Synthesis and characterization of a novel Mn(III)-(γ-diketone) complex with catalytic and antifungal activity

Abstract

A novel Mn(III) complex with γ-diketone having general formula [Mn(hdo)₃], where hdo?=?hexane-2,5-dione ligand, has been synthesized and characterized using UV–vis, FT-IR, ESI-mass and EPR spectra, elemental analysis, powder X-ray diffraction, SEM, and magnetic susceptibility measurements. The X-ray diffraction studies reveal that it has monoclinic lattice system with C₂/C space group and the unit cell dimensions are a?=?9.92245 Å, b?=?10.50696 Å, and c?=?9.80835 Å. The particle size of this complex has been found to be 32.1?nm. The complex was evaluated for its antifungal activity against Aspergillus flavus, Aspergillus niger, and Aspergillus terreus fungal species. The results indicate that the minimum inhibitory concentration of the synthesized complex was 8?ppm for A. niger while for A. flavus and A. terreus it was 6?ppm. β-Diketone Mn(III) complexes inhibit the fungal growth only partially. This communication is the first report of transformation of a keto-group to an ester group catalyzed by a metal complex.     

Simultaneous determination of gold(III), palladium(II), and platinum(IV) with N-phenyl-N′-(sodium p-aminobenzenesulfonate)thiourea

The preparation and characteristics of a new water-soluble reagent, N-phenyl- N'-(sodium p-aminobenzenesulfonate)thiourea (PPT) are described. In the presence of cetyltrimethylammonium bromide (CTMAB) PPT reacts with Au(III), Pd(II), and Pt(IV) to form colored complexes with absorption maxima at 317 nm, 306.1 nm, 778.4 nm, respectively. Optimum conditions for color development were studied. The reagent was used for the simultaneous determination of Au(III), Pd(II), and Pt(IV); Amberlyst A-26 macropore anion-exchange resin was used as a means of rapid separation. The method was applied to the determination of Au(III), Pd(II), and Pt(IV) in catalyst materials and anode mud with satisfactory results.     

Exploring the reactions of β-amyloid (Aβ) peptide 1-28 with Al(III) and Fe(III) ions

The reactions of human β-amyloid peptide 1-28 (Aβ28) with Al(III) and Fe(III) ions were investigated by (1)H NMR and electrospray ionization mass spectrometry (ESI-MS) under pH conditions close to physiological ones. (1)H NMR titrations, performed in the 5.3-8.0 pH range, revealed that no measurable amounts of Aβ28-Al(III) or Aβ28-Fe(III) adducts are formed; such metal adducts could not be obtained even by changing a number of experimental conditions, e.g., temperature, buffer, nature of the salt, etc. These observations were later confirmed by ESI-MS. It is thus demonstrated that Aβ28, at physiological pH, is not able to form binary complexes with Al(III) and Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation. The biological implications of these findings are discussed in the frame of current literature.     

Extraction chromatographic study of aluminium(III) and mutual separation of aluminium(III), gallium(III), indium(III) and thallium(III) with N-n-octylaniline

A selective method has been developed for extraction chromatographic studies of aluminium(III) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline (liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(III) was quantitatively extracted with the 0.065 mol/L N-n-octylaninine from 0.013 to 0.05 mol/L sodium succinate at a flow rate of 1.0 mL/min. The extracted metal ion has been recovered by eluting with 25.0 mL of 0.05 mol/L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration, the reagent concentration, the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient (KdAl(III)) versus N-n-octylaniline concentrationin 0.005 and 0.007 mol/L sodium succinate gave theslopes 0.5 and 0.7 respectively and showed theprobable composition of theextracted species was 1:1 (metal to amine ratio) and the nature of extracted species is [RR''NH2+ Al succinate2-] org. .The extraction of aluminium(III) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(III) has been separated from multicomponent mixtures, pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(III), indium(III), gallium(III) and thallium(III) has been developed by using suitable masking agents. The method is fast, accurate and precise.     

A novel pH-sensitive (±)-α-tocopherol-5-fluorouracil adduct with antioxidant and anticancer properties

A novel pH-sensitive (±)-α-tocopherol-5-fluorouracil (VE-5-FU) adduct with antioxidant and anticancer properties for antioxidant-based cancer chemoprevention was synthesized and utilized for selective drug release in the stomach.     

Cytotoxic properties of platinum(IV) and dinuclear platinum(II) complexes and their ligand substitution reactions with guanosine-5′-monophosphate

The substitution reaction of the Pt(IV) complex [PtCl₄(bipy)] with guanosine-5??-monophosphate (5??-GMP) was studied by UV?CVis spectrophotometry. This reaction was investigated under pseudo-first-order conditions at 37?°C in 25?mM Hepes buffer (pH?=?7.2) in the presence of 10?mM NaCl to prevent the hydrolysis of the complex. The substitution of chlorides in [{trans-Pt(NH₃)₂Cl}₂(??-1,2-bis(4-pyridyl)ethane)](ClO₄)₂ (Pt3) complex by 5??-GMP was followed by ¹H NMR spectroscopy under second-order conditions. Very similar values for the rate constants of both substitution steps were obtained. The Pt(IV) complexes, [PtCl₄(bipy)] and [PtCl₄(dach)], as well as dinuclaer Pt(II) [{trans-Pt(NH₃)₂Cl}₂(??-pyrazine)](ClO₄)₂ (Pt1), [{trans-Pt(NH₃)₂Cl}₂(??-4,4??-bipyridyl)](ClO₄)₂?·?DMF (Pt2) and [{trans-Pt(NH₃)₂Cl}₂(??-1,2-bis(4-pyridyl)ethane)](ClO₄)₂ (Pt3) complexes, displayed potent cytotoxic activity against human ovarium carcinoma cell line TOV21G and lower activity toward human colon carcinoma HCT116 cell line at the same concentrations. Our data indicate that these platinum complexes could be explored further, as potential therapeutic agents for ovarian cancer.     

Phenylmethoxybis(tetrazolium) ion-association complexes with an anionic indium(III) — 4-(2-pyridylazo)resorcinol chelate

Complex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), phenylmethoxybis(tetrazolium) salt (MBT), water and chloroform. The following MBTs, which differ only by the number of -NO₂ groups in their cationic parts, were used: 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis(2,5-diphenyl-2H-tetrazolium chloride) (Blue Tetrazolium chloride, BT), 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (Nitro Blue Tetrazolium chloride, NBT) and 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2,5-di(4-nitrophenyl)-2H-tetrazolium chloride] (Tetranitro Blue Tetrazolium chloride, TNBT). The composition of the formed ternary complexes was determined, In:PAR:MBT=1:2:2, and the optimum conditions for their extraction found: pH, shaking time, concentration of the reagents and the sequence of their addition. Some key constants were estimated: constants of extraction (K_ex), constants of association (β) and constants of distribution (K_D). BT appears to be the best MBT for extraction of the In(III)-PAR species, [In³⁺(OH)₃(PAR)₂]^4?, (Log K_ex=10.9, Log β=9.8, Log K_D=1.12, R%=92.7%). Several additional characteristics concerning its application as extraction-spectrophotometric reagent were calculated: limit of detection (LOD = 0.12 μg cm^?3), limit of quantification (LOD = 0.40 μg cm^?3) and Sandell’s sensitivity (SS =1.58 ng cm^?2); Beer’s law is obeyed for In(III) concentrations up to 3.2 μg mL^?1 with a molar absorptivity coefficient of 7.3×10⁴ L mol^?1 cm^?1 at λ_max=515 nm.      

The Interaction of Arsenazo III with Nd(III)—A Chemometric and Metrological Analysis

Interactions of Arsenazo III with Nd(III) in aqueous solutions (pH range 3 to 4) were studied using a spectrophotometric method. Some discrepancies are present in literature concerning the concentrations of the prevailing species and their composition. Threshold bootstrap computer-assisted target factor analysis (TB CAT) was applied to the evaluation of UV-VIS spectra of Arsenazo III in aqueous solutions containing varying amounts of neodymium(III) ions. The thus obtained experimental data are interpreted with consideration of the measurement uncertainties affecting this system. Within the limits of resolution of the experimental method, two complexes NdAazo and Nd(Aazo)₂ were indicated in the studied pH range. The values of formation constants for log ₁₀ β ₁₁ fall in the range 4.9 to 6.3 and for log ₁₀ β ₁₂ fall between 10.5 and 12.1.     

Development of an efficient liquid-phase peptide synthesis protocol using a novel fluorene-derived anchor support compound with Fmoc chemistry; AJIPHASE®

The development of a novel fluorene-type anchor support molecule and a liquid-phase peptide synthesis protocol (AJIPHASE®) is reported. With this support molecule, the synthesis of a protected peptide with a free carboxyl group could be carried out by repeated coupling/deprotection reactions and isolation by simple precipitation. Cleavage is performed under mild acidic conditions (2% TFA/CHCl₃ or hexafluoroisopropanol) to release the products in good yield and purity. There were no signs of either diketopiperazine formation or the removal of protective groups in the side-chain.     

Slow magnetic relaxation and electron delocalization in an S = 9/2 iron(II∕III) complex with two crystallographically inequivalent iron sites

The magnetic, electronic, and Mo?ssbauer spectral properties of [Fe(2)L(μ-OAc)(2)]ClO(4), 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H(2)L, indicate that 1 is a class III mixed valence iron(II∕III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe(2)](V) cationic configuration with a S(t) = 9∕2 ground state. Fits of the dc magnetic susceptibility between 2 and 300 K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm(-1) for an electron transfer parameter, B, of 950 cm(-1), a zero-field uniaxial D(9∕2) parameter of -0.9(1) cm(-1), and g = 1.95(5). In agreement with the presence of uniaxial magnetic anisotropy, ac susceptibility measurements reveal that 1 is a single-molecule magnet at low temperature with a single molecule magnetic effective relaxation barrier, U(eff), of 9.8 cm(-1). At 5.25 K the Mo?ssbauer spectra of 1 exhibit two spectral components, assigned to the two crystallographically inequivalent iron sites with a static effective hyperfine field; as the temperature increases from 7 to 310 K, the spectra exhibit increasingly rapid relaxation of the hyperfine field on the iron-57 Larmor precession time of 5 × 10(-8) s. A fit of the temperature dependence of the average effective hyperfine field yields |D(9∕2)| = 0.9 cm(-1). An Arrhenius plot of the logarithm of the relaxation frequency between 5 and 85 K yields a relaxation barrier of 17 cm(-1).     

Complexation of Eu(III), Am(III) and Cm(III) with Dicarboxylates: Thermodynamics and Structural Aspects of the Binary and Ternary Complexes

The complexation of Eu(III), Am(III) and Cm(III) with dicarboxylate anions with O, N or S donor groups was measured in I=6.60 mol⋅kg⁻¹ (NaClO₄) at temperatures of 0–60 °C by potentiometry and solvent extraction. The complexation thermodynamics of these complexes show that their stability is due to highly favorable complexation entropies because the complexation enthalpies are endothermic. Luminescence studies with Eu(III) and Cm(III) were used to measure the hydration numbers of the complexes. NMR spectra of ¹H and ¹³C were used to determine the binding modes of La(III) with the ligands. The formation of 1:1:1 ternary complexes of M(EDTA)⁻ with the dicarboxylate ligands was studied to determine changes in coordination of the metal cation with formation of the ternary species. The complexation of ternary complexes changes from bidentate to monodentate as the chain length between the binding sites of the dicarboxylates increases from 1 (malonate) to 4 (adipate). DFT computations were used to confirm the structural aspects of the interaction of these complexes.     

Complexes of palladium,platinum and rhodium with 2,2′-biquinoline and 2-(2′-pyridyl)quinoline

Summary The reactions of 2,2-biquinoline(biq) with M(PhCN)₂X₂ (M=Pd; X=Cl or Br; M=Pt, X=Cl, Br or I), K₂PtCl₄ and RhCl₃·3H₂O and of 2-(2-pyridyl)quinoline (pq) with K₂PtCl₄ and RhCl₃·3H₂O have been investigated. The isolated complexescis-[Pd(biq)X₂] (X=Cl or Br),cis-[Pt(biq)Cl₂],cis-[Pt(biq)Cl₂]·H₂O,trans-[Pt(biq)₂Br₂]·5H₂O, [Pt₃(biq)₂I₆],mer-[Rh(biq)Cl₃-(H₂O)] andmer-[Rh(pq)Cl₃(H₂O)] have been characterized by elemental analyses, conductivity measurements, i.r., electronic, and¹H n.m.r. spectra. The reaction of pq with K₂PtCl₄ in 1M H₂SO₄ gave the salt 2-(2-pyridyl) quinolinium tetrachloroplatinate(II) pentahydrate, (pqH)₂[PtCl₄]·5H₂O; when the reaction was carried out in aqueous acetone,cis-[Pt(pq)Cl₂] was obtained. A new method for the synthesis ofcis-[Rh(biq)₂X₂]X (X=Cl or Br) is described; both compounds have been further characterized by¹H n.m.r.     

Thermal behavior and other properties of Pr(III), Sm(III), Eu(III), Gd(III), Tb(III) complexes with 4,4′-bipyridine and trichloroacetates

A novel mixed-ligand complexes with empirical formulae: Ln(4-bpy)_1.5(CCl₃COO)₃·nH₂O (where Ln(III) = Pr, Sm, Eu, Gd, Tb; n = 1 for Pr, Sm, Eu and n = 3 for Gd, Tb; 4-bpy = 4,4′-bipyridine) were prepared and characterized by chemical, elemental analysis and IR spectroscopy. Conductivity studies (in methanol, dimethylformamide and dimethylsulfoxide) were also described. All complexes are crystalline. The way of metal–ligand coordination was discussed. The thermal properties of complexes in the solid state were studied under non-isothermal conditions in air atmosphere. During heating the complexes decompose via intermediate products to the oxides: Pr₆O₁₁, Ln₂O₃ (for Sm, Eu, Gd) and Tb₄O₇. TG-MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis of Pr(III) and Sm(III) compounds in air.     

Properties of η-pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes with quinolin-8-ol and their cytostatic activity

Reaction of dimers [M(η⁵-C₅Me₅)Cl₂]₂ (M-Rh, Ir) with quinolin-8-ol in molar ratio 1:2 leads to formation of monomer complexes [Rh(η⁵-C₅Me₅)Cl(qol)] (1) and [Ir(η⁵-C₅Me₅)Cl(qol)] (2) (qol = quinolin-8-olate). Compounds 1 and 2 have been characterized with elemental analysis and spectroscopic methods. ¹H NMR spectra revealed that quinolin-8-olate is coordinated via oxygen and nitrogen atoms. The ¹H NMR and ¹³C NMR spectra showed that carbon and hydrogen atoms of pentamethylcyclopentadienyl ligand are equivalent. The structure of rhodium complex has been calculated using DFT B3LYP method. The calculated geometry of complex 1 agrees very well with data found for rhodium complexes containing Cl, C₅Me₅ and qol ligands. Both complexes are active antitumor and antibacterial agents.     

Thermal performance improvement in water nanofluid/GNP–SDBS in novel design of double-layer microchannel heat sink with sinusoidal cavities and rectangular ribs

In this numerical study, laminar flow of water nanofluid/GNP–SDBS (graphene nanoplatelet–sodium dodecylbenzene sulfonate) for 0–0.1% solid nanoparticles mass fraction was investigated for Reynolds numbers of 50–1000 in 3D space via finite volume method. In the newly proposed microchannel design, the cooling fluid is moving in countercurrent in the upper and lower layers of the microchannels, and there are cavities and sinusoidal routes on the solid walls of the microchannel, and the presence of rectangular ribs on the flow centerline along the fluid path enhances mixing for cooling fluid and creates better heat transfer for warm surfaces. The results of this study show that this special design of the microchannel can have a substantial increase in Nusselt number and heat transfer so that in the considered geometry by adding solid nanoparticles mass fraction it is possible to increase average Nusselt number for each Reynolds number by approximately 20%. Also, the mixing of the fluid because of formation of secondary flows has a strong effect on making the temperature distribution uniform in the cooling fluid and solid bed (wall) of the microchannel, especially in the lower layer. The upper layer of the microchannel always has a lower temperature due to indirect contact with heat flux compared with the lower layer. In this study, by increasing Reynolds number and mass fraction of solid nanoparticles the Nusselt number is increased and heat resistance of the lower wall of the microchannel is reduced. Based on the investigation of flow field and heat transfer, the use of the proposed design of the microchannel is recommended for Reynolds number less than 300.

     

Complexes of Iron(III) and Chrom(III) Salen and Saloph Schiff Bases with Bridging 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine

Four new trinuclear Fe(III) and Cr(III) complexes involving tetradenta Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(saloph H₂) with 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine (TNPI-TRIPOD) have been synthesized and characterized by means of elemental analysis carrying out ¹H-NMR., IR spectroscopy, thermal analyses and magnetic susceptibility measurements. The complexes can also be characterized as high-spin distorted octahedral Fe(III) and Cr(III) bridged by nitro. The nitro play a role as bridges for weak anti-ferromagnetic intramolecular exchange.     

Coordination compounds of europium(III) and samarium(III) dibenzoylmethanates with 5-phenyl-2-(2′-pyridyl)-7,8-benzo-6,5-dihydro-1,3,6-triazaindolizine

Novel heteroligand europium(III) and samarium(III) complexes with dibenzoylmethane (HDBM) and 5-phenyl-2-(2??-pyridyl)-7,8-benzo-6,5-dihydro-1,3,6-triazaindolizine (L), Ln(DBM)₃L (Ln = Eu, Sm), were synthesized. The structure of the europium complex was determined by X-ray diffraction. It was shown that the use of L as an auxiliary ligand increases the luminescence intensity of lanthanides severalfold as compared with analogous complexes containing phenanthroline as the second ligand.     

Liquid–liquid extraction of neodymium (III) and europium (III) using synergic mixture of furosemide and tribenzylamine in benzyl alcohol

The extraction behavior of Nd(III) and Eu(III) with 0.05 mol dm⁻³ furosemide in benzyl alcohol as single acidic extractant and then with equimolar (0.05 mol dm⁻³) synergic mixture of furosemide as acidic extractant and tribenzylamine as neutral donor in benzyl alcohol has been studied from aqueous solutions of pH 1 to 6. The effect of various parameters and of various cations and anions on the extraction of these metal ions was investigated. The composition of the extracted adducts was determined by slope analysis method that came out to be [(M(FS)₂)⁺ (CH₃COO)⁻] and [M(FS)₃·3TBA] where M = Nd(III) and Eu(III).

     

Synthesis,crystal structure and other properties of the complexes of Er(III), Yb(III) and Lu(III) with 4,4′-bipyridine and dichloroacetates

A novel mixed-ligand complexes of Er(III), Yb(III) and Lu(III) with title ligands were prepared and characterized by chemical and elemental analysis and IR spectroscopy, conductivity (in methanol, dimethyloformamide and dimethylsulphoxide). The thermal properties of complexes in the solid state were studied. The mode of metal–ligand coordination was discussed. The title compounds are isomorphic and isostructural in solid state. All atoms in studied compounds lie in general positions but occurrence of inversion on the midpoint of the bond linking two pyridine rings leads to existence in asymmetric unit one complex molecule and half of outer coordination sphere 4-bpy molecule. All chelating carboxylate groups are symmetrically bonded to the metal cations. The molecules of studied compounds are connected to the three dimensional network via O–H···O and O–H···N intermolecular hydrogen bonds. In the structures also exist C–H···O, C–H···Cl weak hydrogen bonds and π····π stacking interactions.     

The Study on the Stability Constant and Species Distribution of Eu (III) and Tb (III) Complexes with BDBPH

Biomimetic hydrolysis of DNA or RNA is of increasing importance in biotechnology and medicine. The ability to cleave nucleic acids efficiently, in a non-degradative manner, and with high levels of selectivity for site or structure will be required by many applications for the manipulation of genes, the design of structural probes and the development of novel therapeutics1. There has been much interest in the development of lanthanide complexes as nucleic acid cleavage agents. It has been fou…