Separation of Spectroscopically Uniform Nanographenes
Separation of Spectroscopically Uniform Nanographenes
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DOI：
10.1002/asia.201801632
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发表时间：
2019-05-15
影响因子：
4.1
通讯作者：
Haino, Takeharu
中科院分区：
文献类型：
--
作者：
Yamato, Kairi;Sekiya, Ryo;Haino, Takeharu
激发相关光致发光（PL）是石墨烯量子点（GQD）的公知性质。对于碳基光功能材料的开发，具有均匀的PL特性的GQD是很高的需求。已建立了从主要由GQD-1a和GQD-1b组成的GQD-1混合物中分离光谱均匀的亲脂性GQD-1a的方案。采用普通氧化剥离法从石墨中制备GQD-2，再与对甲氧基苄胺反应，合成GQD-1混合物。经分子排阻层析得到GQD-1a和GQD-1b，其粒径分别为19.8和4.9nm。大的GQD-1a表明PL与激发波长相当无关，而小的GQD-1b的PL依赖于激发。这种依赖于激发态的性质很可能与石墨烯表面上的sp（2）结构域的结构有关。GQD-1a的大sp（2）共轭表面可能具有发育良好的大sp（2）结构域，其带隙没有显著变化。GQD-1b的小的sp（2）共轭表面产生小的sp（2）共轭域，所述小的sp（2）共轭域产生与域大小不同的带隙。
Excitation-dependent photoluminescence (PL) is a well-known property of graphene quantum dots (GQDs). For the development of carbon-based photofunctional materials, GQDs possessing uniform PL properties are in high demand. A protocol has been established to separate spectroscopically uniform lipophilic GQD-1a from a mixture of GQD-1 mainly composed of GQD-1a and GQD-1b. The mixture of GQD-1 was synthesized through the reaction of p-methoxybenzylamine with GQD-2 prepared from graphite by common oxidative exfoliation. Size-exclusion chromatography gave rise to GQD-1a and GQD-1b, with diameters of 19.8 and 4.9nm, respectively. Large GQD-1a showed that the PL was fairly independent of the excitation wavelengths, whereas the PL of small GQD-1b was dependent on excitation. The excitation-dependent nature is most likely to be associated with the structures of sp(2) domains on the graphene surfaces. The large sp(2)-conjugated surface of GQD-1a is likely to possess well-developed and large sp(2) domains, the band gaps of which do not significantly vary. The small sp(2)-conjugated surface of GQD-1b produces small sp(2)-conjugated domains that generate band gaps differing with domain sizes.