Ostrowski Sławomir, Garnuszek Piotr, Dobrowolski Jan Cz
Institute of Nuclear Chemistry and Technology, 16 Dorodna-Street, 03-195 Warsaw, Poland.
Radioisotope Centre POLATOM, National Centre for Nuclear Research, 7 A. Sołtana-Street, 05-400 Otwock, Poland.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Apr 15;231:117791. doi: 10.1016/j.saa.2019.117791. Epub 2019 Nov 21.
Endohedral structures with La or La encapsulated in chiral (1,16)CN or achiral (1,4)CN diazafullerenes were studied at the B3LYP/G-31G*/SDD level. Two stable locations of La and La are possible in each cage but only with La@(1,16)CN can the two isomers coexist. We found that an AIM determined hapticity of the endohedral species selectively differentiates the systems. We predict that there will always exist IR and Raman bands which allow for them to be identified in the presence of the parent cage. For the La@(1,16) CN molecules and the parent diazafullerene, the Raman spectra are likely to reveal a pre-resonance effect even at 785 nm and it seems possible to selectively excite only one isomer. The calculated electronic spectra suggested a chance to determine the less populated diazafullerene in the presence of the more populated one, be it chiral or achiral. For the chiral endohedral isomers, the calculated VCD spectra are quite dissimilar and the two endohedral isomers and the parent heterofullerene seem to be easily detected. Eventually, we defined the endohedral isomerism as follows: The endohedral isomerism is the phenomenon whereby an internal individuum captured in a cage can occupy more than one stable position without changing the cage connectivity.
在B3LYP/G - 31G*/SDD水平下研究了镧（La）或镧被包裹在手性（1,16）-氰基氮杂富勒烯或非手性（1,4）-氰基氮杂富勒烯中的内嵌结构。每个笼中镧和镧有两个稳定位置，但只有在La@(1,16)CN中两种异构体才能共存。我们发现，通过AIM确定的内嵌物种的配体数选择性地区分了这些体系。我们预测，总会存在红外和拉曼光谱带，使得它们在母体笼存在的情况下能够被识别。对于La@(1,16)CN分子和母体氮杂富勒烯，即使在785 nm处拉曼光谱也可能显示出预共振效应，并且似乎有可能仅选择性地激发一种异构体。计算得到的电子光谱表明，在存在较多数量的异构体（无论是手性还是非手性）的情况下，有机会确定数量较少的氮杂富勒烯。对于手性内嵌异构体，计算得到的VCD光谱差异很大，两种内嵌异构体和母体杂富勒烯似乎很容易被检测到。最后，我们将内嵌异构定义如下：内嵌异构是指被捕获在笼中的内部个体能够占据多个稳定位置而不改变笼连接性的现象。
