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Biomineralization of calcium-based biominerals is influenced by organic molecules containing oxygen donor atoms. In this work, we were able to synthesize and stabilize the least stable crystalline phase of CaCO 3 , vaterite , using the biologically useful organic molecule curcumin as the template. The vaterite phase formed was stable in solution at least for 18 h. A comparative study with chemically similar molecule quercetin , a flavonoid, was performed. Though quercetin as a template could not stabilize the vaterite phase, an interesting observation was made in terms of the morphology of the calcite particles obtained. A dumbbell-shaped morphology, different from the usual rhombohedral morphology of the calcite crystals was obtained under ambient conditions. The maturation of the CaCO 3 crystals in solution with time was studied to observe the changes in terms of phase and morphology of the particles. Additionally, extended studies were performed to investigate the influence of the change in parameters such as; template concentration, the sequence of addition, temperature and ionic strength on the phase, morphology and size of the particles in the presence of both the templates. A comparative study between the organic molecules curcumin and quercetin as templates in the in vitro biomineralization of CaCO 3. [Display omitted] [ABSTRACT FROM AUTHOR]

The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the "anionic templating" strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches. [ABSTRACT FROM AUTHOR]

Highlights: [•] Functional organosilicas were obtained from amine and ammonium precursors. [•] Anionic templating allows to access mesostructured materials from cationic precursors. [•] Structured ionosilicas were only obtained in the presence of anionic surfactants. [•] The constitution of the precursor play an important role in view of the formation of structured phases. [Copyright &y& Elsevier]

Ionosilica nanoparticles are original ionic nano-objects at the interface of ionic liquids and mesoporous silica. Ionosilica nanoparticles' synthesis was achieved via sol-gel procedures exclusively from ionic trialkoxysilylated precursors without any silica source. However, the knowledge about the main synthesis parameters for a controlled synthesis of ionosilica nanoparticles remained fragmental so far. In this work, we present a systematic study for ionosilica nanoparticle formation starting from a virtually cationic silylated ammonium precursor. Due to their ionic nature, the behavior of ionic precursors considerably differs from that of conventional molecular silylated precursors. Here, we screened several reaction parameters for ionosilica nanoparticles' formation such as solvent polarity, precursor and surfactant concentrations, and temperature. Our results allow controlling the textures and architectures of ionosilica nanoparticles in terms of porosity (specific surface area) and particle size. The formed ionosilica nanoparticles were thoroughly characterized by means of nitrogen sorption, elemental analysis, electron microscopies, dynamic light scattering (DLS), and solid state NMR measurements. Liquid 1H NMR spectroscopic measurements allowed monitoring the kinetics of the hydrolysis-polycondensation reactions. It appeared that the hydrolysis is relatively fast (30–120 min) whereas the polycondensation reaction requires more time (1–2 days). Finally, we used Forward Osmosis (FO-) experiments as a valuable tool to monitor a possible evolution of the nanoparticles in aqueous media. We observed that the ionosilica nanoparticles showed decreasing osmotic properties in successive FO-regeneration cycles. We attribute these results either to the exchange of the osmotically active halide anions or to particle agglomeration. Ionosilica nanoparticles therefore show limited long-term stability in aqueous media that limit their potential as draw solute in forward osmosis. Image 1 • Identification of key parameters for the controlled formation of ionosilica nanoparticles. • Monitoring of the hydrolysis kinetics of the tris -trialkoxysilylated ionosilica precursor. • Acid-base behavior of the ionosilica nanoparticles and affinities towards various anions. • Determination of the osmotic pressure generated by ionosilica nanoparticles. [ABSTRACT FROM AUTHOR]