Emission Energies and Stokes Shifts for Single Polycyclic Aromatic Hydrocarbon Sheets in Comparison to the Effect of Excimer Formation

Baimei Shi; Dana Nachtigallová; Adélia J A Aquino; Francisco B C Machado; Hans Lischka

doi:10.1021/acs.jpclett.9b02214

Emission Energies and Stokes Shifts for Single Polycyclic Aromatic Hydrocarbon Sheets in Comparison to the Effect of Excimer Formation

J Phys Chem Lett. 2019 Sep 19;10(18):5592-5597. doi: 10.1021/acs.jpclett.9b02214. Epub 2019 Sep 6.

Authors

Baimei Shi¹, Dana Nachtigallová^{2

3}, Adélia J A Aquino^{1

4}, Francisco B C Machado⁵, Hans Lischka^{1

4}

Affiliations

¹ School of Pharmaceutical Sciences and Technology , Tianjin University , Tianjin 300072 , P. R. China.
² Institute of Organic Chemistry and Biochemistry v.v.i. , The Czech Academy of Sciences , Flemingovo nám. 2 , 16610 Prague 6, Czech Republic.
³ Regional Centre of Advanced Technologies and Materials , Palacký University , 78371 Olomouc , Czech Republic.
⁴ Department of Chemistry and Biochemistry , Texas Tech University , Lubbock , Texas 79409 , United States.
⁵ Departamento de Química , Instituto Tecnológico de Aeronáutica , São José dos Campos , 12228-900 São Paulo , Brazil.

PMID: 31479613
DOI: 10.1021/acs.jpclett.9b02214

Abstract

Emission spectra of paradigmatic single-sheet polycyclic aromatic hydrocarbons (PAHs), pyrene, circum-1-pyrene, coronene, circum-1-coronene, and circum-2-coronene and Stokes shifts were computed and compared with previously calculated comparable data for relaxed excimer structures using the SOS-ADC(2), TD-B3LYP, and TD-CAM-B3LYP methods with multireference DFT/MRCI data as the benchmark. Vertical emission transitions and Stokes shifts were extrapolated to infinite PAH size. Comparison of Stokes shifts computed from theoretical monomer and dimer data confirms assumptions that relaxed excimers are responsible for the unusually large Stokes shifts in carbon dots observed in experimental investigations.