Corrado Pelizzi

Antimicrobial and genotoxic activity of 2,6-diacetylpyridine bis(acylhydrazones) and their complexes with some first transition series metal ions. X-ray crystal structure of a dinuclear copper(II) complex.

The antibacterial and antifungal properties of five 2,6-diacetylpyridine bis(acylhydrazones) (acyl:benzoyl, H2dapb; 2-aminobenzoyl, H2dapab; salicyloyl, H2daps; picolinoyl, H2dappc; 2-thenoyl, H2dapt) and of a series of metal complexes were investigated. The x-ray crystal structure of the [Cu(dapt)]2 complex was also determined. It consists of dimeric units in which both copper atoms have sixfold coordination. The evaluation of in vitro antimicrobial properties showed some compounds to exhibit good activity against Gram positive bacteria. In most cases, complexes showed a similar or reduced activity as compared to the ligand itself. Only the iron complexes were found to be more active than the chelating agent involved. None of the compounds showed any significant antifungal activity. The genotoxicity of the compounds described was studied in vitro with Bacillus subtilis rec-assay and Salmonella-microsome reversion assay. No DNA-damaging activity was detected in the Bacillus subtilis rec-assay. H2dapb, H2dapb, and H2dappc were active in the Salmonella test. In several cases, the genotoxic properties of the ligands disappeared in the complexes.

Antimicrobial and mutagenic activity of some carbono- and thiocarbonohydrazone ligands and their copper(II), iron(II) and zinc(II) complexes

Several mono- and bis- carbono- and thiocarbonohydrazone ligands have been synthesised and characterised; the X-ray diffraction analysis of bis(phenyl 2-pyridyl ketone) thiocarbonohydrazone is reported. The coordinating properties of the ligands have been studied towards Cu(II), Fe(II), and Zn(II) salts. The ligands and the metal complexes were tested in vitro against Gram positive and Gram negative bacteria, yeasts and moulds. In general, the bisthiocarbonohydrazones possess the best antimicrobial properties and Gram positive bacteria are the most sensitive microorganisms. Bis(ethyl 2-pyridyl ketone) thiocarbonohydrazone, bis(butyl 2-pyridyl ketone)thiocarbonohydrazone and Cu(H2nft)Cl2 (H2nft, bis(5-nitrofuraldehyde)thiocarbonohydrazone) reveal a strong activity with minimum inhibitory concentrations of 0.7 microgram ml-1 against Bacillus subtilis and of 3 micrograms ml-1 against Staphylococcus aureus. Cu(II) complexes are more effective than Fe(II) and Zn(II) ones. All bisthiocarbono- and carbonohydrazones are devoid of mutagenic properties, with the exception of the compounds derived from 5-nitrofuraldehyde. On the contrary a weak mutagenicity, that disappears in the copper complexes, is exhibited by monosubstituted thiocarbonohydrazones.

Complexes of 2-acetyl-γ-butyrolactone and 2-furancarbaldehyde thiosemicarbazones: antibacterial and antifungal activity.

Cobalt, nickel, copper and zinc coordination compounds of two thiosemicarbazones with general composition ML(2) (L: monodeprotonated ligand corresponding to 2-acetyl-gamma-butyrolactone thiosemicarbazone, HL(1), and 2-furancarbaldehyde thiosemicarbazone, HL(2)) and also complexes with general composition MCl(2)(HL(2)) were synthesized (except [NiCl(2)(HL(2))] and [Co(L(2))(2)]). The interaction of CuCl(2) with HL(2) gave [CuCl(HL(2))], a copper(I) complex. The ligands and metal complexes were characterized by IR, (1)H and (13)C NMR spectroscopy, and magnetic susceptibility measurements. The crystal structure of [Ni(L(2))(2)]x 2dmso was determined and a trans-square planar coordination of the two kappa(2)-N,S chelate rings forming polymeric strips through H-bonds with dmso was observed. Actually, in all the reported complexes both ligands behaved as kappa(2)-N,S chelates, except in the case of [Co(L(1))(2)] in which HL(1) is tridentate kappa(3)-N,S,O. The antimicrobial properties of all compounds were studied using a wide spectrum of bacterial and fungal strains. The copper complexes of HL(2) were the most active against all strains, including dermatophytes and phytopathogenic fungi. Most of the studied compounds, especially [Cu(L(1))(2)], presented good activity against Haemophilus influenzae, a very harmful bacterium to humans.

Synthesis, spectroscopic and structural characterization of chlorobis(methyl pyruvate thiosemicarbazone)copper(I) and chlorobis(triphenylphosphine) (methyl pyruvate thiosemicarbazone)copper(I) toluene solvate (2/1)

Abstract Two new compounds, chlorobis(methyl pyruvate thiosemicarbazone)copper(I), [Cu(Hmpt)2Cl] (A), and chlorobis(triphenylphosphine)(methyl pyruvate thiosemicarbazone)copper(I) toluene solvate (2/1), [Cu(PPh3)2(Hmpt)Cl]·0.5C7H8 (B) have been synthesized and characterized using spectroscopic studies and single-crystal X-ray diffraction methods at 293 K. Compound A crystallizes in space group C2/c, with a = 14.695(1), b = 13.775(1), c = 10.251(1) A, β = 113.38(1)°, V= 1904.7 A3; compound B crystallizes in space group P 1 , with a=17.871(7), b=10.681(2), c=11.695(7) A, α=74.90(1), β=86.65(4), γ=83.66(2)°, V=2141 A3. The crystal structures were solved by the heavy-atom method for A and by direct methods for B and refined to R values of 0.053 for both compounds. In A the copper and chlorine atoms lie on a crystallographic two-fold axis and the trigonal coordination around copper involves, besides chlorine, two sulfur atoms from two Hmpt molecules. In B the copper is tetrahedrally four-coordinated involving a chlorine atom, a sulfur atom from the Hmpt molecule and the phosphorus atoms of the two PPh3 molecules. In both compounds the ligand is neutral, monodentate through the sulfur atom and shows the configuration Z E Z about the C(2)N(3), C(1)N(2) and C(2)C(3) bonds (with respect to possible donating centres O(1), N(3) and S). The main vibrational bands are also reported and discussed.

Aroylhydrazones as chelating agents: d10-metal complexes of pyridine-2-carbaldehyde salicyloylhydrazone and x-ray structure of the zinc derivative

Abstract The title organic ligands (Hsip) gave, by reaction with d10-metal acetates, complexes of the type M(sip)2 (M = Zn, Cd, Hg), in which the ligand behaved as terdentate, producing a distorted octahedral environment around the metal. The 1H and 13C chemical shifts found for these complexes in DMSO are compared with the corresponding ones of the free ligand. The crystal structure of the zinc derivative has been determined from diffractometer data to R = 0.072 for 1086 independent reflections. Crystals are monoclinic, space group C2/c, with unit-cell dimensions a = 18.193(2), b = 24.532(6), c = 11.535(2) A,β = 103.71(1)° and Z = 8. Coordination occurs through the carbonyl oxygens (Zn−O = 2.10, 2.16(1) A), the azomethine nitrogens (Zn−N = 2.04, 2.07(1) A) and the pyridine nitrogen s(Zn−N = 2.24, 2.26(1) A).

ORGANOTIN COMPLEXES WITH PYRROLE-2,5-DICARBOXALDEHYDE BIS(ACYLHYDRAZONES).SYNTHESIS, STRUCTURE, ANTIMICROBIAL ACTIVITY AND GENOTOXICITY

Mono- and bimetallic organotin complexes with pyrrole-2,5-dicarboxaldehyde bis(2-hydroxybenzoylhydrazone) (H5dfps) and pyrrole-2,5-dicarboxaldehyde bis(2-picolinoylhydrazone) (H3dfpp) were synthesized and characterized by IR, 1H and 119Sn NMR spectroscopy. X-ray analysis of the complex [Sn(H3dfps)(C6H5)2].(CH3)2SO revealed a pentacoordination around tin through a N,N,O terdentate ligand behaviour of the hydrazone. This complex is the most active compound, exhibiting MIC values of 3 and 12 micrograms/ml against Gram positive and Gram negative bacteria, respectively. None of the ligands or complexes produced DNA-damage in the Bacillus subtilis rec-assay or showed mutagenic activity in the Salmonella-microsome test.

Palladium(II) complexes containing a P, N chelating ligand Part II. Synthesis and characterisation of complexes with different hydrazinic ligands. Catalytic activity in the hydrogenation of double and triple C-C bonds

Abstract Palladium(II) complexes of the type Pd(PNO)Y (PNO = 2-(diphenylphosphino)benzaldehyde picolinhydrazone, nicotinhydrazone, isonicotinhydrazone; Y = CH3CO2, Cl, I) and Pd(PNS)Y (PNS = 2-(diphenylphosphino)benzaldehyde thiosemicarbazone; Y = CH3CO2, Cl, I) were synthesised and characterised by spectroscopic methods. The X-ray structure of an iodo complex was also determined. The catalytic activity of all the complexes in the homogeneous hydrogenation of terminal double and triple bonds was tested with particular regards to the chemoselectivity from triple to double bond. A correlation between the catalytic activity and the nature of the ligand and Y group was established. In the hydrogenation of phenylacetylene using acetato complexes as catalysts, stable phenylethynylpalladium(II) complexes were recovered and characterised by spectroscopic methods. A facile route of synthesis of alkynyl complexes was also determined.

The different behaviour of the di-2-pyridylketone 2-thenoylhydrazone in two organotin compounds. Synthesis, X-ray structure and biological activity☆

Two organotin compounds [SnPh(dpt)Cl2](1) and [SnPh3Cl(OH2)]·Hdpt (2) (Hdpt = di-2-pyridylketone 2-thenoylhydrazone) have been synthesized and characterized by IR spectroscopy and X-ray diffraction. Hdpt behaves differently in the two compounds: it is deprotonated and ONN tridentate in 1 and uncoordinated in 2, where pairs of hydrogen-bonded [SnPh3Cl(OH2)] and Hdpt molecules are present. The tin environment is octahedral in 1 and trigonal bipyramidal in 2. Compound 2 has shown good antimicrobial activity against Gram-positive bacteria and moulds in vitro. Neither compound showed genotoxic properties.

Transition-metal complexes of isatin-β-thiosemicarbazone. X-ray crystal structure of two nickel complexes

Manganese, iron, cobalt, nickel, copper and zinc complexes of isatin-beta-thiosemicarbazone (H2L) have been synthesized and spectroscopically characterized The X-ray crystal structures of two nickel complexes, namely [Ni(HL)2]. EtOH (1) and [Ni(HL)2]. 2DMF (2), reveal a distorted octahedral coordination with the monodeprotonated ligand that behaves as an O,N,S terdentate. Different packing interactions are determined by the presence of different crystallization solvents, i.e., ethanol in 1 and dimethylformamide (DMF) in 2. 1H and 13C NMR studies of the ligand and zinc complexes in solution were carried out and a complete assignment for the ligand was made by homodecoupling, gradient assisted 2D 1H-13C HMQC and HMBC NMR spectroscopy. Biological studies, carried out in vitro on human leukaemic cell lines U937, have shown that the free ligand and the copper (II) complex are more active in the inhibition of cell proliferation than the nickel complexes. No compound was able to induce apoptosis.

Acenaphthenequinone thiosemicarbazone and its transition metal complexes: Synthesis, structure, and biological activity☆

The reaction of iron, nickel, copper, and zinc chlorides or acetates with acenaphthenequinone thiosemicarbazone, Haqtsc leads to the formation of novel complexes that have been characterized by spectroscopic studies (NMR, IR) and biological properties. The crystal structures of the free ligand Haqtsc 1 and of the compound [Ni(aqtsc)2].DMF 2, have also been determined by X-ray methods from diffractometer data. In 1, the conformation of the two nonequivalent molecules is governed by intramolecular hydrogen bonds, while an intermolecular hydrogen bond is responsible for dimer-like groups formation. In 2, the coordination geometry about nickel is distorted octahedral, and the two ligand molecules are terdentate monodeprotonated. Biological studies have shown that, for the first time at least up the used doses, a free ligand is active both in the inhibition of cell proliferation and in the induced differentiation on Friend erythroleukemia cells (FLC).