Département de chimie moléculaire

The controlled self-assembly of precise and well-defined photochem. and electrochem. active carbohydrate-coated nanoparticles offers the exciting prospect of biocompatible catalysts for energy storage/conversion and biolabeling applications. Here an aq. nanoparticle system has been developed with a versatile outer layer for host-guest mol. encapsulation via $\beta$-cyclodextrin inclusion complexes. A $\beta$-cyclodextrin-modified polystyrene polymer was first obtained by copper nanopowder click chem. The glycopolymer enables self-assembly and controlled encapsulation of tetrazine-naphthalimide, as a model redox-active agent, into nanoparticles via nanopptn. Cyclodextrin host-guest interactions permit encapsulation and internanoparticle crosslinking for the formation of fluorescent compd. and clustered self-assemblies with chem. reversible electroactivity in aq. soln. Light scattering expts. revealed stable particles with hydrodynamic diams. of 138 and 654 nm for nanoparticles prepd. with tetrazine, of which 95{%} of the nanoparticles represent the smaller objects by no. Dynamic light scattering revealed differences as a function of prepn. method in terms of size, 3-mo stability, polydispersity, radius of gyration, and shape factor. Individual self-assemblies were visualized by at. force microscopy and fluorescence microscopy and monitored in real-time by nanoparticle tracking anal. UV-vis and fluorescence spectra provided insight into the optical properties and crit. evidence for host-guest encapsulation as evidenced by solvachromatism and enhanced tetrazine uptake. Cyclic voltammetry was used to investigate the electrochem. properties and provided further support for encapsulation and an est. of the tetrazine loading capacity in tandem with light scattering data. [on SciFinder(R)]