Search results for "Chela"

Characterization of aquatic humic substances and their metal complexes by immobilized metal-chelate affinity chromatography on iron(III)-loaded ion e…

2001

The analytical fractionation of aquatic humic substances (HS) by means of immobilized metal-chelate affinity chromatography (IMAC) on metal-loaded chelating ion exchangers is described. The cellulose HYPHAN, loaded with different trivalent ions, and the chelate exchanger Chelex 100, loaded to 90% of its capacity with Fe(III), were used. The cellulose HYPHAN, loaded with 2% Fe(III), resulted in HS distribution coefficients Kd of up to 10(3.7) mL/g at pH 4.0 continuously decreasing down to 10(1.5) at pH 12, which were appropriate for HS fractionation by a pH-depending chromatographic procedure. Similar distribution coefficients Kd were obtained for HS sorption onto Fe(III)-loaded Chelex 100. …

Interactions of metal ions with two quinolone antimicrobial agents (cinoxacin and ciprofloxacin)

2002

Several novel metal-quinolone compounds have been synthesized and characterized by analytical, spectroscopic and X-ray diffraction methods. The crystal structure of the four compounds, Na(2)[(Cd(Cx)3)(Cd(Cx)3(H2O))].12H2O, [Co(Cp)2(H2O)2].9H2O, [Zn(Cp)2(H2O)2].8H2O and [Cd(HCp)2(Cl)2].4H2O, is presented and discussed: HCx=1-ethyl-1,4-dihydro-4-oxo(1,3)-dioxolo(4,5-g)cinnoline-3-carboxylic acid and HCp=1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid. In all these compounds the quinolone acts as a bidentate chelate ligand that binds through one carboxylate oxygen atom and the exocyclic carbonyl oxygen atom. Complexes of ciprofloxacin were screened for th…

Mono-aryltin(IV) and mono-benzyltin(IV) complexes with pyridine-2-carboxylic acid and 8-hydroxyquinoline. X-ray structure of p-chloro-phenyl-tris(8-q…

1999

Abstract Complexes RSn(O2CPy)3·2H2O and RSn(Ox)3, (PyCOOH=pyridine-2-carboxylic acid, HOx=8-hydroxyquinoline, R=o- and p-Tolyl, o- and p-ClC6H4=o- and p-ClPh, o-ClC6H4CH2=o-ClBenzyl; besides, R=Ph in RSn(Ox)3) have been synthesized and characterized by elemental analysis and determination of molecular weights in CHCl3 solutions. The structure of p-ClPhSn(Ox)3·2CHCl3 has been determined by X-ray diffractometry. The 7-coordinated tin atom of the monomeric compound is in the center of a pentagonal bipyramid formed by (p-ClPh)C and O and N atoms of the chelating Ox− ligands. The latter type of structure would hold for all complexes according to 119Sn Mossbauer (including the determination of th…

Peptide-metal complexes: obtention and role in increasing bioavailability and decreasing the pro-oxidant effect of minerals.

2020

Bioactive peptides derived from food protein sources have been widely studied in the last years, and scientific researchers have been proving their role in human health, beyond their nutritional value. Several bioactivities have been attributed to these peptides, such as immunomodulatory, antimicrobial, antioxidant, antihypertensive, and opioid. Among them, metal-binding capacity has gained prominence. Mineral chelating peptides have shown potential to be applied in food products so as to decrease mineral deficiencies since peptide-metal complexes could enhance their bioavailability. Furthermore, many studies have been investigating their potential to decrease the Fe pro-oxidant effect by f…

STUDIEN ZUM VORGANG DER WASSERSTOFFÜBERTRAGUNG 731HYDROGENOLYSESTUDIEN VON SCHWEFEL-UND PHOSPHOR-VERBINDUNGEN AN RANEY-NICKEL (Ra-Ni)—EINE MATERIALSA…

1985

Abstract The desulfurization and dephosphorization with Raney-Nickel (Ra-Ni) is investigated under standard conditions using the following types of compounds: Mercaptanes. thioethers, di- and trisulfides, sulfonium salts, sulfoxides, sulfones, sulfonic acid derivatives, bidental thioethers before and after the chelation, tertiary phosphines and phosphites, phosphonium salts and amidophosphonium salts, phosphine-metal-complexes, model compounds containing sulfur and phosphorus in the same molecule and samples of aerosil the surface of which is modified with S- and P-functions. The degree of the desulfurization and dephosphorization is dependent on the amount and availability of the “structur…

Synthesis and Structural Study of Tetravalent (Zr 4+ , Hf 4+ , Ce 4+ , Th 4+ , U 4+ ) Metal Complexes with Cyclic Hydroxamic Acids

2015

Six- and seven-membered cyclic hydroxamic acids, such as 1-hydroxypiperidine-2-one (1H, 1,2-PIPOH) and 1-hydroxyazepan-2-one (2H), have recently been identified in some mixed siderophores as one of their three chelating subunits. Compared to their ubiquitous noncyclic counterparts, cyclic hydroxamates are preorganized for metal binding. Surprisingly, the coordination chemistry of these bidentate, monoanionic ligands remains virtually unknown, even in the case of iron(III). We report herein the first structural study of the complexes of 1– and of 6–, an unsaturated seven-membered ring analog of 2–, with tetravalent cations of transition metals (zirconium and hafnium), lanthanide (cerium), an…

Organotin(IV) derivatives of the ambidentate ligand 2-thiouracil. Infrared, Mössbauer, 1H and 13C NMR studies

1984

Abstract Complexes Bu 2 n Sn(s 2 UraH −2 and [Me 2 SnOH] 2 (s 2 UraH −2 have been synthesized. Comparison of infrared spectra of the solid complexes with spectra of s 2 Ura and (PhHg) 2 (s 2 UraH −2 complex and point charge calculations (Mossbauer spectra) allow assignment of structures for the complexes of this ambivalent ligand. Polymeric structures are proposed for the complexes in the solid state, where the organometallic moieties are bonded to exocyclic S and N(3) atoms of the dianionic base, with formation of a four-membered chelate ring for Bu 2 n Sn(s 2 UraH −2 ). For [Me 2 SnOH] 2 (s 2 UraH −2 , 1 H and 13 C NMR data suggest retention of penta-coordination in trifluoacetic acid sol…

Hexacyanocobaltate(III) Anions as Precursors of Co(II)−Ni(II) Cyano-Bridged Multidimensional Assemblies:  Hydrothermal Syntheses, Crystal and Powder …

2005

Three novel cyanide-bridged heterobimetallic coordination polymers have been synthesized by hydrothermal routes, in superheated water solutions, by using K3[Co(CN)6], NiCl2.6H2O, and alpha-diimine ligands: [Ni(CN)4Co(phen)] (1; phen = 1,10-phenanthroline), [Ni(CN)4Co(2,2'-bipy)] (2; 2,2'-bipy = 2,2'-bipyiridine), and [Ni(CN)4Co(2,2'-bipy)2] (3). The isostructural compounds 1 and 2 contain a two-dimensional network with Co(II) centers octahedrally coordinated by one chelating 2,2'-bipy ligand and four cyanide groups of four distinct [Ni(CN)4]2-, through crystallographically equivalent, bridging units. Compound 3 contains one-dimensional zigzag chains in which the Co(II) ion is coordinated by…

Synthesis and Reaction Chemistry of Sb(ECH2CH2NMe2)3(E= O, S)

2012

The antimony aminoalkoxide and aminothiolates Sb(ECH 2CH 2NMe 2) 3 [E = O (1), S (2)] were synthesized and their ability to form adducts with other metal moieties investigated. Compound 1 forms 1:1 adducts with NiI 2 (3) and M(acac) 2 [M = Cd (4), Ni (5)], while 2 undergoes ligand exchange with AlMe 3 to afford Me 2AlSCH 2CH 2NMe 2 (6). The structures of 2-4 and 6 were determined. Compound 2 incorporates three S, N-chelating ligands though the interaction with nitrogen is weaker than in analogous alkoxide complexes. Product 3 reveals one iodine has migrated from nickel to antimony, and all three alkoxide ligands bridge the two metals through μ 2-O atoms. In contrast, in 4, only one alkoxide…

2020

Heteroleptic [Cu(P^P)(N^N)][PF6] complexes, where N^N is 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bpy), 4,5,6-trimethyl-2,2′-bipyridine (4,5,6-Me3bpy), 6-(tert-butyl)-2,2′-bipyridine (6-tBubpy) and 2-ethyl-1,10-phenanthroline (2-Etphen) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP, PIN [oxydi(2,1-phenylene)]bis(diphenylphosphane)) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos, PIN (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane)) have been synthesized and their NMR spectroscopic, mass spectrometric, structural, electrochemical and photophysical properties were investigated. The single-crystal structures of [Cu(POP)(5,5′-Me2bpy)][PF6], [Cu(xantphos)(5,5′…