Search results for " solution"

Designing solid optical sensors for in situ passive discrimination of volatile amines based on a new one-step hydrophilic PDMS preparation

2016

Abstract We reported an optimal material for embedding chemoresponsive dyes based on modified commercial PDMS. A new approach to impart hydrophilicity to H-PDMS in an unique step was developed by addition of tetraethyl orthosilicate (TEOS) and in absence of basic or acid aqueous mixtures or hydroxyl-compounds during the PDMS coating process. This incorporation significantly enhances the performance of PDMS-based devices for sensing applications. New colorimetric sensors for passive detection and in situ discrimination of volatile amines have been obtained. The limit of detection achieved was 1.5 mg m −3 for both, dimethylamine and methylamine, suitable to control real working atmospheres. T…

‘In situ’ preparation of nitrous acid solutions by photoreduction in a flow assembly for analysis of pharmaceuticals

2003

The solutions of nitrite ion, or nitrous acid, are frequently used as reagent in different analytical procedures and in pharmaceutical analysis. The low stability of the aqueous solutions of this reagent implies the tedious work of freshly prepared solutions every day and being kept in the refrigerator. In this paper, a photoreactor formed by a low pressure mercury lamp and nesting in a continuous-flow manifold is studied, tested, and proposed for the in situ reduction of nitrate solution into nitrite. The conversion into nitrite is reproducible and it has been successfully applied to determination of different drugs, mostly from the sulphonamide family, in an FIA assembly.

The effect of early or late R&D inbound alliance on innovation

2016

In the research-and-development (R&D) supply chain, firms can agree an inbound alliance at different times along the R&D process; this decision affects the supplier's effort and the innovation that firms achieve at the end of the agreement. Because the supplier's effort is not entirely observable, firms cannot enforce effort contractually. Early contracts demand greater effort and offer risk-sharing opportunities; in late contracts suppliers have a stronger ex-ante bargaining-power position because of the shorter (and less risky) contract length and the experience suppliers already have. This study argues that later inbound alliances allow a higher innovation value when both partner…

Conformation of the umifenovir cation in the molecular and crystal structures of four carboxylic acid salts

2014

The umifenovir salts of maleic, salicylic, glutaric, and gentisic acid as well as the chloroform solvate of the salicylate were prepared. Single crystals of the five compounds were obtained and their molecular and crystal structures determined by X-ray diffraction. In each structure the conformation of phenyl ring with respect to the indole group of the umifenovir moiety is different. The water solubility and melting points of the studied umifenovir salts have been determined.

New sensing devices part 1: indole-containing polyamines supported in nanosized boehmite particles

2005

The synthesis, characterisation and optical properties of new sensing systems made by attaching different polyamine chains functionalised with an indole fluorophore to a boehmite matrix is reported for the first time. Firstly, a family of tri(alkoxy)alkylpolyaminosilanes have been reacted with indole-3-carboxaldehyde to form the corresponding Schiff bases which were reduced with sodium borohydride. The anchoring to the surface of the boehmite nanoparticles was carried out by reacting the precursors with the hydroxyl groups available in the surface of the support. The characterisation of the materials by elemental microanalysis, X-ray powder diffraction, CP-MAS 29Si NMR and electron microsco…

Sequential injection analysis (SIA)-chemiluminescence determination of indomethacin using tris[(2,2'-bipyridyl)]ruthenium(III) as reagent and its app…

2006

Abstract Automated sequential injection (SIA) method for chemiluminescence (CL) determination of nonsteroidal anti-inflammatory drug indomethacin ( I ) was devised. The CL radiation was emitted in the reaction of I (dissolved in aqueous 50% v/v ethanol) with intermediate reagent tris(2,2′-bipyridyl)ruthenium(III) (Ru(bipy) 3 3+ ) in the presence of acetate. The Ru(bipy) 3 3+ was generated on-line in the SIA system by the oxidation of 0.5 mM tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy) 3 2+ ) with Ce(IV) ammonium sulphate in diluted sulphuric acid. The optimum sequence, concentrations, and aspirated volumes of reactant zones were: 15 mM Ce(IV) in 50 mM sulphuric acid 41 μL, 0.5 mM Ru(bipy) 3 …

Photocatalytic Solar Light H 2 Production by Aqueous Glucose Reforming

2018

Two-Dimensional Assembling of (2,2‘-Bipyrimidine)bis(oxalato)chromate(III) Units through Alkaline Cations

1999

Self-assembling of the tris-chelated [Cr(bpm)(ox)2]- complex with Na+ in aqueous solution leads to the remarkable bimetallic honeycomb layered compound of formula [NaICrIII(bpm)(ox)2]·5H2O (2) (bpm...

ADC-Based Palladium Catalysts for Aqueous Suzuki Miyaura Cross-Coupling Exhibit Greater Activity than the Most Advantageous Catalytic Systems

2013

The reaction between the equimolar amounts of cis-[PdCl2(CNR1)2] (R1 = cyclohexyl (Cy) (1), tBu (2)) and the carbohydrazides R2CONHNH2 (R2 = Ph (5), 4-ClC6H4 (6), 3-NO2C6H4 (7), 4-NO2C6H4 (8), 4-CH3C6H4 (9), 3,4-(MeO)2C6H3 (10), naphth-1-yl (11), fur-2-yl (12), 4-NO2C6H4CH2 (13), Cy (14), 1-(4-fluorophenyl)-5-oxopyrrolidin-3-yl (15), (pyrrolidin-1-yl)C(O) (16)) proceeds in refluxing CHCl3 for ca. 4 h. A subsequent workup provided the aminocarbene species cis-[PdCl2{C(NHNHC(O)R2)═N(H)R1}(CNR1)] (18–33) in good to excellent (80–95%) isolated yields. The coupling of equimolar amounts of cis-[PdCl2(CNR1)2] (R1 = Cy (1), tBu (2), 2,6-Me2C6H3 (Xyl) (3), 2-Cl-6-MeC6H3 (4)) and PhSO2NHNH2 (17) occu…

Synthesis, crystal structure and magnetic properties of the spin crossover system [Fe(pq)3]2+

2008

Abstract Three new compounds formulated (ClO4)2[Fe(pq)3] (1), (BF4)2[Fe(pq)3] · EtOH (2) and {(ClO4)[MnCr(C2O4)3][Fe(pq)2(H2O)2]} (3), where pq is 2,2′-pyridylquinoline, have been synthesised and characterised. Despite the different crystal packing exhibited by 1 and 2, the cationic species [Fe(pq)3]2+ are structurally quite similar. At 293 K, the Fe–N bond lengths are characteristic of the iron(II) in the high-spin state. In contrast to 1, 2 undergoes a continuous spin transition. Indeed, at 95 K its structure experiences a noticeable change in the Fe–N bonds and angles, i.e. the Fe–N bonds shorten by 0.194 A on the average. The magnetic behaviour confirms that 1 is fully high-spin in the …