Tunable self-assembly of triazole-linked porphyrin-polymer conjugates
The convergence of supramolecular chemistry and polymer science offers many powerful approaches for building functional nanostructures with well-defined dynamic behaviour. Herein we report the efficient "click" synthesis and self-assembly of AB2- and AB4-type multitopic porphyrin-polymer conjugates (PPCs). PPCs were prepared using the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) reaction, and consisted of linear polystyrene, poly(butyl acrylate), or poly(tert-butyl acrylate) arms attached to a zinc(II) porphyrin core via triazole linkages. We exploit the presence of the triazole groups obtained from CuAAC coupling to direct the self-assembly of the PPCs into short oligomers (2-6 units in length) via intermolecular porphyrinatozinc-triazole coordination. By altering the length and grafting density of the polymer arms, we demonstrate that the association constant of the porphyrinatozinc-triazole complex can be systematically tuned over two orders of magnitude. Self-assembly of the PPCs also resulted in a 6a K increase in the glass transition temperature of the bulk material compared to a non-assembling PPC. The modular synthesis and tunable self-assembly of the triazole-linked PPCs thus represents a powerful supramolecular platform for building functional nanostructured materials. Tunable building blocks: Triazole-linked porphyrin-polymer conjugates (PPCs) were prepared in high yield using the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) "click" reaction. The triazole groups were introduced from CuAAC coupling to guide the self-assembly of the PPCs into short oligomers (2-6 units in length) via intermolecular porphyrinatozinc-triazole coordination. Association constants of the PPCs could be tuned by altering the polymer microenvironment around the porphyrin core, thus presenting a modular platform for designing self-assembled porphyrin-polymer materials. Copyright
“Clicked” Porphyrin-Cucurbituril Conjugate: A New Multifunctional Supramolecular Assembly Based on Triglycosylated Porphyrin and Monopropargyloxycucurbit[7]uril
The design, synthesis, and characterization of a new multifunctional supramolecular assembly based on a photoactive glycosylated porphyrin and covalently attached monofunctionalized cucurbit[7]uril (CB7) are reported. To obtain the target supramolecular a
Porphyrin-functionalized mesoporous organosilica nanoparticles for two-photon imaging of cancer cells and drug delivery
The synthesis of a zinc porphyrin derivative possessing eight triethoxysilyl groups was performed through a CuAAC-click reaction. This porphyrin was covalently entrapped in ethenylene-bridged mesoporous organosilica nanoparticles which efficiently allowed
Click reaction synthesis and photophysical studies of dendritic metalloporphyrins
Several dendritic zinc(II)-porphyrins bearing carbazole units at the terminals have been prepared through click reaction of azide-substituted Zn-porphyrin precursors and carbazole-based alkynes under [Cu(NCCH 3)4][PF6] cat
Nguyen, Nguyen Tran,Hofkens, Johan,Scheblykin, Ivan G.,Kruk, Mikalai,Dehaen, Wim
p. 1766 - 1777
(2014/03/21)
Click Reaction Synthesis and Photophysical Studies of Dendritic Metalloporphyrins
Several dendritic zinc(II)-porphyrins bearing carbazole units at the terminals have been prepared through click reaction of azide-substituted Zn-porphyrin precursors and carbazole-based alkynes under [Cu(NCCH3)4][PF6] catalysis. This family of new dendritic metalloporphyrins shows dual luminescence from both the upper S2 and the lowest S1 singlet states. The observed trends in the spectroscopic data and the photophysical properties of the dendrimers have been rationalized in terms of the type of meso-spacer between the macrocycle and dendritic shell. The key feature of the meso-spacer is proposed to be the degree of hindrance towards aryl ring rotation relative to the mean porphyrin plane. Based on the observed differences in the S1→S0 fluorescence quantum yield on going from four- to five-coordinate dendrimers, it was shown that dendrimer architectures with all four meso-aryl spacers sterically hindered, are most appropriate to monitor processes related to axial ligation of the dendrimer core, since they provide larger luminescence response differences between the four-coordinate and five-coordinate forms. The blue S2→S0 fluorescence quantum yield has been measured and the observed trend has been rationalized in terms of the S2→S1 energy gap law. No significant differences were observed between the compounds either with different rotational degree of freedom of the meso-spacers or with different ligation states of the dendrimer core.
Nguyen, Nguyen Tran,Hofkens, Johan,Scheblykin, Ivan G.,Kruk, Mikalai,Dehaen, Wim
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p. 1766 - 1777
(2015/10/05)
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