title: Predictions of the geometries and fluorescence emission energies of oxyluciferins.
abstract: The complete active space self-consistent field (CASSCF) method and multiconfigurational second-order perturbation theory (CASPT2) have been used to study the structures and spectra of oxyluciferins (OxyLH2). The ground and lowest-lying singlet excited states geometries have been optimized using CASSCF. CASPT2 has been used to predict relaxed emission energies. The focus is on the lowest-lying singlet excited states of the anionic keto and enol forms of OxyLH2(-1) at the optimized excited-state geometries. The planar keto and enol forms of OxyLH2(-1) are minima on both the S0 and the S1 potential energy surfaces. The twisted keto and enol forms of OxyLH2(-1) are transition states on the S0 and S1 potential energy surfaces. The S1 --> S0 fluorescence emission energies are in the range of 54.2-58.4 kcal/mol for the anionic planar keto forms of OxyLH2, and in the range of 55.7-63.2 kcal/mol for the anionic enol forms of OxyLH2. S0 and S1 potential energy surfaces and thus are not implicated in the emission spectra in the gas phase.
authors: Department of Chemistry, University of Guelph, Guelph, Ontario, Canada.
authors: Tianxiao
authors: T
authors: Yang
authors: John D
authors: JD
authors: Goddard
mesh_terms: D005453:Fluorescence; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D011719:Pyrazines / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D007211:Indoles; D011719:Pyrazines; C014730:oxyluciferin