Intramolecular benzene excimer formation in 13,14-diphenyldibenzo[b,j][4,7]phenanthroline

Jiafen Lin; Lin Ma; Yilun Zhao; Saran Long; Tianjiao Li; Animesh Ghosh; Andrew C Grimsdale; Xiaojun Peng; Licheng Sun; Gagik G Gurzadyan

doi:10.1063/5.0227468

Intramolecular benzene excimer formation in 13,14-diphenyldibenzo[b,j][4,7]phenanthroline

J Chem Phys. 2024 Oct 14;161(14):144310. doi: 10.1063/5.0227468.

Authors

Jiafen Lin¹, Lin Ma², Yilun Zhao², Saran Long¹, Tianjiao Li³, Animesh Ghosh⁴, Andrew C Grimsdale⁴, Xiaojun Peng^{1

5}, Licheng Sun^{3

6

7}, Gagik G Gurzadyan³

Affiliations

¹ State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, China.
² School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China.
³ State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian 116024, China.
⁴ School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
⁵ State Key Laboratory of Fine Chemicals, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
⁶ Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm 10044, Sweden.
⁷ Center of Artificial Photosynthesis for Solar Fuels, School of Science, Westlake University, Hangzhou 310024, China.

PMID: 39399964
DOI: 10.1063/5.0227468

Abstract

13,14-diphenyldibenzo[b,j][4,7]phenanthroline (DBP3) in various solvents was studied by time-resolved fluorescence and fs transient absorption (fs-TA) spectroscopy. An intramolecular benzene excimer is demonstrated to form within DBP3; it exhibits strong redshifted emission with maximum at 540-640 nm. "Intrinsic" fluorescence from DBP3 is dramatically quenched down to τ = 50-400 fs in all the solvents studied. Fs-TA and time-resolved fluorescence spectra have proved that relaxed intramolecular benzene excimer is formed from S1 state via hot excimer state with three lifetime components: 50 fs, ∼3.5 ps, and ∼25 ps, which are of the inertial (electronic) and diffusive parts of the relaxation due to solute-solvent interaction. Formation of triplet states via intersystem crossing was observed directly from the upper excited electronic states of DBP3.