IR, Raman, and UV/Vis Spectra of Corannulene for Use in Possible Interstellar Identification

Abstract

The spectroscopic characterization of corannulene (C(20)H(10)) is carried out by several techniques. The high purity of the material synthesized for this study was confirmed by gas chromatography-mass spectrometry (GC-MS). During a high-performance liquid chromatography (HPLC) process, the absorption spectrum of corannulene in the ultraviolet (UV) and visible (vis) ranges is obtained. The infrared (IR) absorption spectrum is measured in CsI pellets, and the Raman scattering spectrum is recorded for pure crystal grains. In addition to room temperature measurements, absorption spectroscopy in an argon matrix at 12 K is also performed in the IR and UV/Vis ranges. The experimental spectra are compared with theoretical Raman and IR spectra and with calculated electronic transitions. All calculations are based on the density functional theory (DFT), either normal or time-dependent (TDDFT). Our results are discussed in view of their possible application in the search for corannulene in the interstellar medium.

Molecular curvature tradeoffs: Bending a planar trimercury unit over bowl-shaped polyaromatic hydrocarbons

“…The IR data confirmed the involvement of both partners in coordination showing absorption bands of [Hg 3 ] in the 1000e1600 cm À1 region and relatively intense out-of-plane CeH deformation bands of hydrocarbons, which are generally observed at 700e900 cm À1 [22,26]. The lack of hydrogens in [Hg 3 ] also permitted the detection of low to medium intense CeH stretches of polyaromatic ligands.…”

Theoretical study of the corannulene ozonolysis and evaluation of the various reaction paths

“…The performance of the chosen method was checked by comparing the calculated and experimental IR spectra of corannulene. In the experimental IR absorption spectrum of corannulene there is three dominant bands at 547.3, 659.8 and 837.2 cm À1 [37]. Using of scale factor equal to 0.9679 for B3LYP/6-311G(d,p) level of theory leads to calculated bands at 542.05, 651.98 and 827.15 cm À1 that is very close to experimental values and justifies this method for calculations.…”

Infrared spectroscopy of ionized corannulene in the gas phase

“…Good agreement was found between this FT-IR spectrum and a previously recorded spectrum of neutral corannulene. 30 Simulated IR spectra are generated using BP86 and B3LYP methods. Figure 2 compares the experimental spectra of the neutral and protonated corannulene with the B3LYP calculated spectrum, where the frequencies have been scaled by 0.9679.…”