Novel fluorescent anthracene-bodipy dyads displaying sensitivity to pH and turn-on behaviour towards Cu(ii) ions.

Three bichromophoric compounds containing anthracene and bodipy moieties connected by different spacers have been synthesized and fully characterized. The set of spacers comprises a variety of bridges (short and flexible 1,2-diaminoethane in compound 1a, long and flexible 1,8-diaminooctane in compound 1b and short and rigid piperazine in compound 1c). The new compounds show interchromophoric communication via Electronic Energy Transfer (EET). When anthracene is excited, the energy is efficiently transferred to the bodipy moiety. The emission of the acceptor is partially quenched in dyad 1a but remarkably not in 1b and 1c. In an aqueous environment, the fluorescence of the new compounds display sensitivity to pH (emissive at acidic values and non-emissive at neutral ones), a typical behaviour of photoinduced electron-transfer (PET) probes, but with remarkable differences in the pKa of each compound, attributable to the nature of the linker. Additionally, the behaviour in the presence of several metallic cations (Cu2+, Ni2+, Cd2+, Zn2+) has been studied, and a turn-on response towards Cu2+ in water at neutral pH has been found.

Preparation of polymer-supported gold nanoparticles based on resins containing ionic liquid-like fragments: easy control of size and stability.

Crosslinked polymers containing covalently attached functional sites with chemical structures related to those present in ILs and having macroscopic properties very similar to the ones of the corresponding bulk ILs can be advantageously applied to the preparation of gold nanoparticles (AuNPs). The size and morphology of the resulting metal nanoparticles (MNPs) can be easily modulated through a proper combination of the synthetic method used for the generation of the NPs and the structural elements of the polymer. Additionally, the resulting supported AuNPs are demonstrated to be stable for at least eight months with the vials open to the atmosphere. Several synthetic methodologies have been studied, as well as different structural parameters for the functional polymers. Those include the chemical nature (anions and cations) and loading of the ionic liquid-like fragments and the morphology of the polymeric matrix. The results obtained show the potential to prepare supported AuNPs with narrow size distributions and small diameters that can have potential interest for application in different fields.

Synthesis of second-generation self-assembling Gemini Amphiphilic Pseudopeptides.

HYPOTHESIS: The structural modularity of Gemini Amphiphilic Pseudopeptides (GAPs) allows the tuning of the self-assembling properties by slight modifications in the chemical structures. We hypothesized that the introduction of a flexible linker containing a central nitrogen atom in bipodal and tripodal GAPs would improve their self-assembly properties in aqueous media. EXPERIMENTS: After preparation of the corresponding GAPs, a combination of SEM, TEM and AFM techniques were used to study the morphology of the self-assembled structures in different media. The solution structures in non-aggregated states were also analyzed by combining NMR, UV and CD studies. The transition from the non-aggregated species to the hierarchical self-assembly was monitored by ATR FT-IR spectroscopy, while the critical aggregation concentration in water was determined by fluorescence spectroscopy. FINDINGS: The formation of different morphologies (vesicles or fibers) highly depends on the polarity and the pH of the medium. A reasonable mechanism for the self-assembly has been established in agreement with the experimental techniques used, where the protonation of the nitrogen in the linker must play a key role. In general, the obtained GAPs showed an improved formation of vesicles in aqueous media (different pH or ionic strength) with potential applications in biomedicine and drug delivery.