Theoretical Study of the Negative Ion Photoelectron Spectrum of Cyclooctatetraene via Computation of Franck–Condon Factors

Abstract

The equilibrium structures and harmonic vibrational frequencies of the anion and the first triplet state of cyclooctatetraene were computed using the B3LYP, PBE0, and M06-2X approaches of the density functional theory associated with the aug-cc-pVTZ basis set. The first excited singlet state of cyclooctatetraene was calculated using the complete active space self-consistent field method. The photoelectron spectra of cyclooctatetraene anion were simulated for both the triplet and the excited singlet states via computing Franck–Condon factors. The adiabatic electron affinity was computed by extrapolation to the complete basis set limit from the energies calculated using CCSD­(T)/aug-cc-pVXZ (X = D, T, Q). The simulated photoelectron spectrum and the calculated adiabatic electron affinity for the triplet state are in consistence with the experiment. The first excited singlet state, which plays a key role in the photochemistry of cyclooctatetraene, is predicted to possess vibrational structures in its photoelectron spectrum pertinent for experimental identification.

Nonadiabatic Molecular Dynamics Study of the Relaxation Pathways of Photoexcited Cyclooctatetraene

“…Such a photoinduced double-bond shifting reaction may be exploited to design photochemically driven molecular switches, where an “on-state” is characterized by a “through-conjugation” between the π-donor and π-acceptor substituents, whereas an “off-state” refers to a suppression of this through-conjugation. COT thus appears as a particularly suitable candidate for studying both the double-bond shifting and the nonaromatic ( S 0 )/aromatic ( S 1 ) photoswitching process. − …”

Enhancing Students’ Understanding of the Structures and Aromaticities of Cyclobutadiene and Cyclooctatetraene through a Computational Chemistry Exercise

“…The distances are presented in nm, and the angles are in degrees. The values in parentheses are from refs and . b Zero-point-corrected electronic energies, in hartrees. c In kJ/mol. d NA means “Not Applicable” because CBD 2– and CBD 2+ have different numbers of electrons compared to the neutral NBD. e Calculated using the GIAO method. …”

“…The distances are presented in nm, and the angles are in degrees. The values in parentheses are from refs and .…”