Search results for "Chela"

Separation of U(VI) and Th(IV) from Some Rare Earths by Thin Layer Chromatography with Di‐(2‐Ethylhexyl)‐Dithiophosphoric Acid on Silica Gel

2005

Abstract Separation of U(VI) and Th(IV) from some rare earths by TLC has been studied using silica gel H and silica gel H impregnated with ammonium nitrate as the stationary phase. The solvent mixture ethyl‐methyl‐ketone–tetrahydrofuran (6∶3, v/v) containing di-(2‐ethylhexyl)-dithiophosphoric acid was used as the mobile phase. When silica gel H impregnated with 2.5 M NH4NO3 was used as stationary phase, the resolution was much improved and the separation of rare earths from each other was also achieved. The tetrad‐effect was observed in variation of R*m versus the atomic number of rare earths.

Tantalocene complexes as bidentate métalloligands: (C5Me5)(C5H4X)Ta(H2)(PPh2) (C5Me5) (C5H4X)Ta(CO) (PPh2) (X = PPh2, CH2CH2NMe2)

1999

Abstract The synthesis of new bidentate metalloligands derived from tantalocene (C5Me5)(C5H4X)Ta(H2)(PPh2) (X = PPh2, 2P; X = CH2CH2NMe22N) and (C5Me5)(C5H4X)Ta(CO)(PPh2) 4(P,N) is described. When opposed to chromium unsaturated fragments the phosphino functionalised complexes 2P and 4P act as chelating bidentate ligands affording Ta(V) (C5Me5)(C5H4PPh2)Ta(CH2) (μ-PPh2)Cr(CO)4 or Ta(III) (C5Me5)(C5H4PPh2)Ta(CO)(μ-PPh2)Cr(CO)4 bimetallic complexes. The same reaction carried out starting from 2N gives rise to a μ-phosphido, μ-hydrido dibridged complex Cp*(C5H4CH2CH2NMe2)TaH(μ-H)(μ-PPh2)Cr(CO)4.

The chemistry of Cr(VI) adsorption on to poly(p-phenylenediamine) adsorbent

2019

Abstract Water pollution due to industrial processes has necessitated and spurred robust research into the development of adsorbent materials for remediation. Polyphenylenediamines (PPD) have attracted significant attention because of their dual cationic and redox properties. They are able to reduce Cr(VI) to Cr(III) in solution. Interrogation of the chemical processes involved in the Cr(VI) adsorption on para-PPD was primarily by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. It was confirmed that the underlying oxidation of the amino groups to imines during the reduction of Cr(VI) to Cr(III) was irreversible. This process occurred at both acidi…

La potenza del vuoto

2011

(Dipyrido[3,2-a:2',3'-c]phenazine)(glycinato)copper(II) perchlorate: a novel DNA-intercalator with anti-proliferative activity against thyroid cancer…

2012

Abstract A novel copper(II) heteroleptic complex of dipyrido[3,2-a:2′,3′-c]phenazine (dppz) and glycinato (gly) as chelating ancillary ligand, [Cu(dppz)(gly)]ClO 4 ( 1 ), was synthesized and characterized. X-ray crystallography revealed that the coordination geometry of the cationic [Cu(dppz)(gly)] + unit is hexacoordinated and shows a distorted octahedral coordination geometry in the solid state, with the N,N and N,O chelating atoms of dppz and glycinato, respectively, in the square plane and in which the planar units are connected in a monodimensional polymeric array by the apical copper coordination of the second carboxylic oxygen atom. Biological assays showed that 1 exhibits a remarkab…

Cytotoxic hydrophilic iminophosphorane coordination compounds of d8 metals. Studies of their interactions with DNA and HSA

2012

The synthesis and characterization of a new water-soluble N,N-chelating iminophosphorane ligand TPAN-C(O)-2-NC(5)H(4) (N,N-IM) (1) and its d(8) (Au(III), Pd(II) and Pt(II)) coordination complexes are reported. The structures of cationic [AuCl(2)(N,N-IM)]ClO(4) (2) and neutral [MCl(2)(N,N-IM)] M=Pd (3), Pt(4) complexes were determined by X-ray diffraction studies or by means of density-functional calculations. While the Pd and Pt compounds are stable in mixtures of DMSO/H(2)O over 4 days, the gold derivative (2) decomposes quickly to TPAO and previously reported neutral gold(III) compound [AuCl(2)(N,N-H)] 5 (containing the chelating N,N-fragment HN-C(O)-2-NC(5)H(4)). The cytotoxicities of co…

Indefinitely stable iron(IV) cage complexes formed in water by air oxidation

2017

In nature, iron, the fourth most abundant element of the Earth's crust, occurs in its stable forms either as the native metal or in its compounds in the +2 or +3 (low-valent) oxidation states. High-valent iron (+4, +5, +6) compounds are not formed spontaneously at ambient conditions, and the ones obtained synthetically appear to be unstable in polar organic solvents, especially aqueous solutions, and this is what limits their studies and use. Here we describe unprecedented iron(IV) hexahydrazide clathrochelate complexes that are assembled in alkaline aqueous media from iron(III) salts, oxalodihydrazide and formaldehyde in the course of a metal-templated reaction accompanied by air oxidation…

Novel bifunctional DATA chelator for quick access to site-directed PET 68Ga-radiotracers: preclinical proof-of-principle with [Tyr3]octreotide

2017

Molecular imaging of tumors with the PET radionuclide 68Ga has gained momentum in clinical oncology due to the expanding availability of commercial 68Ge/68Ga-generators in combination with state-of-the-art PET/CT and PET/MRI hybrid imaging systems. Concurrently, interesting peptide-based or small-size vectors have been developed for theranostic use in cancer patients. Owing to the short half-life of 68Ga (t1/2 = 67.7 min) and the sensitivity of many targeting biomolecules, labeling and kit reconstitution in mild conditions allowing for quick access to ready-for-injection PET-tracers are highly desirable. The novel DATA ((6-pentanoic acid)-6-(amino)methy-1,4-diazepinetriacetate) chelator pre…

Esse.Re (nel) mondo. Arti visive e rinascita dal 1966 a oggi

2022

Nel complesso quadro distopico della pandemia il saggio prende in esame il progetto espositivo e curatoriale .RE, mostra che non si limita a presentare le ricerche di una selezione di artisti tra i più influenti dei nostri tempi ma si focalizza sull’urgente necessità di problematizzare le dicotomie arte/vita, azione/contemplazione, arte/anti-arte, nella prospettiva di una riflessione critica intorno a una raccolta di opere innovative, tanto nel metodo quanto nel contenuto. Vengono esaminate le opere più significative delle ricerche condotte da Alberto Burri, Saint Clair Cemin, Tony Cragg, Zang Hong Mei, Anselm Kiefer, Jeff Koons, Sol LeWitt, Emil Lukas, Mimmo Paladino, Claudio Parmiggiani, …

Spectroscopic, radiochemical, and theoretical studies of the Ga3+-N-2-hydroxyethyl piperazine-N'-2-ethanesulfonic acid (HEPES buffer) system: evidenc…

2013

Recent reports have claimed a superior performance of HEPES buffer in comparison to alternative buffer systems for 67/68 Ga labeling in aqueous media. In this paper we report spectroscopic (1H and 71 Ga NMR), radiochemical, mass spectrometry and theoretical modeling studies on the Ga3+/HEPES system (HEPES = N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) performed with the aim of elucidating a potential contribution of HEPES in the 68/67 Ga radiolabeling process. Our results demonstrate that HEPES acts as a weakly but competitive chelator of Ga3+ and that this interaction depends on the relative Ga3+: HEPES concentration. A by-product formed in the labeling mixture has been identified …