Synthesis and spectral studies of binuclear ruthenium(II) carbonyl complexes containing bis(β-diketone) and their applications

C–H activation and subsequent C–C bond formation in rigid alkenes catalyzed by Ru(iii) metallates

Pyrazolone derived Ru(iii) complexes were synthesized and applied as catalysts in the C–H activation reaction of α,β-unsaturated carbonyl compounds. In addition to Heck type coupling, ethanol mediated ethoxylation was also witnessed.

Selectfluor facilitated bridging of indoles to bis(indolyl)methanes using methyl tert-butyl ether as a new methylene precursor

A novel, green and efficient method is developed for the synthesis of methylene bridged bis(indolyl)methanes in good to excellent yields. The reaction employs methyl tert-butyl ether (MTBE) as the methylene source and selectfluor as an oxidizing agent. The scope and versatility of the methods have been successfully demonstrated with 48 examples. The metal-free transformation process is suitable for scale-up production. A selectfluor-promoted oxidative reaction mechanism is proposed based on the results of the experimental studies.

Diamine-mediated degradative dimerisation of Morita-Baylis-Hillman ketones

A degradative dimerisation of Morita-Baylis-Hillman ketones was observed in the presence of a primary diamine. The reaction proceeded swiftly to produce methylene-bridged 1,3-dicarbonyl compounds. A brief mechanistic investigation alluded to a retro-Mannich reaction as the key step of the transformation.

Lasing the DNA fragments through β-diketimine framed Knoevenagel condensed Cu(II) and Zn(II) complexes--an in vitro and in vivo approach

The syntheses, structures and spectroscopic properties of Cu(II) and Zn(II) complexes having Knoevenagel condensate β-diketimine Schiff base ligands have been investigated in this paper. Characterization of these complexes was carried out using FTIR, NMR, UV-Vis, elemental analysis, mass and EPR techniques. Absorption titration, electrochemical analyses and viscosity measurements have also been carried out to determine the mode of binding. The shift in ΔEp, E1/2 and Ipc values explores the interaction of CT DNA with the above metal complexes. Interaction of ligands and their complexes with DNA revealed an intercalative mode of binding between them. Antimicrobial studies showed an effective antimicrobial activity of the metal ions after coordination with the ligands. The antioxidant properties of the Schiff base ligands and their complexes were evaluated in a series of in vitro tests by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and H2O2 free radical scavengers. In vivo and in vitro antitumor functions of the complexes against Ehrlich ascites carcinoma tumor model have also been investigated. All the results support that β-diketone derived Knoevenagel condensate Schiff base complexes may act as novel antitumor drugs and suggest that their potent cell life inhibition may contribute to their anti-cancer efficacy.

Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands

Transition metal complexes of various acetylacetone based ligands of the type ML [where M=Cu(II), Ni(II), Co(II); L=3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, (1)H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

Preparation, spectroscopy, EXAFS, electrochemistry and pharmacology of new ruthenium(II) carbonyl complexes containing ferrocenylthiosemicarbazone and triphenylphosphine/arsine

A new series of new hetero-bimetallic complexes containing iron and ruthenium of the general formula [RuCl(CO)(B)(EPh3)(L)] (where E=P or As; B=PPh3, AsPh3, py or pip; L=ferrocene derived monobasic bidentate thiosemicarbazone ligand) have been synthesized by the reaction between ferrocene-derived thiosemicarbazones and ruthenium(II) complexes of the type [RuHCl(CO)(B)(EPh3)2] (where E=P or As; B=PPh3, AsPh3, py or pip). The new complexes have been characterized by elemental analyses, IR, electronic, NMR (1H, 13C and 31P), EXAFS (extended X-ray absorption fine structure spectroscopy) and cyclic voltammetric techniques. Antibacterial activity of the new complexes has been screened against Escherichia coli, Vibrio cholerae, and Pseudomonas aeruginosa species.

Synthesis, Characterization, and Biological Activity of Some Transition Metal Complexes Derived from Novel Hydrazone Azo Schiff Base Ligand

A series of metal(II) complexes ML where M = VO(II), Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized from azo Schiff base ligand (N′E)-N′-(5-((4-chlorophenyl)diazenyl)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide and characterized on the basis of elemental analyses, electronic, IR, and 1H NMR spectra, magnetic susceptibility and also by aid of scanning electron microscopy (SEM), X-ray powder diffraction, fluorescence spectral studies, and molar conductivity measurements. Conductivity measurements reveal that the complexes are nonelectrolytes. Spectroscopy and other analytical studies reveal distorted square planar geometry for copper, square-pyramidal geometry for oxovanadium, and tetrahedral geometry for other complexes. Redox behavior of the copper(II) complex has been studied with cyclic voltammetry, and the biological activities of the ligand and metal complexes have been studied against several microorganisms by the well diffusion method. All synthesized compounds can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligand was measured and found to be higher than that of urea and KDP. The SEM image of the copper(II) complex implies that the size of the particles is 50 nm.

NMR (1D and 2D) and X-ray crystallographic studies of Ni(II) complex with N-(2-mercaptophenyl)-4-methoxysalicylideneimine and triphenylphosphine

Mononuclear nickel(II) complex, viz. [Ni(L)(PPh(3))] (where L is dianion of N-(2-mercaptophenyl)-4-methoxysalicylideneimine) has been synthesized and characterized by means of elemental analysis, electronic, IR and NMR [(1)H, (13)C{(1)H} and (31)P{(1)H}, DEPT, (1)H-(1)H COSY, ge-HSQC, ge-HMBC] spectroscopic techniques. Structural analysis of the complex by single crystal X-ray crystallography indicated the presence of square planar coordination geometry (ONSP) about nickel. One of the phenyl rings of triphenylphosphine involve in C-H...pi interactions with H6b, H13 and H32 to form a three dimensional network which stabilizes the structure of complex.

Synthesis, spectral, catalytic and antimicrobial studies of PPh3/AsPh3 complexes of Ru(II) with dibasic tridentate O, N, S donor ligands

Complexes of the type [Ru(CO)(EPh(3))(B)(L)] (E = P or As; B = PPh(3), AsPh(3), py or pip; L=dianion of the Schiff bases derived from thiosemicarbazone with acetoacetanilide, acetoacet-o-toluidide and o-chloro acetoacetanilide) have been synthesized from the reactions of equimolar amounts of [RuHCl(CO)(EPh(3))(2)(B)] and Schiff bases in benzene. The new complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. The arrangement of PPh(3) groups around ruthenium metal was determined from (31)P NMR spectra. An octahedral structure has been assigned for all the new complexes. All the complexes exhibited catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in presence of N-methylmorpholine-N-oxide as co-oxidant. The complexes also exhibited antibacterial activity against E. coli, Aeromonas hydrophilla and Salmonella typhi. The activity was compared with standard streptomycin.

Synthesis, antimicrobial activities and cytogenetic studies of newer diazepino quinoline derivatives via Vilsmeier–Haack reaction

The study of the Vilsmeier-Haack reagent on 4-hydroxyquinaldines resulted in a new versatile intermediate 4-chloro-3-formyl-2-(2-hydroxy-ethene-1-yl)quinolines, which on further treatment with hydrazine hydrate yielded the desired diazepino quinoline derivatives. All the synthesized diazepino quinoline derivatives are screened for their antibacterial and antifungal activities. Cytogenetic analysis of the samples is also reported.

Spectral, redox and catalytic studies of triphenylphosphine/triphenylarsine complexes of Ru(III) with N, O donor ligands derived from 2-hydroxy-1-naphthaldehyde and primary amines

A series of new mixed ligand hexacoordinated ruthenium(III) Schiff base complexes of the type [RuX(2)(EPh(3))(2)(LL')] (X=Cl, E=P; X=Cl or Br, E=As and LL'=anion of the Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, 4-chloroaniline, 2-methyl aniline and 4-methoxy aniline) are reported. All the complexes have been characterized by analytical and spectral (IR, electronic and EPR) data. The redox behavior of the complexes has also been studied. The complexes exhibit catalytic activity in the oxidation of benzyl alcohol to benzaldehyde in the presence of N-methyl morpholine-N-oxide (NMO). An octahedral structure has been proposed for all of the complexes.

New discrete and polymeric supramolecular architectures derived from dinuclear (bis-β-diketonato)copper(ii) metallocycles

New examples of adducts between di- (and, in one instance, tetra-) functional nitrogen ligands and planar 'platform-like' dinuclear copper(II) complexes, [Cu2L2], incorporating the 1,3-aryl linked bis-beta-diketonato bridging ligand 1,1'-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione) (H2L) have been synthesised. The X-ray structures of six adduct species are reported. The interaction of [Cu2(L)2] with the ditopic ligand aminopyrazine (apyz) yielded the sandwich-like tetranuclear species [(Cu2L2(apyz))2]. A variable-temperature magnetochemical investigation of this product indicated weak antiferromagnetic coupling between the (five-coordinate) copper centres, mediated by the 2-aminopyrazine linkers. An analogous structure, [(Cu2L2(dabco))2] (dabco=1,4-diazabicyclo[2.2.2]octane), was generated when dabco was substituted for aminopyrazine while use of 4,4'-dipyridyl sulfide (dps) and 4,4'-(1,3-xylylene)-bis(3,5-dimethylpyrazole) (xbp) as the ditopic 'spacer' ligands resulted in polymeric species of type [Cu2L2(dps)]n and [Cu2L2(xbp)]n, respectively. These latter species exist as one-dimensional chain structures in which copper(II) centres on different dinuclear platforms are linked in a 'zigzag' fashion. In contrast, with 2,2'-dipyridylamine (dpa) a discrete complex of type [Cu2L2(dpa)2] formed in which one potential pyridyl donor from each 2,2'-dipyridylamine ligand remains uncoordinated. The use of the potentially quadruply-bridging hexamethylenetetramine (hmt) ligand as the linker unit was found to give rise to an unusual two-dimensional polymeric motif of type [(Cu2(L2)2)3(hmt)2]n. The product takes the form of a (6,3) network, incorporating triply bridging hexamethylenetetramine units.

Synthesis and spectral studies of [RuCl(CO)(L)(PPh3)(B)] (HL = 2'-hydroxychalcones and B = PPh3, pyridine or piperidine) and their catalytic and biological applications

The reactions of [RuHCl(CO)(PPh3)2(B)] (B = PPh3, pyridine or piperidine) and 2'-hydroxychalcones led to the formation of [RuCl(CO)(PPh3)(L)(B)] (L = chalconate). The new complexes have been characterized by analytical and spectral (IR, electronic, 1H NMR and 31P NMR) data. They have been assigned an octahedral structure. The complexes have been used as catalysts for the aerial oxidation of cinnamyl alcohol. Some of the complexes have been tested in vitro for growth inhibitory activity against the bacteria E. coli, S. typhi and Pseudomonas sp. and the fungi A. fumigatus.