O. P. Pandey

SYNTHESIS, STRUCTURAL AND BIOCHEMICAL ASPECTS OF TITANOCENE AND ZIRCONOCENE CHELATES OF ACETYLFERROCENYL THIOSEMICARBAZONES

The reactions of bis(cyclopentadienyl)titanium(IV)/zirconium(IV) dichloride with a new class of organometallic thiosemicarbazones (LH), derived by condensing acetylferrocene with substituted thiosemicarbazides, have been studied and two types of bimetallic products, viz. [Cp2M(L)Cl] (M = Ti or Zr) and [CpZr(L)3], have been isolated. On the basis of various physicochemical and spectral studies, five- and seven-coordinate structures have been assigned to these derivatives, respectively. Attempts have been made to establish a correlation between biological activity and the structures of the products.

Syntheses and spectroscopic studies of mono- and di- cyclopentadienylzirconium(IV) derivatives with heterocyclic thiones

Abstract The reactions of dichlorodi-cyclopentadienylzirconium(IV) with two important series of heterocyclic thiones, viz. oxadiazolethione (OxtH) and thiohydantoin (ThtH) in anhydrous tetrahydrofuran (molar ratios 1/1 and 1/3) in the presence of base, led to the formation of derivatives of the types [Cp 2 Zr(Oxt(Cl], [CpZr(Oxt) 3 ], [Cp 2 Zr(Tht)Cl] and [CpZrTht) 3 . The complexes were characterized by elemental analysis, electrical conductance, magnetic measurements and spectral (electronic, infrared and 1 H NMR) studies. Possible structures are proposed for these derivatives.

Synthesis, spectral and antibacterial studies of binuclear titanium(IV) / zirconium(IV) complexes of piperazine dithiosemicarbazones.

The reactions of mono(cyclopentadienyl)titanium(IV) trichloride and bis(cyclopentadienyl)titanium(IV)/ zirconium(IV) dichloride with a new class of dithiosemicarbazone, derived by condensing piperazine dithiosemicarbazide with benzaldehyde (L1H2), 2-chlorobenzaldehyde (L2H2), 4-nitrobenzaldehyde (L3H2) or salicylaldehyde (L4H4) have been studied and different types of binuclear products, viz. [{CpTiCl2}2L], [{Cp2MCl}2L], ((L=L1, L2 or L3), [{CpTiCI}2L4] and [{Cp2M}2L4] (M=Yi or Zr), have been isolated. Tentative structures are proposed for these complexes based upon elemental analyses, electrical conductance, magnetic moment and spectral (electronic, IR, 1H and 13C NMR) data. Attempts have been made to establish a correlation between antibacterial activity and the structures of the products.

Synthesis, spectroscopic and thermal studies on ruthenium(III), rhodium(III) and iridium(III) complexes with hydrazones derived from 2,6-diacetylpyridine and different aromatic hydrazides

SummaryThe reactions of MCl3·3H2O (M=Ru, Rh or Ir) with hydrazones have been studied by three different methods and complexes of the types [M(LH2)(H2O)2]Cl3, [M(L)Cl(H2O)] and [M(LH2)Cl2]Cl·H2O have been isolated. Tentative structural conclusions are drawn for these products based upon elemental analysis, electrical conductance, magnetic moment, and i.r. and1H n.m.r. data. The thermal stability and mode of decomposition for the complexes have been studied by t.g.a., d.t.g. and d.s.c. techniques.

Organophosphorus derivatives containing isatin-3-hydrazones as chemotherapeutants against fungal pathogens of sugarcane.

A total of 20 novel organophosphorus derivatives have been synthesized by the reactions of O,O-diethylchlorophosphate/thiophosphate with isatin-3-(substituted benzoic acid/phenoxy acetic acid hydrazones). The derivatives have been characterized on the basis of analysis and spectral (IR and (1)H and (13)C NMR) data. Fungicidal activities of the derivatives against Colletotrichum falcatum , Fusarium oxysporum , and Curvularia pallescence have been evaluated. The screening results have been correlated with the structural features of the tested compounds. The greater potency has been observed with thiophosphates compared to phosphates, with substituted phenoxy acetic acid hydrazones compared to substituted benzoic acid hydrazones, and with substitutent Cl(-) attached to the aromatic ring compared to other substitutents. O,O-Diethylchlorophosphate compounds containing isatin-3-(4-chlorophenoxy acetic acid hydrazone) (IIe) and the compound containing two molecules of O,O-diethylchlorophosphate attached to isatin-3-(4-hydroxy phenoxy acetic acid) hydrazone (IIh) were proven to be more active than some prevalent commercial synthetic fungicides.

Synthesis and physico-chemical and biological studies on ruthenium (III) complexes with Schiff bases derived from aminocarboxylic acids

SummaryRuthenium(III) complexes of types [Ru(L)3], [Ru(L′)Cl(H2O)2], [Ru(L″)Cl2]n, [Ru(L‴)Cl(H2O)]n(LH =Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; L′H2=Schiff bases derived from anthranilic acid and salicylaldehyde oro-hydroxyacetophenone; L″H=Schiff bases derived fromp-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; L‴H2=Schiff bases derived fromp-aminobenzoic acid and salicylaldehyde oro-hydroxyacetophenone) have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moment and spectral (electronic, i.r. and1H n.m.r.) data. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for all these complexes except [Ru(L″)Cl2]n. The complexes [Ru(L″)Cl2]n are pentacoordinate and a trigonal-bipyramidal environment, D3h, is suggested for the ruthenium(III) ion. The thermal behaviour of these complexes has also been studied by t.g., d.t.g and d.s.c techniques. Heats of reaction for the decomposition steps were calculated from the d.s.c. curves. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid were also investigated.

Syntheses and Spectroscopic Studies on Tetraaza Macrocyclic Complexes of Lanthanum(III)

Abstract Lanthanum(III) macrocyclic complexes of types [La(mac1)] Cl3 and [La(mac2)(H2O)2] Cl3 (mac1 = macrocyclic ligands derived by the condensation of diacetyl or benzil with carbohydrazide; mac2 = macrocyclic ligands derived by the condensation of diacetyl or benzil with semicarbazide, thiosemicarbazide or thiocarbohydrazide) have been prepared and characterized by conductance measurements, infrared and 1H and 13C n.m.r spectroscopies and by thermal and elemental analyses.

Efficacy of organophosphorus derivatives containing chalcones/chalcone semicarbazones against fungal pathogens of sugarcane.

Ten newly synthesized organophosphorus derivatives containing substituted chalcones and substituted chalcone semicarbazones were tested for their antifungal efficacy against Colletotrichum falcatum, Fusarium oxysporum, Curvularia pallescens (all sugarcane pathogens). The O,O-diethylphosphate derivatives containing 2-chlorochalcone and 2-chlorochalcone semicarbazone exhibited 70-85% mycelial inhibition against all the test fungi at 1000 ppm. The screening results were correlated with structural features of the tested compounds.

HomoBinuclear Oxovanadium(IV) Complexes with Octaaza Macrocyclic Ligands Derived from Primary Diamines and 3,6-Dimethyl/diphenyl-4,5-diazaocta-3,5-diene-2,7-dione

The in situ reactions of 3,6-dimethyl/diphenyl-4,5-diazaocta-3,5-diene-2,7-dione with diamines (ethylenediamine, o-phenylenediamine) in the presence of vanadyl salt yielded binuclear macrocyclic complexes of type [(VO)2mac](SO4)2. Attempts to synthesize the corresponding metal-free macrocyclic ligands did not prove successful. The magnetic moment of the complexes decreases from ca. 1.73 (295 K) to 1.65μ B (91 K). The electronic spectra exhibit three bands at ca. 12 000-14 200, 18 200-19 500 and an intense band at ca. 30 000 cm-1. The third band is probably due to a oxo → V(IV) charge-transfer transition. The infrared spectra indicate that the ligands coordinate through four aza nitrogen atoms to each V(IV). The fluid solution EPR spectra show an eight line pattern typical of a mononuclear VO(IV) compound and indicating the absence of VO…VO electron spin interaction. The electrochemical behavior of one complex with regards to oxidation has been studied by cyclic voltammetry in MeCN-MeOH solution.

Synthesis, spectral characterization and antimicrobial studies of nano-sized oxovanadium(IV) complexes with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-thiadiazole and indoline-2,3-dione

A new class of oxovanadium(IV) complexes with Schiff bases derived by the condensation of 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-thiadiazoles and indoline-2,3-dione have been prepared in ethanol in the presence of sodium acetate. Micro-analytical data, magnetic susceptibility, UV-Vis, IR, EPR and XRD spectral techniques were used to confirm the structures. Electronic absorption spectra of the complexes suggest a square-pyramidal geometry. The oxovanadium(IV) complexes have monoclinic crystal system and particle sizes were found to be in the range 18.0 nm to 24.0 nm (nano-size). In vitro antifungal activity of synthesized compounds was determined against fungi Aspergillus niger, Colletotrichum falcatum and Colletotrichum pallescence and in vitro antibacterial activity was determined by screening the compounds against Gram-negative (Escherichia coli and Salmonella typhi) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacterial strains. The oxovanadium(IV) complexes have higher antimicrobial effect than free ligands.