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

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• 作者：Elena Badetti ; Vega Lloveras ; Jose Luis Mu帽oz-G贸mez ; Rosa Mar谋虂a Sebasti谩n ; Anne Marie Caminade ; Jean Pierre Majoral ; Jaume Veciana ; Jos茅 Vidal-Gancedo
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：November 25, 2014
• 年：2014
• 卷：47
• 期：22
• 页码：7717-7724
• 全文大小：507K
• ISSN：1520-5835

文摘

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鈥搗is spectroscopy. The nitroxyl radicals exhibit a strong exchange interaction, which depends on the dendrimer generation and the temperature. An |螖m_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 |螖m_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鈥搗is 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.