Europium confined cyclen dendrimers with photophysically active triazoles
2008 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 18, no 22, 2545-2554 p.Article in journal (Refereed) Published
Dendrimers up to the fourth generation (G1-G4) were successfully synthesized via the efficient copper catalyzed 1,3-dipolar cycloaddition between primary alkynes and azides (CuAAC), also referred to as a click reaction. The synthetic protocol involved the preparation of presynthesized dendron wedges that subsequently were attached to a tetra-valent alkyne functional cyclen core. These constructed structures integrated stable triazole groups "intra-locked'' between the cyclen and dendron wedges. The incorporation of a lanthanide metal ion, europium, into the interior of all cyclen dendrimers was monitored by FT-IR. Interestingly, the photophysical results showed that the proximate triazole not only acts as a stable linker but also as a sensitizers, transferring its singlet-singlet excitation in the ultraviolet region (270-290 nm) to the partially filled luminescent lanthanide 4f shell. An increase of luminescence decay time from the lanthanide D-5(0) -> F-7(2) emission was observed with increasing dendrimer size, indicating that the shielding effect of the dendron wedges is important for the relaxation of the photo-excitation and energy transfer. To the best of our knowledge, this is the first time a set of dendron wedges have successfully been attached to a cyclen metal ion cage via the versatile click reaction. Furthermore, the produced triazoles intra-locked in close proximity to the macrocycle core elucidated an interesting photophysical function.
Place, publisher, year, edition, pages
2008. Vol. 18, no 22, 2545-2554 p.
SITE-ISOLATION; DENDRITIC MACROMOLECULES; PLATINUM(II) ACETYLIDES; LUMINESCENCE PROPERTIES; CORE DENDRIMERS; CLICK CHEMISTRY; COMPLEXES; POLYMERS; MOIETIES; SYSTEMS
IdentifiersURN: urn:nbn:se:kth:diva-8693DOI: 10.1039/b802197jISI: 000256073500004ScopusID: 2-s2.0-44149087379OAI: oai:DiVA.org:kth-8693DiVA: diva2:14080
QC 201006212008-06-042008-06-042010-06-28Bibliographically approved