Search results for "METAL"

DNA-binding of zinc(II) and nickel(II) salphen-like complexes extrapolated at 1 M salt concentration: Removing the ionic strength bias in physiologic…

2020

Abstract The DNA-binding of two salphen-like metal complexes of nickel(II) (1) and zinc(II) (2) was investigated in different ionic strength solutions by absorption spectroscopy. The data analysis allowed us to obtain the values of their extrapolated DNA-binding constant in physiological conditions, with DNA-binding strength in the order Ni > Zn, and to give relative weight to the electrostatic and non-electrostatic contributions to their DNA-interaction.

Reversible isomerization of metal nanoclusters induced by intermolecular interaction

2021

Most inorganic nanoparticles are directly surface-terminated (and -stabilized) by protecting ligands, which could greatly affect the atomic packing and physical/chemical properties of their inorganic cores. Here, we show that the intermolecular interactions between the adsorbed molecules and surface ligands can also affect the core structure of inorganic nanoparticles. Through the coupling/decoupling of cationic surfactants (cetyltrimethylammonium cations, CTA+) and anionic surface ligands (para-mercaptobenzoic acid, p-MBA) in the aqueous phase, we have achieved a reversible transformation between two isomers of [Au25(p-MBA)18]− nanoclusters. The interconversion process between the two isom…

Preparative and spectroscopic features of ferricenium tetrachloroferrate(III). Interconversion to diferricenium ?-oxo-bis[trichloroferrate(III)]

1985

Ferricenium tetrachloroferrate(III)(1), one of the more frequently cited ferricenium salts, has recently attracted biomedical interest because of its pronounced antineoplastic activity against Ehrlich ascites murine tumor. In this paper, synthetic methods are reinvestigated in an effort to prepare pure(1) free from a common contaminant, diferriceniumμ-oxo-bis(trichloroferrate)(3). The oxodiferrate, or mixtures of this salt with(1), can readily be converted into pure(1) under acidic conditions. Conversely, dimerization of(1) with participation of water to give the oxodiferrate(3) is brought about by recrystallization of the former from moist acetonitrile/methanol in the presence of base; thi…

Diphenoxido‐Bridged Co II and Zn II Complexes of Tripodal N 2 O 2 Ligands: Stabilisation of M II ‐Coordinated Phenoxyl Radical Species

2010

Three new tripodal ligands with an N 2 O 2 donor set, namely 2-tert-butyl-6-({(2-hydroxybenzyl)[2-(2-pyridyl)ethyl]amino}-methyl)-4-methylphenol (H 2 L 1 ), 2-tert-butyl-6-({(2-hydroxybenzyl)[2-(2-pyridyl)ethyl]amino}methyl)-4-methoxy-phenol (H 2 L 2 ) and 2-tert-butyl-6-({[2-(dimethylamino)ethyl]-(2-hydroxybenzyl)amino}methyl)-4-methoxyphenol (H 2 L 3 ) have been synthesised. Treatment of the ligands with Co-(CH 3 CO 2 ) 2 ·4H 2 O or [Zn(H 2 O) 6 ][ClO 4 ] 2 in the presence of Et 3 N provides the corresponding Co II and Zn" complexes of composition [M II 2 (L 1 ) 2 ] [M = Co (1) (single-crystals are a solvate with the composition [Co II 2 (L 1 ) 2 ]·2CHCl 3 , i.e. 1·2CHCl 3 ); M = Zn (2)],…

Some aspects of the solid state physics of yellow arsenic

1996

Ag11(SG)7 : A New Cluster Identified by Mass Spectrometry and Optical Spectroscopy

2014

We report a one-step and high yield synthesis of a red-luminescent silver cluster with the molecular formula, Ag11(SG)7 (SG: glutathionate) via reduction of silver ions by sodium borohydride in the presence of the tripeptide, glutathione (GSH). The as-prepared cluster shows prominent absorption features at 485 and 625 nm in its UV-vis absorption spectrum. Aging of the as-prepared cluster solution led to the disappearance of the 625 nm peak, followed by broadening of the 485 nm peak to give three maxima at ?487, 437, and 393 nm in its absorption spectrum. These peaks remain unchanged even after polyacrylamide gel electrophoresis (PAGE), where a single band was observed confirming high purity…

Fabrication and characterization of vacuum deposited fluorescein thin films

2011

Simple vacuum evaporation technique for deposition of dyes on various solid surfaces has been developed. The method is compatible with conventional solvent-free nanofabrication processing enabling fabrication of nanoscale optoelectronic devices. Thin films of fluorescein were deposited on glass, fluorine-tin-oxide (FTO) coated glass with and without atomically layer deposited (ALD) nanocrystalline 20 nm thick anatase TiO2 coating. Surface topology, absorption and emission spectra of the films depends on their thickness and the material of supporting substrate. On a smooth glass surface the dye initially formes islands before merging into a uniform layer after 5 to 10 monolayers. On FTO cove…

Accuracy combining different brands of implants and abutments

2013

Objective: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Study design: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-to- abutment fit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands,…

From Laboratory Mixes Evaluation to Full Scale Test: Fatigue Behavior of Bio-Materials Recycled Asphalt Mixtures

2020

The present paper describes the full-scale accelerated test, carried out on asphalt pavements made up with bio-materials, especially designed to help reusing Reclaimed Asphalt (RA) by re-activating the aged binder. Four pavement sections were evaluated: three pavement sections with innovative bio-materials (bio-recycled asphalt mixtures), and a reference section with a conventional, high modulus asphalt mix (EME2). In this study, fatigue resistance was first evaluated in laboratory, with two-points bending test, and then at full scale under heavy traffic loading, with the IFSTTAR accelerated pavement testing facility. The evolution of bio-materials recycled asphalt mixture characteristics, …

Optical absorption of divalent metal tungstates: Correlation between the band-gap energy and the cation ionic radius

2008

We have carried out optical-absorption and reflectance measurements at room temperature in single crystals of AWO4 tungstates (A = Ba, Ca, Cd, Cu, Pb, Sr, and Zn). From the experimental results their band-gap energy has been determined to be 5.26 eV (BaWO4), 5.08 eV (SrWO4), 4.94 eV (CaWO4), 4.15 eV (CdWO4), 3.9-4.4 eV (ZnWO4), 3.8-4.2 eV (PbWO4), and 2.3 eV (CuWO4). The results are discussed in terms of the electronic structure of the studied tungstates. It has been found that those compounds where only the s electron states of the A2+ cation hybridize with the O 2p and W 5d states (e.g BaWO4) have larger band-gap energies than those where also p, d, and f states of the A2+ cation contribu…