Synthesis and characterization of Fe(III) and Pb(ll) complexes with 3-hydroxypyridine-2(1H)-thiones

Two kinds of 3-hydroxypyridine-2(1H)-thiones were synthesized. The visible (VIS) spectroscopic analysis indicated that 3-hydroxy-1-methylpyridine-2(1H)-thione (4a) and 3-hydroxy-1-(2-hydroxyethyl)pyridine-2(1H)-thione (4b) formed stable 3:1 Fe(III) complexes. The stability constant of the 4b-Fe(III) complex was estimated from the competitive reaction with EDTA and was found to be 36.7 in logbeta3. Treatment of compound 4b with Ga(acac)3 in D2O:CD3OD (9:1) solution afforded 3:1 Ga(Ill) complex, which was assigned by means of 1H nuclear magnetic resonance (1H NMR) spectroscopy. Treatment of compound 4b with Pb(NO3)2 gave 4b-Pb(II) complex. The Pb(II) selectivity over biologically relevant Mg(ll) and Ca(ll) was remarkably improved by adopting N-hydroxyethyl functionality instead of N-methyl group.     

One-Pot Self-Assembly of Dinuclear,Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO₄⁻, CH₃CO₂⁻, Cl⁻, NO₃⁻), sodium azide (NaN₃), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence Co^IICo^III: [Co₂^III(H₂L⁻¹)₂(AP⁻¹)(N₃)](ClO₄)₂ (1), [Co₄(H₂L⁻¹)₂(µ₃-1,1,1-N₃)₂(µ-1,1-N₃)₂Cl₂(CH₃OH)₂]·4CH₃OH (2), [Co₂^IICo₂^III(HL⁻²)₂(µ-CH₃CO₂)₂(µ₃-OH)₂](NO₃)₂·2CH₃CH₂OH (3), and [Co₂^IICo₂^III (H₂L1²⁻)₂(THMAM⁻¹)₂](NO₃)₄ (4). In 1, two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.5430(11) Å) Co-Co intermetallic separation with a coordination number of 7, a rare feature for cobalt(III). In 2, two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ₃-1,1,1-N₃ azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N₃ and two μ₃-1,1,1-N₃ azido bridges generating tetranuclear cationic [Co₄(H₂L⁻¹)₂(µ₃-1,1,1-N₃)₂(µ-1,1-N₃)₂Cl₂(CH₃OH)₂]²⁺ units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the a-axis through H-bonding. In 3, HL²⁻ holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CH₃CO₂⁻, and μ₃-OH⁻ bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ₃-OH⁻ bridges generating cationic tetranuclear [Co₂^IICo₂^III(HL⁻²)₂(µ-CH₃CO₂)₂(µ_3-OH)₂]²⁺ units with an incomplete double cubane core. In 4, H₂L1⁻² holds mixed-valent Co(II)/Co(III) ions in dinuclear units which dimerize through two ethanolic O (μ-RO⁻) in the side arms of the ligands and two ethanolic O (μ₃-RO⁻) of THMAM bridges producing centrosymmetric cationic tetranuclear [Co₂^IICo₂^III (H₂L1⁻²)₂(THMAM⁻¹)₂]⁴⁺ units which grow into 2D-sheets along the bc-axis through a network of H-bonding. Bulk magnetization measurements on 2 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.     

An in vitro antibacterial and antifungal effects of cadmium(II) complexes of hexamethyltetraazacyclotetradecadiene and isomers of its saturated analogue

ObjectiveTo evaluate the antibacterial and antifungal effects of cadmium(II) complexes with hexamethyltetraazacyclotetradecadiene ligands.MethodsFive coordinated square pyramidal cadmium(II) complexes and six coordinated square octahedral cadmium(II) complexes have been synthesized by interaction of 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene (denoted by L.2HClO₄) and C-chiral isomers of its saturated analogue (denoted by ‘teta’ and ‘tetb’) with different salts of Cd²⁺ ion [e.g. CdI₂, Cd(NO₃)₂·6H₂O, CdCl₂·2H₂O and Cd(ClO₄)₂·6H₂O] in methanolic solution. Complexes of the ligands were investigated for antibacterial activity by disc diffusion method and antifungal effect by poisoned food technique.ResultsThe newly synthesized cadmium(II) complexes of the ligands were screened as potential antimicrobial agent against a number of medically important bacteria (Staphylococcus aureus, Bacillus cereus, Salmonella typhi, Shigella dysenteriae and Escherichia coli) and against two fungi (Candida albicans and Aspergillus aculeatus). The growth inhibiting activity of the ligands and complexes against bacteria and fungi were compared with the standard antibiotic ampicillin and commercially important antifungal agent, griseofulvin respectively. Among them some of the macrocyclic complexes were found to be more fungitoxic and antibacterial than the reference antifungal drug griseofulvin and antibacterial drug ampicillin respectively.ConclusionsHexamethyltetraazacyclotetradecadiene ligands and its complexes could be considered as very potential antibacterial and antifungal agent with further investigation.     

Molecular and Polymer Ln2M2 (Ln = Eu,Gd, Tb,Dy; M = Zn,Cd) Complexes with Pentafluorobenzoate Anions: The Role of Temperature and Stacking Effects in the Structure; Magnetic and Luminescent Properties

Varying the temperature of the reaction of [{Cd(pfb)(H₂O)₄}⁺_n·n(pfb)⁻], [Ln₂(pfb)₆(H₂O)₈]·H₂O (Hpfb = pentafluorobenzoic acid), and 1,10-phenanthroline (phen) in MeCN followed by crystallization resulted in the isolation of two type of products: 1D-polymers [LnCd(pfb)₅(phen)]_n·1.5nMeCN (Ln = Eu (I), Gd (II), Tb (III), Dy (IV)) which were isolated at 25 °C, and molecular compounds [Tb₂Cd₂(pfb)₁₀(phen)₂] (V) formed at 75 °C. The transition from a molecular to a polymer structure becomes possible because of intra- and intermolecular interactions between the aromatic cycles of phen and pfb from neighboring tetranuclear Ln₂Cd₂ fragments. Replacement of cadmium with zinc in the reaction resulted in molecular compounds Ln₂Zn₂ [Ln₂Zn₂(pfb)₁₀(phen)₂]·4MeCN (Ln = Eu (VI), Tb (VIII), Dy (IX)) and [Gd₂Zn₂(pfb)₁₀(H₂O)₂(phen)₂]·4MeCN (VII). A new molecular EuCd complex [Eu₂Cd₂(pfb)₁₀(phen)₄]·4MeCN (X)] was isolated from a mixture of cadmium, zinc, and europium pentafluorobenzoates (Cd:Zn:Ln = 1:1:2). Complexes II-IV, VII and IX exhibit magnetic relaxation at liquid helium temperatures in nonzero magnetic fields. Luminescent studies revealed a bright luminescence of complexes with europium(III) and terbium(III) ions.     

Synthesis,Crystal Structure and Luminescent Property of Mg(II) Complex with N-Benzenesulphonyl-L-Leucine and 1,10-Phenanthroline

A new complex [Mg(L)₂(phen)(H₂O)₂](phen)(H₂O)₂ [L= N-benzenesulphonyl-L-leucine] was synthesized by the reaction of magnesium chloride hexahydrate with N-benzenesulphonyl-L-leucine and 1,10-phenanthroline in the CH₃CH₂OH/H₂O (v:v = 5:1). It was characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The crystal of the title complex [Mg(L)₂(phen)(H₂O)₂](phen)(H₂O)₂ belongs to triclinic, space group P-1 with a = 0.72772(15) nm, b = 1.4279(3) nm, c = 1.4418(3) nm, α = 63.53(3)°, β = 79.75(3)°, γ = 81.83(3)°, V = 1.3163(5) nm³, Z =1, D_c= 1.258 μg·m⁻³, μ = 0.177 mm⁻¹, F(000) = 526, and final R₁ = 0.0506, ωR₂ = 0.1328. The complex comprises a six-coordinated magnesium(II) center, with a N₂O₄ distorted octahedron coordination environment. The molecules are connected by hydrogen bonds and π-π stacking to form one dimensional chain structure. The luminescent property of the Mg(II) complex has been investigated in solid.     

The Photoluminescent Properties of New Cationic Iridium(III) Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes

Three cationic iridium(III) complexes [Ir(ppy)₂(phen)][PF₆] (C1), [Ir(ppy)₂(phen)]₂SiF₆ (C2) and [Ir(ppy)₂(phen)]₂TiF₆ (C3) (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline) using different anions were synthesized and characterized by ¹H Nuclear magnetic resonance (¹HNMR), mass spectra (MS), Fourier transform infrared (FTIR) spectra and element analysis (EA). After the ultraviolet visible (UV-vis) absorption spectra, photoluminescent (PL) properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs) as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y₃Al₅O₁₂:Ce³⁺ (YAG). The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W⁻¹ and 11.41 Lm·W⁻¹, respectively.     

Reductive Electropolymerization and Electrochromism of Iron(II) Complex with Styrene-Based Ligand

The benzimidazole-based ligand containing polymerizable styrene group has been prepared via condensation of picolinaldehyde derivative containing styrene moiety and benzimidazole-based hydrazine. The ligand reacted with iron(II) tetrafluoroborate and iron(II) trifluoromethanesulfonate giving red-brown complexes of Fe(II) ions of formula [FeL₂]X₂, where X = CF₃SO₃⁻ (1) or BF₄⁻ (2). Reductive electropolymerization was used to obtain a thin layer of the polymeric complex, poly-1. Further investigation of electrochemical properties of the compound by cyclic voltammetry showed two quasi-reversible redox processes assigned to electrooxidation and electroreduction of the polymer. Spectroelectrochemical measurements confirmed that the polymer undergoes the color changes during oxidation and reduction process. The polymer in its neutral state (Fe(II)) is yellow and it exhibits absorption band at 370 nm, after oxidation to Fe(III) state absorption band shifts to 350 nm and the polymer is almost colorless. While the metal ions are reduced to Fe(I) absorption band at around 410 nm has been observed and the polymer changed its color to intense yellow. The stability of the polymer during multiple oxidation/reduction cycles has also been investigated.     

Crystal Structure,Spectroscopic Characterization,Antioxidant and Cytotoxic Activity of New Mg(II) and Mn(II)/Na(I) Complexes of Isoferulic Acid

The Mg(II) and heterometallic Mn(II)/Na(I) complexes of isoferulic acid (3-hydroxy-4-methoxycinnamic acid, IFA) were synthesized and characterized by infrared spectroscopy FT-IR, FT-Raman, electronic absorption spectroscopy UV/VIS, and single-crystal X-ray diffraction. The reaction of MgCl₂ with isoferulic acid in the aqueous solutions of NaOH resulted in synthesis of the complex salt of the general formula of [Mg(H₂O)₆]⋅(C₁₀H₉O₄)₂⋅6H₂O. The crystal structure of this compound consists of discrete octahedral [Mg(H₂O)₆]²⁺ cations, isoferulic acid anions and solvent water molecules. The hydrated metal cations are arranged among the organic layers. The multiple hydrogen-bonding interactions established between the coordinated and lattice water molecules and the functional groups of the ligand stabilize the 3D architecture of the crystal. The use of MnCl₂ instead of MgCl₂ led to the formation of the Mn(II)/Na(I) complex of the general formula [Mn₃Na₂(C₁₀H₇O₄)₈(H₂O)₈]. The compound is a 3D coordination polymer composed of centrosymmetric pentanuclear subunits. The antioxidant activity of these compounds was evaluated by assays based on different antioxidant mechanisms of action, i.e., with ^•OH, DPPH^• and ABTS^•+ radicals as well as CUPRAC (cupric ions reducing power) and lipid peroxidation inhibition assays. The pro-oxidant property of compounds was measured as the rate of oxidation of Trolox. The Mg(II) and Mn(II)/Na(I) complexes with isoferulic acid showed higher antioxidant activity than ligand alone in DPPH (IFA, IC₅₀ = 365.27 μM, Mg(II) IFA IC₅₀ = 153.50 μM, Mn(II)/Na(I) IFA IC₅₀ = 149.00 μM) and CUPRAC assays (IFA 40.92 μM of Trolox, Mg(II) IFA 87.93 μM and Mn(II)/Na(I) IFA 105.85 μM of Trolox; for compounds’ concentration 10 μM). Mg(II) IFA is a better scavenger of ^•OH than IFA and Mn(II)/Na(I) IFA complex. There was no distinct difference in ABTS^•+ and lipid peroxidation assays between isoferulic acid and its Mg(II) complex, while Mn(II)/Na(I) complex showed lower activity than these compounds. The tested complexes displayed only slight antiproliferative activity tested in HaCaT human immortalized keratinocyte cell line within the solubility range. The Mn(II)/Na(I) IFA (16 μM in medium) caused an 87% (±5%) decrease in cell viability, the Mg salt caused a comparable, i.e., 87% (±4%) viability decrease in a concentration of 45 μM, while IFA caused this level of cell activity attenuation (87% ± 5%) at the concentration of 1582 μM (significant at α = 0.05).     

Reversible Redox Property of Co(III) in Amorphous Co-Doped SiO2/γ-Al2O3 Layered Composites

This paper reports on a unique reversible reducing and oxidizing (redox) property of Co(III) in Co-doped amorphous SiO₂/γ-Al₂O₃ composites. The Fenton reaction during the H₂O₂-catalyzed sol–gel synthesis utilized in this study lead to the partial formation of Co(III) in addition to Co(II) within the composites. High-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analyses for the composite powder sample with a composition of Al:Si:Co = 85:10:5 showed the amorphous state of the Co-doped SiO₂ that modified γ-Al₂O₃ nanocrystalline surfaces. In situ X-ray absorption fine structure (XAFS) spectroscopic analysis suggested reversible redox reactions of Co species in the composite powder sample during heat-treatment under H₂ at 500 °C followed by subsequent cooling to RT under Ar. Further analyses by in situ IR spectroscopy combined with cyclic temperature programmed reduction/desorption (TPR/TPD) measurements and X-ray photoelectron spectroscopic (XPS) analysis revealed that the alternating Co(III)/(II) redox reactions were associated with OH formation (hydrogenation)-deformation (dehydrogenation) of the amorphous aluminosilicate matrix formed in situ at the SiO₂/γ-Al₂O₃ hetero interface, and the redox reactions were governed by the H₂ partial pressure at 250–500 °C. As a result, a supported mesoporous γ-Al₂O₃/Co-doped amorphous SiO₂/mesoporous γ-Al₂O₃ three-layered composite membrane exhibited an H₂-triggered chemical valve property: mesopores under H₂ flow (open) and micropores under He flow (closure) at 300–500 °C.     

Synthesis,Crystal Structure and Luminescent Property of Cd (II) Complex with N-Benzenesulphonyl-L-leucine

A new trinuclear Cd (II) complex [Cd₃(L)₆(2,2-bipyridine)₃] [L = N-phenylsulfonyl-L-leucinato] has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the complex belongs to the orthorhombic, space group P2₁2₁2₁ with a = 16.877(3) Å, b = 22.875(5) Å, c = 29.495(6) Å, α = β = γ = 90°, V = 11387(4) ų, Z = 4, D_c= 1.416 μg·m⁻³, μ = 0.737 mm⁻¹, F (000) = 4992, and final R₁ = 0.0390, ωR₂ = 0.0989. The complex comprises two seven-coordinated Cd (II) atoms, with a N₂O₅ distorted pengonal bipyramidal coordination environment and a six-coordinated Cd (II) atom, with a N₂O₄ distorted octahedral coordination environment. The molecules form one dimensional chain structure by the interaction of bridged carboxylato groups, hydrogen bonds and π-π interaction of 2,2-bipyridine. The luminescent properties of the Cd (II) complex and N-Benzenesulphonyl-L-leucine in solid and in CH₃OH solution also have been investigated.     

Enhanced Antioxidant Activity of Ursolic Acid by Complexation with Copper (II): Experimental and Theoretical Study

The copper (II) complex of ursolic acid (Cu(II) UA) was synthesized and discussed in terms of its infrared, UV–visible spectra, quantum-chemical calculations at B3LYP/6-31G(d) level and antioxidant capacity. The copper (II) complex was stable in methanolic solution with the molar ratio metal:ligand 1:1. The data obtained by FT-IR confirmed the metal ion coordination through the carboxylate anion. The antioxidant properties of ursolic acid and its complex with Cu were discussed on the basis of energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and values of chemical reactivity parameters. The antiradical properties of ursolic acid and the Cu (II) complex were examined against DPPH^• and HO^• radicals, and the ferric reducing antioxidant power (FRAP) was examined. The Cu(II) complex showed higher antioxidant activity than ursolic acid, i.e., in DPPH^• assay, the EC₅₀ for UA was 47.0 mM, whereas, for Cu(II), UA EC₅₀ = 19.5 mM; the FRAP value for UA was 20.8 µM_Fe2+, and 35.4 µM_Fe2+ for Cu(II) UA (compound concentration 3 mM). Although there was no distinct difference in the antioxidant activity against HO^• between these two chemicals, they were both better HO^• scavengers than DPPH^• and showed different kinetics in the reaction with DPPH^•.     

Development of Efficient Photocatalyst MIL-68(Ga)_NH2 Metal-Organic Framework for the Removal of Cr(VI) and Cr(VI)/RhB from Wastewater under Visible Light

Severe environmental pollution is caused by the massive discharge of complex industrial wastewater. The photocatalytic technology has been proved as an effective way to solve the problem, while an efficient photocatalyst is the most critical factor. Herein, a new photocatalyst MIL-68(Ga)_NH₂ was obtained by hydrothermal synthesis and were characterized by PXRD, FTIR, ¹H NMR, and TGA systematically. The result demonstrates that MIL-68(Ga)_NH₂ crystallized in orthorhombic system and Cmcm space group with the unit cell parameters: a = 36.699 Å, b = 21.223 Å, c = 6.75 Å, V = 5257.6 ų, which sheds light on the maintenance of the crystal structure of the prototype material after amino modification. The conversion of Cr(VI) and binary pollutant Cr(VI)/RhB in wastewater under visible light stimulation was characterized by the UV-vis DRS. Complementary experimental results indicate that MIL-68(Ga)_NH₂ exhibits remarkable photocatalytic activity for Cr(VI) and the degradation rate reaches as high as 98.5% when pH = 2 and ethanol as hole-trapping agent under visible light irradiation with good reusability and stability. Owing to the synergistic effect between Cr(VI) and RhB in the binary pollutant system, MIL-68(Ga)_NH₂ exhibits excellent catalytic activity for both the pollutants, the degradation efficiency of Cr(VI) and RhB was up to 95.7% and 94.6% under visible light irradiation for 120 min, respectively. The possible removal mechanism of Cr(VI)/RhB based on MIL-68(Ga)_NH₂ was explored. In addition, Ga-based MOF was applied in the field of photocatalytic treatment of wastewater for the first time, which broadened the application of MOF materials in the field of photocatalysis.     

Miltenberger blood group antigen subtype III (Mi.III) supports Wr(b) expression

Background and Objectives Miltenberger blood group antigens belong to the complex MNS system. Miltenberger antigen subtype III (Mi.III) was previously found to promote the expression of band 3. Here, we investigated whether the direct interaction between band 3 and Mi.III‐specific Gp.Mur (a glycophorin B‐A‐B hybrid) might affect the expression of related blood group antigens such as the Wright b (Wr^b) antigen. Materials and Methods (1) Band 3 genes of Mi.III+ and non‐Mi.III (control) donors were sequenced to determine the genotypes of the Wright antigens. (2) The expression levels of Wr^b, glycophorin A (GPA) and band 3 in Mi.III and the control erythrocytes were quantitatively assessed by flow cytometry. Results Mi.III erythrocytes expressed 22·5 ± 6·6% more Wr^b antigen than the control cells. The increase in Wr^b in Mi.III cells was independent of their GPA levels. Conclusion The elevated Wr^b levels in Mi.III RBCs were likely linked to their higher band 3 levels. Higher band 3 densities on the Mi.III+ cell surface conceivably could drive complex formation between band 3 and GPA/Gp.Mur, thereby increasing the expression of Wr^b.     

Sequence variants of the sarco(endo)plasmic reticulum Ca2+-transport ATPase 3 gene (SERCA3) in Caucasian Type II diabetic patients (UK Prospective Diabetes Study 48)

Abstract Aims/hypothesis. Type II (non-insulin-dependent) diabetes mellitus is a common heterogeneous metabolic disorder of largely unknown genetic aetiology. The sarco(endo)plasmic reticulum Ca²⁺-transport ATPase (SERCA) plays an important part in the glucose-activated beta-cell Ca²⁺ signalling that regulates insulin secretion. Impaired function and expression of SERCA have been shown in islets of Langerhans from diabetic animal models and have also been associated with beta-cell apoptosis. Thus, the SERCA3 encoding gene is a plausible candidate for a primary pancreatic beta-cell defect. Methods. In this study, the entire coding and the promoter regions of SERCA3 gene were screened by single-strand conformation polymorphism analysis in white Caucasian Type II diabetic patients. Results. We found four rare missense mutations [Exon 4: Gln ₁₀₈→His (CAG→CAT), Exon 14: Val ₆₄₈→Met (GTG→ATG) and Arg ₆₇₄→Cys (CGC→TGC), and Exon 15: Ile ₇₅₃→Leu (ATC→CTC)]. The patients with Gln ₁₀₈→His, Val ₆₄₈→Met and Arg ₆₇₄→Cys mutations, which may affect the E1P-E2P transition of SERCA3 during its enzyme cycle, had normal body weight with marked hyperglycaemia and beta-cell dysfunction. That is an unusual phenotype only found in 6 % of the Type II diabetic patients recruited for the UK Prospective Diabetes Study. In addition, five silent polymorphisms, six intron variants and two polymorphisms in the 3' untranslated region of exon 22 were found with similar frequency in diabetic and control subjects. Conclusion/interpretation. Our result suggests that in white Caucasians, the SERCA3 locus possibly contributes to the genetic susceptibility to Type II diabetes [Diabetologia (1999) 42: 1240–1243]. Received: 9 March 1999 and in revised form: 26 April 1999     

Triboluminescence Phenomenon Based on the Metal Complex Compounds—A Short Review

Triboluminescence (TL) is a phenomenon of light emission resulting from the mechanical force applied to a substance. Although TL has been observed for many ages, the radiation mechanism is still under investigation. One of the exemplary compounds which possesses triboluminescent properties are copper(I) thiocyanate bipyridine triphenylphosphine complex [Cu(NCS)(py)₂(PPh₃)], europium tetrakis dibenzoylmethide triethylammonium EuD₄TEA, tris(bipyridine)ruthenium(II) chloride [Ru(bpy)₃]Cl₂, and bis(triphenylphosphine oxide)manganese(II) bromide Mn(Ph₃PO)₂Br₂. Due to the effortless synthesis route and distinct photo- and triboluminescent properties, these compounds may be useful model substances for the research on the triboluminescence mechanism. The advance of TL studies may lead to the development of a new group of sensors based on force-responsive (mechanical stimuli) materials. This review constitutes a comprehensive theoretical study containing available information about the coordination of metal complex synthesis methodologies with their physical, chemical, and spectroscopic properties.     

Snail Based Carbonated-Hydroxyapatite Material as Adsorbents for Water Iron (II)

Carbonated hydroxyapatite (CHAp) adsorbent material was prepared from Achatina achatina snail shells and phosphate-containing solution using a wet chemical deposition method. The CHAp adsorbent material was investigated to adsorb aqua Fe(II) complex; [Fe(H₂O)₆]²⁺ from simulated iron contaminated water for potential iron remediation application. The CHAp was characterized before and after adsorption using infrared (IR) and Raman spectroscopy. The IR and the Raman data revealed that the carbonate functional groups of the CHAp adsorbent material through asymmetric orientation in water bonded strongly to the aqua Fe(II) complex adsorbate. The adsorption behaviour of the adsorbate onto the CHAp adsorbent correlated well to pseudo-second-order kinetics model, non-linear Langmuir and Freundlich model at room temperature of a concentration (20–100 mg L⁻¹) and contact time of 180 min. The Langmuir model estimated the maximum adsorption capacity to be 45.87 mg g⁻¹ whereas Freundlich model indicated an S-type isotherm curvature which supported the spectroscopy revelation.     

Conformation of cyclo(Gly-L-Pro-L-Pro-Gly-L-Pro-L-Pro)(2)Mg complex crystallized from CH(3)CN solution

The cyclic hexapeptides (Gly-L-Pro-L-Pro-Gly-L-Pro-L-Pro) in the (peptide—Mg—peptide)²⁺ complex have nearly identical asymmetric conformations. Each has two cis Pro-Pro linkages and lacks any intraring hydrogen bonds. The Mg²⁺ ion forms six ligands in a regular octahedral array with the carbonyl oxygen atoms of the two Gly residues and one Pro residue of each peptide. The “sandwich” complex has an approximate 2-fold rotation axis through the Mg²⁺ relating the two peptide moieties. Cyclo(Gly-Pro-Pro-Gly-Pro-Pro)₂Mg(ClO₄)₂· 4C²H₃CN crystallizes in space group P3₁ with a = b = 15.744(4) Å, c = 24.002(6) Å, γ = 120°, and Z = 3. A highlight of the structure determination is the ready location of the Mg self-vector in a Harker section and the development of the entire structure by use of the tangent formula starting with the known position of the Mg atom.     

The Highly Expressed and Inducible Endogenous NAD(P)H:quinone Oxidoreductase 1 in Cardiovascular Cells Acts as a Potential Superoxide Scavenger

It has recently been demonstrated that purified NAD(P)H:quinone oxidoreductase 1 (NQO1) is able to scavenge superoxide (O₂^•−) though the rate of reaction of O₂^•− with NQO1 is much lower than the rate of enzymatic dismutation catalyzed by superoxide dismutase (SOD). This study was undertaken to determine if the endogenously expressed NQO1 in cardiovascular cells could scavenge O₂^•−. We observed that NQO1 was highly expressed in cardiovascular cells, including rat aortic smooth muscle A10 and cardiac H9c2 cells, as well as normal human aortic smooth muscle and endothelial cells. NQO1, but not SOD in the cardiovascular cells was highly inducible by 3H-1,2-dithiole-3-thione (D3T). Cytosols from H9c2 and human aortic smooth muscle cells (HASMCs) were isolated to determine the O₂^•− scavenging ability of the endogenously expressed NQO1 by using pyrogallol autooxidation assay. We showed that cytosols from the above cells inhibited pyrogallol autooxidation in an NADPH or NADH-dependent manner. The NADH/NADPH-dependent inhibition of pyrogallol autooxidation by the cytosols was completely abolished by the NQO1-specific inhibitor, ES936, suggesting that the endogenously expressed NQO1 could scavenge O₂^•−. In the presence of NADH/NADPH, cytosols from D3T-treated cells showed increased ability to scavenge O₂^•− as compared to cytosols from untreated cells. This increased ability to scavenge O₂^•− was also completely reversed by ES936. 5-(Diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide spin-trapping experiments using potassium superoxide as a O₂^•− generator further confirmed the ability of NQO1 from HASMCs to scavenge O₂^•−. The spin-trapping experiments also showed that induction of NQO1 by D3T in HASMCs augmented the O₂^•− scavenging ability. Taken together, these results demonstrate that the highly expressed and inducible endogenous NQO1 in cardiovascular cells may act as a potential O₂^•− scavenger.     

Elevated Hb A2 Levels in a Patient with a Compound Heterozygosity for the (β+) −31 (A > G) and (β0) Codon 17 (A > T) Mutations Together with a Single α-Globin Gene

Abstract

We report the molecular and hematological feature of a Thai woman who had clinical diagnosis of β-thalassemia intermedia (β-TI). Hemoglobin (Hb) high performance liquid chromatography (HPLC) analysis identified Hb A (64.4%), Hb F (12.3%) and Hb A₂/E (15.9%) with small peaks of Hb Bart’s (γ4) and Hb H (β4). She was initially diagnosed as EA Bart’s disease, which occurs from combination of Hb H disease and Hb E (HBB: c.79G?>?A) trait. However, the Hb analysis using capillary electrophoresis (CE) demonstrated no Hb E, 68.5% Hb A, 15.5% Hb F and 16.0% Hb A₂. DNA analysis showed a compound heterozygosity for (β⁺) ?31 (A?>?G) (HBB: c.-81A?>?G) and (β⁰) codon 17 (A?>?T) (HBB: c.52A?>?T) mutations and deletional Hb H (–?–^SEA/–α^3.7). Thus, she was finally diagnosed with a combination of Hb H disease and compound heterozygosity of β⁺/β⁰-thalassemia (β⁺/β⁰-thal). The β-globin mutations could affect not only hematological parameters but also elevate the Hb A₂ levels. These effects could not be ameliorated by the coinheritance of Hb H disease. Therefore, a better understanding of the effects of this combination on hematological analysis data will be useful for providing accurate diagnosis, genetic counseling, prevention and control programs of β-thalassemia major (β-TM).     

Strong reversible Fe3+-mediated bridging between dopa-containing protein films in water

Metal-containing polymer networks are widespread in biology, particularly for load-bearing exoskeletal biomaterials. Mytilus byssal cuticle is an especially interesting case containing moderate levels of Fe³⁺ and cuticle protein—mussel foot protein-1 (mfp-1), which has a peculiar combination of high hardness and high extensibility. Mfp-1, containing 13 mol % of dopa (3, 4-dihydroxyphenylalanine) side-chains, is highly positively charged polyelectrolyte (pI ∼ 10) and didn’t show any cohesive tendencies in previous surface forces apparatus (SFA) studies. Here, we show that Fe³⁺ ions can mediate unusually strong interactions between the positively charged proteins. Using an SFA, Fe³⁺ was observed to impart robust bridging (W_ad ≈ 4.3 mJ/m²) between two noninteracting mfp-1 films in aqueous buffer approaching the ionic strength of seawater. The Fe³⁺ bridging between the mfp-1-coated surfaces is fully reversible in water, increasing with contact time and iron concentration up to 10 μM; at 100 μM, Fe³⁺ bridging adhesion is abolished. Bridging is apparently due to the formation of multivalent dopa-iron complexes. Similar Fe-mediated bridging (W_ad ≈ 5.7 mJ/m²) by a smaller recombinant dopa-containing analogue indicates that bridging is largely independent of molecular weight and posttranslational modifications other than dopa. The results suggest that dopa-metal interactions may provide an energetic new paradigm for engineering strong, self-healing interactions between polymers under water.