The influence of a single thiol group on the electronic and optical properties of the smallest diamondoid adamantane

Abstract

At the nanoscale, the surface becomes pivotal for the properties of semiconductors due to an increased surface-to-bulk ratio. Surface functionalization is a means to include semiconductor nanocrystals into devices. In this comprehensive experimental study we determine in detail the effect of a single thiol functional group on the electronic and optical properties of the hydrogen-passivated nanodiamond adamantane. We find that the optical properties of the diamondoid are strongly affected due to a drastic change in the occupied states. Compared to adamantane, the optical gap in adamantane-1-thiol is lowered by approximately 0.6 eV and UV luminescence is quenched. The lowest unoccupied states remain delocalized at the cluster surface leaving the diamondoid's negative electron affinity intact.

Experimental and theoretical study of the absorption properties of thiolated diamondoids

“…6 we present the energies of the first purely diamondoid -S-type state together with the energies of n-‫ء‬ SH states as a function of diamondoid size. 40 By increasing the size of the diamondoid subunit, the purely diamondoid -S transition shifts to lower energies in thiol functionalized diamondoids ͑Fig. 40 Species in which S-type states lie energetically below these states, however, are good candidates for exhibiting fluorescence.…”

Hydrocarbon σ‐radical cations

“…The growing interest to diamondoids is determined by their potential for nanoelectronics140–143 and their oxidation is considered among the most promising preparative functionalization approaches 144–147. The HOMOs of diamondoids are typically highly delocalized and their radical cations display pronounced spin/charge delocalizations over the entire cage.…”

Unconventional molecule-resolved current rectification in diamondoid–fullerene hybrids

“…More specifically, the lowest unoccupied molecular orbital (LUMO) of C 60 lines up closer to the Fermi level of the metallic substrates than does its highest occupied molecular orbital (HOMO). Seminal optical absorption measurements20 revealed that the opposite holds for diamantane. This suggests that diamantane–C 60 (Dia–C 60 ) hybrid molecules should be ideal molecular rectifiers by combining a negative electron affinity moiety (localized on diamantane) with a positive electron affinity segment (localized on C 60 ).…”