Macrocyclic silver and gold complexes containing bis (N-heterocyclic carbene) ligand: Synthesis and structural characterization

Silver and gold complexes, [Ag₂(L)₂](PF₆)₂ and [Au₂(L)₂](PF₆)₂, supported by but-2-yne-1,4-diyl linked bis(N-heterocyclic carbene) ligand have been prepared and structurally characterized. The complexes display novel twisted macrocyclic conformation and weak intramolecular metal–metal interaction. The complexes are intensely emissive in their solid states.     

Synthesis and characterization of dinuclear silver(I) complexes with exchangeable nitrile ligands

We have prepared three silver(I) complexes of the type [Ag₂(P ∩ N)₃(NCR)](BF₄)₂ with (R = Me, Et, Ph). The crystal structures of the complexes were determined. The nitrile ligands can be easily exchanged by re-crystallisation in the respective nitrile. The luminescence properties were also investigated.     

Silver(I) cis-diphenylphosphinoethylene complexes: Spectroscopic and structural characterization

Adducts of the diphosphine cis-Ph₂P(CHCH)PPh₂ (L) with AgX (X = NO₃, BF₄, ClO₄ or CF₃SO₃) have been synthesized and characterized both in solution (¹H, ³¹P NMR) and in the solid state (IR, single crystal X-ray structure analysis). The topologies of the structures in the solid state were found to depend on the nature of the counter-ion X. The adduct AgNO₃:L (2:1)₂ is tetranuclear, derivative of the chair form, the bidentate ligands bridging peripheral silver centers, the nitrates being coordinated through two oxygen atoms, the first O,O′-bridging the second bridging bidentate.     

Synthesis,characterization and mechanochromic behavior of binuclear gold (I) complexes with various diisocyano bridges

A series of binuclear gold (I) complexes were synthesized. Their structures were characterized by elemental analyses, IR spectrometry, UV–Vis spectroscopy and single crystal X-ray diffraction. Their fluorescent mechanochromic (tribochromic) properties were investigated. The results of the mechanochromic studies suggested that the gold complexes with methylsubstituted phenyl bridges exhibited mechanochromism and a 100 nm red-shift of fluorescent spectrum could be observed after grinding. The complex with a diphenylmethane bridge exhibited mechanochromism with a change in fluorescence from green to blue (25 nm red-shift after grinding). The ground complexes reverted to their original states by treatment with CH₂Cl₂. No mechanochromism was observed for either the biphenyl or diphenylethane containing complexes.     

Synthesis and characterization of copper(I) complexes from triphenylphosphine and isatin Schiff bases of semi- and thiosemicarbazide

The reaction of isatin-3-thiosemicarbazone (ITC, 1) or isatin-3-semicarbazone (ISC, 2) with nitrato bis(triphenylphosphine)copper(I) gave the four coordinate copper(I) complexes [Cu(PPh₃)₂(ITC)]NO₃ (3) and [Cu(PPh₃)₂(ISC)]NO₃ (4). The synthesized complexes were characterized by FT-IR, UV–VIS, Raman and elemental analysis. The crystal structure of 3 was investigated by single crystal X-ray diffraction. The ITC coordinates to the copper(I) ion in a bidentate fashion via the N(imine) and S atoms which along with two triphenylphosphine ligands form a tetracoordinate complex. The complex has a distorted tetrahedral coordination environment. Crystal data at 150.0 K: space group P2₁/c with a=12.5777(4), b=15.2062(5), c=21.9057(7) Å, β=95.628(3)^o, Z=4, R ₁=0.049.

     

Synthesis,characterization and catalytic activities of ruthenium complexes containing triphenylphosphine/triphenylarsine and tetradentate Schiff bases

Ruthenium(II) complexes of the type [Ru(CO)(B)(L)] (B=AsPh₃, pyridine, piperidine or morpholine; L=dianion of tetradentate Schiff bases) have been synthesized and characterized by physico-chemical methods. These complexes are found to be effective catalysts in the oxidation of primary and secondary alcohols using N-methylmorpholine-N-oxide as oxidant. The catalytic activity of these triphenylarsine complexes have been compared with that of triphenylphosphine complexes and with similar ruthenium(III) complexes. The formation of high valent Ruⁿ⁺²O species as catalytic intermediate is proposed for the catalytic processes.     

Synthesis,characterization and catalytic activity of Fe(III) complexes containing Schiff base and triphenylphosphine ligands

The oxidation of alcohols to carbonyls was investigated by an efficient catalyst system comprising of Fe(III)–Schiff base–triphenylphosphine complex. The complex chloroN-(2-mercaptophenyl)salicylideneiminebis(triphenylphosphine)iron(III) showed higher activity for oxidation of various alcohols under relatively mild conditions.     

Synthesis, characterization and microbiological response of silver doped bioactive glass nanoparticles

Glass nanoparticles containing 1, 3, 5, and 10 wt% of Ag₂O (coded; GAg1%, GAg3%, GAg5%, and GAg10%, respectively) were synthesized through a quick alkali mediated sol-gel method and were characterized by TEM, XRF, FT-IR, XRD, TGA, and DSC. Thermal analysis showed that all organic and inorganic by-products were completely decomposed before 700 °C and, hence, all glass samples were stabilized at this temperature. XRD confirmed the amorphous nature of all glasses after stabilization. TEM micrographs showed that the average particle sizes of all samples were less than 100 nm in diameter and the XRF showed that the compositions of the obtained glasses were almost consistent with the designed ones. The samples GAg1%, GAg3%, GAg5%, and GAg10%, showed average pore diameters of 19.85, 18.22, 13.32, and 19.62 nm and specific surface areas of 73.18, 100.38, 192.6, and 55.7 m²/g, respectively. In addition, their porosity% was 76.53, 83.20, 77.97, and 79.61%, respectively. The FT-IR spectra of all glasses showed bands located in the range of 1000-1200, 725-800, and 450-480 cm⁻¹ that correspond to the Si-O-Si asymmetric stretching vibration, the Si-O-Si symmetric stretching vibration, and the Si-O-Si bending mode, respectively. Finally, all samples had an anti-bacterial effect against different types of bacteria and the extraction of silver ions from them followed a diffusion-controlled mechanism, which could demonstrate their ability to treat bone infection.     

Synthesis,reactivity, and X-ray structural characterization of a vanadium(III) oxidation pre-catalyst, (CpPOEtCo)VCl2(DMF)

Vanadium complexes are extensively used in the chemical industry as oxidation catalysts. During the course of our investigations into vanadium oxidation catalysis, the rich reactivity of a vanadium(III) scorpionate analogue complex, (CpP^OEtCo)VCl₂(DMF) (1), was investigated. The octahedrally coordinated 1 was prepared by mixing vanadium(III) chloride with Na(CpP^OEtCo) in DMF. The crystal structure of 1 has been determined through X-ray diffraction. Complex 1, C₂₀H₄₂Cl₂CoNO₁₀P₃V, crystallizes in the monoclinic space group P2₁/c with a = 38.566(9) Å, b = 9.499(2) Å, c = 18.149(4) Å, and β = 100.485(4)° with Z = 8. Complex 1 was found to be an effective pre-catalyst for the oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone. The reactivity studies, oxidative catalytic ability, as well as X-ray structural characterization of (CpP^OEtCo)VCl₂(DMF) will be discussed. ((CpP^OEtCo) = [η⁵-cyclopentadienyltris(diethylphosphito-κ¹P) cobaltate(III)⁻; DMF = N,N-dimethylformamide).     

Structural and photophysical characterization of gold(I) complexes bearing naphthyl chromophores

We prepared two chlorido-gold(I) complexes of the type L–Au–Cl bearing a naphthyl moiety: Complex 1 with L = tris-1-naphthyl-phosphine shows standard linear coordination without further aggregation in the solid state. Complex 2 with L = 2-naphthyl-isonitrile is engaged in a complex network of aurophilic and π–π interactions. The two complexes show similar luminescence behaviour in solution at room temperature with both intraligand fluorescence and phosphorescence. At 77 K the emission spectra are dominated by intraligand phosphorescence, which is typical of gold complexes with extended π-chromophores.     

Synthesis and structural characterization of two chain complexes of Mn(II) containing 2-aminopyridinium

The 2-aminopyridine ligand has been exploited in preparation of divalent metal complexes of the formulae [H(2-ampy)][MnCl₃(H₂O)] 1 and [H(2-ampy)]₂[Mn₂Cl₆(2-ampy)₂] 2, where 2-ampy is 2-aminopyridine. Their crystal structures have been determined by X-ray crystallography. Both complexes self-assemble through similar hydrogen bonding motifs which involve three N–H⋯Cl interactions between the 2-aminopyridinium cation and the chloride atoms. Each repeating unit of complexes 1 and 2, [MnCl₃(H₂O)]⁻ and [Mn₂Cl₆(2-ampy)]²⁻, respectively, is doubly edge-sharing to form one-dimensional chains which are cross-linked by hydrogen bonding to the [H(2-ampy)]⁺ cations. In complex 2, two different 2-aminopyridine molecules were observed. One bridges the Mn atoms directly, while the other, through hydrogen bonding interaction, bridges Mn atoms via the chloride atoms. The structural role of the 2-aminopyridinium cation on the aggregation of the metal ions is discussed.     

Calamitics, cubics, and columnars-liquid-crystalline complexes of silver(I)

The study of metallomesogens has added several new dimensions to the wider field of liquid crystals. In this Account, just one family of complexes is considered, namely alkoxystilbazole complexes of various silver(I) salts. These complexes show an incredibly rich and diverse mesomorphism ranging from nematic and smectic to columnar phases; in particular, many complexes show the still rare thermotropic cubic phase. Through systematic structural variations, it has been possible to gain a good understanding of the factors influencing the behavior of these fascinating systems.     

Synthesis, structural characterization and microbial activities of mixed ligand copper(II) complexes of 2,2′-bipyridine and acetylacetonate

Two new mixed ligand complexes of copper(II) with acetylacetonate (acac) and 2,2′-bipyridine (bpy) belonging to the class of cytotoxic and antineoplastic compounds known as CASIOPEINAS® have been synthesized and characterized on the basis of analytical and spectroscopic data. Molecular structures of the complexes, [Cu(acac)(bpy)Cl][Cu(acac)(bpy)(H₂O]Cl.H₂O and [Cu(acac)(bpy)Br]H₂O, were established by single crystal X-ray study. The Cu(II) ion in both the complexes exhibited square pyramidal geometry with acac and bpy in the equatorial plane and halide/water in the axial position. Interestingly, for the complex with chloride anion, two types of complexes with chloride and water at the axial positions were derived from the same reaction and co-crystallized in the asymmetric unit with strong intermolecular interactions. Microbial property of these two complexes as antibacterial and antifungal agents has been investigated and some of the results are comparable to that of the standard drugs such as E. coli, P. aeruginosa, S. aureus, S. pyogenes, A. niger and C. albicans, used in this study.     

Synthesis,crystal structures,and biological activities of 2-thiophene N(4)-methylthiosemicarbazone and its unusual hexanuclear silver(I) cluster

2-Thiophene N(4)-methylthiosemicarbazone (HL) and its Ag(I) complex of formula [Ag₆(L)₆? 4DMF] 1 have been synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction studies. The silver(I) complex 1 with a 1:1 metal–ligand molar ratio is an unusual hexanuclear cluster with 6 silver atoms in different environments: four silver atoms of them are considered to be 3-coordinate form, which are coordinated by two thiolate sulfur atoms and one imine nitrogen and the other two silver atoms are considered to be 4-coordinate form, which are coordinated by three thiolate sulfur atoms and one imine nitrogen, with four thiolate sulfur bridging two silver atoms and two thiolate sulfur bridging three silver atoms. Biological studies, carried out in vitro against bacteria, fungi and SMMC-7721 liver cancer cell line, respectively, have shown that the free ligand and the title complex show distinct difference in the biological property.     

Synthesis,crystal structures and photoluminescences of silver(I) complexes with chelating carboxylic and pyrazine derivatives

Four mixed-ligand silver(I) coordination polymers (CPs) {Ag2(tpyz)(L)}_n (1), {Ag4(tpyz)2(L)2}_n (2), {Ag2(mpyz)(L)}_n (3) as well as its isomer (4), (tpyz-2,3,5-trimethylpyrazine, mpyz = 2,3,5,6-tetramethylpyrazine, H2L = (+)-camphoric acid), were synthesized with reactions of L and pyrazine derivatives with silver nitrate in different solvent systems. Systematic characterizations with single-crystal X-ray diffraction indicate that, 1 and 3 show a 3D framework which constructed by silver(I) and L anion, the pyrazine derivatives only give one N to connect to metal, which may be due to the disorder of the methyl which shares the same carbon with carboxylate; 2 and 4 demonstrate a 2D 4 ⁴–sql network. The difference between two: one structure is single layer and the other is double layer. Furthermore, 4 contains a 1D helical chains which connected by Ag(I) and mpyz ligand. Meanwhile, the L anion exhibits different coordination modes in 1–4. 1–4 spanning from two-dimensional network to three-dimensional framework suggest that the kinds of pyrazine derivatives and solvents play significant roles in the formation of such coordination architectures. The thermogravimetric analyses (TGA), IR, and photoluminescence were also measured.     

Palladium (II) and platinum (II) complexes containing organometallic thiosemicarbazone ligands: Synthesis,characterization, X-ray structures and antitubercular evaluation

A new series of palladium (II) and platinum (II) complexes containing ferrocenyl and cyrhetrenyl thiosemicarbazone ligands were synthesized and characterized. The two-step reaction of the organometallic thiosemicarbazones with i) K₂MCl₄ and ii) PPh₃ and their subsequent recrystallization from CH₂Cl₂/hexane yielded the binuclear complexes [Mˋ{ML_n(η⁵-C₅H₄)C(H)NNC(S)NHR}–(Cl)(PPh₃)] (M′Pd, Pt; ML_nRe(CO)₃, FeCp; RH, CH₃). The structures of the products were inferred from elemental analyses and IR, ¹H and ³¹P NMR spectroscopies. The molecular structures of 2b and 3d were confirmed by single crystal X-ray analysis. All complexes were screened in vitro against Mycobacterium tuberculosis and exhibited only moderate activity in the low micromolar range.     

Synthesis,structural characterization,opto-electrical properties of Ir(III) complexes with imidazolium-based carbene ligands

A series of Ir(III) complexes with N–heterocyclic carbenes (NHC) ligands (1–3) were synthesized and characterized. The opto-electrical properties of these complexes were investigated spectroscopically, electrochemically and theoretically. All complexes exhibit ligand-based ¹π,π* transitions in the UV region, ¹MLCT absorption in the UV region, and weak low energy ³π, π* transition in visible region. These complexes all exhibit blue phosphorescence at both room temperature and 77 K, which is dominated by ³π,π* character. DFT calculation results indicate their lowest unoccupied molecular orbitals (LUMO) from − 0.47 to − 0.33 eV and the highest occupied molecular orbitals (HOMO) from − 4.97 to − 5.33 eV. The opto-electrical properties can be influenced drastically by NHC ligands, which would be useful for rational design of optical functional materials.     

Synthesis and structural studies of a 1:2 adduct of silver(I) tetrakis(pyrazolyl)borate(III) with a tertiary phosphine

The synthesis and spectroscopic (IR, far-IR, ¹H and ³¹P NMR) characterization of the new complex Ag(pzTp)(PPh₃)₂ is reported, with a single crystal X-ray structure determination showing it to assume the form [(Ph₃P)₂Ag(pz₂Bpz₂)]. Although the silver atom is essentially four-coordinate P₂AgN₂, Ag–P 2.4154(4) Å, 2.5123(4) Å, Ag–N 2.315(1) Å, 2.357(1) Å at ca. 150 K, NMR spectroscopy clearly distinguishes between the bonding character of the two different phosphorus atoms.     

Synthesis and X-ray structural characterization of square-pyramidal copper(II) complex with aminoguanidine derivative

Aminoguanidine and its derivatives have shown antiglycation activity and are effective antioxidants. Complexes with ligands derived from aminoguanidine are relevant to both medicinal and bioinorganic chemistry. In this article, we describe the synthesis and characterization of a new mononuclear complex of copper(II) with a chelating ligand derived from aminoguanidine. Single crystals of the resulting complex were obtained by recrystallization from isopropanol. The molecular structure of the complex was obtained by X-ray diffraction which shows a distorted square pyramidal geometry, where copper(II) is coordinated to four nitrogen atoms (base of the pyramid) and to one chlorine atom (pyramid peak). The spectroscopic behavior (FT-IR and UV–vis) of both the complex and the ligand were examined.     

二（2—苯并咪唑亚甲基）胺过渡金属配合物的合成及表征

合成了二（２－苯并咪唑亚甲基）胺及其四种全新的过渡金属的双核配合物。通过元素分析,红外光谱和紫外光谱对配体及配合物进行了结构表征。