Shape Selectivity in Fullertube Chromatographic Separation

Abstract

Following the 1985 discovery of the first nanocarbon, fullerene C 60 , theorists have envisioned molecules made of a tubular monolayer carbon segment enclosed by hemifullerene end-caps. These molecular hybrids between fullerenes and carbon nanotubes, known as fullertubes, were once thought to be impossible to isolate due to their minimal yields and the absence of suitable isolation techniques. However, since 2020, an increasing number of fullertubes with 100 or more atoms [1-3] have been discovered and successfully isolated. Contrary to earlier assumptions, it is now recognized that large fullertubes can indeed be separated from fullerenes by utilizing their distinct shapes, although the potential structural configurations grow exponentially as the number of atoms grows [4]. In this presentation, we will explore the influence of molecular nanocarbon shapes on their separation via reversed-phase liquid chromatography. A thorough grasp of this factor is crucial to establish interaction models able to predict, with the help of simple ab initio calculations, retention times that are reliable enough to help with isomeric identification. Lastly, we will examine how these models can contribute to the development of chromatographic columns leveraging shape selectivity to separate molecular nanocarbons, such as fullertubes. References: [1] Koenig, R. M.; Tian, H.-R.; Seeler, T. L.; Tepper, K. R.; Franklin, H. M.; Chen, Z.-C.; Xie, S.-Y.; Stevenson, S. Fullertubes: Cylindrical Carbon with Half-Fullerene End-Caps and Tubular Graphene Belts, Their Chemical Enrichment, Crystallography of Pristine C90-D5h(1) and C100-D5d(1) Fullertubes, and Isolation of C108, C120, C132, and C156 Cages of Unknown Structures. J. Am. Chem. Soc. 2020 , 142 (36), 15614–15623. [2] Liu, X.; Bourret, E.; Noble, C. A.; Cover, K.; Koenig, R. M.; Huang, R.; Franklin, H. M.; Feng, X.; Bodnar, R. J.; Zhang, F.; Tao, C.; Sublett, D. M.; Dorn, H. C.; Stevenson, S. Gigantic C120 Fullertubes: Prediction and Experimental Evidence for Isomerically Purified Metallic [5,5] C120-D5d(1) and Nonmetallic [10,0] C120-D5h(10766). J. Am. Chem. Soc. 2022 , 144 (36), 16287–16291. [3] Bourret, E.; Liu, X.; Noble, C. A.; Cover, K.; Davidson, T. P.; Huang, R.; Koenig, R. M.; Reeves, K. S.; Vlassiouk, I. V.; Côté, M.; Baxter, J. S.; Lupini, A. R.; Geohegan, D. B.; Dorn, H. C.; Stevenson, S. Colossal C130 Fullertubes: Soluble [5,5] C130-D5h(1) Pristine Molecules with 70 Nanotube Carbons and Two 30-Atom Hemifullerene End-Caps. J. Am. Chem. Soc. 2023 , 145 (48), 25942–25947. [4] Bourret, E.; Stevenson, S.; Côté, M. Anisotropic Contributions in the Chromatographic Elution Behavior of Fullerenes and Fullertubes. J. Phys. Chem. C 2024 , 128 (31), 13283–13298. Figure 1