Can a functionalized phosphine ligand promote room temperature luminescence of the [Ru(bpy)(tpy)]2+ core?

Unexpected room temperature luminescence is observed and rationalized by highly challenging excited state calculations for a functionalized phosphine ligand coordinated on the [Ru(bpy)(tpy)](2+) core.     

Reactions of organic peroxy radicals,RO2, with substituted and biogenic alkenes at room temperature: unsuspected sinks for some RO2 in the atmosphere?

Until now the reactions of organic peroxy radicals (RO₂) with alkenes in the gas phase have been essentially studied at high temperature (T ≥ 360 K) and in the context of combustion processes, while considered negligible in the Earth''s atmosphere. In this work, the reactions of methyl-, 1-pentyl- and acetylperoxy radicals (CH₃O₂, C₅H₁₁O₂, and CH₃C(O)O₂, respectively) with 2-methyl-2-butene, 2,3-dimethyl-2-butene and for the first time the atmospherically relevant isoprene, α-pinene, and limonene were studied at room temperature (298 ± 5 K). Monitoring directly the radicals with chemical ionization mass spectrometry led to rate coefficients larger than expected from previous combustion studies but following similar trends in terms of alkenes, with (in molecule⁻¹ cm³ s⁻¹) = 10⁻¹⁸ to 10⁻¹⁷ × 2/2 and = 10⁻¹⁴ to 10⁻¹³ × 5/5. While these reactions would be negligible for CH₃O₂ and aliphatic RO₂ at room temperature, this might not be the case for acyl-, and perhaps hydroxy-, allyl- and other substituted RO₂. Combining our results with the Structure–Activity Relationship (SAR) predicts k^II(298 K) ∼10⁻¹⁴ molecule⁻¹ cm³ s⁻¹ for hydroxy- and allyl-RO₂ from isoprene oxidation, potentially accounting for up to 14% of their sinks in biogenic-rich regions of the atmosphere and much more in laboratory studies.

The reactions of organic peroxy radicals with alkenes, overlooked until now, could be more significant than expected for some RO₂ in the atmosphere.     

Application of conjoint liquid chromatography with monolithic disks for the simultaneous determination of immunoglobulin G and other proteins present in a cell culture medium

The aim of this study was to develop a chromatographic method, as a substitute for enzyme-linked immunosorbent assays, for the rapid and simultaneous detection of IgG, insulin, and transferrin present in a cell culture medium. Conjoint liquid chromatography (conjoint LC) using monolithic disks was applied for this purpose. An anion-exchange disk was combined with a Protein G affinity disk in a preparative HPLC system. IgG bound to the Protein G disk, whereas transferrin and insulin were captured on the quaternary ammonium (QA) disk. Using this method, it was possible to simultaneously determine the concentrations of IgG, transferrin, and insulin in the cell culture medium. Thus, conjoint LC could be used for the rapid and simultaneous detection of different proteins present in a cell culture medium.     

Rewriting systems in alternating knot groups with the Dehn presentation

Every tame, prime and alternating knot is equivalent to a tame, prime and alternating knot in regular position, with a common projection. In this work, we show that the Dehn presentation of the knot group of a tame, prime, alternating knot, with a regular and common projection has a finite and complete rewriting system. Although there are rules in the rewriting system with left-hand side a generator and which increase the length of the words we show that the system is terminating.      

Preparation of amphiphilic glycerol-substituted zinc phthalocyanines using copper-free Sonogashira cross-coupling in aqueous medium

Palladium-catalyzed copper-free Sonogashira cross-coupling reactions were performed on a protected and unprotected monoiodotriglycerol substituted Zn(II) phthalocyanine with various alkynes in organic and aqueous medium. From the silyl protected alkyne derivative, a protected homo coupled dimeric product was also prepared using Glaser coupling. All products were purified by reverse phase HPLC and the assigned structures were confirmed by mass and UV-vis spectroscopy.     

N-Boc and N-CBz Ethyl Oxamates: New Gabriel Reagents

N-Boc and N-CBz ethyl oxamates can be directly coupled with various halides under Gabriel conditions which afford the corresponding N-protected amines after mild deprotection with LiOH.     

Adiabatic versus nonadiabatic photoisomerization in photochromic ruthenium sulfoxide complexes: a mechanistic picture from density functional theory calculations

Polypyridine ruthenium sulfoxide complexes are intriguing compounds which can display both photochromic and electrochromic properties. These properties are based on the Ru-S → Ru-O linkage isomerization capability of the sulfoxide group. The photoisomerization mechanism is of particular importance in order to understand the photophysical properties of such molecules. Density functional theory calculations demonstrate that the main photoisomerization mechanism is nonadiabatic for the system under study in agreement with the experimental observations. Indeed, funnels for efficient radiationless decay back to the ground state are shown to be easily accessible compared to transition states on the adiabatic triplet potential energy surface. However, we highlight for the first time that triplet metal-centered states play a central role in the photoisomerization mechanism of these compounds.     

Designer amphiphiles based on para-acyl-calix[8]arenes

The synthesis of a series of fully O-derivatised para-acyl-calix[8]arenes is described, where the acyl function is either octanoyl or hexadecanoyl. The groups attached at the phenolic face are, carboxymethoxy (anionic), carboxypropoxy (anionic), 4-sulfonatobutoxy (anionic), ethoxycarboxymethoxy (neutral), ethoxycarboxypropoxy (neutral), 2-methoxyethoxy (neutral) and 2-(2-methoxy)diethoxy (neutral). The use of specific synthetic routes has allowed complete substitution in high yields for all the compounds obtained. The interfacial properties of the compounds have been studied and stable monolayers have been obtained for certain compounds in the series having para-octanoyl substituents; all compounds studied in the series having para-hexadecanoyl substituents formed stable monolayers at the air-water interface. The interactions between O-4-sulfonatobutoxy-para-ocatanoylcalix[8]arene and a series of serum albumins have been studied by dynamic light scattering and specific adsorption of the calix-[8]-arene derivative onto the proteins observed. The anionic derivatives O-4-sulfonatobutoxy-para-ocatanoylcalix[8]arene and O-carboxymethoxy-para-ocatanoylcalix[8]arene have been shown to possess anticoagulant properties but to have no haemolytic toxicity.     

Characterization of CO2 Plasma and Interactions with Polypropylene Film

The interactions between CO₂ plasma, less degrading than O₂ plasma, and polymeric surfaces are studied. CO₂ discharge and the relationships between the density of plasma reactive species are analyzed by optical emission spectroscopy and mass spectrometry. The optical emission spectrum was identified and five principal systems of carbon monoxide were assigned: the 4th and 3rd positive systems, Angstrom and 3A systems. Other systems dealing with ionized species CO⁺ ₂ and CO⁺ were also found. Mass spectrometry showed that the carbon monoxide and atomic oxygen were created through CO₂ dissociation by electronic impact. The detected molecular oxygen coming from the atomic oxygen recombination was associated with the power. The study of plasma/polymer interface showed the consumption of ionized species, the appearance of atomic hydrogen due to methyl groups transformation into exomethylene groups onto the polypropylene surface, and a degradation mechanism dependent on atomic oxygen density in the plasma phase.     

Investigation of redox properties of different PtSn/Al2O3 catalysts.

Alumina-supported Sn and PtSn particles are studied by 119Sn M?ssbauer spectroscopy after oxidation and reduction under various conditions. The observed species of Sn(IV), Sn(II) and Sn(0) are grouped in several categories, each being characterised by distinct structural properties. Tin phases in contact with the support or with platinum are identified. The results are used to establish a model describing the phase transformations occurring in PtSn particles under oxidising or reducing conditions. Particular attention is paid to the reduction/reoxidation mechanisms governing H2/O2 double titrations. An increased reactivity of tin towards oxygen, induced by the contact with platinum, is demonstrated. It is shown that tin contributes to the oxygen uptake VO1 of a first titration cycle by platinum-catalysed transformation of Sn(II) into an oxometallic phase Pt(x)Sn(O). The oxygen titre VO2 of a second cycle is due to O2 chemisorption on platinum only.