Gigantic C 120 Fullertubes: Prediction and Experimental Evidence for Isomerically Purified Metallic [5,5] C 120 -D 5d (1) and Nonmetallic [10,0] C 120 -D 5h (10766).

We report the first experimental characterization of isomerically pure and pristine C 120 fullertubes, [5,5] C 120 -D 5d (1) and [10,0] C 120 -D 5h (10766). These new molecules represent the highest aspect ratio fullertubes isolated to date; for example, the prior largest empty cage fullertube was [5,5] C 100 -D 5d (1). This increase of 20 carbon atoms represents a gigantic leap in comparison to three decades of C 60 -C 90 fullerene research. Moreover, the [10,0] C 120 -D 5d (10766) fullertube has an end-cap derived from C 80 -I h and is a new fullertube whose C 40 end-cap has not yet been isolated experimentally. Theoretical and experimental analyses of anisotropic polarizability and UV-vis assign C 120 isomer I as a [5,5] C 120 -D 5d (1) fullertube. C 120 isomer II matches a [10,0] C 120 -D 5h (10766) fullertube. These structural assignments are further supported by Raman data showing metallic character for [5,5] C 120 -D 5d (1) and nonmetallic character for C 120 -D 5h (10766). STM imaging reveals a tubular structure with an aspect ratio consistent with a [5,5] C 120 -D 5d (1) fullertube. With microgram quantities not amenable to crystallography, we demonstrate that DFT anisotropic polarizability, augmented by long-accepted experimental analyses (HPLC retention time, UV-vis, Raman, and STM) can be synergistically used (with DFT) to down select, predict, and assign C 120 fullertube candidate structures. From 10 774 mathematically possible IPR C 120 structures, this anisotropic polarizability paradigm is quite favorable to distinguish tubular structures from carbon soot. Identification of isomers I and II was surprisingly facile, i.e., two purified isomers for two possible structures of widely distinguishing features. These metallic and nonmetallic C 120 fullertube isomers open the door to both fundamental research and application development.