Papers by Keyword: Schiff-Base

Abstract: A series of ferrocene schiff bases derived from Thiadiazole have been synthesized and characterized by IR, 1H NMR, and elemental analysis, the results conformed well with expected structures. The synthesized compounds were screened in vitro for their antibacterial activity against three Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains. The results showed that these compounds are a series potential new drugs in antibacterial activity against one or more species.

Abstract: The syntheses, physico-chemical and spectroscopic characterization of ovan-type Schiff-base ligands (L1, L2) and their novel mononuclear Pd(II) complexes (PdL1, PdL2) are reported herein. Elemental analysis, FT-IR, ¹H NMR as well as magnetic susceptibility measurements characterised the compounds. The catalytic potential of the Pd(II) complexes for Heck coupling reaction were investigated and monitored using GC. It was observed that both Pd(II) complexes displayed properties of good catalysts for the reaction, indicated by 100% conversion of the starting materials to the subtituted alkene product after 6 hours of reaction time at 100°C in inert conditions. The catalytic activity was compared with the reaction without Pd(II) complexes.

Abstract: The efficiency of two Schiff base compounds namely (E)-N¹-benzylidene-N⁴-phenylbenzene-1,4-diamine (K1) and (E)-N¹-(4-methoxybenzylidene)-N⁴- phenylbenzene-1,4-diamine (K2) as corrosion inhibitors were compared with its parent amine namely N-phenyl-1,4-phenylenediamine (NPPD). Investigations have been made at 25 0C by electrochemical impedance spectroscopy (EIS) and polarization measurements in which the corrosion rates decrease and the percentage inhibition efficiencies and surface coverage degree increase with increasing additive concentration. The adsorption of inhibitors appears to follows Langmuir adsorption isotherm model. Results show K1 to have the highest inhibition efficiency among the three investigated compounds.

Abstract: In this study, Schiff base ligands of (E)-3-(2-aminophenylimino)indolin-2-one, (L1); (E)-3-(2-amino-5-nitrophenylimino)indolin-2-one, (L2); and (E)-3-(2-amino-5-chlorophenylimino) indolin-2-one, (L3) were synthesized via condensation reaction of isatin with o-phenylenediamine, 4-nitro-o-phenylenediamine and 4-chloro-o-phenylenediamine respectively. All the synthesized compounds were characterized by various of physicochemical techniques such as melting point, elemental analysis, infrared spectroscopy, and ¹H nuclear magnetic spectroscopy. Conductivity studies of these ligands were investigated by impedance analyzer which the samples were prepared in the form of tablets. The electrical conductivities of the prepared compounds were measured by applying alternating current (ac) voltage. The conductivity values were calculated and result obtained shows that L2 has the highest conductivity value, followed by L3 and L1.

Abstract: A Schiff base, 3-(phenylimino)indolin-2-one, was successfully obtained from the condensation reaction of isatin and aniline in absolute ethanol with a yield of 72%. The ligand was successfully characterized via physical and spectroscopic techniques namely melting point, Elemental Analysis (C, H, N), 1H Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. The corrosion inhibiting property of the Schiff base and that of a mixture of its starting materials on mild steel in 1 M HCl solution was studied through Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR). The concentration of the Schiff base and the precursor molecules were varied from 1 x 10-3 M to 1 x 10-5 M. The results showed that the percentage of inhibition efficiencies increased with the increase of compound’s concentrations. Comparing the two sets of results for the Schiff base and the mixture of its starting materials, it was shown that the Schiff base was a much better inhibitor than the mixture of the starting materials, clearly indicating the importance of the presence of imine group (C=N) bearing lone pairs of electrons and π electrons in corrosion inhibition.

Abstract: Two ligands and four complexes are successfully synthesized by reacting 1,8-diaminonapthelene with aldehyde/ketone derivatives in ratio amine:aldehyde/ketone (1:2) for ligands formation and 1:1 ratio (ligand:metals) for complexes formation. The compounds were characterized through CHNS elemental analysis, IR spectroscopy, 1H NMR spectroscopy, melting point determination, and magnetic susceptibility determination. The neurotoxicity screening of compounds was screened using neuroblastoma SH-SY5Y cell lines and it was indicate the cells were non-toxic either for ligands and complexes after 24 hours exposure.

Abstract: The complex of ZnL2Cl4 was synthesized by using zinc chloride hydrate and ligand 2-[(4-Methylpiperazin-1-yl)iminomethyl]phenol(L) under reflux conditions and anhydrous ethanol as solvent. The complex was characterized by elemental analysis, Infrared spectroscopy, solid fluorescence. Experimental results showed that the free ligand was thermally stable, and emitted intensive blue fluorescence at the peak wavelength of 493 nm. Compared with the fluorescent emission of free ligand, the complex of ZnL2Cl4 is blue-shifted to 448 nm in solid-state and exhibiting stronger blue fluorescence.

Abstract: With 2,2',5',2''-Terthiophene as starting material, two liquid crystalline compounds containing Schiff’s base unit were synthesized in this paper. The structure of the compounds was confirmed by FTIR and ¹H NMR. The thermally induced phase transition behaviors were investigated by POM and DSC, and the temperature ranges of liquid crystal phase of the two compounds were compared. Results showed that the symmetric compound exhibited a lower clearing point temperature and broader temperature range of liquid crystal phase.

Abstract: We have investigated the third order nonlinear optical properties of pyrrole Schiff bases synthesized by condensing pyrrole-2-carboxaldehyde with two different diamines. The nonlinear optical measurements were performed using the nano- second laser pulses at 532nm wavelengthby employing the Z-scan technique. The Z- scan spectra reveal a large negative non-linear refraction co-efficient .The nonlinear refractive index was found to be of the order of 10 ^-14cm2/W and the magnitude of third order susceptibility was of the order of 10 ^-13esu. These compounds exhibit good optical power limiting property under nano-second regime and TPA (Two Photon Absorption) is the dominating process leading to the non-linear behavior.

Abstract: The preparation and characterization of a novel mixed metal complex of europium (III) and terbium (III) of a tripodal heptadentate Schiff-base ligand N [CH2CH2N=CH (2-OH-3-MeC6H3)]3 (H3L1) have been studied. The complex was prepared by the reaction of [EuL1] and [TbL1] in N, N-dimethylformamide. The ratio of europium (III) to terbium (III) in the mixed metal complex was found to be 3 to 7. The molecular structure of [Eu0.3Tb0.7L1] was determined by X-ray crystallography. The crystal structure analysis revealed that the Schiff-base behaves as a tri-deprotonated heptadentate ligand encapsulating the each metal ion within the N4O3 cavity. Under the excitation of UV light, the solid state of the complex exhibited red emission corresponding to europium (III) ion. The emission bands of 5D0 → 7Fj (j = 2, 3, 4) were observed at 609, 652, and 706 nm, respectively. On the other hand, the green emission corresponding to terbium (III) ion was not observed.