Synthesis,characterization and solid‐phase extraction properties of novel bis(diazo‐azomethine) ligands supported on mesoporous silica

The novel mesoporous silica‐supported bis(diazo‐azomethine) compounds have been synthesized and characterized successively. In the first step, 1,3‐phenylenedimethanamine and 4,4′‐diaminodiphenylmethane were diazotized, and the obtained bis(diazonium) cations were coupled with 2,4‐dihydroxybenzaldehyde. The synthesized bis(diazo‐carbonyl) compounds, 5,5′‐((1,3‐phenylenebis(methylene))bis(diazene‐2,1‐diyl))bis(2,4‐dihydroxybenzaldehyde) (A1) and 5,5′‐((methylenebis(4,1‐phenylene))bis(diazene‐2,1‐diyl))bis(2,4‐dihydroxybenzaldehyde) (A2) were chemically supported on amino‐modified silica‐gel (as L1 and L2). Elemental analysis, liquid chromatography‐mass spectroscopy, liquid‐phase NMR (¹H and ¹³C) and solid‐phase NMR (CP‐MAS ²⁹Si and ¹³C), FT‐IR, TG/DTA, scanning electron microscopy and energy‐dispersive X‐ray spectroscopy techniques were used for characterizations of all the synthesized compounds. The syringe and batch techniques were applied for the solid‐phase extraction properties of Pb(II), Cu(II), Cd(II) and Cr(III) ions using an inductively coupled plasma‐atomic emission spectroscopy instrument. The recoveries of Pb(II), Cu(II), Cd(II) and Cr(III) ions have been achieved to 95–99% with the (RSDs) of ± 2–3% in optimum conditions.     

Esterified porphyrazine complexes: Synthesis,characterization, aggregation behavior,and theoretical study

Magnesium porphyrazine having eight 5-hydroxypentylthio groups at the peripheral positions, was synthesized from 2,3-bis(5-hydroxypentylthio) maleonitrile. By the esterification reaction of octakis(5-hydroxypentylthio) porphyrazinato] Mg(II) with 3,4,5-trimethoxybenzoic acid in dicyclohexylcarbodiimide and toluene-p-sulfonic acid, esterified MgPz appending [5-thiopentyl 2-methoxy-4,6-bis(trifluoromethyl) benzoate] substituent was obtained. Further reaction of the metal-free porphyrazine with Co(II), Cu(II), Zn(II), and Fe(II) acetates have produced the metallo-porphyrazines. By reacting FePzCl with pyridine or pyrazine, the monomeric bis-axial and the oligomeric complexes were synthesized as the novel stable complexes, respectively. Their characterizations were performed by using elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR, mass and UV-Vis spectral data. The aggregation investigations carried out in different concentrations indicate that 3,4,5-trimethoxybenzyloxy-substituted porphyrazine compounds do not have any aggregation behavior in different concentrations. Quantum chemical computations were also done to the structural and electronic properties of target compounds.     

Phosphorus Schiff base ligand and its complexes: Experimental and theoretical investigations

A phosphorus-containing Schiff base was prepared from bis{3-[2-(4-amino-1,5-dimethyl-2-phenylpyrazol-3-ylideneamino)ethyl]indol-1-ylmethyl}phosphinic acid and paraformaldehyde as a novel antibacterial compound. The reaction of the Schiff base ligand with VO(IV), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and Pt(IV) led to binuclear species of metal complexes, depending on the ratio of metal ion and ligand. The ligand and its complexes were investigated using elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, UV–visible and mass spectra, thermogravimetric analysis, conductivity measurements and thermal analysis. The results showed that the Schiff base behaves as a tetradentate ligand; moreover, on the basis of conductance results, of all the prepared complexes are non-electrolytes, excepting the Pt(IV) complex. The metal complexes were found to be formed with a metal-to-ligand ratio of 2:1, except for the Pt(IV) complex with a ratio of 1:1. The activation thermodynamic parameters (ΔE*, ΔH*, ΔS*, ΔG* and K) and the activation energy of thermal decomposition were determined from thermogravimetric analysis using the Coats–Redfern method. The biological activities of the metal complexes were screened against the growth of bacteria and fungi in vitro to assess the antimicrobial potential and study the toxicity of the compounds. The prepared compounds have noteworthy antimicrobial properties.     

Transition metal complexes of a novel quinoxaline‐based tridentate ONO donor ligand: synthesis,spectral characterization,thermal, in vitro pharmacological and molecular modeling studies

Co(II), Ni(II), Cu(II) and Zn(II) complexes of a novel tridentate heterocyclic ligand, 3‐{[(2‐benzoyl‐4‐chlorophenyl)imino]methyl}quinoxalin‐2(1H)‐one, have been synthesized. The ligand and the metal complexes were characterized using elemental analysis, molar conductance and magnetic susceptibility measurements, and UV–visible, Fourier transform infrared, ¹H NMR, ¹³C NMR, electron spin resonance and DART mass spectral data. The ligand behaves as a tridentate one, coordinating through two oxygen atoms from two keto groups and through the azomethine nitrogen atom. The thermal properties of the newly synthesized compounds were determined using thermogravimetric analysis. The ligand and its metal complexes were subjected to powder X‐ray diffraction analysis by which average crystallite size and unit cell parameters were calculated. The electrochemical behaviour of the compounds was studied using cyclic voltammetry. The ligand and the metal complexes were screened for their in vitro antimicrobial activities against the bacterial strains E. coli, K. pneumoniae, S. pneumoniae and S. aureus and the fungal species A. niger, A. flavus, P. chrysogenum and R. stolonifer. DNA binding, DNA cleavage and antioxidant activities of the compounds were also evaluated. The compounds bind with DNA through groove binding. The Cu(II) and Zn(II) complexes exhibit higher superoxide anion and hydrogen peroxide scavenging activities, respectively. The Cu(II) complex exhibits better anticancer activity against the MCF7 cell line. The compounds were subjected to molecular docking study against B‐DNA dodecamer d(CGCGAATTCGCG)₂ and vascular endothelial growth factor receptor kinase to justify the experimental DNA binding and MTT assay. Density functional theory studies were used to optimize the geometry of the compounds and to calculate the nonlinear optical properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of Electronic and Steric Factors on the Magnetic Properties of Novel Homo- and Heterobinuclear Transition-Metal Complexes with Asymmetric 2,6-Diformyl-4-R-Phenol Bis(Hydrazones)

A series of novel homo- and heterobinuclear copper(II), manganese(II), and VO²⁺ complexes with asymmetric 2,6-diformyl-4-R-phenol bis(hydrazones) are synthesized. The values of exchange parameters of these compounds are determined. The comparison of experimental results with the quantum-chemical calculations of the model fragments of binuclear metal chelates allows one to elucidate the main electronic and geometric factors determining the character of changes in the magnetic properties in systematic series of transition-metal complexes with bis(hydrazones).     

Antimicrobial agents: synthesis,spectral, thermal,and biological aspects of a polymeric Schiff base and its polymer metal(II) complexes

Some new coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) obtained by the interaction of metal acetates with polymeric Schiff base containing formaldehyde and piperazine have been investigated. Structural and spectroscopic properties have been studied by elemental, spectral (FT-IR, ¹H-NMR, and UV-Vis), and thermogravimetric analysis. UV-Vis spectra and magnetic moments indicate that Mn(II), Co(II), and Ni(II) polymer metal complexes are octahedral, while Cu(II) and Zn(II) polymer metal complexes are square planar and tetrahedral, respectively. All compounds were screened for their antimicrobial activities against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans, Agelastes niger, and Microsporum canis using the Agar well diffusion method with 100?µg?mL^?1 of each compound.     

Electrical and photoelectrical behaviour of heterojunctions based on novel oligomeric metal complexes

Naringenin‐based Schiff base ligands with 4‐aminobenzoic hydrazide were obtained as a unilateral form ( L¹ ). The ligand was oligomerized by oxidative polycondensation reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 °C to form a functional oligomer ( L² ), and its transition metal complexes such as those with Cu(II), Ni(II) and Zn(II) were prepared. The monomer and the oligomeric compounds were characterized using various techniques. Optical and electrical properties of the complexes were also investigated. All compounds showed indirect band gaps and they can be accepted as being in the semiconductor class. Organic–inorganic hybrid devices were obtained using n‐Si inorganic semiconductor and the complexes. The characteristic parameters of the devices were determined using current–voltage (I–V) and capacitance–voltage measurements in the dark. Photoelectrical properties of the devices were investigated using I–V measurements under a solar simulator with an AM1.5 global filter. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis,electrochemical, and antibacterial activity of some novel N<Subscript>4</Subscript>O<Subscript>2</Subscript> ligand derivativies

A novel ligand has been synthesized by the condensation of 1,3-diaminoprophane (HL) wıth isonitroso-p-chloroacetophenone. The complexes of cobalt(II), nicel(II), cupper(II) and zinc(II) with HL were prepared. All compounds were characterized by spectroscopic techniques and its antibacterial activities were determined by the disc diffusion method used against to those gram-positive and-negative bacteria. All compounds were investigated by cyclic voltammetry at 25°C. The voltammograms were recorded with a potential scan of 100 mV s⁻¹. The text was submitted by the authors in English.     

Metal‐based sulfonamides: synthesis,characterization, antibacterial,antifungal and cytotoxic properties of pyrrolyl‐ and thienyl‐derived compounds

Pyrrolyl and thienyl derived sulfonamides and their metal [cobalt(II), copper(II), nickel(II) and zinc(II)] complexes were synthesized and characterized by elemental analyses, molar conductances, magnetic moments, IR, ¹H NMR, ¹³C NMR and electronic spectral data. These compounds were screened for in‐vitro antibacterial activity against four Gram‐negative (Escherichia coli, Shigella flexeneri, Pseudomonas aeruginosa and Salmonella typhi) and two Gram‐positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains, and for in‐vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies revealed that all compounds showed significant to moderate antibacterial activity; however, the zinc complexes were shown to be the most active against various species. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties of all the synthesized ligands and their metal complexes. Only two compounds ( 14 and 19 ) displayed potent cytotoxic activity as LD₅₀ = 5.5637 × 10^?4 and 4.4023 × 10^?4 M ml^?1 respectively, against Artemia salina. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,characterization and catalytic,cytotoxic and antimicrobial activities of two novel cyclotriphosphazene‐based multisite ligands and their Ru(II) complexes

Two novel cyclotriphosphazene ligands ( 2 and 3 ) bearing 3‐oxypyridine groups and their corresponding Ru(II) complexes ( 4 and 5 ) were synthesized and their structures were characterized using Fourier transform infrared, ¹H NMR and ³¹P NMR spectroscopic data and elemental analysis. The Ru(II) complexes were used as catalysts for catalytic transfer hydrogenation of p‐substituted acetophenone derivatives in the presence of KOH. Additionally, the cytotoxic activities of compounds 2 , 3 , 4 , 5 were evaluated against PC3 (human prostate cancer), DLD‐1 (human colorectal cancer), HeLa (human cervical cancer) and PNT1A (normal human prostate) cell lines. Finally the antimicrobial activities of compounds 2 , 3 , 4 , 5 were evaluated against a panel of Gram‐positive and Gram‐negative bacteria and yeast cultures. The complexes showed efficient catalytic activity towards transfer hydrogenation of acetophenone derivatives, especially those bearing electron‐withdrawing substituents on the para‐position of the aryl ring. The compounds were found to have moderate to high cytotoxic and antimicrobial activities, and Ru(II) complexation enhanced both cytotoxic and antimicrobial activities in comparison with the parent compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel nonperipheral octa-3-hydroxypropylthio substituted metallo-phthalocyanines: synthesis,characterization, and investigation of their electrochemical,photochemical and computational properties

The current study describes the synthesis, electrochemical, computational, and photochemical properties of octa (3-hydroxypropylthio) substituted cobalt (II) ( 4 ), copper (II) ( 5 ), nickel (II) ( 6 ) and zinc(II) ( 7 ) phthalocyanine derivatives. These novel compounds were characterized by elemental analysis,¹H,¹³C NMR, FT-IR, UV-Vis, and MS. The redox behaviors of these metallo-phthalocyanines were investigated by the cyclic voltammetric method. The optimized molecular structure and gauge-including atomic orbital (GIAO)¹H and¹³C NMR chemical shift values of these phthalocyanines in the ground state had been calculated by using B3LYP/6–31G(d,p) basis set. The outcomes of the optimized molecular structure were given and compared with the experimental NMR values. The photochemical properties including photodegradation and singlet oxygen generation of zinc(II) phthalocyanine were studied in DMSO solution for the determination of its photosensitizer behaviors.     

Synthesis, characterization and thermal behaviour of ortho-metallated Pd(II) complexes containing N-benzoylthiourea derivatives

The synthesis and characterization (elemental analysis, ¹H and ¹³C NMR spectroscopy and single crystal X-ray diffraction) of the first ortho-metallated Pd(II) complexes containing N-benzoyl thiourea ligands are described. Four of these compounds showed liquid crystal properties which were investigated by mean of DSC and polarised light microscopy and their mesogenic properties are compared to those of ortho-metallated imine Pd(II) complexes with other types of co-ligands.     

Structural diversity of a series of chlorocadmate(II) and chlorocuprate(II) complexes based on benzylamine and its N-methylated derivatives

Protonated benzylamine and its N-methylated derivatives, [C₆H₅CH₂NH_3?n(CH₃)_n]⁺ (n?=?0?3), have been adopted as cations in chlorocadmate(II) and chlorocuprate(II) complexes, showing inorganic–organic hybrid architectures. For the Cd(II) compounds, the anionic structures vary from perovskite-type layers (n?=?0) to chains (n?=?1–3). For Cu(II) compounds, the anionic structures range from perovskite-type layers (n?=?0), chains (n?=?1) to mononuclear species (n?=?2–3). Coordination geometries of the metal ions and intermolecular interactions have been analyzed. Their dielectric properties have been measured.     

Cu(II), Ni(II) and Fe(II) complexes with a new substituted [1,2,4] triazole Schiff base derived from 4-amino-5-(thien-2-yl ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one and 2-hydroxy-1-naphthaldehyde: synthesis,characterization and a comparison of theoretical and experimental results by Ab inito calculation

The synthesis and structural properties of two novel compounds, 4-amino-5-(thien-2-yl ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one and 4-{[(2-hydroxy-1-naphthyl)methyl-ene]amino}-5-(thien-2-ylmethyl) − 2,4-dihydro-3H-1,2,4-triazol-3-one have been described. 4-Amino-5-(thien-2-ylmethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one was synthesized by treating N-propionyl-2-thien-2-ylethane-hydrazonoate with hydrazine hydrate and the Schiff base was obtained from condensation of substituted amine with 2-hydroxy-1-naphthaldehyde. The Cu(II), Ni(II) and Fe(II) complexes were prepared and characterized by elemental analyses, IR, magnetic moment, UV–Vis, mass spectral data and ¹H- and ¹³C-NMR IR spectra. The Schiff base is coordinated to the metal ions in a tridentate manner with OON donors of the phenolic O, carbonyl O and triazolic N. From the magnetic and UV spectral data, it was found the geometrical structure of Cu(II) and Fe(II) ions are octahedral while Ni(II) ion is square planar.Ab-inito 6-31 G* level calculations provided structural information and IR data that were in good agreement with experimental results.     

Preparation and Characterization of Novel Asymmetrical Schiff-Base Ligands Derived from 2-methyl-7-formyl-8-hydroxyquinoline and their Metal Complexes

Two novel asymmetrical Schiff-base ligands, H₂L¹ and H₂L², were prepared by reacting two half-unit Schiff-base compounds with 2-methyl-7-formyl-8-hydroxyquinoline. The two half-unit Schiff-base compounds were initially prepared by condensing dimedone with either ethylenediamine or p-phenylenediamine, respectively. Both ligands are dibasic and contain two sets of NO coordinating sites. Twelve metal complexes were obtained by reacting both ligands with Cu(II), Ni(II), Co(II), Mn(II), Fe(III), VO(IV) cations. The ligands and their metal complexes were characterized by elemental analysis, IR, UV-Vis, ESR and mass spectra, also magnetic moments of the complexes were determined. Visible spectra of the complexes indicated distorted octahedral geometries around the metal cations. ESR spectra indicated mononuclear and dinuclear structures of the complexes of ligands H₂L¹ and H₂L², respectively. Magnetic moments of the complexes were rather low compared with those expected for octahedral geometries and indicated polymeric linkage of the metal complex molecules within their crystal lattices. The insolubility of the metal complexes in most organic solvents support the polymeric structures.     

Synthetic,spectroscopic, fluorescence,and biological investigation of Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff bases derived from 3-formyl-2-mercaptoquinolines (Quinol-2-thiones)

Co(II), Ni(II), Cu(II), and Zn(II) complexes have been prepared with Schiff bases derived from 3-formyl-2-mercaptoquinoline and substituted anilines. The prepared Schiff bases and chelates have been characterized by elemental analysis, molar conductance, magnetic susceptibilities, electronic, IR, ¹H-NMR, ESR, cyclic voltammetry, FAB-mass, and thermal studies. The complexes have stoichiometry of the type ML₂ · 2H₂O coordinating through azomethine nitrogen and thiolate sulfur of 2-mercapto quinoline. An enhancement in fluorescence has been noticed in the Zn(II) complexes whereas quenching occurred in the other complexes. The ligands and their metal complexes have been screened in vitro for antibacterial and antifungal activities by MIC methods with biological activity increasing on complexation. Cu(II) complexes show greater bacterial than fungicidal activities. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties of the ligands and their corresponding complexes. Only four compounds have exhibited potent cytotoxic activity against Artemia salina; the other compounds were almost inactive for this assay.     

Synthesis, characterization and biological activity of some new VO(IV), Co(II), Ni(II), Cu(II) and Zn(II) complexes of chromone based NNO Schiff base derived from 2-aminothiazole

Coordination compounds of VO(IV), Co(II), Ni(II), Cu(II) and Zn(II) with the Schiff base obtained through the condensation of 2-aminothiazole with 3-formyl chromone were synthesized. The compounds were characterized by ¹H, ¹³C NMR, UV–Vis, IR, Mass, EPR, molar conductance and magnetic susceptibility measurements. The Cu(II) complex possesses tetrahedrally distorted square planar geometry whereas Co(II), Ni(II), and Zn(II) show distorted tetrahedral geometry. The VO(IV) complex shows square pyramidal geometry. The cyclic voltammogram of Cu (II) complex showed a well defined redox couple Cu(II)/Cu(I) with quasireversible nature. The antimicrobial activity against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger was screened and compared to the activity of the ligand. Emission spectrum was recorded for the ligand and the metal(II) complexes. The second harmonic generation (SHG) efficiency was measured and found to have one fourth of the activity of urea. The SEM image of the copper(II) complex implies that the size of the particles is 2 μm.     

Novel 13,14‐dimethyl‐5,8‐dioxa‐2,11,13,14‐tetraaza‐1,12‐diphosphabicyclo [10.1.1] tetradecane 1,12‐dioxide ligand and its Ni(II), Co(II), and Cu(II) complexes: Synthesis,characterization, antimicrobial,DNA cleavage,and computational studies

A novel diazadiphosphetidine ligand derived from the reaction of 2,4‐dichloro‐1,3‐dimethyl‐1,3,2,4‐diazadiphosphetidine‐2,4‐dioxide and 2,2′‐(ethane‐1,2‐diylbis[oxy])bis(ethan‐1‐amine) and its Ni(II), Cu(II), and Co(II) complexes have been synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility, and conductivity methods, and screened for antimicrobial, DNA binding, and cleavage properties. Spectroscopic analysis and elemental analyses indicate the formula [M(H₂L)Cl₂] for the Cu(II), Co(II), Ni(II), and Zn(II) complexes and octahedral geometry for all the complexes. The non‐electrolytic nature of the complexes in dimethyl sulfoxide (DMSO) was confirmed by their molar conductance values, which are in the range 12.32–6.73 Ω^?1 cm² mol^?1. Computational studies have been carried out at the density functional theory (DFT)‐B3LYP/6‐31G(d) level of theory on the structural and spectroscopic properties of diazadiphosphetidine H₂L and its binuclear Cu(II), Co(II), Ni(II), and Zn(II) complexes. Six tautomers and geometrical isomers of the diazadiphosphetidine ligand were confirmed using semiempirical AM1 and DFT method from DMOL³ calculations. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA by agarose gel electrophoresis in the presence and absence of an oxidant (H₂O₂) and a free‐radical scavenger (DMSO), indicated no activity for the ligand and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H₂O₂.     

Synthesis and characterization of some binuclear metal complexes with a pentadentate azodye ligand: An experimental and theoretical study

A novel series of binuclear complexes with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) ions derived from a pentadentate azo dye ligand (H₃L) was synthesized and structurally investigated by various physicochemical analyses, namely, scanning electron microscopy, transmission electron microscopy, NMR, UV–visible spectroscopy, and Electron-Spin Resonance (ESR) studies. The infrared spectral data revealed characteristic bands due to ν(N=N) and ν(C=O) at 1606 and 1631 cm⁻¹ in the free ligand. However, their positions shifted and appeared at ~1564 and ~1592 cm⁻¹ on coordination, suggesting the involvement of carbonyl oxygen and azo nitrogen in complex formation. The spectral data suggested octahedral geometry for the complexes. The kinetic parameters such as order and activation energy were determined from the thermal decomposition values. X-ray powder diffraction analysis showed the orthorhombic nature of the cadmium complex. Furthermore, Density functional theory (DFT) calculations were also recorded to describe the insight bonding. The synthesized compounds were tested for in vitro antibacterial activity against K. aerogenes, S. aureus, B. acidoterrestris, E. coli, and V. cholerae strains by the cup-plate method. In addition, the interactions that occurred in the protein–ligand complexes have been predicted by docking analysis.     

Synthesis,structural characterization,and antibacterial studies of a tetradentate macrocyclic ligand and Its Co(II), Ni(II), and Cu(II) complexes

A novel macrocyclic tetradentate ligand 1,5,8,12-tetraaza-2,4,9,11-tetraphenyl-6,7:13,14-dibenzocyclohexadeca- 1,4,8,11-tetraene (L) has been synthesized. Cobalt(II), nickel(II), and copper(II) complexes of this ligand have been prepared and characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, and mass, IR, electronic, and ESR spectral studies. The molar conductance measurements correspond to a nonelectrolytic nature for all the complexes, which can be formulated as [M(L)X₂] (where M = Co(II), Ni(II), and Cu(II); X = Cl⁻ and NO₃⁻). On the basis of IR, electronic, and ESR spectral studies, an octahedral geometry has been assigned to the Co(II) and Ni(II) complexes, whereas a tetragonal geometry was found for the Cu(II) complexes. The investigated compounds and uncomplexed metal salts and the ligands were tested against bacterial species like Sarcina lutea, Escherchia coli, and Staphylococcus aureus. The metal complexes have higher activity than the free ligand and metal salts. The text was submitted by the authors in English.