Colossal C Fullertubes: Soluble [5,5] C-D(1) Pristine Molecules with 70 Nanotube Carbons and Two 30-Atom Hemifullerene End-caps.

We report the seminal experimental isolation and DFT characterization of pristine [5,5] C-D(1) fullertubes. This achievement represents the largest soluble carbon molecule obtained in its pristine form. The [5,5] C species is the highest aspect ratio fullertube purified to date and now surpasses the recent gigantic [5,5] C-D(1). In contrast to C, C, and C fullertubes, the longer C-D has nanotubular carbons (70) than end-cap fullerenyl atoms (60). Starting from 39,393 possible C isolated pentagon rule (IPR) structures and after analyzing polarizability, retention time, and UV-vis spectra, these three layers of data remarkably predict a single candidate isomer and fullertube, [5,5] C-D(1). This structural assignment is augmented by atomic resolution STEM data showing distinctive and tubular "pill-like" structures with diameters and aspect ratios consistent with [5,5] C-D(1) fullertubes. The high selectivity of the aminopropanol reaction with spheroidal fullerenes permits facile separation and removal of fullertubes from soot extracts. Experimental analyses (HPLC retention time, UV-vis, and STEM) were synergistically used (with polarizability and DFT property calculations) to down select and confirm the C fullertube structure. Achieving the isolation of a new [5,5] C-D fullertube opens the door to application development and fundamental studies of electron confinement, fluorescence, and metallic character for a fullertube series of molecules with systematic tubular elongation. This [5,5] fullertube family also invites comparative studies with single-walled carbon nanotubes (SWCNTs), nanohorns (SWCNHs), and fullerenes.