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The [Pd(AEMP)Cl2] complex [AEMP = 2-(2-aminoethyl)-1-methylpyrrolidine] was prepared and characterized by single-crystal X-ray diffraction and spectroscopic analyses. The structure of the complex was found to be square-planar with some distortion. The geometric optimizations of the ligand and complex were performed with the DFT/B3LYP method by using Gaussian 09. The stoichiometry and stability constants of the complexes formed in the reaction of [Pd(AEMP)(H2O)2]2+ with dicarboxylic acids and DNA constituents were investigated at 0.1 m ionic strength and 25 °C. The results show that both DNA constituents and cyclobutanedicarboxylate (CBDCA) coordinate to [Pd(AEMP)(H2O)2]2+ to form the quaternary complex [Pd(AEMP)(CBDCA-O)DNA], where CBDCA-O represents cyclobutanedicarboxylate coordinated through one carboxylate oxygen atom to the PdII center. The speciation concentration distributions in solution were evaluated. The biological activity for DNA cleavage and cytotoxicity of the [Pd(AEMP)Cl2] complex was studied. [ABSTRACT FROM AUTHOR]

Amino acid esters (L) react with [Pd(Eten)(H 2 O) 2 ] 2+ (Eten = N -ethyl ethylenediamine) giving mixed ligand complexes of the type [Pd(Eten)L] 2+ . Base hydrolysis of [Pd(Eten)L] 2+ was studied by pH-stat technique from which rate constants for the base hydrolysis of the esters were obtained. The glycine methyl ester hydrolysed significantly, whereas the methionine methyl and histidine methyl esters hydrolysed much slower. The mode of coordination of the ester plays a role in the catalysis, and possible mechanisms for these reactions are considered. Activation parameters were determined for the hydrolysis of the glycine methyl ester. The effect of the dielectric constant of the medium on the hydrolysis process was also investigated. The B3LYP/LANL2DZ method was used for geometric optimization of the free ligand and the complex using the Gaussian 09 program. The calculations are compared with the kinetic data. In addition, the vibrational frequencies of the molecules were computed for the optimized geometries. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Cu(II) complex involving bio-relevant ligands was investigated. [•] The manuscript is in the domain of SAA as it deals with spectral and potentiometric study. [•] The activation of amino acid ester hydrolysis was studied. [•] The results is expected to contribute to the chemistry of plant hormone. [Copyright &y& Elsevier]

Abstract: In the present study, a new hydrazone ligand (2-((2-phthalazin-1-yl)hydrazono)methyl)phenol) prepared by condensation of hydralazine (1-Hydralazinophthalazine) with salicylaldehyde (SAH). The synthesized SAH-hydrazone and its metal complexes have been characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV–vis and thermal analysis (TGA). The analytical data of the complexes show the formation of 1:1 [M:L] ratio, where M represents Ni(II), Co(II) and Cu(II) ions, while L represents the deprotonated hydrazone ligand. IR spectra show that SAH is coordinated to the metal ions in a tridentate manner through phthalazine-N, azomethine-N and phenolic-oxygen groups. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. Proton-ligand association constants of (SAH) and the stepwise stability constants of its metal complexes are determined potentiometrically in 0.1M NaNO3 at different temperatures and the corresponding thermodynamic parameters were derived and discussed. The order of −ΔG° and −ΔH° were found to obey Mn2+

Abstract: The synthesis and X-ray structural characterization of Pd(DMPA)Cl2 complex, where DMPA= N,N-dimethylaminopropylamine, is reported. The complex crystallizes in the space group P21/c, a =8.8923(4), b =10.9050(5), c =11.5006(7) Å, β =120.00(18)°, V =948.25(8) Å3, Z =4. The palladium centre has a typical square-planar geometry with a tetrahedral distortion. Stoichiometry and stability constants of the complexes formed between [Pd(DMPA)(H2O)2]2+ and some selected DNA constituents and cytsteine are investigated at 25°C and at constant 0.1M ionic strength. The concentration distribution diagrams of the various species formed are evaluated. The equilibrium constants for the displacement of coordinated ligands as inosine by cysteine are calculated. The results are expected to contribute to the chemistry of tumour therapy. [Copyright &y& Elsevier]

Abstract: Pd(dmen)Cl2 complex was synthesized and characterized, where dmen=N,N-dimethylethylenediamine. Stoichiometry and stability constants of the complexes formed between [Pd(dmen)(H2O)2]2+ and various biologically relevant ligands such as amino acids, peptides and dicarboxylic acids are investigated at 25°C and at constant 0.1M ionic strength. The concentration distribution diagrams of the various species formed are evaluated. The equilibrium constants for the displacement of coordinated ligands as inosine, glycine or methionine by cysteine are calculated. The results are expected to contribute to the chemistry of tumour therapy. [Copyright &y& Elsevier]

Abstract: In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and 1H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. [Copyright &y& Elsevier]

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]

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]

Complex-formation equilibria involvingtrans-diamine palladium(II) (PdII), 4,4?-bipyridine (bpy), and inosine were investigated at 25?°C and 0.1?M (NaNO3) ionic strength. The stability constants of all possible mono-nuclear and binuclear complexes were determined. The concentration distribution diagram for the binuclear complexes of PdII-bpy-inosine reveals the complexes that predominate in the physiological pH range and the quite feasible interaction of the binuclear complex PdII-bpy-PdIIwith inosine as a DNA constituent. On the basis of DFT calculations (B3LYP/LANL2DZp), the structures of the investigated equilibrium species show typical bond lengths for Pd–O and Pd–N bonds. The C–C bond in [Pd(4,4?-bpy)(NH3)2(OH2)]2+is clearly shortened to 1.47?Å, leading to reduced aromaticity in bpy. Comparison with model compounds suggests that the uncoordinated aromatic ring can be understood as an electron donating group. [ABSTRACT FROM AUTHOR]