Thermo‐Raman spectroscopy of selected layered double hydroxides of formula Cu6Al2(OH)16CO3 and Zn6Al2(OH)16CO3

Raman spectroscopy using a hot stage was used to characterise layered double hydroxides (LDHs) of the formula (Cu,Zn)₆Al₂(OH)₁₆(CO₃)^·4H₂O. The spectra were used to assess the molecular assembly of the cations in the LDH structure. The sharp band at 1058 cm⁻¹for the Zn₆Al₂(OH)₁₆(CO₃)^·4H₂O is assigned to the ν₁CO₃²⁻ symmetric stretching mode. This band shifts to higher wavenumbers and is observed at 1103 cm⁻¹at 600 °C. It is proposed that metal carbonate species formed during the decomposition of the hydrotalcite structure is responsible for the increase in the band position. The Cu–Al hydrotalcite did not show the same trend. The symmetric stretching mode of carbonate is observed at around 1110 cm⁻¹, and at temperatures above 200 °C a shoulder appears at around 1210 cm⁻¹, suggested to be due to CuCO₃. Copyright © 2008 John Wiley & Sons, Ltd.     

Substrate pre-treatment of flexible material for printed electronics with carbon nanotube based ink

In this work, an innovative solution was developed in order to make paper-based material, used traditionally in the packaging and labelling industries, compatible with the printing of functional conductive inks. In order to avoid the deterioration of the ink functionalities due to different paper properties, a UV-curing inkjettable primer layer was developed. This pre-treatment enables homogeneous surface properties such as smoothness, absorption capacity and surface energy to be obtained, for almost all the examined substrates. To confirm the positive impact of such pre-treatment, conductivity has been measured when using a new conductive ink, combining the processability of the PEDOT-PSS conductive polymer with the high electrical properties of carbon nanotubes (CNTs). Significant improvement has been measured for all paper materials and similar conductivity (close to reference PET film) has been obtained whatever the substrate involved. This pre-treatment now makes it possible to consider paper-based material as a potential substrate for printed electronics. In this case, the substrate adaptation technique offers an innovative solution to produce low-cost and flexible electronics.     

Tuning the conversion of cyclohexane into cyclohexanol/one by molecular dioxygen, protons and reducing agents at a single non-porphyrinic iron centre and chemical versatility of the tris(2-pyridylmethyl)amine TPAFe(II)Cl2 complex in mild oxidation chemistry

We report that the oxygen sensitivity of some Fe(II) complexes with tripodal ligands can be used, with benefit, in the oxidation of cyclohexane under mild conditions. Depending on the solvent, two very different reaction pathways are involved, which share the coordination of O(2) to the metal as the common initial step. We have synthesized a series of α-chlorinated tripods in the tris(2-pyridylmethyl)amine series Cl(n)TPA (n = 1-3) and fully characterized the corresponding FeX(2) complexes (X = Cl, CF(3)SO(3)). The single-crystal X-ray structure analyses of the FeCl(2) complexes are reported. In CH(3)CN, the FeCl(2) complexes react smoothly with O(2), whereas the Fe(CF(3)SO(3))(2) complexes are non-sensitive. In CH(3)CN, the reaction of the oxygen-sensitive Cl(n)TPAFeCl(2) (n = 0-3) with O(2), acetic acid and zinc amalgam, in the presence of cyclohexane, affords a mixture of cyclohexanol/one in an ≈ ol/one ratio of 3.1 and a selectivity of the C3°/C2° in the adamantane conversion that is consistent with a metal-oxo based oxidation. Limited efficiency (≈ 2 TON) was observed for the parent TPAFeCl(2) complex and Cl(1)TPAFeCl(2), whereas both other complexes turned out to be poorly active. The TPAFeCl(2) complex was used to address mechanistic questions: when the reaction was carried out in pyridine, the ol/one ratio shifted to 0.15 while efficiency was improved by 7-fold. In pyridine and in the presence of a spin trap (DMPO), the radical-based character of the reaction was definitely established, by contrast with acetonitrile, where no oxygenated radicals were detected. Thus, the reactivity differences arise from involvement of two distinct active species. The dichotomous radical/biomimetic pathway is discussed to interpret these results.     

Cationic lipo-thiophosphoramidates for gene delivery: synthesis, physico-chemical characterization and gene transfection activity--comparison with lipo-phosphoramidates

The synthesis of cationic lipo-thiophosphoramidates, a new family of cationic lipids designed for gene delivery, is reported herein. This new class of lipids is less polar than its oxygenated equivalent the lipo-phosphoramidates. Fluorescence anisotropy and FRET were used to determine the fluidity and fusogenicity of the lipo-phosphoramidates 3a-b and lipo-thiophosphoramidates 7a-b. The determination of both the size and the zeta potential of the nano-objects (liposomes and lipoplexes) and the determination of the DNA binding ability of the liposomes have completed the physico-chemical characterizations of the cationic lipids studied. Finally, the cationic lipids 3a-b and 7a-c have been evaluated as synthetic vectors for gene transfection into a variety of mammalian cell lines. The lipo-thiophosphoramidate 7a proved to be an efficient and low toxicity synthetic vector even when used at low lipid to DNA charge ratios.     

Synthesis and Crystal Structure of the Azide K4[Re6Sei8(N3)a6]·4H2O; Luminescence,Redox, and DFT Investigations of the [Re6Sei8(N3)a6]4– Cluster Unit

The reaction of K₄[Re₆Seⁱ₈(OH)^a₆] · 8H₂O with NaN₃ in water results in the formation of [Re₆Seⁱ₈(N₃)^a]^4– units that crystallize with K⁺ and H₂O to form K₄[Re₆Seⁱ₈(N₃)^a₆] · 4H₂O [P2₁/c (N°14), a = 9.0595(3) Å, b = 13.2457(4) Å, c = 13.2040(5) Å, β = 94.472(1)°]. In the solid state, the unit is characterized by N₃ linear groups forming bond angles of roughly 120° with the Re₆ cluster. The positions of the ν_as and ν_sy bands as well as N–N–N deformation modes of the N₃ groups are discussed. Luminescence properties of the [Re₆Seⁱ₈(N₃)^a]^4– unit were measured in the solid state and in an acetonitrile solution. The redox potential of the [Re₆Seⁱ₈(N₃)^a]^4–/[Re₆Seⁱ₈(N₃)^a]^3– system was measured in acetonitrile. Experimental results were analyzed in the light of density functional theory calculations.     

Brilliant BODIPY-fluorene Copolymers With Dispersed Absorption and Emission Maxima

Four systems 1a - d were prepared to investigate the optical properties of copolymers comprised of polyfluorene doped with BODIPY-based fluors. The underlying hypothesis was energy harvested via the strong absorptivity of the major component, fluorine, would be primarily emitted from the BODIPY parts at much higher wavelengths. Optimization of the polymerization process as a function of the mol % of BODIPY, indicated that the brightest polymers were formed when approximately 4 fluorene units were co-polymerized with every BODIPY precursor. These polymers were cast into nanoparticles of ca 40 nm diameter. Treatment of clone 9 rat liver cells with suspensions of these particles resulted in uptake without encapsulation in lysosomes, or organelle targeting.