Elodie Boisselier

Dendrimers Designed for Functions: From Physical, Photophysical, and Supramolecular Properties to Applications in Sensing, Catalysis, Molecular Electronics, Photonics, and Nanomedicine

3.15. Miscellaneous Photophysical Studies 1874 3.16. Dendritic Fluorescent Sensors 1875 3.17. Nonlinear Optical Properties 1875 4. Supramolecular Properties 1876 4.1. Concepts and Pioneering Studies 1876 4.2. H-Bonding 1877 4.3. Electrostatic Binding 1877 4.4. Combined H-Bonding/Ionic Bonding 1879 4.5. Coordination of Metal Ions 1880 4.6. Intradendritic π-π Interactions 1880 4.7. Encapsulation of Neutral Guest Molecules 1881 4.8. Interdendritic Supramolecular Associations 1883 4.8.1. Liquid Crystals 1883 4.8.2. Other Dendritic Self-Assemblies 1884 4.9. Supramolecular Assemblies between Dendrimers and Surfactants or Polymers 1885

Four Generations of Water‐Soluble Dendrimers with 9 to 243 Benzoate Tethers: Synthesis and Dendritic Effects on Their Ion Pairing with Acetylcholine, Benzyltriethylammonium, and Dopamine in Water

Water-soluble benzoate-terminated dendrimers of four generations (from G0 with 9 branches to G3 with 243 branches) were synthesized and fully characterized. They form water-soluble assemblies by ion-pairing interactions with three cations of medicinal interest (acetylcoline, benzyltriethylammonium, and dopamine), which were characterized and investigated by 1H NMR spectroscopy, whereas such interactions do not provoke any significant shift of 1H NMR signals with the monomeric benzoate anion. The calculated association constants confirm that the dendritic carboxylate termini reversibly form ion pairs and aggregates. Diffusion coefficients and hydrodynamic diameters of the dendrimers, as well as changes thereof on interaction with the cations, were evaluated by DOSY experiments. The lack of increase of dendrimer size on addition of the cations and the upfield shifts of the 1H NMR signals of the cation indicate encapsulation within the hydrophobic dendrimer interiors together with probable backfolding of the benzoate termini.

Interactions and encapsulation of vitamins C, B3, and B6 with dendrimers in water.

Titrations of commercial diaminobutane (DAB) and polyamidoamine (PAMAM) dendrimers by vitamins C (ascorbic acid, AA), B(3) (nicotinic acid), and B(6) (pyridoxine) were monitored by (1)H NMR spectroscopy using the chemical shifts of both dendrimer and vitamin protons and analyzed by comparison with the titration of propylamine. Quaternarizations of the terminal primary amino groups and intradendritic tertiary amino groups, which are nearly quantitative with vitamin C, were characterized by more or less sharp variations (Deltadelta) of the (1)H chemical shift (delta) at the equivalence points. The peripheral primary amino groups of the DAB dendrimers were quaternarized first, but not selectively, whereas a sharp chemical-shift variation was recorded for the inner methylene protons near the tertiary amines, thereby indicating encapsulation, when all the dendritic amines were quaternarized. With DAB-G5-64-NH(2), some excess acid is required to protonate the inner amino groups, presumably because of basicity decrease due to excess charge repulsion. On the other hand, this selectivity was not observed with PAMAM dendrimers. The special case of the titration of the dendrimers by vitamin B(6) indicates only dominant supramolecular hydrogen-bonding interactions and no quaternarization, with core amino groups being privileged, which indicates the strong tendency to encapsulate vitamins. With vitamin B(3), a carboxylic acid, titration of DAB-G3-16-NH(2) shows that only six peripheral amino groups are protonated on average, even with excess vitamin B(3), because protonation is all the more difficult due to increased charge repulsion, as positive charges accumulate around the dendrimer. Inner amino groups interact with this vitamin, however, thus indicating encapsulation presumably with supramolecular hydrogen bonding without much charge transfer.

Ferrocenyl dendronized polymers

Styrenic dendrons functionalized with ferrocenyl and chloromethylsilyl termini were synthesized and polymerized by the AIBN-initiated radical polymerization procedure yielding a ferrocenyl dendronized polymer and a chloromethylsilyl dendronized polymer, respectively. The latter polymer was functionalized with ferrocenyl groups using “click” chemistry. The ferrocenyl dendronized polymers are soluble in common organic solvents such as tetrahydrofuran, dichloromethane, and chloroform. They show a reversible ferrocenyl wave in cyclic voltammetry (CV) and form derivatized Pt electrodes. Their sizes and shapes were examined by size exclusion chromatography (SEC), atomic force microscopy (AFM), dynamic light scattering (DLS) and DOSY 1H NMR spectroscopy.

New water-soluble polyanionic dendrimers and binding to acetylcholine in water by means of contact ion-pairing interactions

A new water-soluble polyanionic dendrimer containing 81 benzoate termini (diameter: 11+/-1 nm from DOSY NMR spectroscopy) has been synthesized; it interacts with acetylcholine cations in water-soluble assemblies in which each carboxylate terminus reversibly forms contact ion pairs and aggregates at the tether termini, as shown by 1H NMR spectroscopy.