Perylene derivative films: Emission from higher singlet excited state

Author(s)

Fernandes, Jose Diego ^[1] ; Pazin, Wallance Moreira ^[1] ; Macedo, Wagner Costa ^[1] ; Teixeira, Silvio Rainho ^[1] ; Lima, Sergio Antonio Marques ^[1] ; Batagin-Neto, Augusto ^[2] ; Constantino, Carlos Jose Leopoldo ^[1]

Affiliation

^[1] Sao Paulo State Univ UNESP, Sch Technol & Appl Sci, BR-19060900 Presidente Prudente, SP - Brazil

^[2] Sao Paulo State Univ UNESP, Campus Itapeva, BR-18409010 Itapeva, SP - Brazil

• Document type: Journal article
• Source: Journal of Luminescence; v. 226, OCT 2020.
• Web of Science Citations: 0

Abstract

Transitions from the singlet electronic excited states higher than S-1 level (S-2) to the fundamental state (S-0) are unlikely, although such transitions are observed for perylene derivative compounds. This rareness led us to investigate the role of the molecular structure of two perylene derivatives (bis(butylimido) - BuPTCD and bis (phenetylimido) - PhPTCD), as well as their supramolecular arrangements, such as molecular organization, crystallinity, and molecular aggregates (before and after thermal treatment) on the radiative transition S-2 ->-S-0. The emission spectra of BuPTCD and PhPTCD solutions (monomers) indicated that differences in their molecular structures (lateral groups) do not influence such transitions. Besides, it was verified that the relative intensity (RI) S-1 ->-S-0 over S-2 ->-S-0 (RI = I-S1 -> S0/I-S2 -> S0) obtained for BuPTCD and PhPTCD PVD films increases around 15 and 1.5, respectively (in comparison to their respective solutions). However, it was surprising to observe a decrease of RI = I-S1 -> S0/I-S2 -> S0 by a factor of 88 for both BuPTCD and PhPTCD PVD films after their thermal treatment at 200 degrees C for 2 h. The latter led to an increase of the emission intensity from S-2 -> S-0 transition in relation to S-1 -> S-0. The decrease of H aggregates, presence of J aggregates and formation of other types of molecular aggregates, induced by thermal treatment, seem to be the cause of the S-2 ->-S-0 emission increase, which is supported by theoretical calculations. (AU)

• FAPESP's process: 13/14262-7 - Nanostructured films from biologically-relevant materials
• Grantee: Osvaldo Novais de Oliveira Junior
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 16/09633-4 - Mechanism of action of the bioactive compound Artepillin C in membrane biomimetic systems and cytoplasmic membrane of tumor cells
• Grantee: Wallance Moreira Pazin
• Support type: Scholarships in Brazil - Post-Doctorate