From isolated diamondoids to a van-der-Waals crystal: A theoretical and experimental analysis of a trishomocubane and a diamantane dimer in the gas and solid phase

Christoph Tyborski; Reinhard Meinke; Roland Gillen; Tobias Bischoff; Andre Knecht; Robert Richter; Andrea Merli; Andrey A Fokin; Tetyana V Koso; Vladimir N Rodionov; Peter R Schreiner; Thomas Möller; Torbjörn Rander; Christian Thomsen; Janina Maultzsch

doi:10.1063/1.4994898

From isolated diamondoids to a van-der-Waals crystal: A theoretical and experimental analysis of a trishomocubane and a diamantane dimer in the gas and solid phase

J Chem Phys. 2017 Jul 28;147(4):044303. doi: 10.1063/1.4994898.

Authors

Affiliations

¹ Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.
² Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.
³ Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.

PMID: 28764360
DOI: 10.1063/1.4994898

Abstract

The electronic properties of sp²/sp³ diamondoids in the crystalline state and in the gas phase are presented. Apparent differences in electronic properties experimentally observed by resonance Raman spectroscopy in the crystalline/gas phase and absorption measurements in the gas phase were investigated by density functional theory computations. Due to a reorganization of the molecular orbitals in the crystalline phase, the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy gaps are lowered significantly by 0.5 eV-1 eV. The π → π^* transition is responsible for large absorption in both gas and crystalline phases. It further causes a large increase in the Raman intensity of the C=C stretch vibration when excited resonantly. By resonance Raman spectroscopy we were able to determine the C=C bond length of the trishomocubane dimer to exhibit 1.33 Å in the ground and 1.41 Å in the excited state.