title: Luminescent blooming of dendronic carbon nanotubes through ion-pairing interactions with an Eu(III) complex.
abstract: A multiwalled carbon nanotube (MWCNT) scaffold was covalently functionalized with a second-generation polyamidoamine (PAMAM) dendron, presenting four terminal amino groups per grafted aryl moiety. These reactive functions were alkylated to obtain a positively charged polycationic dendron/carbon nanotube system (d-MWCNTs⋅Cl), which eventually underwent anion exchange reaction with a negatively charged and highly luminescent Eu(III) complex ([EuL(4)]⋅NEt(4), in which L = (2-naphtoyltrifluoroacetonate)). This process afforded the target material d-MWCNTs⋅[EuL(4)], in which MWCNTs are combined with red-emitting Eu(III) centers through electrostatic interactions with the dendronic branches. Characterization of the novel MWCNT materials was accomplished by means of TGA and TEM, whereas d-MWCNTs⋅Cl and d-MWCNTs⋅ [EuL(4)] further underwent XPS, SEM and Raman analyses. These studies demonstrate the integrity of the luminescent [EuL(4)](-) center in the luminescent hybrid, the massive load of the cationic binding sites, and the virtually complete anion-exchange into the final hybrid material. The occurrence of the ion-pairing interaction with MWCNTs was unambiguously demonstrated through DOSY NMR diffusion studies. Photophysical investigations show that MWCNTs⋅[EuL(4)] is a highly soluble and brightly luminescent red hybrid material in which MWCNTs act as photochemically inert scaffolds with negligible UV/Vis absorption, compared with the grafted Eu complex, and with no quenching activity. The high dispersibility of MWCNTs⋅[EuL(4)] in a polymer matrix makes it a promising luminophore for applications in material science.
authors.affiliation: Department of Chemistry, University of Namur (FUNDP), Rue de Bruxelles 61, 5000 Namur, Belgium.
authors.forename: Laura
authors.initials: L
authors.lastname: Maggini
authors.forename: Francesca Maria
authors.initials: FM
authors.lastname: Toma
authors.forename: Luigi
authors.initials: L
authors.lastname: Feruglio
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Malicka
authors.forename: Tatiana
authors.initials: T
authors.lastname: Da Ros
authors.forename: Nicola
authors.initials: N
authors.lastname: Armaroli
authors.forename: Maurizio
authors.initials: M
authors.lastname: Prato
authors.forename: Davide
authors.initials: D
authors.lastname: Bonifazi