The cationic polymerization of 1,3-pentadiene isomers initiated by AlCl3 was investigated in nonpolar solvent. It was shown that the polymerization was very sensitive to the initial monomer composition (proportion between the cis and trans isomers). The cis isomer favors the cross-linking reactions and double bond isomerization, whereas the trans isomer induces more cyclization. However, the behavior of the mixture of the two isomers cannot be simply deduced from a linear combination of the behavior of each isomer independently considered. Some polymerizations were realized in different alkanes (pentane, hexane, heptane, and decane). Despite similar polarity, it was observed that the higher the solvent molecular weight, the lower the total polymerization yield. These results were assigned to a different solubility of the Lewis acid and of polymer chains in the different solvents investigated. Finally, two origins of the cross-linked polymer were identified: the heterogeneity of the polymerization medium and intermolecular reactions of the active species with the polymer.

α-Cyclodextrin was transformed in a cationic unit after per substitution with histidine (His-α-CD) and lysine (Lys-α-CD) molecules on the primary face. His-α-CD and Lys-α-CD were used to form electrostatic complexes (CDplexes) with a plasmid DNA encoding luciferase gene, and the ability of CDplexes to transfect mammalian cells was examined using HEK293-T7 cells. The luciferase activity in cells transfected with His-α-CDplexes was 8-fold higher than that obtained Lys-α-CDplexes. When the transfection was carried out in the presence of chloroquine, the luciferase activity with His-α-CDplexes and Lys-α-CDplexes increased 6 and 25 times, respectively. The lower enhancement with His-α-CDplexes confirmed that histidine induced a proton sponge effect inside endosomes upon imidazole protonation, favoring DNA delivery in the cytosol. At the same time, we found that the condensation of DNA with His-α-CD was unexpectedly stronger than that obtained with the lysyl-α-CD counterpart. Moreover, it was as strong as that observed with high molecular weight polylysine. NMR (ROESY and DOSY) investigations in the absence of DNA showed that an inclusion complex is formed between the imidazole ring of histidine and the hydrophobic cavity of CD but no His-α-CD polymers can be formed by intermolecular interactions. These results suggest that intermolecular interactions between imidazole and His-α-CD cavity could be involved to form supramolecular assemblies in the presence of a DNA scaffold leading to DNA condensation into low diameter particles.

The polymerization of 1,3-pentadiene initiated by AlCl3 was investigated in a nonpolar medium at room temperature. It was shown that, besides propagation, the system undergoes various side reactions such as cross-linking, cyclization, double bond isomerization, .... An examination of the various possible structures of the polymer showed that the comparison of the 1 H and 13 C quantitative NMR spectroscopies allows the determination of the relative importance of cyclization and double bond isomerization. It is shown that some of these side reactions can be kept under control: for instance crosslinking could be avoided at low monomer concentration, while cyclization could be strongly decreased at high monomer concentration and by catalyst sublimation. Double bond isomerization was eliminated in the presence of a transfer agent such as methyl-2-butene-2.