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The interaction of dibutyltin(IV) dichloride (DBT) with 1,4-diazacycloheptane (homopiperazine, HP) was investigated. In solutions, the complexes formed a 1:1 complex, its protonated and hydrolyzed forms. The formation constants of the complexes and thermodynamic parameters as ΔH° and ΔS° were estimated. The optimization of the structure of the (Bu)2Sn(HP)Cl2 complex reveals that the tin is six-coordinate in a distorted octahedral geometry, where the two nitrogen atoms of homopiperazine and the two chloride ions are in one plane. The solid (Bu)2Sn(HP)Cl2 complex with homopiperazine was synthesized, and the composition was assigned by elemental micro-analysis and mass spectrum. The complex was investigated by infrared, mass spectra, and thermal measurements. The ligand and its complex were tested against antimicrobial Staphylococcus aureus (+ve), Escherichia coli (−ve), and antifungal Candida albicans and Aspergillus flavus. Anticancer activities of homopiperazine and its dibutyltin(IV) complex were tested against breast cancer cell lines. The molecular docking investigations were performed to know the possible modes of binding to the most active sites of the breast cancer oxidoreductase receptor and those of Escherichia coli. [ABSTRACT FROM AUTHOR]

The newly synthesized Schiff base‐oxime ligand, namely, (2Z,3E)‐3‐((3‐(4‐(3‐(((2E,3E)‐3‐(hydroxyimino)butan‐2‐ylidene)amino)propyl)piperazin‐1‐yl)propyl)imino)butan‐2‐one oxime (H2L) and its Co (II), Cu (II), and Zn (II) complexes were reported. The characterization was accomplished with the aid of CHN‐EA, mass, fourier transform infrared spectroscopy (FT‐IR), electronic spectra, magnetic moment, molar conductance and TGA. According to the spectroscopic approaches, the synthesized ligand (H2L) may act as a tetradentate or hexadentate (bis‐tridentate) coordinating ligand through the azomethine nitrogen, piperazinyl nitrogens, and oximato‐nitrogens affording distorted square planar mononuclear Co (II) complex or tetrahedrally distorted square planar binuclear Cu (II) and Zn (II) complexes whereas the coordination mode varies according to the nature of the metal ion. The microbial resistance of all the synthesized compounds was evaluated and reported. Findings showed that the Cu (II) complex has mostly the highest inhibitory effects against all tested microbial strains. Besides, the anticancer nature of the studied compounds was also evaluated against a panel of three different human cancer cells, including (HCT‐116), (MDA‐MB‐231), (HepG2) in addition to the (WI‐38) used as a healthy cells. In general, the Cu (II) complex displayed the best cytotoxic profiles against the tested cells than the Co (II) and Zn (II) complexes with negligible toxicity towards the (WI‐38) normal cells. The DNA cleavage activities of all tested compounds were assayed against pBR322 plasmid DNA. Whereas, the Cu (II) complex showed the highest DNA cleavage propensity, which proceeds predominantly via the oxidative mechanism. Additionally, flow cytometric analysis dictates that the Cu (II) complex induces cell cycle arrest in S‐phase and apoptotic cell death on HCT‐116 cells. The morphological transformations distinguished in HCT‐116 cells treated with Cu (II) complex have been depicted with the aid of scanning electron microscopy (SEM). The docking results indicate that the Cu (II) complex strongly interacts with human colon cancer (6GUE), Escherichia coli (3T88), Klebsiella pneumoniae (4HL2), and Staphylococcus aureus (3WQU) proteins, through different modes of interactions that harmonize successfully with the experimental results. [ABSTRACT FROM AUTHOR]

The dimethyltin(IV) complex with 1,4‐dizacycloheptane (homopiperazine) was synthesized. The complex is of 1:1 stoichiometry. The complex was characterized by elemental analysis, spectroscopic techniques as infrared (IR) and nuclear magnetic resonance (NMR), and thermal measurements. Homopiperazine coordinates to dimethyltin(IV) by the two nitrogen atoms. The complex decomposes in two steps. The kinetic parameters of thermal decomposition process have been calculated using Coats–Redfern and Horowitz–Metzger methods. The high values of the energy of activation of the complexes reveal the high stability of the complex due to their covalent bond character. The two decomposition steps are endothermic. Density Functional Theory (DFT) calculations have been carried out to investigate the equilibrium geometry of homopiperazine and its complex. The calculated total energies, energies of highest occupied molecular orbital (HOMO), energies of lowest unoccupied molecular orbital (LUMO), and dipole moments are reported. Antibacterial, antifungal, and anticancer activities of homopiperazine and its dimethyltin(IV) complex were tested. The molecular docking studies were performed to find the possible binding modes to the most active sites of the receptor of breast cancer oxidoreductase and those of Escherichia coli. [ABSTRACT FROM AUTHOR]

The reaction of dimethyltin(IV) dichloride (DMT) with homopiperazine (HPIP) was studied. The equilibria of the complexes formed in solution were investigated. The complexes detected are of 1:1 stoichiometry in addition to the protonated and hydrolysed species. The complex formation constants were determined by the use of potentiometric technique and the non-linear computer program Miniquad-75. The dielectric constant effect of the reaction medium on the formation of the complexes was investigated. Formation constants of the complexes were determined at different temperatures and the thermodynamic parameters as ΔH° and ΔS° were estimated and discussed. The ternary complexes of dimethyltin(IV) with HPIP and DNA constituents are formed by a simultaneous mechanism. Their formation constants were determined. The speciation diagrams of the binary and mixed-ligand complexes were evaluated. [ABSTRACT FROM AUTHOR]

Pd(BHEP)Cl2was synthesized and characterized (BHEP = 1,4-bis(2-hydroxyethyl)piperazine). The complex decomposes in two steps, leaving a residue of palladium metal. Amino acid ester (L) reacts with [Pd(BHEP)(H2O)2]2+(BHEP = 1,4-bis(2-hydroxyethyl)piperazine), giving mixed-ligand complexes, [Pd(BHEP)L]2+. The kinetics of hydrolysis of [Pd(BHEP)L]2+have been studied by pH-stat technique, and rate constants were obtained. Rate acceleration observed for glycine methyl ester is high. The effect with methionine methyl ester is much less marked, as the mixed-ligand complexes with these ligands do not involve alkoxycarbonyl donors. Possible mechanisms for these reactions are considered. The thermal stability of Pd(BHEP)Cl2complex was investigated. The role of the complex in the catalysis of amino acid esters was studied. [ABSTRACT FROM AUTHOR]

The interaction of dimethyltin(IV) dichloride (DMT) with 1,4-piperazine (PIP) was investigated. The complex formation equilibria of the complexes formed in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures and in solutions of dioxane–water mixtures of different dielectric constants. The equilibrium constant for the displacement of piperazine coordinated to dimethyltin(IV) by inosine as a representative of DNA was calculated. (DMT)(PIP)·3H2O was synthesized and characterized by elemental analysis, spectral, and thermal techniques. The antitumor activity of the complex was screened. [ABSTRACT FROM PUBLISHER]

Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and itsmetal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1M NaNO3) using a potentiometric technique. The order of -ΔG0 and -ΔH0 was found to obey Co2+ < Ni2+ < Cu2+ > Zn2+, in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K. [ABSTRACT FROM AUTHOR]

Abstract: Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV–vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH2O, where M=Co(II), Ni(II) and Cu(II), L=BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen’s, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu2+, Co2+ and Ni2+ complexes were determined by potentiometric titration method in 50% DMSO–water solution at ionic strength of 0.1M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu2+, Ni2+ and Co2+ form 1:1 complexes. [Copyright &y& Elsevier]