Investigations of N@C 60 and N@C 70 stability under high pressure and high temperature conditions
Investigations of N@C 60 and N@C 70 stability under high pressure and high temperature conditions
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N@C 60 和 N@C 70 在高压和高温条件下的稳定性研究
DOI：
10.1002/pssb.200982270
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Iwasiewicz-Wabnig A
中科院分区：
文献类型：
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作者：
Iwasiewicz-Wabnig A
由于存在未成对的氮电子自旋，包封单个氮原子（N@C60和N@C70）的内嵌富勒烯具有自旋活性。氮的高反应性导致这些分子在高温下的稳定性差，大大限制了其化学处理的可能性。在这项研究中，N@C60和N@C70在甲苯溶液中进行高压（HP）高达0.8 GPa和退火1，2，10或24小时，在室温或高温。在每种情况下，基于处理前后获得的situEPR谱的相对自旋计数来评估存活分子的数量。N@C60和N@C70在高压条件下的热稳定性增强归因于氮杂桥的形成受到抑制，氮杂桥在常压下有利于氮从富勒烯笼中逸出。
Endohedral fullerenes encapsulating single nitrogen atoms (N@C60and N@C70) are spin active, due to the presence of unpaired nitrogen electron spins. High reactivity of nitrogen leads to a poor stability of these molecules at elevated temperatures, drastically restricting possibilities of their chemical treatment. In this study, N@C60and N@C70in toluene solutions were subjected to high pressure (HP) up to 0.8 GPa and annealed for 1, 2, 10 or 24 h, at either room or elevated temperatures. In each case the number of surviving molecules was evaluated based on the relative spin counts ofex situEPR spectra obtained before and after the treatment. The enhanced thermal stability of N@C60and N@C70under HP conditions is attributed to inhibited formation of azabridges, which under normal pressure facilitate the escape of nitrogen from the fullerene cage.