Search results for "MAMI"
showing 10 items of 398 documents
Topologically Controlled Interpolyelectrolyte Complexes
2008
The complexation of a cylindrical polyelectrolyte−brush−surfactant complex (PMMPSS−C12) and an oppositely, highly charged cylindrical polyelectrolyte−brush (PMMPEI−PEO) in dimethylformamide (DMF) l...
Ligand substitution in hexahalorhenate(IV) complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReX5(DMF)] (X=Cl and Br)
2006
Abstract The preparation, crystal structures, and magnetic properties of two rhenium(IV) mononuclear compounds of formula NBu 4 [ReX 5 (DMF)] ( NBu 4 + = tetrabutylammonium cation and DMF = N , N - dimethylformamide ) with X = Cl ( 1 ) and Br ( 2 ) are reported. 1 and 2 are isostructural complexes which crystallize in the monoclinic system with the space group P 2 1 / n . The rhenium atom is six-coordinated with five X atoms and a DMF molecule forming a somewhat distorted octahedral surrounding [values of Re–X varying in the ranges 2.317(1)–2.358(1) ( 1 ) and 2.495(1)–2.518(1) A ( 2 )]. Magnetic susceptibility measurements on samples of 1 and 2 in the temperature range 1.9–300 K are interpr…
The Friedreich's Ataxia protein frataxin modulates DNA base excision repair in prokaryotes and mammals
2010
DNA-repair mechanisms enable cells to maintain their genetic information by protecting it from mutations that may cause malignant growth. Recent evidence suggests that specific DNA-repair enzymes contain ISCs (iron–sulfur clusters). The nuclearencoded protein frataxin is essential for the mitochondrial biosynthesis of ISCs. Frataxin deficiency causes a neurodegenerative disorder named Friedreich's ataxia in humans. Various types of cancer occurring at young age are associated with this disease, and hence with frataxin deficiency. Mice carrying a hepatocyte-specific disruption of the frataxin gene develop multiple liver tumours for unresolved reasons. In the present study, we show that frata…
A fundamental catalytic difference between zinc and manganese dependent enzymes revealed in a bacterial isatin hydrolase
2018
Scientific reports 8(1), 13104 (2018). doi:10.1038/s41598-018-31259-y
Oxidative DNA damage induced by visible light in mammalian cells: extent, inhibition by antioxidants and genotoxic effects
1998
The extent of the indirect DNA damage generated in mammalian cells by visible light because of the presence of endogenous photosensitizers was studied by means of repair endonucleases. In immortalized human keratinocytes (HaCaT cells) exposed to low doses of natural sunlight, the yield of oxidative DNA base modifications sensitive to the repair endonuclease formamidopyrimidine-DNA glycosylase (Fpg protein) generated by this indirect mechanism was 10% of that of pyrimidine dimers (generated by direct DNA excitation). A similar yield of Fpg-sensitive modifications, which include 8-hydroxyguanine, was observed in primary keratinocytes. The relative yield of oxidative base modifications decreas…
Solvent-modulated structures in anilato-based 2D coordination polymers
2017
Abstract This work highlights the key role of the solvents in the structures of the series of 2D compounds [Ln2(C6O4Br2)3·(Solvent)n]·G (G = Guest). This study is based on the affinity and ability of these solvents to coordinate to lanthanides and on their possibility to act as solvation molecules. For this purpose here we focus on the Er(III) ion and on the bromanilato bridging ligand ([C6O4Br2]2− = dianion of 3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone) and we play with three solvents: H2O, DMSO (dimethylsulfoxide) and DMF (dimethylformamide). Here we report the synthesis, crystal structure and magnetic characterization of compounds [Er2(C6O4Br2)3(H2O)6]·12H2O (1), [Er2(C6O4Br2)3(DMSO)4]·2…
Solvent-modulation of the structure and dimensionality in lanthanoid-anilato coordination polymers.
2018
We show the key role that the size and shape of the solvent molecules may play in the dimensionality and structure of a series of lanthanoid–chloranilato coordination polymers. We report the synthesis, structure and magnetic properties of six different coordination polymers prepared with Er(III) and chloranilato (C6O4Cl22− = 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone) and six different solvents: [Er2(C6O4Cl2)3(H2O)6]·10H2O (1), [Er2(C6O4Cl2)3(FMA)6]·4FMA·2H2O (2) (FMA = formamide = NH2CHO), [Er2(C6O4Cl2)3(DMSO)4]·2DMSO·2H2O (3) (DMSO = dimethy sulfoxide = Me2SO), [Er2(C6O4Cl2)3(DMF)6] (4) (DMF = dimethylformamide = Me2NCHO), [Er2(C6O4Cl2)3(DMA)4] (5) (DMA = dimethylacetamide = Me2NC(Me)O) …
Novel Lipophilic Lanthanide Bis-Phthalocyanines Functionalized by Pentadecylphenoxy Groups: Synthesis, Characterization and UV-Photostability
2012
Novel sandwich-type phthalocyanines containing a rare earth metal core (Pr, Nd, Eu-Lu) and macrocycles peripherally substituted by pentadecylphenoxy groups were synthesized using a cardanol-based phthalonitrile precursor and the respective lanthanide acetate. Additionally, the metal free-base analog compound was studied for comparison. The purified reaction products were all found to be thick and viscous substances at room temperature, showing liquid crystalline behavior with a distinct increase in fluidity at ca. 40 ° C. The complexes are readily soluble in chloroalkyl solvents and dissolve fairly well in DMF with some tendency to form aggregates. Besides they are strongly hydrophobic and …
Co-crystallization of Keggin type polyoxometalates [HL]3[PW12O40] and [Ln(DMF)8][PW12O40] (Ln=La, Dy, Yb) (L=N-(2-hydroxyphenyl)-3-methoxy-salicylide…
2016
Abstract Four new Keggin type polyoxometalate clusters [HL]3[PW12O40]·5MeOH (1) and [Ln(DMF)8][PW12O40] {Ln = La (2), Dy (3), Yb (4)} (L = N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine) have been synthesized. Co-crystallization of complex 1 with each of the three complexes 2–4 takes place when the Schiff base ligand is treated with hydrated phosphotungstic acid, H3[PW12O40]·xH2O, hydrated lanthanide nitrate, Ln(NO3)3·6H2O in the presence of Ni(NO3)2·6H2O. The Schiff base ligand is protonated in complex 1 and thus it is neutralizing the charge of the polyoxotungstate anion, [PW12O40]3−. A dimethylformamide (DMF) coordinated trivalent lanthanide ion balances the negative charge of the polyo…
Acetylation of 5-Amino-1H-[1,2,4]triazole Revisited
2002
The products of the acetylation reactions of the common herbicide 5-amino-1H-[1,2,4]triazole were investigated using HPLC, GC-MS, 1H NMR, and FTIR spectroscopy. The conventional annular monoacetylation procedures with acetyl chloride are not regioselective and furnish a mixture of isomers. Traditional diacetylation in neat acetic anhydride under reflux produces a mixture of di-, mono-, and triacetylated derivatives. By using equivalent amounts of acetic anhydride in a dimethylformamide solution, a rapid and selective annular monoacetylation of 5-amino-1H-[1,2,4]triazole was achieved. The monoacetylation proceeds via the formation of the intermediate, 1-acetyl-3-amino-1H-[1,2,4]triazole, whi…