DNA/BSA interaction and in vitro antimicrobial studies of Mn(III) complexes bearing bidentate N,O donor Schiff bases

Journal of the Iranian Chemical Society - Eight new coordination compounds of Mn(III) with (E)-2-((3-(benzyloxypyridinylimino) methyl)-4-bromophenol (L1), (E)-2-((3-(benzyloxypyridinylimino)...     

Diorganotin(IV) complexes of biologically potent 4(3H)-quinazolinone derived Schiff bases: synthesis, spectroscopic characterization, DNA interaction studies and antimicrobial activity

Four Schiff base ligands and their corresponding organotin(IV) complexes have been synthesized and characterized by elemental analyses, IR, (1)H NMR, MS and thermal studies. The Schiff bases are obtained by the condensation of 3-amino-2-methyl-4(3H)-quinazolinone with different substituted aldehydes. The elemental analysis data suggest the stoichiometry to be 1:1 ratio formation. Infrared spectral data agreed with the coordination to the central metal ion through imine nitrogen, lactam oxygen and deprotonated phenolic oxygen atoms. All the synthesized compounds have been evaluated for antimicrobial activity against selected species of microorganisms. In addition, DNA binding/cleavage capacity of the compounds was analyzed by absorption spectroscopy, viscosity measurements and gel electrophoresis methods.     

Diorganotin(IV) complexes derived from thiazole Schiff bases: synthesis,characterization, antimicrobial and cytotoxic studies

Research on Chemical Intermediates - Organotin(IV) complexes are gaining major attention as drug candidates, accordingly we have synthesized a cluster of novel diorganotin(IV) complexes R2SnClL...     

Intramolecular phenylborane complexes with monobasic bidentate Schiff bases

A series of intramolecular complexes with Schiff base ligands having N∩S and N∩O donor systems were synthesized in an open vessel under microwave irradiation (MWI) using a domestic microwave oven. The reaction time has been brought down from hours to seconds with improved yield as compared with the conventional heating. The complexes have been characterized on the basis of elemental analysis, conductance measurements and spectroscopic analysis. Based on the IR, ¹H NMR, ¹¹B NMR and ¹³C NMR spectroscopic studies, a tetrahedral geometry has been proposed for the resulting complexes. The compounds have been screened in vitro against bacteria and fungi to test their antimicrobial property and in vivo in male albino rats to test their antifertility property. The testicular sperm density, motility and density of cauda epididymal spermatozoa along with biochemical parameters of reproductive organs have been examined and discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Oxorhenium(V) complexes containing bidentate N,O-donor ligands of the pyridyl type

The reaction of equimolar quantities of trans-[ReOCl₃(PPh₃)₂] and 8-hydroxyquinoline (Hhqn) in benzene led to the isolation of the six-coordinate complex [ReOCl₂(hqn)(PPh₃)] (1). With 2-pyridine-ethanol (Hhep) the compound [ReOCl₂(hep)(PPh₃)] (2) was obtained. Both hqn and hep ligands act as monoanionic bidentate N,O-donor chelates. Although the two complexes are very similar, there are some significant differences in certain bond distances and angles in them. Both complexes contain the nearly linear trans O=Re–O axis, with this angle equal to 160.9(2)° and 167.8(1)° in 1 and 2, respectively.     

Spectral and biocidal studies of palladium(II) and platinum(II) complexes with monobasic bidentate Schiff bases

The monobasic bidentate Schiff base complexes of palladium(II) and platinum(II) derived from 1H-indol-2,3-dione thiosemicarbazone (L¹H) and 1H-indol-2,3-dione semicarbazone (L²H) have been characterized on the basis of elemental analysis, molecular weight determinations, i.r., ¹H n.m.r. and u.v. spectral studies. Based on these studies a square planar environment around the metal atoms has been proposed. Antimicrobial effects of both the ligands and their complexes on different species of pathogenic fungi and bacteria have been recorded and these are found to possess significant fungicidal and bactericidal properties.     

Oxo-tricyano complexes of molybdenum(IV) and tungsten(IV) with bidentate Schiff bases

Summary The reaction of [M(CN)₄O(OH₂)]^2– (M = Mo or W) with 2-acetylpyridine and methyl-or butyl-amine in a water-MeOH mixture gave [M(CN)₃O(L-L)]^- (L-L= Schiff base ligand), isolated as [AsPh₄]⁺ salts. The complexes have been characterized by elemental analysis, and electronic, i.r. and¹H-n.m.r. spectroscopy. The Schiff base ligands complex in a bidentate manner through the two nitrogen atoms giving mixed-ligand compounds similarly to 2,2-bipyridyl or 1,10-phenanthroline.On leave from the Faculty of Chemistry, Jagiellonian University, Kraków.     

Oxorhenium(V) complexes with tetradentate NSNO pyridylthioazophenolates: syntheses, spectral and electrochemical studies

A family of oxorhenium(V) complexes of newly designed pyridylthioazophenolate ligands has been synthesized and isolated in pure form. The solid state structure of an organic compound (HL1) has been established by X-ray crystallography. The molecular structure observed in the solid state is that the two molecules of the ligand (HL1) in the asymmetric unit have similar geometries, except for the orientation of the pyridine ring. This series of organic moieties acts as tetradentate monobasic NSNO donor chelators in oxorhenium(V) complexes which has been characterized by elemental analyses, IR, ¹H-NMR, UV–Vis. The complexes are 1:1 electrolytes in nature in MeOH solution, the counter anion being ClO ₄ ⁻ . The electrochemical studies of the [Re^VO(L)Cl]ClO₄ complexes in MeCN using TBAP as supporting electrolyte exhibit quasi-reversible voltammogram showing one-electron couple for [Re^VIO(L)Cl]²⁺−[Re^VO(L)Cl]⁺ in the 1.11–1.29 V vs SCE range.     

Triphenylarsenic(V) and -antimony(V) derivatives of multidentate Schiff bases: synthesis,characterization, and antimicrobial activities

Equimolar reactions of Ph _n M(OPr ⁱ )₂ (where M?=?As and Sb) with Schiff bases [OHC₆H₄CH=N(R)OH] in benzene solution yield organoarsenic and -antimony derivatives, (where M?=?As and Sb; n?=?1 and 3; R?=?–CH₂CH(CH₃)–, –(CH₂)₃–, –(CH₂)₂–, and –C(CH₃)₂CH₂–). All these derivatives have been characterized by elemental analyses and molecular weight measurements, and structures have been proposed on the basis of IR, NMR (¹H and ¹³C), and FAB-mass studies. Schiff bases and their corresponding organoantimony derivatives have been screened for antimicrobial activity against Aspergillus flavus (fungus) and Escherichia coli (bacteria).     

Six-coordinated oxovanadium(V) complexes of reduced Schiff bases derived from amino acids: synthesis,reactivity and redox studies

New oxovanadium(V) complexes, [VOL(hq)] (1)–(4) have been prepared by the reaction of [VO(acac)₂] with ligands LH₂ in the presence of 8-hydroxyquinoline (Hhq). LH₂ is the dibasic tridentate ONO Mannich base [(S)-H₂glysal, (S)-H₂alasal, (S)-H₂leusal and (S)-H₂ileusal; S represents the S-enantiomer] obtained by the reduction of the Schiff bases of salicylaldehyde (sal) and the amino acids: glycine (gly), DL-alanine (ala), leucine (leu) and isoleucine (ileu), respectively. Spectral studies suggest an octahedral structure for these complexes. The complexes exhibit a single ⁵¹V-n.m.r. signal at –464.6 to –468.0 p.p.m. due to the existence of a single isomeric species in solution. In the presence of L-ascorbic acid under aerobic conditions [VO(S-glysal)(hq)] (1) and [VO(S-isoleusal)(hq)] (4) are converted into the corresponding dioxo species possible via intermediate reduction. A time- dependent ⁵¹V-n.m.r. study has also been carried out in order to investigate the possible isomerisation and/or further reaction in solution.     

Rhenium(V) complexes with Schiff bases: Synthesis and reaction mechanisms

Summary Some isomers of the ReOX₂LPPh₃ complexes [X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N'-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate] have been synthesized and characterized. Two different mechanisms for reaction of thetrans-ReOX₃(PPh₃)₂ complexes (X = Cl or Br) with the Schiff bases are supported by qualitative studies on such parameters as the Schiff base ligand form, concentration of free triphenylphosphine ligand, reaction solvent and temperature.     

Ruthenium(II) complexes containing bidentate Schiff bases and triphenylphosphine or triphenylarsine

Reactions of ruthenium(II) complexes [RuHX(CO)(EPh₃)₂(B)] (X = H or Cl; B = EPh₃, pyridine (py) or piperidine (pip); E = P or As) with bidentate Schiff base ligands derived by condensingo- hydroxyacetophenone with aniline,o- orp-methylaniline have been carried out. The products were characterized by analytical, IR, electronic and¹H-NMR spectral studies and are formulated as [Ru(X)(CO) (L)(EPh₃)(B)] (L = Schiff base anion; X = H or Cl; B = EPh₃, py or pip; E = P or As). An octahedral structure has been tentatively proposed for the new complexes. The new complexes were tested for their catalytic activities in the oxidation of benzyl alcohol to benzaldehyde.     

Ruthenium(II) complexes containing bidentate Schiff bases and their antifungal activity

The reactions of ruthenium(II) complexes, [RuHCl(CO)(PPh₃)₂(B)] [B = PPh₃, pyridine (py) or piperidine (pip)], with bidentate Schiff base ligands derived by condensing salicylaldehyde with aniline, o-, m- or p-toluidine have been carried out. The products were characterised by analytical, i.r., electronic, ¹H-n.m.r. and ³¹P-n.m.r. spectral studies and are formulated as [RuCl(CO)(L)(PPh₃)(B)] (L = Schiff base anion; B = PPh₃, py or pip). An octahedral structure has been tentatively proposed for the new complexes. The Schiff bases and the new complexes were tested in vitro to evaluate their activity against the fungus Aspergillus flavus.     

Spectroscopic characterization and electrochemical studies of ruthenium(II) carbonyl complexes containing bidentate Schiff bases and triphenylphosphine or a nitrogen heterocycle

Reactions of ruthenium(II) carbonyl complexes of the type [RuHCl(CO)(PPh₃)₂(B)] [B?=?PPh₃, pyridine (py), piperidine (pip) or morpholine (mor)] with bidentate Schiff base ligands derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, o-, m- or p-toluidine in a 1?:?1 mol ratio in benzene resulted in the formation of complexes formulated as [RuCl(CO)(L)(PPh₃)(B)] [L?=?bidentate Schiff base anion, B?=?PPh₃, py, pip, mor]. The complexes were characterized by analyses, IR, electronic and ¹H NMR spectroscopy, and cyclic voltammetric studies. In all cases, the Schiff bases replace one molecule of phosphine and a hydride ion from the starting complexes, indicating that Ru–N bonds in the complexes containing heterocyclic nitrogenous bases are stronger than the Ru–P bond to PPh₃. Octahedral geometry is proposed for the complexes.     

Synthesis,characterization and biological properties of novel ON donor bidentate Schiff bases and their copper(II) complexes

Four novel ON donor Schiff bases (E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol (HL₁),(E)-3-((4-(4-biphenyloxy)phenyliminomethyl)benzene-1,2-diol (HL₂), (E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol (HL₃), (E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol (HL₄) and their copper(II) complexes bis((E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₁)₂) bis((E)-3-((4-(4-biphenyloxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₂)₂), bis((E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₃)₂), bis((E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₄)₂) have been synthesized and characterized by spectroscopic (FTIR, NMR, UV–visible) and elemental analysis. The crystal structures of HL₁, HL₂, HL_3, and HL₄ have been determined, which reveal intramolecular N-H?O (HL₁, HL₂, HL_3, and HL₄) hydrogen bonds in the solid state. Keto-amine and enol-imine tautomerism is exhibited by the Schiff bases in solid and solution states. The Schiff bases and their copper(II) complexes have been screened for their biological activities. In antimicrobial assays (antibacterial and antifungal), HL₄ showed promising results against all strains through dual inhibition property while the rest of the compounds showed activity against selective strains. On the other hand, in cytotoxic, DPPH, and inhibition of hydroxyl (OH) free radical-induced DNA damage assays, the results were found significantly correlated with each other, i.e. the ligands HL₁ and HL₂ showed moderate activity while their complexes Cu(L₁)₂ and Cu(L₂)₂ exhibited prominent increase in activity. As the results of these assays are supporting each other, it represents the strong positive correlation and antioxidant nature of investigated compounds.     

Ruthenium(II)/(III) complexes of bidentate acetyl hydrazide Schiff bases

A series of octahedral Ru^II/Ru^III complexes of the type [Ru(Y)(CO)(BAX)(PPh₃)₂] and [RuCl₂(BAX)(PPh₃)₂] (Y = H or Cl; BAX = benzaldehydeacetylhydrazone anion; X = H, Me, OMe, OH, Cl or NO₂) have been prepared and characterised by spectral, magnetic and cyclic voltammetric studies. The Ru^II complexes are low spin diamagnetic (S = 0) whereas the Ru^III complexes are low spin and paramagnetic (S = 1/2). These Ru^II and Ru^III complexes absorb in the visible region respectively at ca. 16,000 and 28,000 cm^–1 which bands are assigned to the MLCT. The correlation of the _max values of the Ru^III complexes with the ⁺ Hammett parameter, is linear, indicating the profound effect of substituents on the electron density of the central metal. I.r. spectral data reveals that the hydrazone is chelated to ruthenium through the hydrazinic nitrogen and the deprotonated enolic oxygen. The rhombic nature of the e.s.r. spectra of the Ru^III complexes indicates an asymmetry in the electronic environment around the Ru atom. Ru^II complexes in CH₂Cl₂ show an irreversible Ru^II/III redox couple at ca. 0.9–0.5 V, while the Ru^III complexes show two reversible redox couples in the –0.1–0.1 and 0.8–0.6 V range, indicating that the higher oxidation state of ruthenium is stabilised by hydrazones.     

Preparation and structural characterization of oxovanadium(V) complexes with Schiff bases and their inhibition studies on Helicobacter pylori urease

A series of structurally similar dinuclear oxovanadium(V) complexes, [VO₂L]₂ (L?=?L¹?=?2-[(2-methylaminoethylimino)methyl]phenolate (1); L?=?L²?=?2-[(2-ethylaminoethylimino)methyl]phenolate (2); L?=?L³?=?2-[(2-isopropylaminoethylimino)methyl]phenolate (3)), has been synthesized and characterized by physico-chemical methods and single-crystal X-ray diffraction. The V in each complex is octahedral, with three donors of L and one oxo defining the equatorial plane, and with two oxos occupying the axial positions. The complexes were tested for their urease inhibitory activities. The inhibition rate (%) of 1, 2, and 3 at 100?µmol?L^?1 on urease are 67?±?1, 53.5?±?0.9, and 44?±?1. The relationship between structures of the complexes and the urease inhibitory activities indicates that shorter terminal groups of the complexes have stronger activities against urease. Molecular docking study of the complexes with the Helicobacter pylori urease was performed.     

Pt(II) complexes with bidentate and tridentate pyrazolyl-containing chelators: synthesis, structural characterization and biological studies

A series of four Pt(II) complexes anchored by bidentate or tridentate pyrazolyl-alkylamine chelators bearing different substituents at the azolyl rings has been prepared with the aim to assess their interest in the design of novel anticancer drugs. All complexes have been fully characterized by classical analytical methods and three of them were characterized also by X-ray diffraction analysis. Their solution behavior, together with lipophilicity measurements, cell uptake, antiproliferative properties, DNA interaction have been evaluated. Albeit all the complexes were less active than cisplatin on ovarian carcinoma A2780 cell line, greatly retained their activity in the cisplatin-resistant A2780cisR cell line and presented a lower resistance factor compared to cisplatin. Moreover, the Pt(II) complexes under investigation were less prone to undergo deactivation by glutathione, believed to be the major cellular target of cisplatin that inactivates the drug by binding to it irreversibly.