Naphthyl-Fused Phosphepines: Luminescent Contorted Polycyclic P-Heterocycles

This article presents the synthesis of a new family of naphthyl-fused phosphepines through Ni-mediated C−C coupling. Interestingly, the chlorophosphine oxide intermediate shows strong resistance toward oxidation/hydrolysis owing to a combination of steric hindrance and pnictogen interactions. However, it can undergo substitution reactions under specific conditions. The optical/redox properties and the electronic structure of these new π-systems were studied experimentally (UV/Vis absorption, emission, cyclic voltammetry) and computationally (TD-DFT calculations, NICS investigation). Taking advantage of the luminescence of these derivatives, a blue-emitting OLED has been prepared, highlighting that these novel π-conjugated P-heterocycles appear to be promising building blocks for solid-state lighting applications.     

Ru/CdS Quantum Dots Templated on Clay Nanotubes as Visible-Light-Active Photocatalysts: Optimization of S/Cd Ratio and Ru Content

A nanoarchitectural approach based on in situ formation of quantum dots (QDs) within/outside clay nanotubes was developed. Efficient and stable photocatalysts active under visible light were achieved with ruthenium-doped cadmium sulfide QDs templated on the surface of azine-modified halloysite nanotubes. The catalytic activity was tested in the hydrogen evolution reaction in aqueous electrolyte solutions under visible light. Ru doping enhanced the photocatalytic activity of CdS QDs thanks to better light absorption and electron–hole pair separation due to formation of a metal/semiconductor heterojunction. The S/Cd ratio was the major factor for the formation of stable nanoparticles on the surface of the azine-modified clay. A quantum yield of 9.3 % was reached by using Ru/CdS/halloysite containing 5.2 wt % of Cd doped with 0.1 wt % of Ru and an S/Cd ratio of unity. In vivo and in vitro studies on the CdS/halloysite hybrid demonstrated the absence of toxic effects in eukaryotic cells and nematodes in short-term tests, and thus they are promising photosensitive materials for multiple applications.     

Synthesis of Nitro-Aryl Functionalised 4-Amino-1,8-Naphthalimides and Their Evaluation as Fluorescent Hypoxia Sensors

Fluorescent sensors are a vital research tool, enabling the study of intricate cellular processes in a sensitive manner. The design and synthesis of responsive and targeted probes is necessary to allow such processes to be interrogated in the cellular environment. This remains a challenge, and requires methods for functionalisation of fluorophores with multiple appendages for sensing and targeting groups. Methods to synthesise more structurally complex derivatives of fluorophores will expand their potential scope. Most known 4-amino-1,8-naphthalimides are only functionalised at imide and 4-positions, and structural modifications at additional positions will increase the breadth of their utility as responsive sensors. In this work, methods for the incorporation of a hypoxia sensing group to 4-amino-1,8-naphthalimide were evaluated. An intermediate was developed that allowed us to incorporate a sensing group, targeting group, and ICT donor to the naphthalimide core in a modular fashion. Synthetic strategies for attaching the hypoxia sensing group and how they affected the fluorescence of the naphthalimide were evaluated by photophysical characterisation and time-dependent density functional theory. An extracellular hypoxia probe was then rationally designed that could selectively image the hypoxic and necrotic region of tumour spheroids. Our results demonstrate the versatility of the naphthalimide scaffold and expand its utility. This approach to probe design will enable the flexible, efficient generation of selective, targeted fluorescent sensors for various biological purposes.     

Intercomparison of simultaneously obtained infrared (4.8 microm) and visible (515-715 nm) ozone spectra using ACE-FTS and MAESTRO

Laboratory ozone absorption spectra were measured simultaneously in the visible (515-715 nm) and infrared (2070-2140 cm(-1)) spectral regions using SCISAT-1's MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) spectrometers. An intercomparison of these measurements was used to assess the relative accuracy of HITRAN absolute line strengths, for which there was a 4% change between the 2000 and 2004 versions. Results reported here show that Chappuis band cross section strengths are more consistent with the HITRAN 2004 4.8 microm band line strengths than with the 2000 compilation.     

Chemically tuned amphiphilic diblock copolymers dispersed in water: from colloids to soluble macromolecules

We investigate by small-angle scattering the structural behavior in water of a family of asymmetric poly(styrene-stat-(acrylic acid))-block-poly(acrylic acid), i.e., P(S-stat-AA)-b-PAA, diblock copolymers. These diblocks are of constant block ratio and increasing molar fraction, phi(AA), ranging from 0 to 1, of acrylic acid in the first P(S-stat-AA) statistical block. We identify three types of structural behavior in water: (i) for phi(AA) /= 0.50, the diblocks dispersions in water are at equilibrium. For high phi(AA), the diblocks are soluble in water, demonstrating that a transition from colloid-like objects to soluble macromolecules is achieved. Close to the transition, (phi(AA) approximately 0.50), the diblocks form objects interpreted as comprising a water-swollen core formed by the P(S-stat-AA) block, surrounded by a swollen brush composed of the majority PAA block, above a apparent critical micelle concentration. However, these diblocks do not behave as macrosurfactants, and their self-association behavior is rather interpreted as a microphase separation which can arise from the incompatibility between two polymer blocks P(S-stat-AA) and PAA placed in a common solvent water.     

Exploiting scale-free information from expression data for cancer classification

Most studies concerning expression data analyses usually exploit information on the variability of gene intensity across samples. This information is sensitive to initial data processing, which affects the final conclusions. However expression data contains scale-free information, which is directly comparable between different samples. We propose to use the pairwise ratio of gene expression values rather than their absolute intensities for a classification of expression data. This information is stable to data processing and thus more attractive for classification analyses. In proposed schema of data analyses only information on relative gene expression levels in each sample is exploited. Testing on publicly available datasets leads to superior classification results.     

Surface superconductivity of dirty two-band superconductors: applications to MgB2

The minimal magnetic field H(c2) destroying superconductivity in the bulk of a superconductor is smaller than the magnetic field H(c3) needed to destroy surface superconductivity if the surface of a superconductor coincides with one of the crystallographic planes and is parallel to the external magnetic field. While for a dirty single-band superconductor the ratio of H(c3) to H(c2) is a universal temperature-independent constant 1.6946, for dirty two-band superconductors this is not the case. I show that in the latter case the interaction of the two bands leads to a novel scenario with the ratio H(c3)/H(c2) varying with temperature and taking values larger and smaller than 1.6946. The results are applied to MgB(2) and compared with recent experiments (A. Rydh, cond-mat/0307445).