Europium confined cyclen dendrimers with photophysically active triazoles

Antoni, Per, Malkoch, Michael, Vamvounis, George, Nyström, Daniel, Nyström, Andreas, Lindgren, Mikael, and Hult, Anders (2008) Europium confined cyclen dendrimers with photophysically active triazoles. Journal of Materials Chemistry, 18 (22). pp. 2545-2554.

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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 5D0 → 7F2 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.

Item ID: 32731
Item Type: Article (Research - C1)
ISSN: 1364-5501
Funders: Willhelm Beckers Jubileumsfond, Norweigan Research Council, Swedish Research Council
Projects and Grants: Norweigan Research Council (Contract #163529: ‘‘Dendritic nanoporous materials with multifunctionality’’), Swedish Research Council (VR) (Grant 2006-3617)
Date Deposited: 24 Jun 2014 23:40
FoR Codes: 03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030505 Physical Organic Chemistry @ 100%
SEO Codes: 85 ENERGY > 8507 Energy Conservation and Efficiency > 850704 Residential Energy Conservation and Efficiency @ 100%
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