Mononegative Tridentate Research Articles

Two New Inner-sphere Pt(II) Thiosemicarbazone Schiff Base Complexes Immobilized into Magnetic Nanoparticles: Synthesis, Characterization, and Biological Investigations

This study explores the synthesis, characterization, and biological investigations of two new Pt(II) thiosemicarbazone complexes immobilized in magnetic nanoparticles (MNPs). MNPs exhibit distinctive physical and chemical properties that enhance their interactions with biological targets. These traits make them particularly useful, especially when combined with drugs, increasing therapeutic effectiveness while also serving as efficient diagnostic tools in imaging techniques. The two Pt(II) complexes are represented by the formulas [Pt(HL1)(H2O)]Cl and [Pt(HL2)(H2O)2]Cl. The ligand, H2L1 signifies (Z)-2-(2-oxoindolin-3-ylidene)-N-phenylhydrazine-1-carbothioamide, while H2L2 stands for (Z)-N-ethyl-2-(2-oxoindolin-3-ylidene)hydrazine-1-carbothioamide. The ligands and their Pt(II) complexes were characterized through various techniques, including elemental analysis, mass spectrometry, thermal analysis, powder X-ray diffraction (XRD), FT-IR, NMR, and UV–visible spectroscopy. The two complexes form a square planar geometry, in which H2L1 performs as a mononegative tridentate while H2L2 acts as a mononegative bidentate. Density Functional Theory (DFT) calculations were utilized to investigate the molecular configurations of the ligands and its Pt(II) complexes. The UV–visible and fluorescence spectroscopy techniques were employed to examine the interactions between Pt(II) complexes and Bovine Serum Albumin (BSA). DNA fragmentation studies on the Pt(II) complexes were performed and showed that [Pt(HL2)(H2O)2].Cl complex is the strongest degraded on the DNA. [Pt(HL1)(H2O)]Cl and [Pt(HL2)(H2O)2]Cl complexes were immobilized into MNPs to produce Pt(L1)/MNPs and Pt(L2)/MNPs, respectively. Pt(L1)/MNPs and Pt(L2)/MNPs were identified using FT-IR, PXRD, SEM, TEM, EDX, and UV-spectroscopy. In vitro cytotoxicity tests on these compounds against MCF-7 cell line is applied. Additionally, the antimicrobial activity against two gram + ve bacteria (Bacillus subtilis and staphylococcus aureus), and two gram −ve bacterial strains (Escherichia coli and Salmonella typhi) was investigated. Furthermore, the antioxidant properties (DPPH) of the investigated compounds were assessed. The results of the study indicated that the [Pt(HL2)(H2O)2].Cl complex exhibited a higher biological potency compared to both the [Pt(HL1)(H2O)2].Cl complex and their respective ligands. When Pt(II) complexes were incorporated into the MNPs, a significant increase in their biological activity was noted, especially for Pt(L2)/MNPs, which exhibited the strongest antibacterial and anticancer effects.

Investigation of structural, spectral, theoretical, and antimicrobial properties of Iron(III) complexes with thiosemicarbazide ligands

Different thiosemicarbazide ligands, (H2PAPS), (H2PAPT), (H2PABT), have been utilized to synthesize a series of Fe(III) complexes. These complexes were characterized using conventional techniques, and their chemical formulas were determined as [Fe(H2PAPS)Cl3], [Fe(H2PAPT)Cl3(H2O)], and [Fe(HPABT)Cl2(H2O)], respectively. The spectral analysis of the Fe(III) complexes showed that H2PAPS coordinate as a neutral tridentate, while H2PAPT suggests its coordination as a neutral bidentate but in the case of H2PABT, it acts as a mononegative tridentate. The proposed structures of all complexes were found to be octahedral. Confirmation of the geometries of the ligands and their Fe(III) complexes, various parameters were calculated using DFT (density functional theory) with the Materials Studio program. Thermal degradation studies of the complexes were conducted. Additionally, the antibacterial activities of the ligands and their Fe(III) complexes were evaluated. The results showed that Fe(III) complexes exhibited greater antibacterial effects compared to their the free ligands, except for [Fe(H2PAPT)Cl3(H2O)], which demonstrated lower activity than its corresponding ligand. Interestingly, the ligands demonstrated higher cytotoxicity compared to fluorouracil (5-FU), a known anticancer drug. However, the Fe(III) complexes showed lower activity compared to their corresponding ligands in the tested cell lines.

Palladium(ii), platinum(ii), and silver(i) complexes with 3-acetylcoumarin benzoylhydrazone Schiff base: Synthesis, characterization, biomolecular interactions, cytotoxic activity, and computational studies.

New Pd(ii) (C1), Pt(ii) (C2), and Ag(i) (C3) complexes derived from 3-acetylcoumarin benzoylhydrazone (HL) Schiff base were synthesized and characterized by FTIR, 1H NMR, UV-visible spectroscopies along with elemental analysis (C, H, N), magnetic, molar conductivity measurements, and DFT calculations. The obtained results suggested that the ligand had different behaviors in the complexes: mono-negative tridentate (C1) and neutral tridentate (C2) as an ONO-donor and neutral bidentate (C3) as an ON-donor. Quantum chemistry calculations were performed to validate the stability of the suggested geometries and indicated that all the complexes possess tetra-coordinated metal ions. The binding affinity of all the compounds toward calf thymus (ctDNA), yeast (tRNA), and bovine serum albumin (BSA) was evaluated by absorption/emission spectral titration studies, which revealed the intercalative binding to ctDNA and tRNA and static binding upon complex formation with BSA. Molecular insights into the binding affinity of the characterized complexes were provided through conducting molecular docking analysis. Moreover, the cytotoxic activity (in vitro) of the compounds was screened against human cancerous cell lines and a non-cancerous lung fibroblast (WI38) one using cis-platin as a reference drug. The IC50 and selective index (SI) values indicated the higher cytotoxic activity of all the metal complexes compared to their parent ligand. Among all the compounds, the complex C2 showed the highest activity. These results confirmed the improvement of the anticancer activity of the ligand by incorporating the metal ions. In addition, flow cytometry results showed that complexes C1 and C2 induced cell cycle arrest at S and G1/S, respectively.

Newly synthesized lanthanides complexes of ferrocene-based Schiff base with high biological activities and improved molecular docking data

Amino acids are the fundamental building blocks of proteins and are involved in all major biological activities. Schiff bases being active biological moieties and possessing diverse pharmacological activities. Herein, the previously synthesized Schiff base ligand (HL) underwent metal complex formation, to get their La(III), Er(III) and Yb(III) metal complexes. These metal complexes were characterized using different spectroscopic tools as elemental analysis, FT-IR, mass, UV-Vis spectra, thermal analysis (TG) and scanning electron microscope (SEM). According to the elemental analysis data, the complexes were found to have octahedral geometry with the formula [M(L)(H2O)2Cl]Cl.nH2O (M = La(III), n = 2; Er(III), n = 4 and Yb(III), n = 1). The ligand binds to the metal ions with mononegative tridentate mode through the carboxylic oxygen, imidazole nitrogen and azomethine nitrogen as deduced from the IR spectra. The complexes decomposed within two or three steps from room temperature to 1000 °C as elucidated from TG. Also, biological and anticancer activities were tested and promising activities. Molecular docking was studied on two different proteins, the receptor of breast cancer mutant oxidoreductase (3HB5) and the receptor of colon cancer isomerase (2HQ6). The results recommended that Yb(III) complex can be used as breast and colon cancer drugs.

Metal complexes of hydrazone–oxime derivative as promising in vitro antimicrobial agents against some fungal and bacterial strains

In this study, Cu2+, Co2+, Ni2+, Mn2+, Zn2+, Fe3+, VO2+, and UO22+ complexes derived from a NNO tridentate chelating hydrazone–oxime, namely, N′‐((2E,3Z)‐3‐(hydroxyimino)butan‐2‐ylidene)benzohydrazide (H2L,1) were prepared. The elemental, thermo‐gravimetric, spectral, molar conductivity, and magnetic measurements were applied to elucidate the compositions and structures of these new compounds. In addition to the density functional theory (DFT), studies were employed to acquire optimal structures and quantum chemical parameters. The analyses indicate that the chelator reacted as a neutral or mononegative tridentate ligand bonded to the metal ions via the enolic/ketonic carbonylic oxygen, protonated/deprotonated oximatic nitrogen, and azomethine nitrogen atoms adopting square planar or distorted octahedral geometry. The structural characterization of hydrazone–oxime and its complexes was supported by DFT calculations according to the DFT‐B3LYP procedure and 6‐311+G(d,p) basis set. The theoretical data revealed that the reactivity of the complexes is greater than the free hydrazone–oxime (H2L,1), and there is a good agreement between the practical and theoretical data. The thermogravimetric investigation shows that the complexes break down in two to four decomposing steps in temperature range extended from 50 to 1000°C. In vitro antimicrobial activity data demonstrated an increase in activity of the hydrazone–oxime (H2L,1), upon chelation, and some metal complexes show enhanced antibacterial and antifungal agents.

Elucidating of new hydrazide-based complexes derived from Pd(II), Cu(II) and Cd(II) ions: studies concerning spectral, DFT, Hirshfeld-crystal, biological screening beside Swiss-ADME verification

A new hydrazide ligand (HL) was characterized to be used for synthesis of some bivalent complexes via a green approach that free from hazard solvents. All synthesizes were analytically, spectrally and computationally characterized by using all available techniques. A bis-ligands were coordinated with Pd(II) and Cd(II) ions through neutral bidentate mode of C=O and C=N groups. While, a mono-ligand was coordinated with Cu(II) ion through a mono-negative tridentate mode. Such mode of bonding was suggested based on IR and NMR analysis and then confirmed computationally. The charges on N(10), O(12) and N(13) atoms in the ligand indicate their high nucleophilicity. The complexes were suggested in octahedral or square-planer geometry according to UV-Vis spectra and ESR spectrum of Cu(II) complex. The g-factors and anisotropic parameters supported the square planer geometry of [CuCl(L)] complex. The thermogravimetric (TGA) and kinetic analyses were studied for all complexes and supporting their freedom from water molecules and non-spontaneity of degradation stages. Some physical properties were estimated from modelling study and the superiority of most complexes over HL was noticed. Furthermore, all the compounds were tested in vitro against microbial strains and the Cu(II) complex showed high activity. Also, the antioxidant activity was tested by two methods as well as the cytotoxicity was tested against Ehrlich ascites cells and the Cu(II) or Pd(II) complex plays excellent. It is worthy to note that, the in-vitro results were supported by utilizing Swiss-ADME link. The pharmacokinetics of the small molecules (HL & [CuCl(L)]) were calculated to rank their bioavailability via such in-silico way that navigating at various Swiss Drug Design tools. The BOILED-Egg was also obtained to evaluate HIA and BBB as the indicators of passive gastrointestinal absorption and brain penetration barrier, respectively. The blue point appeared in Cu(II) complex egg indicates its effective effluxes by P-glycoprotein (P-gp), whereas the red point appeared in HL egg points to the non-substrate role of HL versus P-gp. Moreover, the ligand appeared oriented mainly towards MAP kinase and mixed lineage kinase 7 by 53.3%, while, the Cu(II) complex appeared oriented mainly towards GABA-A receptors as ligand-gated ion channel by 42.9%.

Synthesis, characterization, design, molecular docking, anti COVID-19 activity, DFT calculations of novel Schiff base with some transition metal complexes

The elemental analyses, infrared, magnetic measures, UV–Visible, 1H NMR, 13C NMR, and XRD analysis were used to study Co(II), Ni(II), and Cu(II) metal complexes (1–3) with a novel Schiff base (HL). The ligand performances as a mononegative tridentate NNO, according to the spectrum data. In Co(II), Ni(II), and Cu(II) metal complexes, an octahedral structure has been proposed based on magnetic and electronic spectrum data. The thermodynamic properties of the ligand and its complexes are measured via the Coats-Redfern and Horowitz-Metzger procedures. The bond angles, the bond lengths, and quantum chemical factors are shown in the molecular modeling using the DFT approach. The ligand and its complexes have been studied via absorption spectra studies in calf thymus DNA binding and also viscosity calf thymus DNA binding studies. Utilizing o-aminophenol such as a reference material catalyzed by metal complexes, dioxygen stimulation in parameters of phenoxazinone synthase activity is comprehensively examined. By interacting by SARS-CoV-2 main protease, which was obtained from the RCSB pdb database PDB ID: 6 W41, to anticipate the action of HL in contradiction of COVID-19 and its anticancer properties with cancer of prostate protein 3qum, the docking binding sites contacts were evaluated. As a result, future research and clinical studies into HL as a potential COVID-19 illness and prostate cancer therapy drug induced. Vinblastine and colchicine viability tests were used to compare the outcomes of the complexes targeting human tumor cell lines MCF-7 and HepG-2. All complexes' in vitro antioxidant properties were measured by DPPH free radical scavenger tests. Additionally, antibacterial action of the ligand and specific complexes was investigated in vitro in contradiction of Gram + ve bacteria (Staphylococcus aureus) and Gram-ve bacteria Escherichia coli (E. coli) utilizing inhibition zone diameter.

Structural, Theoretical and Biological Studies of (Z)-3-Amino-N-(3-Amino Pyrazine-2-Carbonyl) Pyrazine-2-Carbohydrazonic Acid (APA; L) and Its Cu<sup>2+</sup>, Co<sup>2+</sup>, Pt<sup>4+</sup> and Pd<sup>2+</sup> Chelates

New chelates derived from the novel ligand, (Z)-3-amino-N-(3-amino pyrazine-2-carbonyl)pyrazine-2-carbohydrazonic acid (APA, L), with Cu2+, Co2+, Pt4+ and Pd2+ salts were investigated. The results suggest that APA acts as mononegative tridentate in the case of Cu2+, binegative tetradentate in the case of Co2+ and as mononegative bidentate towards Pt4+ and Pd2+ chelates. The results of the corrected μeff. and spectral suggest the structures of the isolated chelates. The results of the corrected μeff. and spectral suggest the geometries of the isolated chelates. Molecular modeling is deduced and chemical reactivity, energy components for chelates and also MEP for APA is illustrated. In Vitro, the SOD and radical scavengers like activity of the synthesized compounds Hep G2 liver cancer cells and cytotoxic activity were checked. Metal chelates show potent anti-oxidative activity. The results of cytotoxic activity assay against hepatocellular carcinoma cell line Hep G2 confirmed that Pt4+ complex has the highest value, while APA, Cu2+, Co2+ and Pd2+ chelates have no significant cytotoxic activity.

Ball milling approach to prepare new Cd(II) and Zn(II) complexes; characterization, crystal packing, cyclic voltammetry and MOE-docking agrees with biological assay

A simple green strategy was efficiently used for quantitative solvent-free synthesis of Cd (II) and Zn (II) complexes by using ball milling technique. The produced complexes were illustrated by using various spectroscopic (1H &13C NMR, IR, EDX, TEM, SEM) and analytical techniques. The octahedral geometry was proposed for such diamagnetic complexes having 1:2 (M:L) molar ratio through mono-negative tri-dentate binding mode. Conformational study was carried out by applying DFT, to predict the optimized configuration for the tested compounds. Surface properties were studied by using Crystal explorer 3.1 software as well as VESTA package. The molecular packing was appeared strong and closely contact within the ligand and Zn(II) complex crystals. The 2D-fingerprint plots displayed the favourable contribution of carbon and oxygen atoms in packing systems. Moreover, the in-vitro antimicrobial assay via MIC technique revealed the moderate or ineffective behaviour predominantly. Such was confirmed through docking simulation approach. The antioxidant assay displayed a promising behaviour in scavenging free radicals that appeared obviously with the two complexes. Also, antitumor assay towards HCT-116 cell line reveals the effectiveness of the two complexes. Finally, the kinetic parameters for Zn (II) were evaluated by applying cyclic voltammetry technique in the absence/presence of ligand using a glassy carbon electrode.

Synthesis, crystal structure, evaluation of urease inhibition potential and the docking studies of cobalt(III) complex based on barbituric acid Schiff base ligand

The discovery of metal-based complexes as potent urease inhibitor is a challenge. In this work, the new [CoL2]NO3 complex of the barbituric acid based ligand, 5-((benzylamino)methylene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (HL) was synthesized. The structural features of the synthesized Co(III) complex were assigned using the single crystal X-ray diffraction techniques, Hirshfeld analysis, DFT calculations and other physicochemical techniques. Its structure comprised CoN4O2 coordination sphere with two ligands units (L¯) as mononegative tridentate NNO-donor ligand. The potency as urease inhibitor was evaluated in vitro. The [CoL2]NO3 complex (IC50 = 16.0 ± 0.54 µM) is better inhibitor than the drug acetohydroxamic acid as a reference (IC50 = 20.3 ± 0.43 µM). The docking studies of the [CoL2]NO3 was carried out using the active center of Jack Bean Urease (PDB 4GY7), and the resulting poses were analyzed visually to understand the interaction pattern.

Two tridentate pyridinyl-hydrazone zinc(II) complexes as fluorophores for blue emitting layers

Two new complexes were obtained by reaction of zinc (II) acetate with 4-fluoro-N'-(pyridin-2-ylmethylene) benzohydrazide or with 4-(hexyloxy)-N'-(pyridin-2-ylmethylene)benzohydrazide ligands in pyridine. Both ligands have a pyridinyl-hydrazone moiety able to act as a mono-negative tridentate ligand toward zinc ion in 2:1 stoichiometric ratio, producing an octahedral environment. The derived complexes are poor emitters in diluted solution. Instead, they exhibit intense blue fluorescence in the solid state due to AIE (aggregation induced emission) effect. The crystalline complexes are bright yellow in natural light and blue under UV–visible light with remarkable Stokes Shifts. Their photoluminescence quantum yields are ranging 20–30%, making them very promising as fluorophore dopants for blue emissive layers. One ligand and its complex were characterized by single crystal X-ray diffraction analysis that revealed an almost planar conformation of two ligands coordinated to the metal and the presence of significant π-π stacking of molecules at about 3.4 Å.

Crystal structure and magneto-structural investigation of alkoxido bridged dinuclear Fe(III) complexes with 1,3-oxazolidine ligands

Four 1,3-oxazolidine based ligands (H2L1−H2L4) were synthesized in solvent-free condition from the reaction of amino alcohols (2-amino-2-(hydroxymethyl)-1,3-propanediol or 2-amino-2-ethyl-1,3-propanediol) and 2-acetylpyridine or 2-pyridinecarboxaldehyde at 110 °C. Four new dinuclear Fe(III) complexes, [Fe2(HL1)(N3)4] (1), [Fe2(HL2)(N3)4] (2), [Fe2(HL3)(N3)4] (3) and [Fe2(HL4)(N3)4] (4), were synthesized with a similar procedure by the reaction of H2L1–4, Fe(NO3)3·9H2O and NaN3 in 1:1:2 molar ratios in methanol. The ligands and complexes were characterized by elemental analysis and spectroscopic methods. The structure of complexes was solved by single-crystal X-ray diffraction analysis which showed complexes 1–4 to be alkoxido-bridged dinuclear Fe(III) complexes. The structural studies indicated that the crystal structure of 2, 3 and 4 consist of a centrosymmetric dinuclear Fe(III) complexes while the asymmetric unit in 1 consists of two halves of the two independent molecules. The Fe(III) ions have similar coordination environments (cis-FeN4O2) in all of 1–4 which can be described as distorted octahedral geometry. The 1,3-oxazolidine ligands act as mononegative tridentate N2O-donor ligand in 1–4. Two azide groups are also coordinated to each Fe(III) ion as terminal monodentate ligands. The alcoholic arms of the 1,3-oxazilidine ligands act as bridging groups between Fe(III) ions and the Fe⋯Fe distances through these bridges are in the range of 3.157–3.198 Å. Magnetic studies in 2–300 K range reveal antiferromagnetic interactions between the Fe(III) ions with values for the magnetic coupling constants in the range −9.4 cm−1 to −9.7 cm−1, with H = −2J(S1S2).

Synthesis, crystal structure and investigation of the catalytic and spectroscopic properties of a Zn(II) complex with coumarin-hydrazone ligand

A Zn(II) complex with coumarin-hydrazone ligand, [ZnCl(HL)(CH3OH)0.76(H2O)0.24]·0.24(CH3OH) (1), was synthesized from the reaction of equimolar amount of ZnCl2·4H2O and (E)-2-hydroxy-N′-(1-(2-oxo-2H-chromen-3-yl)ethylidene)benzohydrazide (H2L) in methanol solvent. The complex was characterized by elemental analysis, spectroscopic methods and single crystal X-ray diffraction studies. Single crystal X-ray analysis indicated that the Zn(II) ion in complex 1 has a distorted square pyramidal environment and the coumarin-hydrazone ligand is coordinated as a mononegative tridentate ONO-donor ligand, (HL)−. The photoluminescent studies indicated that complex 1 has emission at about 470 nm. The catalytic potential of complex 1 was investigated for preparing tetrazole based compounds from the azide-nitrile cycloaddition reactions. The catalytic reactions were carried out in water as a green solvent. The results indicated that complex 1 is an active catalyst for preparing tetrazole compounds. The effects of temperature and electronic properties of the substituent connected to the nitrile group on the activity of this catalytic system were also considered.

Comparative studies on P-vanillin and O-vanillin of 2-hydrazinyl-2-oxo-N-phenylacetamide and their Mn(II) and Co(II) complexes

Synthesis of complexes derived from hydrazones derived from both P-vanillin (H2L1) and its isomer O-vanillin (H2L2) of 2-hydrazinyl-2-oxo-N-phenylacetamide that coordinated with high magnetic metal ions of both Mn(II) and Co(II) were performed and characterized by different physicochemical methods, elemental analysis, (1H NMR, IR, and UV–visible spectra), also thermal analysis (TG and DTG) techniques and magnetic measurements. The molecular structures of the ligands and their Mn(II) and Co(II) complexes were optimized theoretically and the quantum chemical parameters were calculated. IR spectra suggest that the H2L1 behaved in a mononegative bidentate manner with both but H2L2 coordinated as mononegative tridentate with both Mn(II) and Co(II). The electronic spectra of the complexes as well as their magnetic moments suggested octahedral geometries for all the isolated complexes. The calculated values of binding energies indicated the stability of complexes is higher than that of ligand. The kinetic and thermodynamic parameters for the different decomposition steps in complexes were calculated using Coats–Redfern and Horowitz-Metzger equations. Moreover, the prepared ligands and their Mn(II) and Co(II) complexes were individually tested against a panel of gram positive Bacillus Subtilis and negative Escherichia coli microscopic organisms. Additionally cytotoxicity assay of two human tumor cell lines namely; hepatocellular carcinoma (liver) HePG-2, and mammary gland (breast) MCF-7 were tested.

Spectroscopic, DFT and biological studies on some complexes of Girard's T dithiocarbazate and its application in removal of some heavy metal ions by flotation technique

A new metal complexes of potassium 2-(trimethylglycyl) hydrazine -1-carbodithioate chloride [KHdGT] with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), Cd(II) and U(VI)O2 were prepared and characterized using spectroscopic IR, UV-Vis., ESR, 1H NMR and TG analysis. The IR records proved that the ligand behaved as mononegative tridentate SSO with Co(II), binegative tetradentate SNNO with Cu(II), Zn(II), Cd(II) and U(VI)O2, mononegative SNNO in Ni(II) and Mn(II) complexes. Computational DFT were performed for [KHdGT] by (B3LYP) function together utilizing “6-311++G(d,p)” basis set while semi-empirical method was utilized for its Co(II), Cu(II) and Zn(II) chelates to infer the entire geometry stabilization and ordinary-style examination for separated chelates. The electronic parameters, for example frontier molecular orbitals, dipole moments and infrared intensities were ascertained. In addition, the prepared chelate used for the separation of Cu(II), Cd(II), Ni(II) and Pb(II) ions from aqueous solution by the inexpensive, simple and rapid flotation technique. The cytotoxic, antioxidant and SOD-like activities were studied for KHdGT and its complexes.

New bioactive Pt(II) binary and ternary metal complexes with guaifenesin drug: Synthesis, geometrical structure, and spectroscopic and thermal characterization

Three new binary and ternary metal complexes of Pt(II) with guaifenesin (GFS) drug have been prepared by chelation to guaifenesin ligand (as primary ligand) and glycine amino acid (HGly) and 1,10‐phenanthroline (1,10‐Phen) (as secondary ligands). Characterization was conducted based on elemental analysis, molar conductance, infrared (IR) spectroscopy, thermogravimetric analysis and X‐ray diffraction. The complexes were found to have the formulae [Pt(GFS)2]⋅3H2O (1), [Pt(GFS)2(Gly)]Cl⋅H2O (2) and [Pt(GFS)2(Phen)]Cl2 (3). Magnetic and spectroscopic data revealed complexes 1–3 to have octahedral geometry. IR spectra suggested that GFS ligand coordinated in mononegative tridentate mode (OOO) for 1 but in neutral bidentate mode (OO) for 2 and 3. In addition, HGly behaves as mononegative bidentate coordinated to Pt(II) metal via deprotonated carboxylate O and amino group. IR data also evidenced the bidentate nature of 1,10‐Phen ligand. The molecular and electronic structure of Pt(II) complex 1 was optimized theoretically and the quantum chemical parameters were calculated. Complexes 1–3 were screened for their antibacterial activity on Gram‐positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram‐negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and for their in vitro antifungal activity against Candida albicans. The three Pt(II) complexes showed remarkable biological and cytotoxic activity. The chelates were also screened for their in vitro anticancer activity against the MFC7 breast cell line. Complex 3 showed the highest activity with a low IC50 value of 3.38 μg ml−1.

Structural, DFT and biological studies on Cr(III) complexes of semi and thiosemicarbazide ligands derived from diketo hydrazide

Three ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Cr(III) chloride complexes were prepared and characterized by conventional techniques. The data confirmed that the complexes have the following formulaes, [Cr(H2PAPS)Cl3], [Cr(HPAPT)Cl2(H2O)2] and [Cr(HPABT)Cl2(H2O)]. The IR spectra of complexes shows that H2PAPS behaves as neutral tridentate via both CO of hydrazide moiety and CN(azomethine) due to enolization of CO isocyanate without deprotonation. H2PAPT suggests the coordination as mononegative bidentate via both CO of hydrazide moiety in keto and deprotonated enolic oxygen atoms. H2PABT act as mononegative tridentate via carbonyl oxygen (CO)3, the deprotonated enolic oxygen atom (CO)1 and NH1 groups. The experimental IR data of ligands are compared with those obtained theoretically from DFT calculations. Also, the bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the ligand molecules. The calculated values of binding energies indicates the higher stability of metal complexes than of ligands. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods.

Ligational, potentiometric and floatation studies on Cu(II) complexes of hydrazones derived from p and o-vanillin condensed with diketo hydrazide

Copper (II) complexes of both 2-(2-(4-hydroxy-3-methoxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide (H2L1) and 2-(2-(2-hydroxy-3-methoxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide (H2L2) have been prepared and investigated by analytical, magnetic and spectroscopic techniques. IR spectra displayed that (H2L1) behaves as mono-negative tridentate or mono-negative tetradentate in both of [Cu(HL1)Cl]·(2H2O) and [Cu2(HL1)Cl3(H2O)](1.5H2O), respectively. But (H2L2) behaves as neutral bidentate or bi-negative pentadentate in both of [Cu(H2L2)2Cl2]·(2H2O) and [Cu2(L2)Cl2(H2O)]·(2H2O), respectively. 1H NMR spectra showed the replaceable hydrogens of the prepared ligands. The magnetic moment values helped to investigate the geometry of the complexes. Thermogravimetric studies gave a general pattern for the main stages of the thermal decomposition with kinetic data to evaluate thermodynamic parameters ΔH* and ΔG* for each step of degradation to compare between stability of those complexes. Also pH-metric measurements were used to evaluate the proton–ligand formation constants and the stability constants of metal complexes at 298°K. Floatation procedure was carried out to investigate the optimum conditions for Cu(II) separation by ligand molecules.

Semi- and thiosemicarbazide Mn(II) complexes: Characterization, DFT and biological studies

One NO and two NOS donor ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Mn (II) complexes were prepared from the chloride salt and characterized by conventional techniques. The isolated complexes were assigned the formulaes, [Mn(HPAPS)2], [Mn(HPAPT)Cl] and [Mn(HPABT)Cl(H2O)2], respectively. The IR study of ligands and their complexes shows that H2PAPS behaves as a mononegative tridentate via both CO of hydrazide moiety in keto and deprotonated enol form and CN (azomethine) due to enolization of CO cyanate moiety without deprotonation. H2PAPT behaves as mononegative tridentate via CO of hydrazide moiety, deprotonated thiol CS and NH group. Finally H2PABT behaves as mononegative tridentate via deprotonated enolized CO of hydrazide moiety, CO of benzoyl moiety and NH group. The IR spectra of ligands from DFT calculations are compared with those obtained experimentally. Also, HOMO, LUMO, the bond lengths, bond angles, and dipole moments have been calculated. The calculated HOMO–LUMO energy gap reveals that charge transfer occurs within the molecule. The binding energy values display the high stability of complexes. The kinetic and thermodynamic parameters were determined by Coats–Redfern and Horowitz–Metzger methods. The antibacterial activities were also tested against Bacillus subtilis and Escherichia coli bacteria. Finally, the antitumor activities of the Ligands and their Mn(II) complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells.

Supramolecular nickel complex based on thiosemicarbazone. Synthesis, transfer hydrogenation and unexpected thermal behavior

The cationic thiosemicarbazone complex of nickel containing triphenylphosphine as coligand was synthesized through the isopropanol-assisted hydrogen transfer reaction. The thiosemicarbazone ligand (LH2) and its cationic nickel complex, [Ni(LH)(PPh3)]+Cl−·(CH3)2CHOH, were characterized by elemental analysis, IR, 1H NMR and UV–Vis spectroscopies. The molecular structure of the complex was also determined by single crystal X-ray diffraction technique. In addition computational studies at B3LYP/6-311G(d,p) (main group) and LANL2DZ (Ni) level were carried out for theoretical characterization of the ligand and complex. Structural analysis of the complex indicated the presence of square-planar coordination geometry (ONNP) about nickel in which the thiosemicarbazone ligand coordinated as mononegative tridentate. Isopropyl alcohol catalyzed efficiently the transfer hydrogenation and the cationic complex formed through inter conversion azinyl–azinylidene. All spectral data support the formation of the ligand and its nickel complex and the results calculated using theoretical methods coincide well with the experimental findings. The thermal degradation of the complex was investigated using thermogravimetric and differential thermal analyses techniques in nitrogen and oxygen atmosphere. The oxidative-thermal decomposition of the compound showed volatilization of nickel as unexpected behavior unlike nitrogen atmosphere.