1,3,5-Trifluoro-2,4,6-triiodobenzene: A neglected NIR phosphor with prolonged lifetime by σ-hole and π-hole capture

Zheng Fei Liu; Xue Chen; Wen Xin Wu; Gui Qi Zhang; Xin Li; Zhen Zhen Li; Wei Jun Jin

doi:10.1016/j.saa.2019.117428

1,3,5-Trifluoro-2,4,6-triiodobenzene: A neglected NIR phosphor with prolonged lifetime by σ-hole and π-hole capture

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jan 5:224:117428. doi: 10.1016/j.saa.2019.117428. Epub 2019 Jul 26.

Authors

Zheng Fei Liu¹, Xue Chen¹, Wen Xin Wu¹, Gui Qi Zhang¹, Xin Li¹, Zhen Zhen Li¹, Wei Jun Jin²

Affiliations

¹ College of Chemistry, Beijing Normal University, Beijing, Beijing, 100875, China.
² College of Chemistry, Beijing Normal University, Beijing, Beijing, 100875, China. Electronic address: wjjin@bnu.edu.cn.

PMID: 31376727
DOI: 10.1016/j.saa.2019.117428

Abstract

Room temperature phosphorescence (RTP) materials have become a hot topic in fields of organic light-emitting dioes, biological sensing and imaging. The present work reports firstly that 1,3,5-trifluoro-2,4,6-triiodobenzene (TITFB) can act as a simple pure organic NIR phosphor due to its novel function in promoting n-π∗ transition. Also, TITFB crystal has longer phosphorescence lifetime than other ordinary multiiodoluminophors and TITFB powder. Based on the TITFB crystal structure, σ-hole and π-hole capture mechanism of n-electron is proposed, i.e., the excited state energy is decreased and n-electrons are stabilized to cause slower radiative decay rate due to the restriction of σ-hole and π-hole bond. Both computational and experimental studies support the mechanism. The new electron-capture mode is more conducive to understanding pure organic ultralong lifetime RTP.

Keywords: Halogen bond; Room temperature phosphorescence; σ-Hole and π-hole capture.