Search results for "ALK"

Straightforward synthesis of bioconjugatable azo dyes. Part 1: Black Hole Quencher-​1 (BHQ-​1) scaffold

2014

Abstract Azo dyes are currently used to quench the fluorescence of energy donors in bioassays through Forster resonance energy transfer (FRET) phenomenon. Common examples of such dark quenchers are DABCYL and the three members of Black Hole Quencher® (BHQ) family. Yet, only carboxylic acid and phosphoramidite derivatives of such azo dyes are presently commercially available. This Letter presents a straightforward synthesis method to novel bioconjugatable quenchers derived from BHQ-1 scaffold and equipped with a reactive group being either azido, terminal alkyne, or maleimide. The potential utility of the ‘clickable’ azido and thiol-reactive derivatives was notably demonstrated through the p…

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on …

2016

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs are tested in perovskite solar cells and power conversion efficiencies (PCE) of up to 18.1% under 1 sun irradiation are measured. This value is comparable with the 17.8% efficiency obtained using 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene as a reference compound. Similarly, a significant quenching of the photoluminescence in the first nanosecond is observed, ind…

Interactions in water-alcohol mixtures: Conductance of lithium picrate in solutions of water and isomeric pentanols at 25�C

1982

Conductance measurements of lithium picrate in solutions of water in n-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol have been carried out at 25°C. Ionic association and conductance were found to change with water content and with the molecular structure of the alcohols (i.e. position of the OH group and degree of branching of the alkyl chain). These results indicate that both conductance and ion pair formation are not the consequence of the simple motion of ions in the electrical field as required by the continuum model. A more realistic approach, involving the internal structure of the solvent mixtures, has been considered.

Tetra-alkoxy substituted PPV derivatives: a new class of highly soluble liquid crystalline conjugated polymers

2011

Two first examples of highly soluble tetra-alkoxy substituted PPV derivatives, poly(2,3,5,6-tetrahexyloxy-1,4-phenylene vinylene) (TH-PPV) and poly[2,3,5,6-tetra(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] TEH-PPV, are presented. Both polymers have been fully characterized and the solubility and UV-Vis absorption characteristics have been studied in various organic solvents. Due to the symmetric nature of the repeating unit, TH-PPV and TEH-PPV have an inherently regioregular nature, which is unusual for PPV-type polymers. Observations from polarized light microscopy and differential scanning calorimetry indicate that TH-PPV exhibits thermally induced order resulting in a liquid crystalline m…

Composite soy lecithin–decylpolyglucoside vesicles: A theoretical and experimental study

2008

In the present work, vesicles made with soy lecithin and a commercial mixture of alkyl polyglucosides were prepared and characterized. Vesicles with a constant amount of soy lecithin and an increasing amount of a decylpolyglucoside surfactant, (OrNS10), were formulated and their physicochemical properties were studied with the aim to design a drug delivery system suitable for different applications. To this purpose, morphology, size distribution, ζ-potential and apparent viscosity of the prepared vesicles were studied. Vesicles were also characterized by using optical and light polarized microscopy, transmission electron microscopy and photon correlation spectroscopy. A stability study was …

Thermodynamics of Aqueous Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide)/Surfactant Mixtures. Effect of the Copolymer Molecular Weig…

2004

A calorimetric study was performed to focus attention on the interactions between copolymers and anionic surfactants in aqueous solutions. Three aspects were analyzed: (1) the hydrophobicity of the surfactant, (2) the change of the copolymer molecular weight, and (3) the nature of the hydrophilicity of the copolymer. To this purpose, the family of sodium alkanoates (sodium octanoate through sodium dodecanoate) and the triblock copolymers EO76PO 29EO76 (F68), EO103PO39EO 103 and EO132PO50EO132 were investigated. Comparing F68 and EO13PO30EO13 (L64), previously studied by us, provided information on the effect of the copolymer hydrophilicity. The experimental data were analyzed by means of a …

Propargyl-functional aliphatic polycarbonate obtained from carbon dioxide and glycidyl propargyl ether.

2013

The synthesis of propargyl-functional poly(carbonate)s with different content of glycidyl propargyl ether (GPE) units is achieved via the copolymerization of propargyl glycidyl ether and carbon dioxide. A new type of functional poly(carbonate) synthesized directly from CO(2) and the glycidyl ether is obtained. The resulting polymers show moderate polydispersities in the range of 1.6-2.5 and molecular weights in the range of 7000-10 500 g mol(-1). The synthesized copolymers with varying number of alkyne functionalities and benzyl azide are used for the copper-catalyzed Huisgen-1,3-dipolar addition. Moreover, the presence of vicinal alkyne groups opens a general pathway to produce functional …

1983

The synthesis and the phase behaviour of liquid crystalline main chain polymers are described. In these poly- and copolyesters the mesogenic units are linked by highly flexible oligodimethylsiloxane spacers. The comparison of their phase behaviour with that of polyesters known from the literature shows that dimethylsiloxane spacers as a replacement for alkyl spacers are leading to a drastic decrease of the transition temperatures. Depending on the length of the spacer glass transitions as low as −111°C can be achieved. The widths of the liquid crystalline phases thereby are retained up to a spacerlength of 13 oxydimethylsilanediyl (dimethylsiloxane) units. The homopolyesters mainly show sme…

Characterization and Processability of Blends of Polylactide Acid with a New Biodegradable Medium-Chain-Length Polyhydroxyalkanoate

2015

In this work the processability and the mechanical performance of polylactide acid (PLA) based blends with a sample of a new biodegradable medium-chain-length poly (hydroxyalkanoate) (PHA) were investigated. The two polymers are incompatible with scarce adhesion and with the dispersed PHA particles size increasing with the PHA content. Rheological tests in shear flow indicate that adding PHA improves the processability of the matrix by increasing the content of this second component in the blend, as observed also for the torque curves, due to the very low viscosity of this new sample of PHA. The processability is only slightly worsened in non-isothermal elongational flow as the melt strengt…

"Dormant" secondary metal-alkyl complexes are not omnipresent.

2006

This theoretical study was inspired by the perpetual debate over the so-called “dormancy” of the active sites in propylene polymerization, i.e., a drop in their activity after a regioerror (2,1-insertion), which was reported to occur in many (although not all) catalytic systems. To explore the range of possible situations, we have selected two homogeneous systems of fundamentally different structure: an octahedral system of C 2 symmetry with a tetradentate O N N O ligand and a bridged indenyl catalyst. This choice was not accidental; it is in these two systems where the experimentalists cannot reach a consensus about dormancy. Our density-functional theory calculations explain why in certa…