919988-18-4Relevant articles and documents
Self-assembling amphiphilic Janus dendrimers: Mesomorphic properties and aggregation in water
Fedeli, Elisabetta,Lancelot, Alexandre,Serrano, José Luis,Calvo, Pilar,Sierra, Teresa
, p. 1960 - 1967 (2015/03/18)
The self-assembly behaviour both in bulk and in water of amphiphilic dendrimeric derivatives based on bis-MPA is the central theme of this article. The designed molecules possess two parts with different polarity; this feature is the key factor that forces their self-assembly in water into supramolecular architectures, due to hydrophobic interactions between the lipophilic fractions of the molecules, and the appearance of mesomorphic order in bulk in response to a variation of temperature (thermotropic liquid crystals). The effects provoked by the hydrophilic/lipophilic balance of the molecule were studied varying the generation of the corresponding dendrons and combining them via CuAAC click chemistry in order to obtain symmetrical and unsymmetrical final Janus dendrimers. The ability of the aggregates formed in water to encapsulate hydrophobic drugs has also been explored.
Europium confined cyclen dendrimers with photophysically active triazoles
Antoni, Per,Malkoch, Michael,Vamvounis, George,Nystroem, Daniel,Nystroem, Andreas,Lindgren, Mikael,Hult, Anders
experimental part, p. 2545 - 2554 (2009/12/25)
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.
