Karimah Kassim

Synthesis and Characterization of Palladium(II) Schiff Base and their Catalytic Activities for Heck Reaction

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.

N-[(E)-4-Chloro-benzyl-idene]-N'-phenyl-benzene-1,4-diamine.

The title compound, C19H15ClN2, adopts an E configuration with respect to the position of the chlorobenzene and diphenylamine groups on the C=N azomethine bond. The molecule is not planar, the central six-membered ring making angles of 12.26 (10) and 44.18 (11)° with the 4-chlorophenyl and phenyl rings, respectively. In the crystal structure, weak C—H⋯π interactions contribute to the stabilization of the packing.

Investigation on effects of substituents in N,N′-dibensylidene ethane-1,2-diamine towards corrosion inhibition on steel in 1M HCl

Abstract Schiff base compounds, namely, N,N′-dibensylideneethane-1,2-diamine (baen), N,N′-bis(4-chlorobenzylidene)ethane-1,2-diamine (cbaen), N,N′-bis(4-methyl benzylidene)ethane-1,2-diamine (mbaen) and 4-(((2-4-hydroxybenzylidene amino)ethylimino) methyl)phenol (hbaen) were tested as corrosion inhibitors on mild steel in 1M HCl via polarisation method. These compounds were synthesised from the corresponding substituted benzaldehydes and ethylenediamine. Results indicate that the presence of chloro, methyl and hydroxyl substituents enhance the inhibitive properties of N,N′-dibensylideneethane-1,2-diamine. Cbaen achieved the highest inhibition efficiency of 80·76% at 1 × 10–3 M.

2-(4-Chloro­phen­yl)-1-phenyl-1H-benz­imidazole

In the title compound, C19H13ClN2, the dihedral angle formed by the imidazole core with the chlorophenyl and phenyl rings are 24.07 (4) and 67.24 (4)°, respectively.

(E)-2-[1-(3-Amino-4-chloro-phenyl-imino)eth-yl]-4-bromo-phenol.

The title Schiff base compound, C14H12BrClN2O, exists in an E configuration with respect to the central C=N double bond. The amino group adopts a pyramidal configuration. The dihedral angle between the two benzene rings is 76.88 (10)° and an intramolecular O—H⋯N hydrogen bond forms a six-membered ring, generating an S(6) ring motif. In the crystal structure, molecules are linked into chains along [010] via N—H⋯O hydrogen bonds. The presence of π–π interactions [centroid–centroid distance = 3.6244 (12) Å] further stabilizes the crystal structure.

Corrosion Inhibition of Mild Steel by N-phenyl-1,4-phenylenediamine and its Schiff Base Derivatives in 1M HCl

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.

Electrodeposition of Salicylideneaniline and its Corrosion Behavior

Electrodeposition was carried out on mild steel surface in 0.3 M sodium hydroxide solution (70% distilled water: 30% ethanol) containing 0.1 M salicylideneaniline using cyclic voltammetry and chronoamperometry techniques. Both techniques show the formation of the films on the mild steel surface. The corrosion behavior of electrodeposited mild steel was studied using electrochemical impedance spectroscopy (EIS) technique at various immersion times in 0.5 M sodium chloride solution (NaCl). The study indicates that the resistance of mild steel against corrosion increases after being electrodeposited with salicylideneaniline. However the films tend to diminished after 24 hours being immersed in 0.5 M NaCl solution.

6,6′-Dimeth­oxy-2,2′-[(E,E′)-(4-chloro-m-phenyl­ene)bis­(nitrilo­methyl­idyne)]diphenol

The title compound, C22H19ClN2O4, has the appearance of a warped butterfly. One 2-hydroxy-3-methoxybenzylideneamino fragment is planar [with a maximum deviation of 0.056 (3) Å] and forms a dihedral angle of 9.85 (9)° with the central benzene ring. The other fragment is not planar; however, the methoxyphenol group is planar [with the maximum deviation of 0.033 (2) Å] and makes a dihedral angle of 41.7 (3)° with the central benzene ring. The molecule is stabilized by intramolecular O—H⋯N hydrogen bonding. The crystal structure is stabilized by weak intermolecular C—H⋯O hydrogen bonding and C—H⋯π interactions.

(E,E)-N,N′-Bis(4-chloro­phen­yl)ethyl­enediamine

Schiff bases have found extensive application in coordination chemistry as ligands. They can be designed to be multidentate, offering several binding sites for most metals, leaving vacant coordination sites for potential catalytic (Drozdzak et al., 2005) or enzymatic (Zhang et al., 2005) activities. Aromatic rings that are commonly designed into the structure of Schiff bases offer an infinite number of possibilities of introducing functional groups at various positions, fine-tuning the properties of the ligands and hence their metal complexes. This may enhance the applicability of the ligands and complexes as antimicrobial agents (Coombs et al., 2005), antitumor agents (Kandemirli et al., 2005), corrosion inhibitors (Emregul et al., 2006), coating materials (Atta et al., 2006), sensors (Ganjali et al., 2006) and many more physical and biological applications. The title compound, (I), is similar to (E,E)-N,N0-bis(4-tolylmethylidene)ethylenediamine, (II) (Kassim et al., 2006) except that the chloro group attached to the 4-position of the benzene is replaced by a methyl group.

Corrosion inhibition study of a Heterocyclic Schiff base Derived from isatin

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.