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Hydroxamic acids [R(CO)N(OH)R'] are flexible compounds for organic and inorganic analyses due to their frailer structures compared to the carboxylic acid. The syntheses and characterization of benzohydroxamic acid (BHA), its CH3-, OCH3-, Cl- para-substituted derivatives and their Cr(III) complexes are reported herein. The metal complexes were synthesized by reacting the hydroxamic acids with chromium(III) chloride hexahydrate in 2:1 molar ratio. The compounds were characterized via melting point, elemental analysis, FTIR, 1H and 13C NMR, TGA, mass spectrometry, molar conductance and UV-Visible. Data analysis suggests that each complex has the Cr(III) center coordinated to the carbonyl and hydroxy oxygen atoms of the hydroxamic acids in bidentate O,O manner and two water molecules to form octahedral geometry. Non-electrolytic behavior of the complexes was shown through their low molar conductivity. Cytotoxicity study against HCT116 and alpha-glucosidase inhibition test revealed that all complexes have higher activity than their parent ligands. Molecular docking study shows that the docking of active complexes is thermodynamically favorable and the inhibition efficiency may depend on the types and the numbers of molecular interactions established in the corresponding stable conformers.

Two tetradentate phenolic Schiff base ligands namely 2,2'-((1 E ,1' E )-(1,2-phenylenebis(azanyl-ylidene))bis(methanylylidene))diphenol, L1H , 2,2'-((1 E ,1' E )-(1,2-phenylenebis(azanylylidene))bis-(methanylylidene))bis(4-fluorophenol), L1F and their new nickel(II) complexes were successfully synthesized, characterized and evaluated for their in vitro anticancer activities against human colon cancer cell lines, HCT116. The compounds were characterized using FT-IR, 1 H and 13 C NMR, UV-Visible, elemental analysis and melting point. The anticancer results revealed that the parent ligands were more active than their corresponding complexes with L1F being the most potent anticancer compound with IC 50 of 2.8 mg/ml.

A Schiff base ligand, 6,6′-dimethoxy-2,2′-[o-phenylenebis(nitrilomethylidyne)]diphenolato (LA), and its mononuclear and dinuclear Ni(II) and Co(II) complexes were synthesized. Structural elucidation was carried out via elemental analysis, molar conductivity, IR, NMR, UV–Vis spectroscopy, TGA and magnetic susceptibility. Single crystal X-ray diffraction of the Ni(LA) complex revealed a square planar geometry of the Ni(II) centre, with the ligand acting as a tetradentate ONNO chelate. Upon coordination to the metal centers, the ν(C N) and ν(C O) peaks shifted to lower frequencies, with appearance of new peaks assignable to ν(M N) and ν(M O) in the ranges 535–560 and 421–460 cm−1, respectively. Ni(LA) and Ni2(LA) complexes are diamagnetic, whereas the Co(LA) and Co2(LA) complexes are paramagnetic with 3 unpaired electrons each. All the complexes displayed low molar conductivities in acetonitrile indicating non-electrolytic behavior. Anticancer screening against human colorectal cancer HCT116 cell lines revealed that both dinuclear complexes were more active than their mononuclear counterparts. Ni2(LA) showed the highest potency with an IC50 value of 0.81 μM.

This paper reports the synthesis, characterization, anticancer screening and quantum chemical calculation of a tetradentate Schiff base 2,2'-((1E,1'E)-((2,2-dimethylpropane-1,3-diyl)bis- (azanylylidene))bis(methanylylidene))bis(4-fluorophenol) (L2F) and its Pd (II) complex (PdL2F). The compounds were characterized via UV-Visible, NMR, IR spectroscopy and single crystal x-ray diffraction. Density Functional Theory (DFT) and time-dependent DFT calculations in gas and solvent phases were carried out using B3LYP, B3P86, CAM-B3LYP and PBE0 hybrid functionals combined with LanL2DZ basis set. Complexation of L2F to form PdL2F was observed to cause a bathochromic shift of the maximum absorption bands of n-π* from 327 to 410 nm; an upfield shift for δ (HC = N) from 8.30 to 7.96 ppm and a decreased wavenumber for ν(C = N) from 1637 to 1616 cm-1. Overall, the UV-Vis, NMR and IR spectral data are relatively well reproduced through DFT and TD-DFT methods. L2F and PdL2F showed IC50 of 90.00 and 4.10 μg/mL, respectively, against human colorectal carcinoma (HCT116) cell lines, signifying increased anticancer activity upon complexation with Pd (II).

Hydroxamic acids [R(CO)N(OH)R'] are flexible compounds for organic and inorganic analyses due to their frailer structures compared to the carboxylic acid. The syntheses and characterization of benzohydroxamic acid (BHA), its CH

Hydroxamic acids (RCONHOH) are versatile compounds that constitute a significant biological importance. The syntheses, physico-chemical and characterization of benzohydroxamic acid (BHA) and its metal complexes (VO(IV), Cr(III) and Ni(II)) are reported herein. The metal complexes were synthesized via condensation reaction of BHA and metal salts in 2:1 molar ratio using ethanol as reaction medium. The compounds were characterized by elemental analysis, spectral (infrared, UV-Vis, 1 H and 13 C NMR,), TGA, magnetic susceptibility as well as molar conductance. The spectral study analysis reveals that all complexes coordinated to the metal via oxygen atoms ( O,O ) in bidentate manner to form octahedral for [Cr(BHA 2 ).2H 2 O]H 2 O, tetrahedral for [Ni(BHA) 2 ] and square pyramidal geometry for [VO(BHA) 2 ]. The molar conductance values suggested that all complexes were non-electrolytes. A cytotoxicity study against HCT116 displayed that VO(IV) has better IC 50 values than the parent ligand, BHA but not considered as potent anticancer agents.

Coupling reaction between aryl halide and terminal alkyne in Sonogashira coupling reaction is important due to its extensive application in the resynthesis of natural products, production of drugs, dyes, and polymers. Efforts to increase rate of reaction has involved exploration of new catalysts. The current catalysts such as phosphine-based complexes are costly, air-sensitive and environmentally harmful. Nickel(II) Schiff base complexes were synthesized by reacting aromatic Schiff base ligands 2,2'-((1 E ,1' E )-(1,2-phenylenebis(azanylylidene))bis(metha-nylylidene))diphenol (L1H), 2,2'-((1 E ,1' E )-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis(4-fluorophenol) (L1F), and 2,2'-((1 E ,1' E )-(1,2-phenylenebis(azanylylidene))bis-(methanylylidene))bis(4-methylphenol) (L1M) with nickel(II) acetate tetrahydrate to form NiL1H, NiL1F and NiL1M. The chemical structures were elucidated through physicochemical and spectral techniques namely elemental analysis, melting point, FTIR, 1 H and 13 C NMR, magnetic susceptibility and molar conductivity. All nickel(II) complexes were tested as catalysts in homogenous Sonogashira reaction between iodobenzene and phenylacetylene in DMSO for 12 hours at 140 o C. NiLF, a new nickel(II) complex, converted the highest percentage of iodobenzene (91%) while NiLH and NiLC converted 78% and 83% of iodobenzene, respectively.

This paper reports the synthesis, characterisation and DFT analysis of an N,O bidentate Schiff base, (( E )-(4-methoxybenzylimino)methyl)phenol, (L1c) and its Ni(II) and Pd(II) complexes. The structures were elucidated via elemental analysis, UV–Visible, NMR, IR and single crystal X-ray diffraction. Complexation of L1c with Ni(II) and Pd(II) was observed to induce different degrees of bathochromic effect on n → π ∗ and π → π ∗ electronic transitions. A comparison of the experimental data of UV–Visible, NMR, IR and X-ray with those calculated using DFT and TD-DFT methods where five hybrid functionals were tested in gas, IEF-PCM and SS-PCM models was also carried out. The results show that the reproduction of maximum absorption bands n → π ∗ and π → π ∗ is strongly related to the tested hybrid functionals and solvatochromic effects. Relatively good concordance was obtained between experimental and calculated NMR chemical shifts, IR and X-ray parameters. A bioactivity evaluation against HCT116 and Escherichia coli displayed that the parent ligand L1c is a more superior anticancer and antibacterial agent than the positive controls of 5FU and gentamicin respectively. However, both complexes showed poor activity as anticancer agent and no activity observed against tested bacteria.

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.

In the present work, a polydentate Schiff base ligand (SB) was synthesized via condensation reaction between o-vanillin and Cl-m-phenylenediamine. Dinuclear complexes of Co(II) and Cu(II) were prepared by conventional method with SB:metal ratio of 1:1 whereas tetranuclear complexes were obtained via microwave-assisted synthesis with SB:metal ratio of 1:2. Characterization was carried out through elemental analysis (C,H,N), molar conductivity, magnetic susceptibility, Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (NMR) spectroscopy. The experimental data indicated that the metal ions of the dinuclear and tetranuclear complexes were coordinated to the ligand through azomethine nitrogen, methoxy oxygen and deprotonated phenolic oxygen. The effective magnetic moment values of Co(II) complexes suggested tetrahedral geometry with 3 unpaired electrons. The shifting of n(C=N), n(C-O)phenolic and n(C-O)methoxy band to lower frequencies in all complexes indicated that coordination to metal centres occurred through these moieties. New weak peaks in the region 436 -559 cm-1 were assignable to n(M-N) and n(M-O). SB and its complexes were screened to be positive for anticancer activities against human colon cancer cell (HCT116). Tetranuclear Cu4SB and Co4SB metal complexes revealed IC50 values of 4.2 and 6.87, respectively; indicated to be more potent anticancer agents than the dinuclear counterparts and the parent ligand.

This paper reports the synthesis and characterization of three salophen ligands; 2,2'-((1E,1'E)-(1,2 phenylenebis(azanylylidene))bis(methanylylidene))diphenol [L1H], 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis (methanylylidene))bis(4-chlorophenol) [L1C] and 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis(4-methoxylphenol) [L1OME]. The compounds were prepared from condensation reaction between salicylaldehyde, and its derivatives, with ortho-phenylenediamine. Their palladium(II) complexes, namely PdL1H, PdL1C and PdL1OME were synthesized through insertion reaction between the ligands with palladium(II) acetate. All compounds were characterized through melting point, elemental analysis, infrared spectroscopy, 1H and 13C NMR spectroscopy. Palladium(II) complexes were tested as homogenous catalysts in copper-free Sonogashira coupling reaction between iodobenzene and phenylacetylene in DMSO using triethylamine as base with 1.0 mmol% catalyst loading. The most performing catalyst was PdL1OME with 91% conversion followed by PdL1H (83%) and PdL1C (27%).

Complexes of Pd(II) and Ni(II) have been synthesized with general composition ML2X2 (M =Pd(II), Ni(II); L = benzylsalicylideneimine and X = OCH3, F). All synthesized compoundshave been characterized using elemental analysis, magnetic susceptibility measurements,infrared and NMR spectral studies that led to the conclusion that the ligands act as bidentatemanner to form square planar geometry for all complexes. As an extending work, the modeldevelopment of these complexes using multilayer feedforward neural network wereperformed. NiL1d, PdL1d, NiL1c and PdL1c were fed to the training network as inputs andbacteria as output. Levenberg Marquardt training algorithm was used during the networktraining with 10 nodes in hidden layer. The results of testing network showed that theregression, R is 1, indicating that the developed model is good. This is supported by the small mean square error (MSE) is 1.948x10-28 at epochs 5. The finding in this study is significant, thus contributed to the design of antibacterial agent especially to the bidentate Schiff base complexes.Keywords: Schiff base, palladium(II), nickel(II), antibacterial, regression, neural network.

Six new Pd(Il) and Ni(Il) metal complexes of N, O-bidentate (LI, L2) and ONNO-tetradentate (L3) Schiff base ligands have been synthesized. The compounds were characterized via various physicochemical and spectroscopic techniques namely elemental analysis (CHN), FT-IR, 1H and 13C NMR. as well as magnetic susceptibility measurement. All complexes showed diamagnetism indicating that they are square planar complexes. Catalytic performance of Pd(Ll)2 and Pd(L2)2 were investigated/or Heck cross-coupling reaction under optimum operating parameters, monitored using GC-FID for 6 h of reaction time in inert conditions. High catalytic activities of up to 90% were observed in the presence of triethylamine as base and DMA as solvent at J0()"C with I mmol% catalyst loading. The mechanism of catalyzed Heck reaction is proposed to go through a series of conversion of Pd(0)/Pd(Il).

In the title compound, [Ni(C(15)H(13)FNO(2))(2)], the Ni(II) atom is tetra-coordinated by two N atoms and two O atoms from two 2-[(4-fluoro-benz-yl)imino-meth-yl]-6-meth-oxy-phenolate ligands in a square-planar geometry. The two N atoms and two O atoms around the Ni(II) atom are trans to each other, as the Ni(II) atom lies on an inversion centre. In the fluoro-phenyl group, five C atoms and an F atom are disordered over two sets of positions of equal occupancy. In the crystal, the complex mol-ecules are linked via inter-molecular C-H⋯F hydrogen bonds, forming chains along [001].

In the title compound, [Pd(C15H13FNO2)2], the PdII atom is tetracoordinated by two N atoms and two O atoms from the two 2-[(4-fluorobenzyl)iminomethyl]-6-methoxyphenoxy ligands, forming a square-planar geometry. The two N atoms and the two O atoms around the PdII atom are trans to each other. The dihedral angle between the two fluoro-substituted benzene rings is 39.03 (6)°. The molecular structure is stabilized by an intramolecular C—H...O hydrogen bond. In the crystal, weak intermolecular C—H...π interactions occur.

Two vanadium(IV) complexes of hydroxamic acid derivatives namely benzohydroxamic acid (BHA) and salicylhydroxamic acid (SHA) are synthesized and characterized using elemental analysis, infrared spectroscopy and 1H NMR spectroscopy. Through infrared investigation, it is intimated that the hydroxamic acids coordinate to the metal centers as O,O bis-bidentate ligands, each acting as singly deprotonated hydroxamato moieties. Upon in-vitro cytoxicity investigation on liver cell-lines using MTT assay, all the ligands are revealed to be non-toxic whereas the complexes showed very much enhanced toxicity with the lowest cell viability of 17.8% after a 72-hour exposure to the compounds.

In the title compound, [Ni(C15H13FNO2)2], the NiII atom is tetra­coordinated by two N atoms and two O atoms from two 2-[(4-fluoro­benz­yl)imino­meth­yl]-6-meth­oxy­phenolate ligands in a square-planar geometry. The two N atoms and two O atoms around the NiII atom are trans to each other, as the NiII atom lies on an inversion centre. In the fluoro­phenyl group, five C atoms and an F atom are disordered over two sets of positions of equal occupancy. In the crystal, the complex mol­ecules are linked via inter­molecular C—H⋯F hydrogen bonds, forming chains along [001].

In the title compound, [Pd(C15H14NO)2], the Pd atom lies on an inversion center and is coordinated by two ligand molecules through the O and N atoms in a bidentate manner, forming a slightly distorted square-planar geometry. The dihedral angle between the two benzene rings in the ligand is 76.53 (19)°. The molecular packing is stablized by C—H...O and C—H...π interactions.