Infrared,Raman, 1H NMR,TG, and SEM properties of the charge-transfer interactions between tris(hydroxymethyl)methane with the acceptors picric acid,chloranilic acid,and 1,3-dinitrobenzene

Intermolecular charge-transfer complexes (CT) between the tris(hydroxymethyl)methane (THM) as a donor and picric acid (PA), chloranilic acid (CLA) and 1,3-dinitrobenzene (DNB) as a π-acceptor have been structurally, thermally and morphologically studied in methanol at room temperature. Based on elemental analyses (CHN), the stoichiometry of the obtained CT complexes (THM: acceptor molar ratios) was determined to be 1 : 1 for all three complexes. The CT complexes have been characterized via elemental analyses (CHN), IR, Raman and 1H NMR spectroscopy in order to predict the position of the CT interaction between the donating and accepting sites. Thermal decomposition behavior of these complexes was also investigated, and their kinetic thermodynamic parameters were calculated with Coats-Redfern and Horowitz-Metzger methods. Finally, the microstructure properties of these complexes were observed using scanning electron microscope (SEM).     

Synthesis,characterization, EPR,electrochemical, and in situ spectroelectrochemical studies of salen-type oxovanadium(IV) and copper(II) complexes derived from 3,4-diaminobenzophenone

A new half unit and some new symmetrical or asymmetrical VO(IV) and Cu(II) complexes of tetradentate ONNO Schiff base ligands were synthesized. The probable structures of the complexes have been proposed on the basis of elemental analyses and spectral (IR, UV–Vis, electron paramagnetic resonance, ESI-MS) data. VO(IV) and Cu(II) complexes exhibit square pyramidal and square-planar geometries, respectively. The complexes are non-electrolytes in dimethylformamide (DMF) and dimethylsulfoxide. Electrochemical behaviors of the complexes were studied using cyclic voltammetry and square wave voltammetry. Half-wave potentials (E _1/2) are significantly influenced by the central metal and slightly influenced by the nature of substituents on salen. While VO(IV) complexes give VO^IV/VO^V redox couples and a ligand-based reduction process, Cu(II) complexes give only a ligand-based reduction. In situ spectroelectrochemical studies were employed to determine the spectra of electrogenerated species of the complexes and to assign the redox processes. The g-values were calculated for all these complexes in polycrystalline state at 298?K and in frozen DMF (113?K). The evaluated metal–ligand bonding parameters showed strong in-plane σ-bonding for some Cu(II) complexes.     

Synthesis,characterization, antifungal,antibacterial and DNA cleavage studies of some heterocyclic Schiff base metal complexes

Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from indole-3-carboxaldehyde and m-aminobenzoic acid were synthesized and characterized by elemental analysis, molar conductance, IR, UV–Vis, magnetic moment, powder XRD and SEM. The IR results demonstrate the bidentate binding mode of the ligand involving azomethine nitrogen and carboxylato oxygen atoms. The electronic spectral and magnetic moment results indicate that Co(II) and Ni(II) complexes have tetrahedral geometry, while Cu(II) complex is square planar. Powder XRD and SEM indicate the crystalline state and surface morphology studies of the complexes. The antimicrobial activity of the synthesized ligand and its complexes were screened by disc diffusion method. The results show that the metal complexes were found to be more active than the ligand. The nuclease activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence of H₂O₂. The Cu(II) complex showed increased nuclease activity in the presence of an oxidant when compared to the ligand and other complexes.     

Synthesis, characterization, and the photochromic, luminescence, metallogelation and liquid-crystalline properties of multifunctional platinum(II) bipyridine complexes

A series of multifunctional platinum(II) bipyridine complexes were designed, synthesized, and characterized by (1)H NMR, fast atom bombardment mass spectrometry (FAB-MS), and elemental analysis. Their electrochemical and photophysical properties were investigated. The photochromic properties of the spironaphthoxazine-containing complexes were also studied. Some of these complexes were shown to be capable of forming stable thermoreversible metallogels in organic solvents. In contrast to typical thermotropic organogels and metallogels, one of the complexes could form metallogels in dodecane and is very stable towards external stimuli. The photochromic activation parameters for the bleaching reaction of a representative spironaphthoxazine-containing complex in a dodecane gel were determined through kinetic studies at various temperatures. Lamellar liquid-crystalline behavior was also observed in one of the complexes, and the liquid-crystalline properties were studied by thermogravimetry analysis (TGA), polarized optical microscopy (POM), differential scanning calorimetry (DSC), variable-temperature X-ray diffraction (XRD), and variable-temperature infrared (IR) spectroscopy.     

Synthesis,Spectral Characterization,Antitumor, Antioxidant,and Antimicrobial Studies of New Potential ONS Schiff Base Complexes

Novel Co(II), Ni(II), Cu(II), and Zn(II) complexes derived from 2‐aminopyridine‐3‐thiol and 4‐oxo‐4H‐chromene‐3‐carbaldehyde were synthesized and characterized by spectroscopic (IR, ¹H NMR, UV–vis, ESR, and MS) and other analytical methods. Molar conductance data and magnetic susceptibility measurements provide evidence for the monomeric and monobasic nature of the complexes. The molar conductance measurement of the complexes in DMSO corresponds to their non‐electrolytic nature. All the complexes are of high‐spin type. On the basis of the different spectral studies, the six‐coordinated geometry may be assigned for all the complexes. IR spectral studies indicate the binding sites of the ligand with the metal ion. The Schiff base acts as tridentate ligand coordinated through deprotonated thiolic (SH) sulfur, azomethine (─CH═N─) nitrogen, and carbonyl (−C═O) oxygen atoms. The ligand field parameters were calculated for Co(II) and Ni(II) complexes and their values were found to be in the range reported for an octahedral structure. The data show that the complexes have an ML₂‐type composition. The activation thermodynamic parameters are calculated using the Coast–Redfern, Horowitz–Metzger (HM), Piloyan–Novikova (PN), and Broido equations. The X‐ray diffraction data suggest a triclinic system for all compounds. Different surface morphologies were identified from SEM micrographs. Human tumor cell lines A427 (lung cancer cell line), LCLC‐103H (large cell lung cancer), SISO (uterine adenocarcinoma), and 5637(human bladder carcinoma) grown in RPMI‐1640 medium were elevated. The biological screening data show that the complexes show growth inhibitory activity against various microorganisms. The octahedral geometry of the complexes is confirmed using density functional theory (DFT) from DMOL³ calculations, electronic and magnetic moment measurements, ESR, and ligand field parameters.     

Metal complexes of porphycene,corrphycene, and hemiporphycene: stability and coordination chemistry

Porphyrin (P), porphycene (Pc), corrphycene (Cn), and hemiporphycene (Hpc) represent a series of well defined "4-N in" constitutional porphyrin isomers. These isomers, in the form of their octaethyl derivatives, represent a congruent set of porphyrinoids whose properties can be compared. In this study we report how variations in electronic structure and nitrogen-core size in the free-base forms of these four systems are reflected in the properties of their corresponding metal complexes. Specifically, the effects that these differences have on the axial ligation properties of the Zn(II), Mg(II), Ni(II), and Co(II) complexes of P, Pc, Cn, and Hpc in toluene using pyridine as the axial ligand are detailed. Also reported are the relative stabilities of these complexes under acidic conditions. It is shown that for the zinc, magnesium, and cobalt complexes, there are distinct differences in the ability to maintain four-, five-, or six-coordinate geometries in the presence of similar concentrations of pyridine. By contrast, no apparent differences in axial ligand binding affinity are seen for the four nickel complexes. Little difference in stability was likewise seen when these same complexes were subject to acid-mediated demetallation, with all four falling into stability class II, according to the accepted porphyrin stability ranking system. High stabilities were also seen in the case of the cobalt complexes, with the Pc and Cn complexes being of stability class III and the P and Hpc derivatives falling into stability class II. The Zn(II) and Mg(II) complexes were all far less stable than the corresponding Ni(II) and Co(II) complexes. In this case, semiquantitative analyses of the rate of acid-induced decomposition revealed the following stability sequence P>Cn>Hpc>Pc for both the Zn(II) and Mg(II) complexes. Single-crystal X-ray diffraction structures were solved for the Zn(II), Mg(II), and Ni(II) complexes of the octaethyl derivatives of Hpc, Cn, and Pc as well as a Co(II) octamethylcorrphycene and are reported as part of this study. These solid-state structures confirm four-coordinate species for the Ni(II) complexes, four- and five-coordinate species for the Mg(II) and Zn(II) complexes, and a six-coordinate species for the lone Co(II) complex.     

Synthesis,characterization, antibacterial studies and quantum-chemical investigation of the new fluorescent Cr(III) complexes

Coordination of the ligands derived from benzimidazole with Cr(III) led to the formation of new fluorescent Cr (III) complexes. The structures of the new complexes were established by spectral, analytical data and Job’s method and an octahedral geometry was proposed for the complexes. Also, the DFT methods were employed to gain a deeper insight into geometry and spectral properties of the new Cr (III) complexes. The DFT-calculated vibrational modes of Cr(III) complexes are in good agreement with the experimental values, confirming suitability of the optimized geometries for the complexes. Fluorescent ligands and chromium complexes were spectrally characterized by UV–Vis and fluorescence spectroscopy. Results revealed that Cr(III) complexes generate fluorescence in dilute solution of DMSO. Calculated electronic absorption spectra were also provided by time-dependent density functional theory (TD-DFT) method. The new complexes exhibited potent antibacterial activity against a panel of strains of Gram negative bacterial and Gram positive species and their MIC was also determined. Two strains of Gram positive and two strains of Gram negative bacteria.     

Synthesis,crystal structure,spectroscopic, and biological studies on Cu(II) complexes of N,O donor dimethyl isoxazole Schiff bases

Cu(II) complexes with Schiff bases DMIIMP, DMIIMBD, DMIIMBP, DMIIMCP, DMIIMMP, and DMIIMNP (see Introduction for definitions) are derived from condensation of 3,4-dimethyl 5-amino-isoxazole with salicylaldehyde and substituted salicylaldehydes. The newly synthesized ligands were characterized by IR, UV-Vis, ¹H NMR, ¹³C NMR, mass spectra, and elemental analysis. The Cu(II) complexes were characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, thermogram, DTA, and single crystal analysis. The complexes have general formula [M(L)₂]. The Schiff bases are bidentate coordinating through the azomethine nitrogen and phenolic oxygen of salicylaldehydes. Based on the analytical and spectral data, four-coordinate geometry is assigned for all the complexes. ESR and single crystal analysis suggests square planar geometry for all complexes. [Cu(DMIIMP)₂] crystallizes in the orthorhombic system. Antimicrobial studies of Schiff bases and their metal complexes show significant activity with the metal complexes showing more activity than corresponding Schiff bases. Cytotoxicity of the copper complexes on human cervical carcinoma cells (HeLa) was measured using the Methyl Thiazole Tetrazolium assay.     

Synthesis,characterization, and catalytic ethylene oligomerization of pyridine-imine palladium complexes

Two neutral five-membered pyridine-imine palladium complexes with the bulky dibenzhydryl (CH(Ph)2) substituted aniline were synthesized and fully characterized by nuclear magnetic resonance (NMR) and X-ray crystal diffraction.Well-defined cationic palladium complexes were further obtained by treatment of chloromethylpalladium complexes with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF) in CH3CN.Cationic palladium complexes were capable of catalyzing ethylene oligomerization without any cocatalysts.The influences of catalyst structure,reaction temperature,and ethylene pressure on ethylene oligomerization were studied in detail.The introduction of bulky benzhydryl (CH(Ph)2) on the ortho position of the aniline moiety enhanced catalytic activity,thermal stability of the catalyst,and molecular weight of the obtained products.Highly branched oligomers with molecular weights of 600-800 g/mol and narrow polydispersities (1.03-1.12) were produced.     

Synthesis,characterization, thermal,and redox properties of a vic-dioxime and its metal complexes

A new vic-dioxime ligand containing benzophenone hydrazone units, N′-(benzophenone hydrazone)glyoxime [LH₂] has been prepared from benzophenone hydrazone and anti-chloroglyoxime in absolute ethanol. Mononuclear nickel(II), cobalt(II), copper(II), zinc(II), and cadmium(II) complexes were also synthesized. Ligand and complexes were characterized by elemental analyses, FT-IR, ¹H NMR, and ¹³C NMR spectroscopy, magnetic moments, and DTA/TG techniques. On the basis of the magnetic and spectral evidences a square-planar geometry for Ni(II) and Cu(II) complexes, tetrahedral for Cd(II) and Zn(II) complexes, and octahedral for Co(II) complex were proposed. Redox behaviors of ligand and its complexes were also investigated by cyclic voltammetry at the glassy carbon electrode.     

Elaborated spectral,modeling, QSAR,docking, thermal,antimicrobial and anticancer activity studies for new nanosized metal ion complexes derived from sulfamerazine azodye

New azodye ligand (H₂L) and its relative Cr(III)-, Mn(II)-, Fe(III)-, Co(II)-, Ni(II)-, Cu(II)-, Zn(II)- and Cd(II)-nanosized complexes were prepared. A new synthesized compounds were characterized using spectral (mass, IR, UV–Vis, XRD, and ESR) and analytical (elemental, molar conductance, thermal and magnetic moment measurements) tools. Infrared spectra showed that the ligand behaves as a monobasic bidentate, coordinating with central atoms through carbonyl oxygen and α-hydroxyl group. The geometrical structures of Cr(III) and Fe(III) complexes were found to be in octahedral configuration, whereas Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes have tetrahedral forms. XRD patterns reflect an amorphous appearance of all investigated complexes. TEM images showed nanosized particles and identical distribution over the complex surface. Molecular modeling for the drug ligand and its metal ion complexes were performed using Gaussian09 program to assert on their structural formulae. Some essential parameters were extracted using HOMO and LUMO energies. AutoDock tools 4.2 was used to simulate the interaction process with infected cell proteins to expect the experimental pathway. The inhibition activity of drug ligand and its metal ion complexes was evaluated towards different types of bacteria and fungi through in vitro antimicrobial activities. The antitumor activities of all compounds are straightened towards human liver carcinoma (HEPG2) cell lines. Fe(III) and Co(II) complexes exhibited IC₅₀ of 2.90 and 4.23 µg mL^?1, respectively, which means they are more potent anticancer drug than the standard (doxorubicin, IC₅₀ = 4.73 µg mL^?1). Therefore, the two complexes may consider promising anticancer drugs.

     

EPR, mass, IR, electronic, and magnetic studies on copper(II) complexes of semicarbazones and thiosemicarbazones

Copper(II) complexes having the general composition Cu(L)(2)X(2) [where L = isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC), and 4-aminoacetophenone thiosemicarbazone (LLD) and X = Cl(-), 1/2SO(4)(2-)] have been synthesized. All the Cu(II) complexes reported here have been characterized by elemental analyses, molar conductance, magnetic moment susceptibility, EI mass, (1)H NMR, IR, EPR, and electronic spectral studies. All the complexes were found to have magnetic moments corresponding to one unpaired electrons. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies.     

Ligational behavior of a bidentate coumarin derivative towards CoII,NiII, and CuII: synthesis,characterization, electrochemistry,and antimicrobial studies

A series of new Co(II), Ni(II), and Cu(II) complexes of Schiff base derived from coumarin have been prepared and characterized by analytical and spectral methods. The Schiff base is synthesized by the condensation of 2,6-diaminopyridine and 3-acetylcoumarin in 1 : 1 stoichiometric ratio. All complexes have 1 : 1 metal : ligand ratio except the nickel complex, where it was found to be 1 : 2. UV-Vis spectra and magnetic moment studies confirm the existence of tetrahedral and octahedral geometries around cobalt(II) and nickel(II) metal ions, respectively, but copper(II) chloride/nitrate/sulfate complexes have square-planar geometry and copper(II) acetate complex is distorted octahedral. ESR spectra of copper complexes at room temperature and liquid nitrogen temperature were tetragonal. All the complexes were found to be more active against bacteria except Ni(II) complex; only CuLSO₄ and CuL(CH₃COO)₂ have shown the enhanced activity against fungi.     

Raman spectroscopic studies on tropolone complexes with La, Nd, Sm, Yb

The complexes of tropolone (HL) with different lanthanide metals of lanthanum (La), neodymium (Nd), samarium (Sm), ytterbium (Yb) have been prepared respectively in the non-aqueous solution by the direct electrochemical oxidation of sacrificial metal anodes, and characterized by normal Raman spectroscopy. By comparing the spectra of the ligands and their complexes, the stretching vibrational band of OH disappeared in complexes, and the frequencies shifts of some relevant bands were observed, particularly for the stretching vibration of CO. In the low frequency region, new metal ion sensitive bands at 400-700 cm(-1) were observed, which could be assigned to the stretching vibrational mode of the bonding of lanthanide with oxygen. The stretching vibration of lanthanide-oxygen of tropolonate complexes showed a metal ion sensitivity. All the obvious change in spectral feature of Raman spectra revealed that CO and OH were coordinated with the center metal ions through oxygen atoms. Based on Raman results, the structures of the above complexes were proposed.     

Dioxo- and oxovanadium(V) complexes of thiohydrazone ONS donor ligands: synthesis, characterization, reactivity, and antiamoebic activity

As a contribution to the development of novel vanadium complexes with pharmacologically interesting properties, two neutral dioxovanadium(V) complexes [VO2(Hpydx-sbdt)] (1) and [VO2(Hpydx-smdt)] (3) [H2pydx-sbdt (I) and H2pydx-smdt (II) are the Schiff bases derived from pyridoxal and S-benzyl- or S-methyldithiocarbazate] have been synthesized by the reaction of [VO(acac)2] and the potassium salts of the ligands in methanol followed by aerial oxidation. Heating of the methanolic solutions of these complexes yields the oxo-bridged binuclear complexes [{VO(pydx-sbdt)}2mu-O] (2) and [{VO(pydx-smdt)}2mu-O] (4). The crystals and molecular structures of 1, 3 x 1.5H2O, and 4 x 2CH3OH have been determined, confirming the ONS binding mode of the dianionic ligands in their thioenolate form. The ring nitrogen of the pyridoxal moiety is protonated in complexes 1 and 3. Acidification of 1 and 3 with HCl dissolved in methanol afforded oxohydroxo complexes, while in a methanolic KOH solution, the corresponding dioxo species K[VO2(pydx-sbdt/smdt)] are formed. Treatment of 1 and 3 with H2O2 yields (unstable) oxoperoxovanadium(V) complexes, the formation of which has been established spectrophotometrically. In vitro antiamoebic activities (against HM1:1MSS strain of Entamoeba histolytica) were established for all of the dioxo- and oxovanadium(V) complexes. The complexes 1, 2, and 4 were more effective than metronidazole, a commonly used drug against amoebiasis, suggesting that oxovanadium(V) complexes derived from thiohydrazones may open a new dimension in the therapy of amoebiasis.     

Luminescence of LnIII dithiocarbamate complexes (Ln = La, Pr, Sm, Eu, Gd, Tb, Dy)

We have discovered room temperature photoluminescence in Sm3+ and Pr3+ dithiocarbamate complexes. Surprisingly, these complexes exhibit more intense emission than those of the Eu3+, Tb3+, and Dy3+ analogues. The electronic absorption, excitation, and emission spectra are reported for the complexes [Ln(S2CNR2)3L] and NH2Et2[Ln(S2CNEt2)4], where Ln = Sm, Pr; R = ethyl, ibutyl, benzyl; and L = 1,10-phenanthroline, 2,2'-bipyridine, and 5-chloro-1,10-phenanthroline. The lowest ligand-localized triplet energy level (T1) of the complexes are determined from the phosphorescence spectra of analogous La3+ and Gd3+ chelates. The luminescence decay curves were measured to determine the excited-state lifetimes for the Pr3+ and Sm3+ complexes. X-ray crystal structures of Sm(S2CNiBu2)3phen, Pr(S2CNEt2)3phen, and Pr(S2CNiBu2)3phen are also reported.     

Synthesis, characterization, redox property and biological activity of Ru(II) carbonyl complexes containing O,N-donor ligands and heterocyclic bases

Stable ruthenium(II) carbonyl complexes having the general composition [RuCl(CO)(PPh3)(B)(L)] (where B=PPh3, pyridine, piperidine or morpholine; L=anion of bidentate Schiff bases (Vanmet, Vanampy, Vanchx)) were synthesized from the reaction of [RuHCl(CO)(PPh3)2(B)] with bidentate Schiff base ligands derived from condensation of o-vanillin with primary amines such as methylamine, 2-aminopyridine and cyclohexylamine. The new complexes were characterized by elemental analysis, IR, UV-Vis and 1H NMR spectral data. The redox property of the complexes were studied by cyclic voltammetric technique and the stability of the complexes towards oxidation were related to the electron releasing or electron withdrawing ability of the substituent in the phenyl ring of o-vanillin. An octahedral geometry has been assigned for all the complexes. In all the above reactions, the Schiff bases replace one molecule of PPh3 and hydride ion from the starting complexes, which indicate that the Ru-N bonds present in the complexes containing heterocyclic nitrogen bases are stronger than the Ru-P. The Schiff bases and their ruthenium(II) complexes have been tested in vitro to evaluate their activity against bacteria, viz., Staphylococcus aureus (209p) and E. coli (ESS 2231).     

Synthesis,characterization, equilibrium studies,and biological activity of complexes involving copper(II), 2-aminomethylthiophenyl-4-bromosalicylaldehyde Schiff base,and selected amino acids

Ternary complexes of copper(II) with 2-aminomethylthiophenyl-4-bromosalicylaldehyde (ATS) and some amino acids have been isolated and characterized by elemental analyses, IR, magnetic moment, molar conductance, UV–vis, mass spectra, and ESR. The proposed general formulas of the prepared complexes are [Cu(ATS)(AA)]·nH₂O (where AA?=?glycine, alanine, and valine). The low molar conductance values suggest the non-electrolytic nature of the complexes. IR spectra show that ATS is coordinated to copper in a bidentate manner through azomethine-N and phenolic-OH. The amino acids also are monobasic bidentate ligands via amino and ionized carboxylate groups. The magnetic and spectral data indicate the square-planar geometry of Cu(II) complexes. The geometry of the Cu(II) complexes has been fully optimized using parameterized PM3 semiempirical method. The Cu–N bond length is longer than that of Cu–O in the isolated complexes. Also, information is obtained from calculations of molecular parameters for all complexes including net dipole moment of the metal complexes, values of binding energy, and lipophilicity value (log P). The antimicrobial activity studies indicate significant inhibitory activity of complex 3 against the selected types of bacteria. The mixed ligand complexes have also been studied in solution state. Protonation constants of ATS and amino acids were determined by potentiometric titration in 50% (v/v) DMSO–water solution at ionic strength of 0.1?M NaCl. ATS has two protonation constants. The binary and ternary complexes of copper(II) involving ATS and some selected amino acids (glycine, alanine, and valine) were examined. Copper(II) forms [Cu(ATS)], [Cu(ATS)₂], [Cu(AA)], [Cu(AA)₂], and [Cu(ATS)(AA)] complexes. The ternary complexes are formed in a simultaneous mechanism.     

Synthesis, structure, theoretical studies, and Ligand exchange reactions of monomeric, T-shaped arylpalladium(II) halide complexes with an additional, weak agostic interaction

A series of monomeric arylpalladium(II) complexes LPd(Ph)X (L = 1-AdPtBu2, PtBu3, or Ph5FcPtBu2 (Q-phos); X = Br, I, OTf) containing a single phosphine ligand have been prepared. Oxidative addition of aryl bromide or aryl iodide to bis-ligated palladium(0) complexes of bulky, trialkylphosphines or to Pd(dba)2 (dba = dibenzylidene acetone) in the presence of 1 equiv of phosphine produced the corresponding arylpalladium(II) complexes in good yields. In contrast, oxidative addition of phenyl chloride to the bis-ligated palladium(0) complexes did not produce arylpalladium(II) complexes. The oxidative addition of phenyl triflate to PdL2 (L = 1-AdPtBu2, PtBu3, or Q-phos) also did not form arylpalladium(II) complexes. The reaction of silver triflate with (1-AdPtBu2)Pd(Ph)Br furnished the corresponding arylpalladium(II) triflate in good yield. The oxidative addition of phenyl bromide and iodide to Pd(Q-phos)2 was faster than oxidative addition to Pd(1-AdPtBu2)2 or Pd(PtBu3)2. Several of the arylpalladium complexes were characterized by X-ray diffraction. All of the arylpalladium(II) complexes are T-shaped monomers. The phenyl ligand, which has the largest trans influence, is located trans to the open coordination site. The complexes appear to be stabilized by a weak agostic interaction of the metal with a ligand C-H bond positioned at the fourth-coordination site of the palladium center. The strength of the Pd.H bond, as assessed by tools of density functional theory, depended upon the donating properties of the ancillary ligands on palladium.     

Novel metal complexes of 3-acetylcoumarin-2-hydrazinobenzothiazole Schiff base: Design,structural characterizations,DNA binding,DFT calculations,molecular docking and biological studies

Five new Cu (II), Zn (II), Pd (II), Ru (III) and Ag(I) complexes, derived from the 3-acetylcoumarin-2-hydrazinobenzothiazole Schiff base (Hachbt), have been synthesized and characterized. The structures were established with the aid of elemental analyses (C, H, N), FT-IR, ¹H-NMR, ESR, UV–visible and ESI-mass spectra. The complexes were also investigated by magnetic susceptibility, thermal gravimetric analysis (TG-DTA) and cyclic voltammetry measurements. The results suggest that the Schiff base ligand behaves in two different ways: neutral mono/bidentate or mono-negative bi/tridentate. The calf thymus DNA (CT DNA) binding affinities of Hachbt and its complexes have been examined by UV–visible spectroscopy. The antifungal activity of the compounds was also screened against two fungal species of wood-decay basidiomycetes using the agar dilution method. Different complexes caused a reduction in the fungal colony diameters at a media concentration of 100 μg/ml. The best antifungal activity was observed for the Pd (II) and Ag(I) complexes with a 60% and 79% reduction, respectively. The effect of the complexes on the ability of the same fungi to decolorize poly-R dye on agar plates was also tested. All of the complexes showed an enhanced effect on the decolorization ability and the Cu (II) and Ru (III) complexes exhibited the strongest effect at a media concentration of 5 μg/ml. Theoretical studies were performed for all the complexes using the DFT/B3LYP/6–31 + g(d) basis set for calculations on the ligand atoms and LAN2DZ for the Pd (II) complex. The optimized geometries were found to be in a good agreement with the proposed structures. The molecular docking calculations show that the binding affinity of the Pd (II) complex is −309.170-309.2 kcal/mol, which suggests complexation with the DNA minor groove.