Complexes In DMSO Research Articles

ChemInform Abstract: Synthesis of Tertiary Aryl Amines of Various Aryl Halides and Secondary Amines Using ortho‐Palladated Complex of Tribenzylamine.

The activity of dimeric [Pd{C6H4(CH2N(CH2Ph)2)} (μ-Br)]2 complex as an efficient, air- and moisture-tolerant catalyst was investigated in amination reactions of various aryl halides with secondary amines. Substituted tertiary aryl amines were produced in excellent yields and short reaction times using catalytic amounts of this dimeric complex in DMSO at 120°C. Copyright © 2013 John Wiley & Sons, Ltd.

Synthesis, Characterization, Thermal Analyses, Crystal Structure Determination, and Luminescent Properties of a New Indium(III) Complex: [In(4,4′-dtbu-2,2′-bipy)Cl3(DMSO)].2DMSO

[In(4,4′-dtbu-2,2′-bipy)Cl3(DMSO)].2DMSO (1) complex was obtained from the reaction of 1 equivalent of InCl3.4H2O with 1 equivalent of 4,4′-di-tert-butyl-2,2′-bipyridine (4,4′-dtbu-2,2′-bipy) in a methanol solution. This compound was recrystallized in a DMSO/methanol solution to obtain suitable crystals for X-ray studies. This complex was characterized by elemental analysis, IR, UV-Vis, 1H NMR, 13C{1H} NMR, and luminescence spectroscopy and its structure was studied by the single-crystal diffraction method. The thermal stability of 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA).

Structure of Silver–N-Heterocyclic Carbenes in Solution: Evidence of Equilibration in DMSO at Very Different Time Scales by 1H NMR Experiments

Ag–N-heterocyclic carbene (NHC) complexes can occur as neutral [(NHC)AgX] and/or ionic [(NHC)2Ag][AgX2] species in solution. Herein, the behavior of four complexes bearing common bulky N,N′-diaryl NHCs was examined in DMSO. 1H NMR experiments performed systematically in CDCl3 and in DMSO-d6 were used to detect DMSO or chloride ion induced equilibration between the neutral and ionic forms at very different time scales. We observed that solubilization of IMesAgCl and SIMesAgCl in DMSO at 300 K led in less than a few minutes to a complete equilibration. Here, magnetization exchange rate constants were determined from EXSY experiments. In contrast, IPrAgCl and SIPrAgCl, which possess more bulky NHCs, were found to exhibit much lower exchange rates (or no exchange) at 300 K. IPrAgCl was shown to slowly generate an increasing amount of homoleptic cationic complex in DMSO for several hours before reaching equilibrium. In this case, the initial rate of formation of the cationic complex was determined.

Copper(II) Complexes of 2-(Methylthiomethyl)anilines: Spectral and Structural Properties and In Vitro Antimicrobial Activity

Copper(II) complexes of 2-(methylthiomethyl)anilines (1a–1f) have been obtained and characterized by elemental analyses, IR, electronic spectra, conductivity, and X-ray crystallography. The complexes (2a–2f) have the structural formula [CuCl2L] with the bidentate ligand coordinating through sulfur and nitrogen. The single crystal X-ray diffraction data reveal that the copper complex (2f) has a tetragonally distorted octahedral structure with long Cu–Cl equatorial bonds. Magnetic susceptibility measurements indicate the availability of one unpaired electron in the complexes and the conductivity measurements in DMF show their behaviour as nonelectrolytes. The solid reflectance spectra and the electronic spectra of the complexes in DMSO were determined. The ligands and their copper complexes were screened for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, and C. albicans. The methoxysubstituted complex (2c) showed more promising antibacterial activity against S. aureus and B. subtilis than other compounds at the concentration tested.

DFT, characterization and investigation of vibrational spectroscopy of 4-(4-hydroxy)-3-(2-pyrazine-2-carbonyl)hydrazonomethylphenyl-diazen-yl-benzenesulfonamide and its copper(II) complex

Azo-Schiff-base complex of Cu(II) has been synthesized and characterized by elemental, spectral and thermal studies. The conductance data indicate the non-electrolytic nature of the complex. The IR spectra of the prepared complex was suggested that the azo-Schiff-base ligand [4-(4-hydroxy)-3-(2-pyrazine-2-carbonyl)hydrazonomethylphenyl-diazen-yl-benzenesulfonamide] (H2L) behaves as a tri-dentate ligand through the carbonyl oxygen atom, azomethine nitrogen atom and phenolic oxygen atom (ONO). The surface morphology (SEM) of the ligand and its copper(II) complex was studied using SEM analysis. X-ray powder diffraction (XRD) helps to determine the cell parameters of the complex. Transmission electron microscopy (TEM) indicated spherical particles of ∼200nm diameter. The physico-chemical studies revealed octahedral geometry around copper ion. The EPR spectra of copper complex in DMSO at 300 and 77K were recorded and their salient feature was reported. The redox behavior of the ligand and its copper(II) complex were studied using cyclic voltammetry. Thermal properties and decomposition kinetics of copper(II) complex was investigated. The interpretation mathematical analysis and evaluation of kinetic parameters (E, A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats–Redfern (CR), Horowitz–Metzger (HM) and Piloyan–Novikova (PN) equations. Moreover, the density functional theory studies are discussed for ligand, using DFT/B3LYP with 6-31G* and 6-311G* level of theory, the absorption spectra has been computed by using time dependent at TD-DFT/B3LYP with 6-31G* and 6-311G* level of theory. The HOMO–LUMO energy gap of studied systems has been discussed.

Base‐Catalyzed Hydrolysis of a Ru II –Chloro–dmso Complex and Its Reactivity towards L ‐Methionine

Detailed NMR characterization of the reaction product with L-methionine, supported by theoretical calculations, indicated that the NH2 group is the primary target for coordination to the metal center and not the thioether moiety.

Synthesis, structural characterization and biological studies of copper complexes with 2-aminobenzothiazole derivatives

Novel copper complexes of 2-aminobenzothiazole derivatives were synthesized by the condensation of Knoevenagel condensate acetoacetanilide (obtained from substituted benzaldehydes and acetoacetanilide) and 2-aminobenzothiazole. They were thoroughly characterized by elemental analysis, IR, 1H NMR, UV–Vis., MS Spectra, molar conductance, magnetic moment and electrochemical studies. These spectral studies suggested that distorted square planar geometry for all the complexes. Molar conductance data and magnetic susceptibility measurements provide evidence for monomeric and neutral nature of the complexes. The electrochemical behaviour of the ligand and complexes in DMSO at 298K was studied. The present ligand systems stabilize the unusual oxidation states of copper ion during electrolysis. Antibacterial screening of the ligands and their complexes reveal that all the complexes show higher activities than the free ligands.

Synthesis, characterization and electrochemical studies of heterometallic manganese(IV)–zinc(II) and manganese(IV)–copper(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

Five manganese(IV) complexes [Mn(L)(bpy)] (1) and heterobimetallic complexes [MMn(L)Cl2(H2O)4]·1.5H2O (M=ZnII(2), CuII(3)) and [MnM(L)(bpy)Cl2] (M=ZnII(4), CuII(5)] have been synthesized from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (H4L) in methanol medium. The composition of the complexes have been established based on the data obtained from analytical, thermoanalytical and mass spectral studies. The structures of the complexes have been discussed in the light of molar conductance, magnetic moment, electronic, EPR, IR, FT-IR spectroscopic studies and transmission electron microscopies. The molar conductance values of these complexes in DMSO suggest their non-electrolytic nature. The μeff value for the complexes (1), (2) and (4) fall in the range 3.82–4.12 BM characteristic of the presence of the manganese(IV) in them. The complex (3) has μeff value of 3.70 BM at RT indicating considerable antiferromagnetic interaction between Mn(IV) and Cu(II). The μeff value of 4.72 BM for complex (5) is slightly lower than 4.90 BM for S=2 ground state. In the complex (1) to (3), the ligand is coordinated to the metal centres as tetradentate ligand while in the complexes (4) and (5) as hexadentate ligand. Manganese(IV) has distorted octahedral stereochemistry in all complexes. Copper(II) has distorted octahedral and square planar stereochemistry in complexes (3) and (5) while zinc has distorted octahedral and tetrahedral stereochemistry, respectively. EPR studies of the complexes are also reported. The electron transfer reactions of the complexes have also been investigated by cyclic voltammetry.

Synthesis, spectroscopy, and magnetic characterization of copper(II) and cobalt(II) complexes with 2-amino-5-bromopyridine as ligand

The synthesis, spectroscopic, and magnetic characterization of two new copper(II) and cobalt(II) complexes are described. Both two compounds have the general formula [M(L)2(Cl)2] (M = Cu (I), Co (II); L = 2-amino-5-bromopyridine). These complexes were prepared in one-step synthesis and characterized by elemental analysis, FT-IR, UV-Vis, and EPR spectroscopy. Moreover, the single crystal structure of complex I was studied by the X-ray diffraction method. This compound consists of mononuclear units consisting of two ligands linked to metal via the nitrogen of pyridine ring. The UV-Vis spectra of copper(II) and cobalt(II) complexes show three and five absorption bands, respectively, attributed to the d-d transition of the metal ion, ligand → metal charge transfer and π → π* or n → π* transitions of the ligand. The FT-IR spectra show MN2Cl2 vibrations at 500–300 cm−1. The complexes show room temperature magnetic moments of 1.78 and 4.12 μB for Cu(II) and Co(II), respectively. The X-band electron spin resonance (ESR) spectra of Cu(II) complex in DMF or DMSO frozen at liquid nitrogen temperature show the typical ΔMS = ±1 transition.

Metal ion detection by naphthylthiourea derivatives through ‘turn-on’ excimer emission

The detection of multiple heavy and transition metal (HTM) ions has been achieved through ‘turn-on’ excimer emission by three naphthylthiourea derivatives (L1, L2 and L3) in DMSO. Mechanistic studies suggest that the photoinduced electron transfer from the thiourea moiety to the naphthalene excimer is suppressed in the presence of Hg2+, Cu2+, Co2+ and Ag+, leading to enhanced emission intensity from the excimer. Interestingly, the ligands were able to detect all the above said HTM ions through ‘turn-on’ fluorescence, at micromolar concentrations of the analytes. While Hg2+ and Cu2+ ions were detected by all the ligands, Co2+ and Ag+ ions were detected only by L2 and L3, respectively. Furthermore, the detection of Hg2+ ions by L1 has been demonstrated in aqueous condition, wherein the fluorescence quantum yield showed the highest value (0.25 ± 0.01), compared to other metal–ligand complexes in DMSO. To the best of our knowledge, this is the first report regarding multi-ion detection by thiourea based ligands through ‘turn-on’ excimer emission.

Synthesis of tertiary aryl amines of various aryl halides and secondary amines using ortho‐palladated complex of tribenzylamine

The activity of dimeric [Pd{C6H4(CH2N(CH2Ph)2)} (μ‐Br)]2 complex as an efficient, air‐ and moisture‐tolerant catalyst was investigated in amination reactions of various aryl halides with secondary amines. Substituted tertiary aryl amines were produced in excellent yields and short reaction times using catalytic amounts of this dimeric complex in DMSO at 120°C. Copyright © 2013 John Wiley & Sons, Ltd.

Synthesis, structural and corrosion inhibition properties of some transition metal(II) complexes with o-hydroxyacetophenone-2-thiophenoyl hydrazone

A series of metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with o-hydroxyacetophenone-2-thiophenoyl hydrazone (Hhath) have been synthesized. The metal complexes were characterized with the help of elemental analyses, magnetic susceptibility measurements, electronic, IR, NMR and ESR spectral techniques. The structures of Hhath ligand and its Mn(II) complex were determined by single crystal X-ray diffraction studies. Hhath displays E configuration about the >CN– bond. The molecular structure of ligand is stabilized by inter- and intra-molecular H-bonding whereas, [Mn(hath)2] complex is stabilized by π–π and C–H⋯π interactions. In all the complexes, ligand behaves as mono-anionic tridentate and binds to the metal ions via deprotonated phenolate-oxygen, carbonyl-oxygen and azomethine-nitrogen. Magnetic moments and electronic spectral studies suggest an octahedral geometry around metal ion in all the complexes. Frozen solution ESR spectra of Cu(II) complex in DMSO gives axial signal and suggests 2B1g as the ground state. The ligand and its metal complexes showed appreciable corrosion inhibition activity against corrosion of mild steel in 1M HCl solution. The inhibition efficiency of the inhibitors was found to increase with time up to 12h and thereafter almost constant. The metal complexes showed greater inhibition efficiency than the free ligand.

Synthesis, characterization and catalytic application of some novel binuclear transition metal complexes of bis-(2-acetylthiophene) oxaloyldihydrazone for C[sbnd]N bond formation

In the present work, synthesis, characterization and catalytic properties of some novel complexes derived from a Schiff base bis-(2-acetylthiophene) oxaloyldihydrazone with various transition metal ions and precursors have been reported. The complexes were characterized by IR, NMR, ESR, electronic and mass spectroscopy, magnetic moments and TGA studies. Molecular structures of the ligand and its Cu(I) complex are determined by single crystal X-ray diffraction. Electronic spectral studies exhibit a 6-coordinated geometry around metal centers for Co(II), Ni(II) and Cu(II) complexes, whereas 4-coordinated geometry for Cu(I) and Zn(II) complexes. ESR spectra indicate a distorted octahedral geometry for Cu(II) complex in DMSO frozen solution. The electro-chemical studies of Ni(II) and Cu(II) complexes reveal a metal based reversible redox behavior. The catalytic activity of the complexes has been demonstrated for the cross-coupling of arylboronic acids with various N-nucleophiles. Ni(II) complex exhibited the maximum impact on catalytic activity with the product yields ranging from 62% to 82%.

Mononuclear copper(II) complexes of bis-triazole-based macrocyclic Schiff base hydrazones: direct synthesis, EPR studies, magnetic and thermal properties

Mononuclear copper(II) complexes of 1,2,4-triazole-based Schiff base macrocyclic hydrazones, III and IV, have been reported. The prepared amorphous complexes have been characterized by spectroscopic methods, electron spray ionization mass spectrometry, and elemental analysis data. Electrochemical studies of the complexes in DMSO show only one quasi-reversible reduction wave at +0.43 V (ΔE = 70 mV) and +0.42 V (ΔE = 310 mV) for III and IV, respectively, which is assigned to the Cu(II) → Cu(I) reduction process. Temperature dependence of magnetic susceptibilities of III and IV has been measured within an interval of 2–290 K. The values of χM at 290 K are 1.72 × 10−3 cm3 mol−1 and 1.71 × 10−3 for III and IV, respectively, which increases continuously upon cooling to 2 K. EPR spectra of III and IV in frozen DMSO and DMF were also reported. The trend g|| > g⊥ > ge suggests the presence of an unpaired electron in the dx2−y2 orbital of the Cu(II) in both complexes. Furthermore, spectral and antimicrobial properties of the prepared complexes were also investigated.

Solvent-dependent conformational polymorphism in the crystal structure of mercuric bromide adduct of 1,1′-bis(diphenylphosphino)ferrocene

Two polymorphs of dinuclear mercury–iron complexes, [HgBr2(dppf)] (1) where dppf is 1,1′-bis(diphenylphosphino)ferrocene, are prepared and crystal structures are determined by X-ray crystallography. The reaction of mercury(II) bromide with dppf in methanol–dichloromethane led to orange block polymorph. After crystallization of this complex in DMSO, a red needle polymorph was obtained.

Fe2L3]4+ Cylinders Derived from Bis(bidentate) 2-Pyridyl-1,2,3-triazole “Click” Ligands: Synthesis, Structures and Exploration of Biological Activity

A series of metallosupramolecular [Fe2L3](BF4)4 “click” cylinders have been synthesized in excellent yields (90%–95%) from [Fe(H2O)6](BF4)2 and bis(bidentate) pyridyl-1,2,3-triazole ligands. All complexes were characterized by elemental analysis, IR, UV-vis, 1H-, 13C- and DOSY-NMR spectroscopies and, in four cases, the structures confirmed by X-ray crystallography. Molecular modeling indicated that some of these “click” complexes were of similar size and shape to related biologically active pyridylimine-based iron(II) helicates and suggested that the “click” complexes may bind both duplex and triplex DNA. Cell-based agarose diffusion assays showed that the metallosupramolecular [Fe2L3](BF4)4 “click” cylinders display no antifungal activity against S. cerevisiae. This observed lack of antifungal activity appears to be due to the poor stability of the “click” complexes in DMSO and biological media.

Spectroscopic and physico-chemical characterization of Ir(I) and Ru(III) complexes of 32-membered unsymmetrical dinucleating macrocyclic ligand

Reactions of the macrocyclic ligand [L·2HClO4] with the reactants [Ir(CO)(Ph3P)2Cl] and [RuCl3(AsPh3)2CH3OH], produces bimetallic complexes with the stoichiometries [Ir2L(Ph3P)2Cl(ClO4)] (I) and [Ru2LCl4(ClO4)2] (II), respectively. Physico-chemical and spectroscopic data of the complexes confirms the encapsulation of two metal ions in the macrocyclic cavities via coordination through nitrogen atoms of the unsymmetrical aza groups, which results in homo-dinuclear macrocyclic complexes. The macrocyclic ligand has accommodated both the lower, Ir(I), and higher, Ru(III), oxidation states of metal ions, which shows the flexible nature and capability of macrocycle to form stable complexes. The mode of bonding and geometry of the complexes have been established on the basis of FT-IR, NMR, ligand field spectral, magnetic susceptibility and conductivity measurements. The thermodynamic first ionic association constants (K1), corresponding free energy change (ΔG) and other related parameters from conductometric studies using the Fuoss and Edelson method of complexes in DMSO have been determined and discussed.

Preparation and characterization of some gold nanometric compounds with simple organic materials as precursor: Spectroscopic, biological and anti-cancer assessments

This study reports the synthesis of the gold nano-particles assembly mediated by some amino acids, such as ornithine (Orn), isoleucine (i-Leu), serine (Ser) and histidine (His). The structural characterization of [Au2(AA)2(Cl)2]2+Cl2 (where AA=Orn, i-Leu, Ser and His) compounds were done by using elemental analysis, molar conductance, FT-IR, Raman, UV–vis, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) spectroscopy. It has been found from the elemental analysis, spectroscopic and the thermal studies that the amino acids ligand behaves as bidentate ligand forming chelates with 1:1 (metal:ligand) stoichiometry. The molar conductance measurements of the complexes in DMSO indicate that the complexes are electrolyte. The thermal decomposition mechanisms were discussed for compounds Orn, i-Leu, Ser and His and occurred in two consecutive steps. The TG curves of the gold(III) compounds suggest the loss of the ligands (Orn, i-Leu, Ser and His) within two steps, with probable formation of a gold free metal. The biological and anti-cancer activities (Breast carcinoma cells (MCF-7-cell line) of the nano-sized complexes have also been studied.

Synthesis, Spectroscopy, and Magnetic Characterization of Copper(II) and Cobalt(II) Complexes with 2-Amino-5-bromopyridine as Ligand

The synthesis, spectroscopic, and magnetic characterization of two new copper(II) and cobalt(II) complexes are described. Both two compounds have the general formula [M(L)2(Cl)2], in which L= 2-amino-5-bromopyridine. These complexes were prepared in one-step synthesis and characterized by elemental analysis, FTIR, UV-Vis, and EPR spectroscopy. Moreover, the single crystal structure of complex (1) was studied by the X-ray diffraction method. This compound consists of mononuclear units consisting of two ligands linked to metal via the nitrogen of pyridine ring. The UV-Vis spectra of copper(II) and cobalt(II) complexes show three and five absorption bands, respectively, attributed to the d-d transition of the metal ion, ligand → metal charge transfer, and π→π∗ or n→π∗ transitions of the ligand. The FTIR spectra show MN2Cl2 vibrations at 500–300 cm−1. The complexes show room temperature magnetic moments of 1.78 BM and 4.12 BM for Cu(II) and Co(II), respectively. The X-band electron spin resonance (ESR) spectra of Cu(II) complex in DMF or DMSO frozen at liquid nitrogen temperature show the typical ΔMS=±1 transition.

Trichloridothallium(III) Complexes with Bipyridine Derivatives: From Structure to Luminescence Properties.

Several new thallium(iii) complexes, [Tl(4,4′-dmbpy)Cl3(DMSO)]·H2O (1), [Tl(4,4′-dtbpy)Cl3(DMSO)] (2), [Tl(5,5′-dmbpy)Cl3(DMSO)]·(5,5′-dmbpy) (3), and [Tl(6-mbpy)Cl3(DMSO)] (4) (4,4′-dmbpy = 4,4′-dimethyl-2,2′-bipyridine, 4,4′-dtbpy = 4,4′-ditert-butyl-2,2′-bipyridine, 5,5′-dmbpy = 5,5′-dimethyl-2,2′-bipyridine, and 6-mbpy = 6-methyl-2,2′-bipyridine) were prepared from the reaction of TlCl3 with the mentioned ligands in DMSO. The four complexes were fully characterised and their structures were determined by X-ray diffraction. These complexes have a bidendate nitrogenous ligand, a DMSO molecule, and three chloride anions (in the facial position) attached to a TlIII metal centre in a distorted octahedral environment. The stability of the complexes in DMSO is evident by a 203,205Tl–1H spin–spin coupling, determined by 1H NMR spectroscopy. Interestingly, six bond hydrogen–thallium coupling was observed with a coupling constant of 6JTlH = 20 Hz. The absorption and emission spectra of the complexes were investigated. These studies revealed that upon coordination to TlIII, the luminescent intensity is increased in comparison with the related unbound ligands.