Properties Of Mixed-ligand Complexes Research Articles

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-leucine and 8-hydroxyquinoline) with Fe (III ),Cr (III) La(III)) and Ru(III ) ions

The research includes the synthesis and identification of the mixed ligands complexes of M+3 Ions in general composition ,[M(Leu)2(Q)]
 Where L-leucin (C6H13NO2)symbolized as( Leu H) as a primary ligand and
 8-hydroxyqinoline,(C9H7NO) symbolized as (8-HQ) as a secondary ligand .
 The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2)(metal): Q-:2Leu-] with M(III ) ions, were 
 M(III) = Fe (III ),Cr (III) La(III)) and Ru(III )
 The reaction gave solid crystalline complexes which have been characterized us the following techniques: Thermal stability, Solubility, Molar conductivity, Determination the percentage of the metal in the complexes by (AAS). Spectroscopic Methods [FT-IR and UV-Vis], and. The proposed structure of the complexes using program, chem. office 3D(2006) .], Biological effects for some complexes were investigated .
 Numerous papers have been published on metal complexation of amino acids and derivatives during the past ten years. Metal amino acid complexes have long been of interest as models for metal –Ligand systems and interaction which may occur in nature(1)Biological importance of several amino acids their complexes with transition metals is well documented(2-3)The amino acid L- leucin and various transition metals are important in the biological functions of humans, animals, and plants. L- leucine is one of the twenty major amino acids and is considered an essential amino acid (4)
 8-hydroxyqinoline or 8-qinolineis an organic compound with the formula C9H7NO2 is the name most commonly used ,while its trivial name is (oxine),which is conventionally used for the description of chelate compounds Oxinates ,as out of seven possible hydroxyqinoles, only 8-hydroxyqinoline forms chelate with metal ions . [5-6]
 Ruthenium polypyridyl and phenanthroline complexes have been extensively investigated because of their interesting photochemical[7],catalytic [8], biological [9] and electrochemical [10,11] properties.
 Lanthanide(III) carboxylates have been widely studied in recent years due to their physico-chemical properties, variety of structural types and potential uses as fluorescent sensors. The isomers of mono-,di- and trimethoxybenzoates of rare earth elements(III) have been examined. [12-13]
 A series of ruthenium metal complexes involving mono-sulfonylated non-innocent o-phenylenediamine ligands have been characterized in detail using NMR, MS, FT-IR, X-Ray, UV-vis and electrochemical studies. [14]
 In this paper we present the synthesis and study of Cr(III),Fe(III) La(III) and Ru(III) complexes with amino acid (L-leucin) as a primary ligand and 8-hydroxyqinoline as a secondary ligand have been used, respectively.

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-Leucine and 8-hydroxyquinoline) with some metals Ions

يتضمن البحث تحضير وتشخيص معقدات للايونات M+2 مختلطة الليكاند بالصيغة العامة : Na[M(Leu)2(Q)] باستعمال الحامض الاميني (الليوسين ) ليكانداً أولي والليكاند )8-هيدروكسي كوينولين) ليكانداً ثاني إذ ان الليوسين (C6H13NO2) بالرمز( (LeuH و8-هيدروكسي كوينولين (C9H7NO) بالرمز (8-HQ) وذلك بمفاعلة الليكاندان مع كلوريدات العناصر باستعمال الايثانول مذيباً وفي درجة حرارة المختبروبنسب مولية [(1:1:2) (metal) : Q- : 2Leu -] معM(II) إذ إن: P b(II)] و M(II) =[Mn(II), Fe(II),Co(II), Ni(II),Cu(II), Zn(II), Pd(II),Sn(II)

Structural aspects, spectroscopic and third order nonlinear optical properties of mixed ligand complexes from NNO tridentate Schiff base: Crystal structure of a rare proton bridged Ni(II) complex

Three novel mixed ligand complexes of cadmium(II), zinc(II) and nickel(II), derived from the parent Schiff base 4-chloro-2-((2-(dimethylamino)ethylimino)methyl)phenol, were synthesized and characterized by means of single crystal XRD, elemental analysis, IR, electronic and NMR spectral studies. In all the three complexes either reactant amine or aldehyde coordinates to the metal centers along with Schiff base and nickel(II) complex is having a rare proton bridged structure. While complex 1 crystallizes in orthorhombic Pbca space group, both complexes 2 and 3 crystallize in triclinic P1‾ space group. Different types of intermolecular interactions present in the crystal systems paved way to form 1D and 2D supramolecular assemblies and the visual analysis of those intermolecular interactions was achieved through Hirshfeld surface analysis. All the three complexes exhibited a negative solvatochromic behavior. Photoluminescent studies were carried out and quenching of fluorescence was observed in all complexes which is supported by the quantum yield values. Third order NLO properties were investigated by Z-scan technique with 75 fs laser pulse at 800 nm. NLO responses of the complexes were controlled by nonlinear refractive processes which make them suitable candidates for optical switching applications.

Syntheses, Structures, and Magnetic Properties of Mixed-ligand Complexes of Co(II) Based on N-Heterocyclic and Different Carboxylate Ligands

Two novel transition-metal coordination polymers with the formulas [Co(L1)(bbi)(H2O)]n (1) and {[Co(L2)(phen)]·H2O}n (2) (H2L1 = 1,4-naphthalenedi- carboxylic acid, H2L2 = 5-OH-1,3-benzenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole), phen = 1,10-phenanthroline) have been hydrothermally synthesized and characterized by techniques of single crystal X-ray diffraction, infrared spectra, elemental analysis, powder X-ray diffraction, and variable-temperature magnetic susceptibility measurements. X-ray crystal structure analyses reveal that complex 1 exhibits 2D framework with 4-connected sql topology and is further extended into a 3D supramolecular architecture via strong O–H···O and weak C–H···O hydrogen-bonding interactions, while complex 2 features a 1D ladder-like chain with a 3-connected (42·6) topological structure. Magnetic studies showed the presence of an antiferromagnetic interaction between adjacent Co(II) ions in both complexes. Two new mixed ligand complexes of cobalt based on N-heterocylic and carboxylate ligands were readily obtained and characterized. The topological structures, thermal stabilities and magnetic properties of which are observed and discussed.

Synthesis, characterization and biological properties of mixed ligand complexes of cobalt(II/III) valproate with 2,9‐dimethyl‐1,10‐phenanthroline and 1,10‐phenanthroline

The synthesis of mononuclear cobalt(II/III) complexes with two different ligands (complex 2: [Co(valp)2(2,9‐dmp)] and complex 3: [Co(valp)2(H2O)(1,10‐phen)]) was investigated and the characterization of both complexes was achieved using IR, UV–Vis, and single crystal X‐ray diffraction. Using single crystal X‐ray diffraction, the crystal structure of each of the complexes was determined. Additionally, the biological activity of these complexes was studied in five gram‐positive and four gram‐negative bacterial strains. Whereas in all gram‐negative bacteria tested, cobalt valproate complexes did not show any anti‐bacterial activity, both complexes had effects on gram positive bacteria. Complex 2 demonstrated good anti‐bacterial activity against all gram‐positive bacteria with inhibition zone diameter (IZD) ranging between 15–28 mm. Complex 3 exhibited low inhibition activity against all gram‐positive bacteria except E. faecalis with IZD ranging between 11.3–13.7 mm. Moreover, as an indication of its uses as industrial catalyst, the rate of bis(p‐nitrophenyl) phosphate (BNPP) hydrolysis when catalyzed by these complexes was measured at different temperatures, concentrations and pH. Complex 2 proved to be a better catalyst to induce the hydrolysis of BNPP.

Effect of the donor–acceptor properties of ligands on the spectroscopic and electrochemical properties of mixed-ligand complexes of Pt(II) and Ir(III) with cyclometalated 2-phenylbenzothiazole

The results of the spectroscopic NMR (1H, 13C, and 195Pt), infrared, optical, and voltammetric characteristics of the mixed-ligand complexes of Pt(II) and Ir(III) with metalated 2-phenylbenzothiazole and tert-butylisocyanide (tBuNC), acetonitrile (AN), ethylenediamine (En), O-ethyldithiocarbamate (Exn–), and diethyldithiocarbamate (Dtc–) ions are presented. It is demonstrated that the change in donor–acceptor interaction of ligands tBuNC, AN, En, Exn–, and Dtc– with metal leads to an increase in the energy of the highest occupied molecular orbital of the complexes and is accompanied by a shift of the cathode potential of the metal-centered oxidation, a bathochromic shift of the spin-allowed and spin-forbidden metal-tocyclometalated ligand optical charge transfer transitions, and an increase the degree of mixing of the 1MLCT and triplet intraligand states, responsible for the phosphorescence of the complexes.

Synthesis, crystal structure, spectroscopic and biological properties of mixed ligand complexes of cadmium(II), cobalt(II) and manganese(II) valproate with 1,10-phenanthroline and imidazole

Metal complexes of the type [Cd(valp)2(imidazole)2], 1, [Cd(valp)2(phen)H2O], 2 [Co(valp)2(imidazole)2], 3, [Co(valp)2(phen)H2O], 4 and [Mn(valp)2(phen)H2O], 5 (valp: sodium valproate, phen: 1,10-phenanthroline) have been synthesized and characterized. The geometry of the complexes 1–5 was established by single crystal X-ray diffraction. Evaluation of cytotoxic activity of the complexes 1–5 against HeLa, Hep-G2, A2780, LS-174, B16, MS1 and MRC-5 cell lines proved that complexes 1 and 3 exhibited cytotoxic specificity and a significant cancer cell inhibitory rate compared to complexes 2, 4 and 5. The complexes were also evaluated for their anti-bacterial activity using in vitro agar diffusion method. Two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and three Gram-negative (Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa) species of bacteria were used for testing anti-bacterial activities.

Synthesis, crystal structure, spectroscopic and biological properties of mixed ligand complexes of zinc(II) valproate with 1,10-phenanthroline and 2-aminomethylpyridine

Mononuclear zinc(II) complexes with mixed ligands formulating [Zn(valp)2(1,10-phen)H2O] (2), and [Zn(valp)(2-picam)2](valp) (3) (valp=valproate, phen=1,10-phenanthroline, 2-picam=2-aminomethylpyridine (2-picolylamine)) have been synthesized and characterized using IR, 1H NMR, 13C{1H} NMR and UV–Vis spectroscopic techniques, as well as single-crystal X-ray diffraction. Zn(II) cation in 2 exhibits a distorted octahedral environment resulting from one bidentate phen ligand, one valproate ligand with asymmetric chelating mode, and another one with monodentate mode and a molecule of water. Complex 3 has two bidentate 2-ampic ligands and two valproate ligands. Only one of the carboxylate ligands was bonded to Zn(II) in a monodentate mode. The second valproate ligand acted as a counter ion and was bonded to the NH2 groups of 2-picam through hydrogen bonding. The Zn(II) cation in 3 has a distorted trigonal bipyramidal arrangement. The complexes were also evaluated for their anti-bacterial activity using in vitro agar diffusion method. Three Gram-positive (Micrococcus luteus, Staphylococcus aureus, and Bacillus subtilis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis) species of bacteria were used for testing anti-bacterial activities. Complex 2 showed considerable activity against all tested microorganisms. The effect of complexation on the anti-bacterial activity of the parent ligand of 2 was also investigated. The anti-bacterial activity of 1,10-phen against both Gram-positive and Gram-negative bacteria was reduced upon complexation with zinc valproate. Complex 3 showed weak inhibition activity against S. aureus, B. subtilis, E. coli and K. pneumoniae.

Dicoumarol complexes of Cu(II) based on 1,10-phenanthroline: Synthesis, X-ray diffraction studies, thermal behavior and biological evaluation

A series of Cu(II) complexes containing dicoumarol derivatives and 1, 10-phenanthroline have been synthesized. Structural and spectroscopic properties of ligands were studied on the basis of mass spectra, NMR (1H and 13C) spectra, FT-IR spectrophotometry and elemental analysis, while physico-chemical, spectroscopic and thermal properties of mixed ligand complexes have been studied on the basis of infrared spectra, mass spectra, electronic spectra, powder X-ray diffraction, elemental analysis and thermogravimetric analysis. X-ray diffraction study suggested the suitable octahedral geometry for hexa-coordinated state. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (S*), pre-exponential factor (A), enthalpy (H*) and Gibbs free energy (G*) have been calculated using Freeman–Carroll method. Ferric-reducing antioxidant power (FRAP) of all complexes were measured. All the compounds were screened for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Streptococcus pyogenes and Bacillus subtilis, while antifungal activity against Candida albicans and Aspergillus niger have been carried out. Also compounds against Mycobacterium tuberculosis shows clear enhancement in the anti-tubercular activity upon copper complexation.

Synthesis, characterization and luminescent properties of mixed ligand complexes of nickei(II) with 1,1-dicarboethoxyethylene-2,2-dithiolate and some nitrogen donors

Synthesis, characterization and luminescent properties of mixed ligand complexes of nickei(II) with 1,1-dicarboethoxyethylene-2,2-dithiolate and some nitrogen donors

Synthesis, crystal structures and theoretical study of mixed ligand complexes of lanthanides acetylacetonates with o-phenanthroline and 2,2′-dipyridyl: The unexpected inverted electrostatic trend in stability

Synthesis of mixed ligand complexes [Lu(acac) 3phen] 1 and [Lu(acac) 3dipy] 2 was carried out. Complexes 1 and 2 have mononuclear structures with six oxygen atoms and two nitrogen atoms in the coordination sphere of the central Lu 3+ ion. Theoretical calculations of structures and properties of mixed ligand complexes [Ln(acac) 3Q] (where Ln=La, Gd, Lu; Q=phen, dipy) were performed at the DFT/B3PW91 level. The natural bond orbital analysis (NBO) was used to characterize the electronic structures of complexes. The features of crystal structures of complexes [Ln(acac) 3Q] in lanthanide row were explained taking into account the bond nature. The influence of both nature of central lanthanide ion and neutral additional ligand on structures and properties of complexes under investigation is discussed. The Ln(acac) 3—Q bond energy was found to be decreased from La-based complexes to Lu-based compounds. Thus, the unexpected inverted electrostatic trend, i.e. a decrease in stability along the lanthanide series, has been found out.

Synthesis, structure and redox properties of mixed ligand complexes of trivalent ruthenium with deprotonated 2-carbamoylpyridine derivatives and 2,2′-bipyridine

Five mixed ligand complexes of trivalent ruthenium with general formula [Ru(L)(bpy)Cl 2], where L= p-substituted N-phenyl derivatives of 2-carbamoylpyridine and bpy=2,2′-bipyridine, have been synthesised and characterised. X-ray crystal structural characterisation of a representative complex, i.e. where L=2-( N-(4-nitrophenyl)carbamoyl)pyridine, shows that the amide-containing ligand coordinates to the ruthenium(III) centre via the pyridyl nitrogen and the amidato nitrogen, forming a five-membered chelate ring. The complexes are paramagnetic (low spin d 5, S=1/2) and show a single signal in their EPR spectra in 1:1 dichloromethane–toluene solution at 77 K. In dichloromethane solution, these complexes show intense ligand to metal charge transfer transitions in the visible region. All the complexes display two cyclic voltammetric responses, a ruthenium(III)–ruthenium(IV) oxidation in the range from +0.63 to +0.93 V and a ruthenium(III)–ruthenium(II) reduction in the range from −0.63 to −0.73 V(vs ferrocene–ferrocenium couple). The potentials of both couples for all the complexes are found to be sensitive to the nature of the substituents present on the amide ligands, L.

Spectral and luminescent properties of mixed-ligand complexes of palladium(II) and 7,8-benzoquinoline

Spectral and luminescent properties of mixed-ligand palladium(II) complexes—[PdBhq(μ-Cl)]2, [PdBhqEn]ClO4, and [PdBhqBpy]ClO4, where Bhq stands for the 7,8-benzoquinoline ion—were studied. The absorption spectra of these complexes in the 25000–40000-cm− range were found to have a number of spin-allowed transitions of the 1(π-π*) type involving orbitals of the 7,8-benzoquinoline ligand. The luminescent characteristics of these compounds in a glass-forming matrix at 77 K are primarily determined by the participation of the 3(π-π*) states of the 7,8-benzoquinoline ligand.

Synthesis, structure, and magnetic properties of mixed-ligand complexes of manganese and gadolinium hexafluoroacetylacetonates with 4-phenyl-2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl nitroxide

Complexes of manganese(II) and gadolinium(III) hexafluoroacetylacetonates with stable nitroxide 4-phenyl-2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl (L), Mn(hfac)2L2 and Gd(hfac)3L2, have been synthesized. The results of an X-ray study of these complexes (Mn(hfac)2L2: a=21.762(4), b=9.685(1), c=22.073(3) A, β=114.94(1)°, space group Cc, Z=4; Gd(hfac)3L2: a=22.079(4), b=11.562(2), c=21.302(4) A, β=112.25(1)°, space group Cc, Z=4) have shown that both compounds have a molecular structure with the paramagnetic ligand coordinated via the oxygen atom of the N-oxide group. According to the results of static magnetic susceptibility measurements, the energies of exchange interactions between unpaired electrons of L and of metal ions are less than 1 cm−1 in magnitude.

Synthesis, spectroscopy and photophysical properties of mixed ligand complexes of europium(III) and terbium(III)

Abstract The synthesis and spectroscopic properties of mixed-ligand complexes of Eu III and Tb III with picolinic acid- N -oxide (picNO) plus either 2,2:6′:2″-terpyridine (terpy) or 1,10-phenanthroline ( o -phen) are described. The complexes were characterized by means of chemical analysis, IR, UV absorption and luminescence spectroscopy, excitation spectra and lifetime measurements. A 4f-4f intensity discussion for the Eu III complexes is presented.

Synthesis, characterization, spectroscopic and photophysical studies of ternary complexes of Eu(III) with 3-aminopyrazine-2-carboxylic acid (HL) and heterobiaryl ligands (2,2′-bipyridine and 1,10-phenanthroline)

The synthesis and spectroscopic properties of mixed ligand complexes of Eu(III) with 3-aminopyrazine-2-carboxylic acid (HL) and two heterobiaryl ligands (2,2′-bipyridine and 1,10-phenanthroline) are described. These complexes were characterized by means of chemical analysis, IR, UV and luminescence spectra, 5D 0 ← 7F 0 selective excitation spectra and 5D 0 excited state lifetimes. The complexes show strong ligand-centred absorption in the UV range, efficient energy transfer from the ligands and intense metal-centred emission in the visible range. The structures of the complexes in the solid state and in solution were deduced from spectroscopic and lifetime data. It was found that the complexes exist as different linkage isomers depending on the medium. The high quantum efficiencies indicate that these complexes can be used as light conversion molecular devices either in the solid state or in solution.

Intramolecular ligandligand interactions in mixed ligand complexes

One of the most important properties of mixed ligand complexes is direct and metal ion-mediated ligandligand interactions, the latter being known as π-acidπ-base interactions around the central metal ion. Examples of direct intramolecular ligandligand interactions are ionic and hydrogen bonds between charged and/or polar side groups and hydrophobic interactions between coordinated aromatic rings and side chain aliphatic groups or aromatic rings (aromatic ring stacking). Ionic interactions were found to exist in aqueous solutions of low-molecular weight mixed ligand complexes, e.g., Cu(A)(B), where A refers to acidic amino acids (aspartate or glutamate) and B to monoprotonated basic amino acids (zwitterionic arginine, lysine, or ornithine) [1]. The ligandligand interactions in the M(L-A)(L-B) systems (MCu(II) or Pd(II) give rise to a CD spectral magnitude anomaly which is dependent on the solvent polarity and the ionic strength, and the rotamer populations calculated from the NMR coupling constants are affected by the interactions in the Pd(II) complexes [1,2]. On the other hand, the hydrogen bonding between the carboxylate group of histidinate (His) and the polar side group of asparaginate (Asn), serinate (Ser), threoninate (Thr), etc. (reffered to as AA) in the ternary systems M(AA)(His) was confirmed by evidence from synthetic and CD and NMR spectral studies [3]. The infrared spectra of the isolated complexes indicated the existence of geometric isomerism in the diastereomers of M(A)(B) and M(AA)(His). On the basis of the steric requirements for the intramolecular ligandligand interactions, the geometry of M(L-A)(L-B) and M(D-AA)(L-His) has been inferred to be trans and that of M(D-A)(L-B) and M(L-AA)(L-His) cis with respect to the amine nitrogens. this is further supported by our recent infrared spectral study of the crystalline 63Cu- and 65Cu(AA)(L-His) complexes (AA = L-Asn, D-Asn, L-Thr, L-Ser, orD-Ser), which shows that only Cu(L-AA)(L-His) exhibits a metal isotope shift ( ca. 1 cm −1) of the CuNH 2 symmetric stretching band. The finding is reasonably explained by the cis structure for Cu(L-AA)(L-His) as established for AA = Asn and Thr by X-ray analysis and the trans structure for Cu(D-AA)(L-His) where the isotope shift is not observed because the symmetric stretching mode does not involve the displacement of Cu. Possibilities of ligandligand interactions in mixed ligand heteronuclear complexes will also be discussed.

Highly luminescent polypyridyl complexes of osmium(II)

The spectral and electrochemical properties of mixed ligand complexes of Os are reported. The data indicated that excited-state lifetimes are progressively enhanced by the substitution of ligands that are ..pi.. acceptors, i.e., acetonitrile or alkylarylphosphines substituted for biopyridyl or phenanthroline. Thus, by making proper substitutions, it should be possible to obtain a graded series of low-lying metal to ligand charge-transfer excited stat lifetimes which extend from tens of nanoseconds to lifetimes even longer than the approx. 500 and 800 ..mu..s that have been observed for the phenanthroline and bipyridyl complexes of Ru. (BLM)