Eu³âº-based bridged silsesquioxanes for transparent luminescent solar concentrators.

The sol-gel preparation of a bridged silsesquioxane containing europium(III) salts and 2-thenoyltrifluoroacetone has been achieved from a new ethane tetracarboxamide-based organosilane. Free-standing films with thicknesses up to 440 µm and maximum absolute quantum yield (q) of 0.34 ± 0.03 (excitation at 320 nm) were prepared by the drop cast method, while thin films (∼200-400 nm) spin-coated on glass substrates led to highly luminescent coatings with q = 0.60 ± 0.02 (excitation at 345 nm). The thin films were tested as planar luminescent solar concentrators and the optimized device displays an optical conversion efficiency of 12.3% in the absorbing spectral region of the active layer (300-380 nm).

Tailoring the hydrophilic/lipophilic balance of clickable mesoporous organosilicas by the copper-catalyzed azide-alkyne cycloaddition click-functionalization.

We have designed and synthesized a clickable bridged silsesquioxane material featuring pendant alkyne chains as an aggregate of golf-ball-like nanoparticles, as evidenced by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and small- and wide-angle X-ray scattering (SWAXS). Using the copper-catalyzed azide-alkyne cycloaddition reaction with a range of organic azides of variable characteristics, we transformed this parent bridged silsesquioxane into new materials with tunable hydrophilic/lipophilic balance in high conversions while preserving the original morphology. N2, cyclohexane, and water sorption experiments were used to quantify the affinity of these materials toward the sorbates through the determination of their Henry's constants. This resulted in the following hydrophilic scale: M-OH > M-PEG > M-C6 > M-Ph > M-F > M-C16, which was mostly confirmed by SWAXS measurements.

Biodegradable ethylene-bis(propyl)disulfide-based periodic mesoporous organosilica nanorods and nanospheres for efficient in-vitro drug delivery.

Periodic mesoporous organosilica nanorods and nanospheres are synthesized from 1,4-bis(triethoxysilyl)ethylene and bis(3-ethoxysilylpropyl)disulfide. The nanosystems present the long-range order of the hexagonal nanostructure. They are degraded in simulated physiological conditions. The loading and release of doxorubicin with these nanosystems are both pH dependent. These nanoparticles are endocytosed by breast cancer cells and are very efficient for doxorubicin delivery in these cells.

Self-assembly of bridged silsesquioxanes: modulating structural evolution via cooperative covalent and noncovalent interactions.

The self-assembly of a bis-urea phenylene-bridged silsesquioxane precursor during sol-gel synthesis has been investigated by in situ infrared spectroscopy, optical microscopy, and light scattering. In particular, the evolution of the system as a function of processing time was correlated with covalent interactions associated with increasing polycondensation and noncovalent interactions such as hydrogen bonding. A comprehensive mechanism based on the hydrolysis of the phenylene-bridged organosilane precursor prior to the crystallization of the corresponding bridged silsesquioxane via H-bonding and subsequent irreversible polycondensation is proposed.

Investigation on the vibrational and structural properties of a self-structured bridged silsesquioxane.

The crystalline structure of ureidopyrimidinone-based silane (UPY) has been determined. The local and long range order structuring of the bridged silsesquioxane (MUPY) resulting from the sol-gel hydrolysis-condensation of the former precursor has been investigated by MFTIR (Mid Fourier Transform InfraRed) combined with DFT (Density Functional Theory) and XRD (X-ray diffraction) studies. These studies showed that a long range structuring exists within the organic fragments with the transcription of the DDAA (Donor-Donor-Acceptor-Acceptor) H-bonding array from UPY to MUPY whereas a disordered siloxane network was revealed in the hybrid material.

2D assembly of non-interacting magnetic iron oxide nanoparticles via"click" chemistry.

Azide-terminated magnetic iron oxide nanoparticles have been assembled in 2D on alkyne-terminated self-assembled monolayers (SAMs) by the copper(i) catalyzed alkyne-azide cycloaddition (CuAAC) "click" reaction; the kinetics of the reaction is an important parameter to control the interparticle distance and thus the dipolar interactions.

Click approaches to functional water-sensitive organotriethoxysilanes.

The derivatization of functional organic fragments with triethoxysilyl groups to afford hydrolyzable organosilanes with targeted properties using the copper-catalyzed alkyne azide cycloaddition reaction under strictly anhydrous conditions is described according to two approaches, starting from five silylated substrates. This high yield, fast, and selective method is applicable to a wide range of substrates and is expected to lead to important achievements in the field of functional hybrid silica.

Organic-inorganic hybrid silica material derived from a monosilylated Grubbs-Hoveyda ruthenium carbene as a recyclable metathesis catalyst.

The synthesis of a monosilylated Grubbs-Hoveyda ruthenium alkylidene complex is described, as well as the preparation and characterization of the corresponding material by sol-gel cogelification with tetraethoxysilane (TEOS) and the assay of this recyclable supported catalyst in ring-closing diene and enyne metathesis reactions under thermal and microwave conditions.

In situ X-ray measurements to probe a new solid-state polycondensation mechanism for the design of supramolecular organo-bridged silsesquioxanes.

A long-range ordered organic/inorganic material is synthesized from a bis-silane, (EtO)(3)Si-(CH(2))(3)-NHCONH-C(6)H(4)-NHCONH-(CH(2))(3)-Si(OEt)(3). This crosslinked sol-gel solid exhibits a supramolecular organization via intermolecular hydrogen bonding interactions between urea groups (-NHCONH-) and covalent siloxane bonding, triple bond Si-O-Si triple bond. Time-resolved in situ X-ray measurements (coupling small- and wide-angle X-ray scattering techniques) are performed to follow the different steps involved in the synthetic process. A new mechanism based on the crystallization of the hydrolyzed species followed by their polycondensation in solid state is proposed.

Ionic liquid crystals based on mesitylene-containing bis- and trisimidazolium salts.

The synthesis of novel ionic liquid crystals (ILCs) based on bis- and trisimidazolium salts (I-, BF4-, and [N(SO2CF3)2]-) bearing hydrophobic hexadecyl chains and a bridging mesitylene moiety is reported. The study of their mesomorphic properties is presented, including the characterization of the Smectic A phase by differential scanning calorimetry and polarized optical microscopy. A detailed powder X-ray diffraction (p-XRD) study as a function of temperature confirmed that cooling gives rise to a glass transition from the liquid-crystalline smectic A phase to a metastable lamellar phase. In addition, in the case of bisimidazolium iodide, the ability of these molecules to form self-aggregates in solution has been demonstrated by diffusion nuclear magnetic resonance (NMR) experiments.

Vapour diffusion hydrolysis of a self-assembled silylated organogel, the OG-HG transcription process: a new way to cast and handle fluorescent silsesquioxane.

A new method of hydrolysis-polycondensation of silsesquioxanes, the OG-HG (Organo Gel-Hybrid Gel or Organised Gel-Hydrolysed Gel) process allows the transcription of the supramolecular architecture of organogels to corresponding hybrid silsesquioxanes.