Radical Dendrimers: A Family of Five Generations of Phosphorus Dendrimers Functionalized with TEMPO Radicals

Abstract

Five novel generations of phosphorus dendrimers based on a cyclotriphosphazene core with stable TEMPO radicals end groups have been synthesized and studied by EPR, SQUID, 1 H NMR, 31 P NMR, FT-IR, and UV−vis spectroscopy. The nitroxyl radicals exhibit a strong exchange interaction, which depends on the dendrimer generation and the temperature. An |Δm s | = 2 transition has been observed in each generation in dilution conditions demonstrating the intramolecular origin of the radicals interaction. There exists a direct proportionality between the EPR |Δm s | = 2 transition intensity and the number of radicals by generation; consequently, the utility of EPR for the determination of the substitution efficiency on dendrimers by paramagnetic species is quite good. From the UV−vis characterization, we have observed that the molar extinction coefficient value is also proportional to the number of TEMPO groups. The magnetic properties of the zero, first and fourth generation dendrimers studied by SQUID magnetometry show antiferromagnetic interaction between radicals.

Covalently Functionalized Graphene by Radical Polymers for Graphene-Based High-Performance Cathode Materials

“…Typical vibrations of -CH 2 -and -CH 3 units were located at around 2960 and 2930 cm -1 , respectively. Moreover, a new absorption peak of nitroxyl radical moieties appeared at 1359 cm -1 in FT-IR spectrum after oxidization, 25,26 which indicated the successful preparation of G-g-PTMA. Besides these characteristic signals, a weak band at 1631 cm -1 in the spectrum of G-g-PTMPM should be assigned to the vibration of adsorbed water molecules.…”

Tuning Spin‐Spin Interactions in Radical Dendrimers

“…Dendrimers are globular, nearly perfectly monodisperse macromolecules, synthesized with an unprecedented control over their architecture . The term “radical dendrimers” has been used in the case of highly functionalized dendrimers with organic radicals . Nowadays there is an increasing interest for the application of radical dendrimers as contrast agents in Magnetic Resonance Imaging (MRI), Dynamic Nuclear Polarization (DNP), as additive or active materials in organic solar cells for solar energy conversion, and environmentally friendly organic electronic applications .…”

On Eccentricity-Based Topological Indices and Polynomials of Phosphorus-Containing Dendrimers

“…For a study of distance-based topological indices, see [19][20][21]. In this paper, we compute several distance-based indices, namely, the eccentric-connectivity index, the total eccentric-connectivity index, and the modified eccentric-connectivity index for the phosphorus-containing dendrimer Cyclotriphosphazene (N 3 P 3 ) [22]. We also compute the corresponding polynomials of these indices for the same dendrimer.…”