Copper(II) complexes of 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Mononuclear copper(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in ethanolic solution and characterized by physical and spectral methods. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and ¹H- and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate as neutral ligands via the thiosemicarbazone moiety's azomethine nitrogen and thione sulfur, except for the piperidylthiosemicarbazone, which undergoes deprotonation and coordinates via the thiolato sulfur, as well as through the azomethine nitrogen. Complexes formed in the presence of triethylamine also form complexes with the anionic form of these thiosemicarbazones.     

Copper(II) complexes of 4-formylantipyrine N(4)-substitutedthiosemicarbazones

Copper(II) complexes between three 4-formylantipyrine N(4)-substituted thiosemicarbazones and four copper(II) salts have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic and 1H and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both mononuclear and binuclear complexes have been formed with bridging ligands for the latter, being either chloro or acetato. The stoichiometries of the complexes are dependent on both the steric requirements of the thiosemicarbazone ligands and the electronic effects of their N(4)-substituents.     

Copper(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Mononuclear and binuclear copper(II) complexes with four 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r., electronic, and e.s.r. spectra of the complexes, as well as i.r., electronic, and n.m.r. spectra of the thiosemicarbazones, have been obtained. These thiosemicarbazones coordinate as anionic or neutral ligands via the thiosemicarbazone moiety's imine nitrogen and thiolate/thione sulfur, the former on loss of the hydrazido hydrogen, N(2)H.     

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones coordinated either as neutral or monoanionic ligands, [M(HL)X2] and [M(L)X], respectively, have been prepared and characterized. I.r., electronic and e.s.r spectra of the complexes, as well as 1H-n.m.r. spectra of the thiosemicarbazones, have been obtained. The N(4)-dialkyl and azacyclothiosemicarbazones and their copper(II) complexes show significant growth inhibitory activity against both Aspergillus niger and Paecilomyces variotii.     

Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones

Summary Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones, coordinated either as a neutral or a monoanionic ligand, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as¹H- and¹³C-n.m.r. spectra of the thiosemicarbazones, have been recorded. Both the thiosemicarbazones and their copper(II) complexes show either modest or no growth inhibitory activity againstAspergillus niger, but theN(4)-dialkyl- and 3-azacyclo-derivatives, and particularly their copper(II) complexes, have considerable activity againstPaecilomyces variotii.     

Copper(II) complexes of 2-formyl-,2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m-, N(4)-p-chlorophenylthiosemicarbazones

Summary Cu^II complexes of 2-formyl, 2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m- and N(4)-p-chlorophenylthiosemicarbazones, coordinated either as a neutral or monoanionic ligand, have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as ¹H- and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their Cu^II complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. Some of the thiosemicarbazones demonstrated significant activity against tumour cell strains.     

Biological activity of Co(III) and Ni(II) complexes of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone: Synthesis, characterization, crystal structure of Co(III) complex of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone1

Transition metal complexes formulated as [Co(L)₂]ClO₄ (I) and [Ni(L)₂] · H₂O (II), where HL = pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone, have been synthesized. Complex I was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. In complex I, the ligand is N₂S tridentate, coordinating to the metal center through pyridine nitrogen, imine nitrogen and sulfur atoms. Hydrogen bonds link the different components to stabilize the crystal structure. Preliminary in vitro screening indicated that the free ligand was active against various bacteria and fungi and all the tested compounds showed significant antitumor activity against K562 leukaemia cell line, and can therefore be candidates for further stages of screening in vitro and/or in vivo.     

Copper(II) complexes of 2-formyl-, 2-acetyl- and 2-benzoyl-pyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxy-phenyl- and N(4)-p-nitrophenylthiosemicarbazones

Summary Cu^II complexes of 2-formyl-, 2-acetyl- and 2-benzoylpyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxyphenyl- and N(4)-p-nitrophenyltniosemicarbazones, coordinated either as neutral or monoanionic ligands, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as ¹H-and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. However, some of these thiosemicarbazones possess significant activity against a number of tumour cell strains.     

Copper(II) complexes of N,N-dimethyl-2-picolinamine N-oxide

Cu(II) complexes have been prepared with N,N-dimethyl-2-picolinamine N-oxide (DMA) employing the tetrafluoroborate, nitrate, chloride and bromide salts. Complexes having 1:2 and 1:1 metal ion to ligand ratios have been isolated. Characterization has been accomplished by IR, electronic and ESR spectral measurements of the solid state. Significant changes occurred when spectral measurements of acetonitrile solutions of the various solids were attempted indicating alteration of the Cu(II) bonding occurs. Thermal data on the solids are included.     

Copper(II) complexes with N,N-dimethylbiguanide

The N,N-dimethylbiguanide (HDMBG) complexes [Cu₂(HDMBG)₂Cl₄] (1) and respectively [Cu(HDMBG)₂]Cl₂·2H₂O (2) exhibit in vitro antimicrobial activity. The complexes were characterised by IR, electronic as well as EPR spectra. The IR spectra of complexes show the pattern of N,N-dimethylbiguanide coordinated as chelate. The electronic and EPR data are in agreement with a square pyramidal stereochemistry for (1) and a square planar one for (2). The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative strains (Escherichia coli, Klebsiella spp. and Enterobacter sp.) isolated from the hospital environment. The thermal analysis has evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. The thermal behaviour in nitrogen is complex according to TG and DTA curves including melting, dehydration as well as compounds decomposition.     

Copper (II) complexes of N4,N4-disubstituted thio- and selenosemicarbazones of 2-acetylpyridine: ESR studies

Copper(II) complexes of 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(pyridinyl)ethylidene]hydrazide, and its selenium analog, 3-azabicyclo[3.2.2]nonane-3-selenocarboxylic acid 2-[1-(2-pyridinyl)ethylidene]hydrazide, were studied by ESR spectrometry in chloroform solution at room temperature and at liquid nitrogen temperature. ESR spectra were also observed for the complexes as magnetically doped samples in the corresponding Ni(II) lattices at room temperature. Nitrogen superhyperfine splitting is observed at room temperature in all the spectra. Splitting patterns indicate the non-equivalent nature of the two coordinating nitrogen atoms. The covalency parameter for the metal—ligand bond was determined for selected complexes. An order of ligand field strength has been proposed based on the magnitude of the g_| component of g observed in the polycrystalline state.     

Ruthenium(II) 2-hydroxybenzophenone N(4)-substituted thiosemicarbazone complexes

New ruthenium(II) complexes with 2-hydroxybenzophenone N(4)-substituted (Me, Ph and/or piperidyl) thiosemicarbazones have been prepared and characterised by elemental analysis, molar conductivity, thermal analysis, spectroscopy (i.r., ¹H-n.m.r. and u.v.–vis.) and by cyclic voltammetry. The thiosemicarbazones coordinate to ruthenium(II) as mononegative tridentate ligands via the deprotonated hydroxyl group, N¹ nitrogen and thione sulphur centres. The redox properties, nature of the electrode processes and the stability of the complexes towards oxidation in CH₂Cl₂ are discussed. The change in the E _1/2 values of the complexes can be related to the basicity of the N(4)-substituents. All the complexes display an irreversible one-electron charge-transfer couple in the potential range studied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Copper(II) complexes of 2-formyl-, 6-methyl-2-formyl- and 2-benzoylpyridine N(4)-(2-methylpyridinyl)-,N(4)-(2-ethylpyridinyl)-and N(4)-methyl(2-ethylpyridinyl)thiosemicarbazones

Summary The title complexes of general formula [Cu(HL)Cl₂] or [Cu(L)Cl] have been isolated and characterized by ¹H and ¹³C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectral data for the Cu^II complexes are compared with those of previously studied complexes. The antitumour and antiviral activities of the thiosemicarbazones and their complexes are discussed.     

Nickel(II) complexes of 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Mononuclear nickel(II) complexes with 2-aminoacetophenone thiosemicarbazones and three N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate both as neutral and anionic ligands via the thiosemicarbazone moiety's azomethine nitrogen and thione/thiolato sulfur [on loss of the N(2) hydrogen].     

Copper(II) complexes of 6-methyl-2-formylpyridine 4N-substituted thiosemicarbazones

Summary Copper(II) complexes of 6-methyl-2-formylpyridine thiosemicarbazone, and its ⁴N-methyl-, ⁴N-ethyl-, ⁴N-phenyl-,⁴ N-dimethyl-, ⁴N-diethyl-, ⁴N-dipropyl-, 3-pyrrolidinyl, 3-piperidinyl- and 3-hexamethyleneiminylthiosemicarbazone derivatives were prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as ¹H and ¹³C n.m.r. spectra of the thiosemicarbazones, were obtained. The thiosemicarbazones and their copper(II) complexes show either modest or no growth inhibitory activity against Aspergillus niger, but the ⁴N-dialkyl- and 3-azacyclo-derivatives exhibit considerable activity against Paecilomyces variotii.     

Copper(II) complexes of formyl- and acetylpyrazine N(4)- (2–methylpyridinyl)-, N(4)-(2–ethylpyridinyl)- and N(4)-methyl- (2–ethylpyridinyl)thiosemicarbazones

The title complexes of general formula [Cu(HL)Cl2] or [Cu(L)Cl] were isolated from boiling EtOH. The thiosemicarbazones have been characterized by their 1H- and 13C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectra of the copper(II) complexes are compared with data on previously studied complexes. The antitumour and antiviral activities of the thiosemicarbazones and their complexes are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Cobalt(II) complexes with 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Cobalt(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate both as neutral and anionic ligands via the thiosemicarbazone moiety's imine nitrogen and thione/thiolato sulfur [on loss of the N(2) hydrogen].     

Iron(III), cobalt(II,III), copper(II) and zinc(II) complexes of 2-pyridineformamide 3-piperidylthiosemicarbazone

Reduction of 2-cyanopyridine by sodium in the presence of 3-piperidylthiosemicarbazide produces 2-pyridineformamide 3-piperidylthiosemicarbazone, HAmpip. Complexes with iron(III), cobalt(II,III) copper(II) and zinc(II) have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. In addition, the crystal structures of HAmpip, [Fe(Ampip)₂]ClO₄, [Cu(HAmpip)Cl₂]·CH₃OH and [Zn(HAmpip)Br₂]·C₂H₆SO have been determined. Coordination is via the pyridyl nitrogen, imine nitrogen and thiolato or thione sulfur when coordinating as the anionic or neutral ligand, respectively.     

Copper(II) complexes with imidazol-4-yl derivatives of 2-imidazoline nitroxides

Cu(hfac)₂LH, Cu(hfac)₂L¹H, Cu(hfac)(CF₃COO)LH, Cu(LH)₂(NO₃)₂, and Cu(L¹H)₂(NO₃)₂, where LH and L¹H are nitronyl- and iminonitroxides, respectively, containing an imidazol-4-yl substituent in the side chain have been synthesized. In the solid state, the molecules are linked by intermolecular NH⋯O hydrogen bonds, leading to the formation of dimers, bands, or polymer layers. The antiferromagnetic exchange interactions between the odd electrons of the paramagnetic centers are concentrated in the Cu(II)-coordinated nitroxide exchange clusters. The energies of these interactions are between −154 and −350 cm⁻¹.