Search results for "Chemical process"

Fluorescence emission and enhanced photochemical stability of Zn(II)-5-triethyl ammonium methyl salicylidene ortho-phenylendiiminate interacting with…

2010

Abstract The photophysical and photochemical properties of the cationic Zn II complex of 5-triethyl ammonium methyl salicylidene ortho-phenylendiimine (ZnL 2+ ) interacting with native DNA were investigated by steady state and time-resolved fluorescence spectroscopies. Experimental results indicate that, in the presence of DNA, ZnL 2+ is efficiently protected from a photochemical process, which occurs when it is in the free state dispersed in aqueous solution. The analysis of the absorption and emission spectra of ZnL 2+ , both stored in the dark and after exposure to tungsten lamp light for 24 h, corroborated by quantum chemical calculations, allowed us to point out that ZnL 2+ undergoes a…

Синтезы промежуточныхъ продуктовъ искусственныхъ органическихъ красокъ [Синтезы промежуточных продуктов искусственных органических красок]

1917

Comments on 'formation and characterization of nanotubes of La(OH) 3 obtained using porous alumina membranes'

2010

New experimental evidence concerning the formation of La(OH)3 nanowires on anodic alumina membranes by cathodic polarization in 0.05 M lanthanum nitrate solution is provided to further support the conclusions previously reached in our work (Bocchetta et al 2007 Electrochem. Commun. 9 683-8) and recently criticized by González-Rovira et al (Nanotechnology 2008 19 495305). Some unconvincing aspects of the paper of González-Rovira et al, according to which the same electrochemical process should lead to the formation of hydroxycarbonate nanotubes, are also discussed.

Preparation of Biomolecule Microstructures and Microarrays by Thiol-ene Photoimmobilization

2009

A mild, fast and flexible method for photoimmobilization of biomolecules based on the light-initiated thiol-ene reaction has been developed. After investigation and optimization of various surface materials, surface chemistries and reaction parameters, microstructures and microarrays of biotin, oligonucleotides, peptides, and MUC1 tandem repeat glycopeptides were prepared with this photoimmobilization method. Furthermore, MUC1 tandem repeat glycopeptide microarrays were successfully used to probe antibodies in mouse serum obtained from vaccinated mice. Dimensions of biomolecule microstructures were shown to be freely controllable through photolithographic techniques, and features down to 5 …

Triazolopyridopyrimidines: an emerging family of effective DNA photocleavers. DNA binding. Antileishmanial activity.

2015

Triazolopyridopyrimidines 3-phenyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-d]pyrimidine (1a), 6,8-di(pyridin-2-yl)-[1,2,3]triazolo[1',5':1,6]pyrido[2,3-d]pyrimidine (1b) and 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-d]pyrimidine (1c) were prepared and their electrochemical and luminescence properties were studied in depth. The DNA binding ability of this series of compounds has been investigated by means of UV-vis absorption and fluorescence titrations, steady-state emission quenching with ferrocyanide as well as viscosity measurements. Results have shown that triazolopyridopyrimidine 1a interacts strongly at DNA grooves. This compound also displays pref…

Interfacial photochemistry of biogenic surfactants: a major source of abiotic volatile organic compounds

2017

Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous …

Synthesis and coordination properties of an azamacrocyclic Zn(II) chemosensor containing pendent methylnaphthyl groups

2008

The synthesis of a polyazamacrocycle constituted by two diethylenetriamine bridges functionalized at their central nitrogen with naphth-2-ylmethyl units and interconnected through 2,6-dimethylpyridine spacers (L1) is reported. The protonation behaviour of the new macrocycle in water and in water-ethanol 70/30 v/v mixed solvent has been examined by means of pH-metric, UV-Vis and steady-state fluorescence techniques. The fluorescence emission is slightly quenched following the deprotonation of the central tertiary amines and more deeply quenched upon deprotonation of the secondary amino groups. pH-Metric titrations show that in water-ethanol 70/30 v/v L1 forms stable mononuclear complexes wit…

Stimuli responsive hybrid magnets : tuning the photoinduced spin-crossover in Fe(III) complexes inserted into layered magnets

2013

The insertion of a [Fe(sal_2 trien)]^+ complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin crossover (LIESST effect) in compounds [Fe^{III}(sal_2 trien)][Mn^{II}Cr^{III}(ox)_3]·CHCl_3 (1·CHCl_{3}) [Fe^{III}(sal_{2} trien)][Mn^{II}Cr^{III}(ox)_{3}]·CHBr_{3} (1·CHBr_{3}) and [Fe^{III}(sal_{2} trien)][Mn^{II}Cr^{III}(ox)_{3}]·CH_{2}Br_{2} (1·CH_{2}Br_{2}). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn^{II} and Cr^{III} ions linked through oxalate ligands and a layer of [Fe(sal_{2} trien)]^{+} complexes and solvent molecules (CHCl_{3} CHBr_{…

Tuning the photocatalytic activity of bismuth wolframate: Towards selective oxidations for the biorefinery driven by solar-light

2017

The sol–gel entrapment of nanostructured Bi2WO6 enhances the activity and the selectivity of the short-gap semiconductor in the sunlight-driven photo-oxidation of trans-ferulic and trans-cinnamic acid dissolved in water with air as the primary oxidant. Valuable products such as vanillin, benzaldehyde, benzoic acid and vanillic acid are obtained. This provides the proof of concept that photocatalysis could be a promising technology in tomorrow's solar biorefineries.

Photoemission study of the reactivity of barium towards SiOx thermal films

2011

Abstract Barium was deposited at room temperature on a thermal silicon oxide layer and the interfacial reaction was monitored by synchrotron induced photoemission (both core level and valence band). The first step of the growth consists of an interfacial reaction which leads to the formation of an interfacial silicate layer. The next step consists in formation of barium oxide while metallic barium occurs subsequently. The deposit can be also homogenized by annealing above 575 K. This results in the formation of several layers of silicate by consumption of silicon oxide. In the case of fractional coverage, subsequent annealing at 975 K induces the decomposition of barium silicate. However, s…