X-band e.p.r. spectra of mixed-ligand copper(II) complexes

E.p.r. spectra of [Cu(et2dtc)2], Na[Cu(asp/glut)(et2dtc)] and Na2[Cu(asp/glut)(et2dtc)2] in the polycrystalline state have been recorded and discussed. The complexes display an antiferromagnetic exchange interaction, increasing in the order: Na2[Cu(asp/glut)(et2dtc)2] < Na[Cu(asp/glut)(et2dtc)] < [Cu(et2dtc)2] This revised version was published online in June 2006 with corrections to the Cover Date.     

Anti-Obesity Potential of Ponciri Fructus: Effects of Extracts,Fractions and Compounds on Adipogenesis in 3T3-L1 Preadipocytes

Background: Ponciri Fructus, a crude drug consisting of the dried immature fruits of Poncirus trifoliata (L.) Raf., is a popular folk medicine used for the treatment of allergy and gastrointestinal disorders in Korea and China. In this study, the anti-adipogenic activity of extracts and isolated compounds were evaluated using 3T3-L1 preadipocytes. Methods: Dried immature fruits were extracted and fractionated into n-hexane, ethyl acetate (EtOAc), n-butanol and water-soluble fractions. The ethanol extract and fractions were tested for anti-adipogenic activity in the 3T3-L1 cell line. The active fractions (n-hexane and EtOAc fractions) were further subjected to chromatographic techniques to isolate and identify active compounds. Furthermore, the isolated compounds were evaluated for their anti-adipogenic activity. Results: Altogether, seven compounds, including two flavonoids, one phytosteroid and four coumarin derivatives, were isolated. Ethanol extract, n-hexane fraction, EtOAc fraction and three isolated compounds (phellopterin, oxypeucedanin and poncirin) showed significant anti-adipogenic activity as observed by reduced lipid deposition in differentiated 3T3-L1 cells. Further, oxypeucedanin downregulated the key adipogenic markers, such as peroxisome proliferator-activated receptors proteins γ (PPAR-γ), sterol response element binding proteins-1 (SREBP-1), CCAAT/enhancer binding proteins-α (C/EBP-α), adipocyte-specific lipid binding proteins (FABP-4), adipocyte fatty acid binding proteins (aP2), lipoprotein lipase (LPL) and leptin. Conclusion: This study indicated that the ethanol extract, hexane fraction and ethyl acetate fraction of P. trifoliata fruits possess strong anti-adipogenic activity, containing the active compounds such as phellopterin, oxypeucedanin and poncirin. Further research is recommended to explore their efficacy and safety in animal and clinical models.     

Oxovanadium(IV) complexes of cyclohexanone semicarbazone and cyclohexanone thiosemicarbazone

Summary Oxovanadium(IV) complexes, VOL₂X₂ (X = Cl, Br and 0.5 SO₄), have been synthesised and characterised by elemental analysis, room temperature magnetic moment, electronic, i.r. and electron spin resonance studies. The complexes are hexacoordinate and have a distorted octahedral structure.     

E.p.r. spectra of mixed valence copper(II)-copper(I) systems

Summary Mixed valence (thiosemicarbazone)₂Cu^II-Cu^I complexes were prepared and their e.p.r. spectra in the polycrystalline state studied. Complexes derived from acetophenone- and propiophenonethiosemicarbazones exhibit strong copper(II)-copper(II) and copper(II)-copper(I) interactions, whereas those derived from benzyl methyl ketone and cyclohexanone show strong copper(II)-copper(I) interaction but almost no copper(II)-copper(II) interaction.     

Studies on chromium(III) complexes of some new dithiocarbamato ligands

Summary Tris-chelates of chromium(III) have been synthesised with five new dithiocarbamates, [RR'NCS₂]^–, where R=PhCH₂ and R/t'=H, PhCH₂, Me, Et and i-Pr. Magnetic moments together with electronic, i.r. and e.s.r spectra of the complexes have been described. Various ligand-field parameters have been evaluated and discussed.     

Synthesis,magnetic moments and X-band e.p.r. spectra of binuclear and trinuclear copper(II) complexes

The imidazole-bridged binuclear copper(II) complex, [(Cl)2(imH)2Cu(imH)2Cu(bipy)(Cl)2] and the trinuclear copper (II) complex [(Cl)2(bipy)Cu(imH)2Cu(imH)2Cu(bipy)(Cl)2] have been synthesized by direct coupling between [Cu(imH)4(Cl)2] and [Cu(bipy)Cl2] in the appropriate stoichiometric ratios. The complexes show subnormal magnetic moments and e.p.r. spectra, characteristic of the triplet state. The antiferromagnetic coupling constant, J, has been obtained for both the complexes.     

Mössbauer studies of some iron(II) complexes of cyclohexanonesemicarbazone

Summary Mössbauer studies of high-spin iron(II) complexes of the type FeL₂X₂ [L = cyclohexanonesemicarbazone (CHSC); X = Cl, NO₃, 0.5 SO₄, NCS] have been carried out at room and at liquid nitrogen temperature. The results reveal doublet ground states for Fe(CHSC)₂Cl₂ and Fe(CHSC)₂(NO₃)₂ and singlet ground states for Fe(CHSC)₂SO₄ and Fe(CHSC)₂(NCS)₂.     

Paramagnetic resonance in imidazolate-bridged homobinuclear (copper-copper) and heterobinuclear (copper-zinc) complexes

Bridged homobinuclear (copper-copper) and heterobinuclear (copper-zinc) complexes of diethylenetriamine have been prepared with 2-methyl-imidazole as bridging ligand. EPR spectra of the polycrystalline complexes have been studied at room temperature and also at liquid nitrogen temperature. Low temperature EPR and electronic spectroscopic studies of 50% aqueous DMSO of [(dien)Cu-(Melm)-Zn(dien)]3+ solutions show the imidazolate bridged complex to exist mainly over the pH range approximately 7.0 < pH < 10.0. At low pH the 2-MelmH+ ion and mononuclear copper and zinc complexes are formed. Above pH > 10.0 hydroxide ion splits the imidazolate bridge.     

Polarographic reduction of nickel(II), copper(II) and zinc(II) in the presence of 2,3-dihydroxypyridine and 2-amino-3-hydroxypyridine

Summary Nickel(ll), copper(II) and zinc(II) give diffusion-controlled irreversible single reduction waves in the presence of 2,3-dihydroxypyridine (DHP) and 2-amino-3-hydroxypyridine (AHP). Values of transfer coefficients () and formal rate constants (k _f ⁰ , h) have been calculated. The AHP complexes are more easily reduced than the corresponding DHP complexes.