Metabolic contrast agents produced from transported solid 13C-glucose hyperpolarized via dynamic nuclear polarization.

Magnetic Resonance Imaging combined with hyperpolarized 13C-labelled metabolic contrast agents produced via dissolution Dynamic Nuclear Polarization can, non-invasively and in real-time, report on tissue specific aberrant metabolism. However, hyperpolarization equipment is expensive, technically demanding and needs to be installed on-site for the end-user. In this work, we provide a robust methodology that allows remote production of the hyperpolarized 13C-labelled metabolic contrast agents. The methodology, built on photo-induced thermally labile radicals, allows solid sample extraction from the hyperpolarization equipment and several hours' lifetime of the 13C-labelled metabolic contrast agents at appropriate storage/transport conditions. Exemplified with [U-13C, d7]-D-glucose, we remotely produce hyperpolarized 13C-labelled metabolic contrast agents and generate above 10,000-fold liquid-state Magnetic Resonance signal enhancement at 9.4 T, keeping on-site only a simple dissolution device.

Molecular Semiconductors for Logic Operations: Dead-End or Bright Future?

The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V-1 s-1 . However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.

Investigation of mixed ionic/nonionic building blocks for the dual templating of macro-mesoporous silica.

Traditional porous monoliths Si(HIPE) (High Internal Phase Emulsion), prepared from the Tetradecyltrimethylammonium Bromide (TTAB)/dodecane/water system, offer high specific surface area, mainly due to microporosity. Aside, mesoporous materials SBA-15, prepared from Pluronic P123, have a high specific surface area, but are obtained as powder, which limits their applications. Starting from the mixed TTAB-P123 surfactant, it is expected to tune the mesoporosity of Si(HIPE), while keeping their monolithic character. The ternary TTAB/P123/water phase diagram was established by varying the weight ratio between these two surfactants. The micellar structure as well as the structural parameters of the liquid crystal domains were determined by SAXS (Small Angle X-ray Scattering). The effect of dodecane solubilization was also investigated and concentrated emulsions were formulated from the (P123/TTAB)/dodecane/water systems. After this soft matter dedicated study, the acquired knowledge was transferred toward the hierarchical porous silica generations, where the sol-gel process is involved. Mixing P123 with TTAB, macro-mesoporous monolithic silica with an enhanced contribution of the specific surface area due to mesoporosity can be prepared. The variation of the TTAB/P123 weight ratio allows controlling the porosity at the mesoscale. Moreover, the macroporosity can be tuned by changing the preparation method, by mixing either the two micellar solutions or directly the two surfactants prior the emulsification process.

Diazene-Functionalized Lamellar Materials as Nanobuilding Blocks: Application as Light-Sensitive Fillers to Initiate Radical Photopolymerizations.

New polysilsesquioxane-based lamellar materials, functionalized with radical precursors, were synthesized. They play a double role in the preparation of composite materials: first, as filler homogeneously dispersed in the monomer after delamination, second as radical initiator in photopolymerization. These polysilsesquioxanes enable fast and efficient photopolymerization upon UV light for thick samples. High conversions in monomers as well as the formation of hybrid polymers covalently linked to the filler are observed. This strategy, based on a double bottom-up approach, avoids the solubility/dispersion problem encountered in the classical preparation of composite polymers from preformed organic polymers.

EPR investigation of zinc/iodine exchange between propargyl iodides and diethylzinc: detection of propargyl radical by spin trapping.

The production of propargyl radicals in the reaction of dialkylzincs with propargyl iodides in nondegassed medium was investigated by EPR using tri-tert-butylnitrosobenzene (TTBNB) as a spin trap. The radical mechanism and the nature of the observed species were confirmed by the trapping of propargyl radicals generated by an alternative pathway: i.e., upon irradiation of propargyl iodides in the presence of hexa-n-butyldistannane. In dialkylzinc-mediated experiments a high concentration of adduct was instantaneously observed, whereas no spontaneous production of spin adduct was detected in a blank experiment performed with the propargylic iodide and TTBNB in the absence of diethylzinc. Under irradiation in the presence of distannane, two different species were observed at the very beginning of the irradiation; the nitroxide resulting from the trapping of propargyl radical at the propargyl carbon remained the only species detected after irradiating for several minutes. The absence of adducts resulting from the trapping of allenyl canonical forms was supported by DFT calculations and by the preparation of an authentic sample.