Premium
Unraveling the Mechanisms of the Excited‐State Intermolecular Proton Transfer (ESPT) for a D‐π‐A Molecular Architecture
Author(s) -
Hong DanLi,
Luo YangHui,
He XiaoTong,
Zheng ZiYue,
Su Shan,
Wang JiaYing,
Wang Cong,
Chen Chen,
Sun BaiWang
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900856
Subject(s) - excited state , intramolecular force , intermolecular force , chemistry , photochemistry , hydrogen bond , proton , fluorescence , photoexcitation , photoluminescence , relaxation (psychology) , molecule , materials science , stereochemistry , optoelectronics , atomic physics , physics , organic chemistry , optics , psychology , social psychology , quantum mechanics
Precise revealing the mechanisms of excited‐state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound ( E )‐4‐(((4 H ‐1,2,4‐triazol‐4‐yl)imino)methyl)‐2,6‐dimethoxyphenol (TIMDP) adopting a D‐π‐A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO 4 –H 2 O–OH(TIMDP)–N(TIMDP) hydrogen‐bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g., UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen‐bonding bridge, resulting in crystals of [HTIMDP] + ⋅ [H 2 O] ⋅ [ClO 4 ] − . As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D‐π‐A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters.