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showing 10 items of 3084 documents
Micellar Liquid Chromatography: Fundamentals
2015
The reversed phase liquid chromatography (RPLC) mode with surfactant above the critical micellar concentration (CMC) has been called micellar liquid chromatography (MLC). In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and micellar pseudo-phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and mice…
Sequestration of alkyltin(IV) cations by complexation with amino-polycarboxylic chelating agents
2013
Abstract The binding capacity of four amino-polycarboxylic ligands (APCs) [nitrilotriacetate (NTA), ethylenediamine- N , N , N′ , N′ -tetraacetate (EDTA), (S,S)-ethylenediamine- N , N ′-disuccinic acid (S,S-EDDS) and diethylenetriamine- N , N , N′ , N″ , N″ -pentaacetate (DTPA)] towards mono-, di- and tri-alkyltin(IV) cations [(CH 3 )Sn 3 + , (CH 3 ) 2 Sn 2 + , (C 2 H 5 ) 2 Sn 2 + , (CH 3 ) 3 Sn + or (C 2 H 5 ) 3 Sn + ] was studied, in aqueous solutions, by ISE-H + potentiometry, at I = 0.1 mol L − 1 (NaCl) and at T = 298.15 K. In all the systems R x Sn (4 − x)+ − APC (R = CH 3 or C 2 H 5 ) a strong 1:1 species is formed together with protonated, hydroxo and dinuclear complexes. The valu…
Coordination properties of the ACE inhibitor captopril towards Me2Sn(IV)2+ in aqueous solution, and biological aspects of some dialkyltin(IV) derivat…
2003
Abstract The coordination of Me 2 Sn(IV) 2+ (M) to captopril { N -[( S )-3-mercapto-2-methylpropionyl]- l -proline, H 2 (cap), H 2 L} in aqueous solution was studied by means of potentiometric titration, electrospray mass spectrometry, 1 H-NMR spectroscopy and Mossbauer spectroscopy in the pH range 2–11 ( I =0.1 mol dm −3 NaClO 4 , 298 K). The results obtained with these methods proved that only monomeric complexes are formed in solution. In the acidic pH range, species with a metal-to-ligand ratio of 1:1 exist. The neutral complex ML, similarly to the complex Me 2 Sn(cap) crystallized in the same pH range, adopts a tbp structure with eq S − and ax COO − , while, instead of the coordina…
Synthesis of Water-Soluble Copolymers Carrying Long-Chain (C12 to C30 ) Aliphatic Moieties
2011
Water-soluble copolymers from mono-1-alkyl itaconates and N-vinyl-2-pyrrolidone are synthesized and characterized. Themono-1-alkyl itaconates are prepared from itaconic anhydride and the related alcohol: 1-dodecanol, 1-octadecanol, 1-docosanol, and 1-triacontanol. The mono-1-triacontyl itaconate is synthesized fromplant growth regulator policosanols extracted from Agave fourcrouydes, where 1-triacontanol is the major product. The reactivity ratios, calculated according to the Mao-Huglin method for copolymerizations conducted to medium-high conversions, indicate a tendency toward alternation for all copolymerization reactions. Water solubility of copolymers is provided as a function of copol…
Gold based plasmonic stripes co-integrated with low loss Si3N4 platform in aqueous environment
2018
We demonstrate a butt-coupled interface between LPCVD Si 3 N 4 and gold based plasmonic waveguides in aqueous environment, exhibiting 2.3dB coupling loss and 75μm propagation length at 1550nm, towards future employment in biosensing applications.
Photocatalytic Oxidation of Cyanides in Aqueous Titanium Dioxide Suspensions
1997
The photocatalytic oxidation of free cyanides in aqueous suspensions containing polycrystalline TiO2(anatase) powders irradiated in the near-UV region has been investigated. The rate of cyanide photooxidation has been studied by varying the following operative parameters: (i) initial cyanide concentration; (ii) catalyst concentration; (iii) initial pH; (iv) power of irradiation; and (v) chloride ion concentration in the reacting mixture. Under the used experimental conditions the photoreaction proceeded at a measurable rate until the complete disappearance of cyanides. The kinetics of cyanide photooxidation is affected by the catalyst concentration, the chloride ion concentration, and the p…
[Mnii2(bpym)(H2O)8]4+ and [Miv(CN)8]4– (M = Mo and W) as building blocks in designing bpym- and cyanide-bridged bimetallic three-dimensional networks…
2002
One-pot reaction between the dinuclear [MnII2(bpym)(H2O)8]4+ complex and the mononuclear [MIV(CN)8]4− unit (M = Mo and W; bpym = 2,2′-bipyrimidine) in aqueous solution yields the novel heterobimetallic complexes of formula {(μ-bpym)[Mn(H2O)]2-(μ-NC)6M(CN)2} with M = Mo (1) and W (2). 1 and 2 are isostructural three-dimensional compounds where the manganese atoms are bridged by bisbidentate bpym and hexakismonodentate octacyanometalate units. Variable-temperature magnetic susceptibility data of 1 and 2 show the occurrence of a significant antiferromagnetic coupling between the high spin manganese(II) ions through bridging bpym (Jca. −1.1 cm−1, the exchange Hamiltonian being defined as H = −J…
On the Existence of Different Zeolite-Associated Topological Redox Isomers. Electrochemistry of the Y Zeolite-Associated Mn(Salen)N3 Complex
2002
The electrochemical properties of Y zeolite-associated MnIII(salen)N3 (salen = trans-(R,R)-1,2-bis(salicyldeneamino)cyclohexane) has been investigated using polymer film electrodes immersed into neutral aqueous solutions. Zeolite Y-associated Mn(III)−salen complexes are reduced in one-electron reversible process at −0.25 V versus SCE. The electrochemical response is discussed in terms of the existence of two topological redox isomers: a weakly boundary-associated Mn(salen) complex, whose electrochemical response corresponds to a reversible one-electron transfer controlled by diffusion of the positive ions of the supporting electrolyte through the zeolite surface windows and channels, and a…
New cyclic tetranuclear copper(II) complexes containing quadrilateral cores: Synthesis, structure, spectroscopy and their interactions with DNA in aq…
2017
Abstract Three new cyclic tetranuclear copper(II) complexes, Tetrakis{3-[(2-pyridylmethyl)-amino]-propionato}(tetrachloro)tetracopper(II)methanolhydrate (1·CH3OH·H2O), Tetrakis{3-[(2-pyridylmethyl)-amino]-propionato}(tetrathiocyanato)tetracopper(II) (2) and Tetrakis{3-[(2-pyridylmethyl)-amino]-propionato}(tetraazido)tetracopper(II) (3) have been synthesized by exploiting the chelating ability and bridging potential of a carboxyamine functionalized tridentate ligand, HL (HL = 3-[(2-Pyridylmethyl)-amino]-propionic acid). Complexes 1, 2 and 3 have been synthesized by carrying out reaction of the ligand HL with stoichiometric amounts of CuCl2·2H2O, CuCl2·2H2O/NH4SCN, and CuCl2·2H2O/NaN3, respec…
Hydrogen-bond tuning of ferromagnetic interactions: synthesis, structure and magnetic properties of polynuclear copper(ii) complexes incorporating p-…
2006
The reaction of copper(II) hydroxide with 2,2'-bipyridine (bipy) (1 : 1) in alkaline aqueous solution (pH 14) at room temperature affords the alternating carbonate/hydroxo-bridged copper(II) polymeric chain compound {[Cu3(bipy)3(mu-OH)2(mu-CO3)2].11H2O}n, 1, as determined by single-crystal X-ray diffraction. The structure of 1 is built up from two similar centro-symmetric dinuclear [(bipy)Cu(mu-OH)]2 cores which link together via bridging carbonate groups to mononuclear [(bipy)Cu] fragments to form the chain. Interdigitation of adjacent chains through pi-pi interactions, which involve each bipy ligand, forms sheets that are separated by the water molecules of crystallisation. Variable-tempe…