TY - JOUR
T1 - Radical dendrimers: A family of five generations of phosphorus dendrimers functionalized with TEMPO radicals
AU - Badetti, Elena
AU - Lloveras, Vega
AU - Muñoz-Gómez, Jose Luis
AU - Sebastián, Rosa Maŕa
AU - Caminade, Anne Marie
AU - Majoral, Jean Pierre
AU - Veciana, Jaume
AU - Vidal-Gancedo, José
PY - 2014/11/25
Y1 - 2014/11/25
N2 - © 2014 American Chemical Society. 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, 1H NMR, 31P 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 |fms| = 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 |Δms| = 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.
AB - © 2014 American Chemical Society. 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, 1H NMR, 31P 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 |fms| = 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 |Δms| = 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.
UR - https://www.scopus.com/pages/publications/84912571645
U2 - 10.1021/ma502062q
DO - 10.1021/ma502062q
M3 - Article
SN - 0024-9297
VL - 47
SP - 7717
EP - 7724
JO - Macromolecules
JF - Macromolecules
IS - 22
ER -