Adsorption and corrosion inhibition accomplishment for thiosemicarbazone derivatives for mild steel in 1.0 M HCl medium: Electrochemical, XPS and DFT studies

Four benzaldehyde thiosemicarbazone derivatives namely as 2-benzylidene-N-phenylhydrazinecarbothioamide (L1), 2-(4-hydroxybenzylidene)-N-phenylhydrazinecarbothioamide (L2), 2-(4-chlorobenzylidene)-Nphenylhydrazinecarbothioamide (L3), and 2-(4-methylbenzylidene)-N-phenylhydrazinecarbothioamide (L4) were successfully synthesized and elucidated by physical and spectral techniques, to be specific,melting point, elemental analysis (CHNS), infrared spectroscopy (FTIR) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR). These organic corrosion inhibitors behaviour for mild steel (MS) in 1.0 M HCl solution was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Fromthe electrochemical measurements, most ligands behave as efficient inhibitors for theMS in 1.0MHCl solution which contribute the maximum inhibition efficiency up to 93.38% for L3. The potentiodynamic polarization measurements unfolds each synthesized compoundweremixed-type inhibitor based on the shifting of corrosion potentials (Ecorr) found to be lesser than±85 mV. The electrochemical impedance spectroscopy (EIS) analysis revealed retardation of metal corrosion succeeded by cause of adsorption of the four thiosemicarbazone derivatives inhibitor molecules at the metal/solution interface. The adsorption of thiosemicarbazone molecules on the low carbon steel surface in 1.0 M HCl solution obeys Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrates in the presence of optimum concentration of L1-L4 inhibitors at 0.04mMindicates greatly reduced surface roughness ofMS in comparisonwith uninhibited solution. The findingswere further reinforced via surface elemental analysis ofmetal/solution interface viaX-ray Photoelectron Spectroscopy (XPS), which unveils L3 exhibit the greatest inhibition efficiency. The most plausible reason is due to benzene rings in the molecular structure increases the adsorption ability in supporting the substituent of chloro as well as conjugated double bond of C=N and C=S that chemisorbed along the surface of metal. The oxide species of FeO, Fe2O3 and FeOOH found to be chemisorbed and physisorbed on MS surface. The impact of molecular properties on the corrosion inhibition and the adsorbed sites of L1-L4 on the metal were investigated using density functional theory calculations (DFT) at the B3LYP/6–311+G (d,p) level of theory. Fromthe Frontier Molecular Orbitals (FMO), the Highest OccupiedMolecular Orbitals (HOMO) discloses adsorption of L2 on theMS surface generally due to 2-(4-hydroxybenzylidene)-N-hydrazinecarbothioamide, whereas for L1, L3 and L4 associated to the inclusion of phenyl carbothioamide. The Lowest Occupied Molecular Orbitals (LUMOs) of L1-L4 are comparatively resembling and delocalized of all molecules. DFT reveals protonated thiosemicarbazones exhibits high correlations coefficients as up to 99–100% in comparison to the corresponding neutral forms of themolecules. The increase in the inhibition efficiency of protonated L1, L2 and L3 is proportional to the ΔN and DM

Synthesis, Characterization and Morphological Study of Nicotinamide and <i>p</i>-Coumaric Acid Cocrystal

Cocrystallization is one of the potent methods used to modify the physicochemical properties of drugs. Cocrystal of nicotinamide (NIC):p-coumaric acid (COU) was synthesized by a slow evaporation method using acetonitrile. The cocrystals with different feed molar ratios (NIC:COU : 1:1, 1:2, and 2:1) were characterized using DSC, PXRD, and FTIR, which revealed the formation of different polymorphs for each feed molar ratio. A single crystal of the NIC:COU (1:1) cocrystal was analyzed using single crystal X-ray diffraction (SCD), and 1H-NMR revealed a greater cocrystal structure stability compared to the previously published cocrystal. The intermolecular hydrogen bonds, N-H···O, and O-H···O interactions played a major role in stabilizing the cocrystal structure. A molecular modeling technique was used for prediction and surface chemistry assessment of the morphology showed an elongated (along y-axis) octagonal crystal shape which was in a reasonable agreement with the experimental crystal morphology. The reduction in values of the cocrystal solubility in ethanol was supported by the DSC data and simulation of crystal facets where most the crystal facets exposed to polar functional groups. At the concentration of 31.3 µM, NIC:COU (1:1) cocrystal showed more effective DPPH scavenging with 77.06% increased activity compared to NIC at the same concentration

3-[3-(2-Fluorobenzoyl)thioureido]propionic acid

In the title compound, C10H11FN3O3S, the 2-fluorobenzoyl and proponic acid groups maintain a trans–cis conformation with respect to the thiono C   S bond across their C—N bonds. The propionic acid group adopts an anti conformation about the C—C bond, with an N—C—C—C torsion angle of 173.8 (2

Crystal structure of bis(2-{1-[(E)-(4-fluorobenzyl)imino]ethyl}phenolato-κ2N,O)palladium(II)

The asymmetric unit of the title complex, [Pd(C15H13FNO)2], contains one half of the molecule with the PdII cation lying on an inversion centre and is coordinated by the bidentate Schiff base anion. The geometry around the cationic PdII centre is distorted square planar, chelated by the imine N- and phenolate O-donor atoms of the two Schiff base ligands. The N- and O-donor atoms of the two ligands are mutually trans, with Pd—N and Pd—O bond lengths of 2.028 (2) and 1.9770 (18) Å, respectively. The fluorophenyl ring is tilted away from the coordination plane and makes a dihedral angle of 66.2 (2)° with the phenolate ring. In the crystal, molecules are linked into chains along the [101] direction by weak C—H...O hydrogen bonds. Weak π–π interactions with centroid–centroid distances of 4.079 (2) Å stack the molecules along c

Physical Mixture Interaction of Acetaminophenol with Naringenin

The interaction of Active Pharmaceutical Ingredient (API) with other compounds will affect drugs stability, toxicity, modified dissolution profiles or may form a new compound with the different crystal structure. Acetaminophenol (APAP), the most common drug used widely (also known as Panadol) was mixed with Naringenin (NR) to glance for a new phase of interactions leading to new compound phase. The amide-acid supramolecular heterosynthon; N-H…O interaction between acid and the respective base were observed in the APAP-NR mixture blends. The interaction was prepared by the binary interaction from neat grinding and liquid-assisted grinding techniques at a different stoichiometry of binary mixture ratio of APAP-NR which were 1:1, 1:2 and 2:1 molar ratio. The interaction was estimated using Group Contribution Method (GCM) and physicochemical properties were characterized by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), powder X-ray diffraction (PXRD) and Differential Scanning Calorimetry (DSC) analysis. The GCM calculation gave good interaction strength at 212.93 MPa1/2. The ATR-FTIR, DSC and PXRD results obtained revealed an interaction with new phase formed

(E)-1-(4-Hydroxybenzylidene)-4-methylthiosemicarbazide

The title compound, C9H11N3OS, is derived from methylthiosemicarbazide and hydroxybenzylidene fragments with a trans configuration at the C=N bond. The structure is stabilized by intermolecular N—H...S, N—H...O and O—H...S hydrogen bonds that form a two-dimensional network parallel to (102)

3-[3-(2-Fluorobenzoyl)thioureido]propionic acid

In the title compound, C10H11FN3O3S, the 2-fluorobenzoyl and proponic acid groups maintain a trans–cis conformation with respect to the thiono C=S bond across their C—N bonds. The propionic acid group adopts an anti conformation about the C—C bond, with an N—C—C—C torsion angle of 173.8 (2)°. The amino groups are involved in the formation of intramolecular N—H...O and N—H...F hydrogen bonds. In the crystal, pairs of O—H...O hydrogen bonds link molecules into inversion dimers

Crystal structure of (E)-N′-benzylidene-2-methoxybenzohydrazide

In the title benzoylhydrazide derivative, C15H14N2O2, the dihedral angle between the planes of the two phenyl rings is 12.56 (9)°. The azomethine double bond adopts an E configuration stabilized by an N—H...O hydrogen bond. In the crystal, the components are linked by C—H...O interactions to form chains along the b axis