Br interactions

Abstract Fractional crystallisation of the mixture, resulting from the direct reaction of mercury(II) bromide with triphenylphosphine (PPh3) and pyrimidine-2-thione (pmtH), gives crystals of [HgBr2(PPh3)2] (1) and [HgBr2(PPh3)(pmtH)] (2). The complexes have been characterised by their elemental analyses, melting points and their FT-IR, far-IR, and UV–Vis spectroscopic data. The crystal structures of both [bis(triphenylphosphine) dibromo mercury(II)] (1) and [dibromo (pyrimidine-2-thionato)(triphenylphosphine) mercury(II)] (2) complexes have been established by single crystal X-ray crystallography at room temperature. Molecule 1 is monomeric with tetrahedral geometry around the metal ion. Two bromide atoms are co-ordinated to the mercury(II) ion [Hg(1)Br(1)=2.627(2) and Hg(1)Br(2)=2.6368(14) A] while two triphenylphosphine molecules are also co-ordinated to the metal ion via their phosphorus atoms with Hg(1)P(1) and Hg(1)P(2) bond distances of 2.550(4) and 2.491(5) A, respectively. The complex is covalent in the solid state. The unit cell of 2 consists of a molecule with tetrahedral geometry around the mercury(II) ion. A triphenylphosphine ligand and a pyrimidine-2-thione molecule are co-ordinated to the metal ion through their phosphorus and sulfur atoms with Hg(1)P(1) and Hg(1)S(2) bond lengths of 2.450(2) and 2.4795(19) A, respectively. Two bromide atoms are also co-ordinated to the mercury ion [Hg(1)Br(1)=2.7065(10) and Hg(1)Br(2)=2.6997(11) A]. The entire complex is covalent in the solid state. Extended intra-molecular linkages via NH⋯Br interactions lead to a polymeric structure. Extended CH⋯Br contacts link the alternate parallel chains forming a supramolecular assembly.

Synthesis, Characterization, and Biological Studies of Organotin(IV) Derivatives with o- or p-hydroxybenzoic Acids

Organotin(IV) complexes with o- or p-hydroxybenzoic acids (o-H2BZA or p-H2BZA) of formulae [R2Sn(HL)2] (where H2L = o-H2BZA and R = Me- (1), n-Bu- (2)); [R3Sn(HL)] (where H2L = o-H2BZA and R = n-Bu- (3), Ph- (4) or H2L = p-H2BZA and R = n-Bu- (5), Ph- (6)) were synthesized by reacting a methanolic solution of di- and triorganotin(IV) compounds with an aqueous solution of the ligand (o-H2BZA or p-H2BZA) containing equimolar amounts of potassium hydroxide. The complexes were characterized by elemental analysis, FT-IR, Far-IR, TGA-DTA, FT-Raman, Mössbauer spectroscopy, 1H, 119Sn-NMR, UV/Vis spectroscopy, and Mass spectroscopy. The X-ray crystal structures of complexes 1 and 2 have also been determined. Finally, the influence of these complexes 1–6 upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX) was kinetically studied and the results showed that triorganotin(IV) complex 6 has the lowest IC50 value. Also complexes 1–6 were studied for their in vitro cytotoxicity against sarcoma cancer cells (mesenchymal tissue) from the Wistar rat, and the results showed that the complexes have high activity against these cell lines with triphenyltin((IV) complex 4 to be the most active one.

A new polymeric complex of silver(I) with a hybrid pyrazine–bipyridine ligand – synthesis, crystal structure and its photocatalytic activity

The 2,3-bis(6′-methyl-2,2′-bipyridin-6-yl)pyrazine ligand L reacts with trifluoromethanesulfonate silver(I) to give a coordination polymer {[AgL](CF3SO3)}n in which metal ions are in a distorted tetragonal pyramidal coordination geometry. The complex has been characterized by spectroscopic techniques, elemental analysis, X-ray diffraction, and UV-Vis spectroscopy. The methylene blue (MB) degradation was studied using UV-Vis spectrophotometry. After 400 min of exposure to UV light MB was completely decomposed. Degradation of MB after exposure to sunlight was considerably slower: 34% after 400 min and 90% after 133 h. Photodegradation of the dye follows second-order kinetics. {[AgL](CF3SO3)}n is an active photocatalyst for MB degradation under UV-Vis and sunlight irradiation.