Properties of non-IPR fullerene films versus size of the building blocks

Abstract

This perspective focuses on the cage size dependent properties of novel solid fullerene nanofilms grown by soft-landing of mass-selected C(n)(+) (48, 50, 52, 54, 56, 58, 62, 64, 66 and 68) onto room temperature graphite surfaces under ultra-high vacuum conditions. Such non-isolated-pentagon-ring (non-IPR) fullerene materials are not accessible to standard fullerene preparation methods. The component molecular building blocks of non-IPR films were generated by electron impact induced ionization/fragmentation of sublimed IPR-C(70)(D(5h)) (-->C(n) (n = 68, 66, 64, 62)) or IPR-C(60)(I(h)) (-->C(n) (n = 58, 56, 54, 52, 50)). Non-IPR fullerene films on graphite grow via formation of dendritic C(n) aggregates, whereas deposition of IPR fullerenes under analogous conditions (via deposition of unfragmented C(60)(+) and C(70)(+)) leads to compact islands. The latter are governed by weak van der Waals cage-cage interactions. In contrast, the former are stabilized by covalent intercage bonds as mediated by the non-IPR sites (primarily adjacent pentagon pairs, AP). A significant fraction of the deposited non-IPR C(n) cages can be intactly (re)sublimed by heating. The corresponding mean desorption activation energies, E(des), increase from 2.1 eV for C(68) up to 2.6 eV for C(50). The densities of states in the valence band regions (DOS), surface ionization potentials (sIP) and HOMO-LUMO gaps (Delta) of semiconducting non-IPR films were measured and found to vary strongly with cage size. Overall, the n-dependencies of these properties can be interpreted in terms of covalently interconnected oligomeric structures comprising the most stable (neutral) C(n) isomers-as determined from density functional theory (DFT) calculations. Non-IPR fullerene films are the first known examples of elemental cluster materials in which the cluster building blocks are covalently but reversibly interconnected.

Bottom‐Up C60 Fullerene Construction from a Fluorinated C60H21F9 Precursor by Laser‐Induced Tandem Cyclization

“…In particular, the approach seems to be attractive for the isomer specific synthesis of highly reactive non-IPR fullerenes. [22] Additionally, the technique allows simple post-synthetic manipulation of the nanostructures obtained, which is often a difficult task. The desired nanostructure can be synthesized, "purified" during ion selection and deposited on a surface.…”

Soft‐ and reactive landing of ions onto surfaces: Concepts and applications

“…Soft‐ and reactive landing of mass‐selected ions onto surfaces has become a subject of substantial interest due to its potential as a method for the highly‐controlled preparation of materials for a variety of practical applications and fundamental investigations in chemistry, physics, and materials science (Grill et al, ; Gologan et al, , ; Laskin et al, ; Wang et al, ; Johnson et al, ; Cyriac et al, ; Verbeck et al, ). Recent studies have suggested future applications of ion soft landing in the separation of proteins and conformational enrichment of peptides (Gologan et al, ; Wang & Laskin, ), production of peptide and protein microarrays for high‐throughput biological screening (Ouyang et al, ; Blake et al, 2004b; Volny et al, ), preparation of thin films for use in composite materials (Saf et al, ; Rauschenbach et al, ), characterization of redox‐active proteins (Pepi et al, ), chiral enrichment of organic compounds (Nanita et al, ), processing of graphene (Rader et al, ), deposition of carbon clusters (Loffler et al, ), and preparation of model catalysts through deposition of ionic clusters, nanoparticles, and organometallics (Judai et al, ; Vajda et al, ; Kaden et al, ).…”

Capturing the Antiaromatic #6094C68 Carbon Cage in the Radio‐Frequency Furnace

“…For instance, the D 5 h ‐C 70 cage, which dominates (besides I h ‐C 60 ) in conventional fullerene synthesis, might be regarded as a potential precursor for C 68 , especially when the close structural relationship is taken into account 10. The C 2 fragmentation of C 70 was predicted theoretically36 and recently such a process has been realized experimentally for bulk amounts 37. Due to the high symmetry of D 5 h ‐C 70 there are only eight nonequivalent possibilities for C 2 elimination.…”