jz0c01297_si_001.pdf (2.52 MB)
Enhancing Intersystem Crossing to Achieve Thermally Activated Delayed Fluorescence in a Water-Soluble Fluorescein Derivative with a Flexible Propenyl Group
journal contribution
posted on 2020-07-03, 02:03 authored by Yingnan Wu, Yanliang Zhao, Panwang Zhou, Daoyuan Zheng, Honglei Wang, Shanliang Tang, Jiarui Tian, Songqiu Yang, Weiqiao Deng, Keli Han, Fengling SongIt
is a challenge to rationally design an organic molecule with
thermally activated delayed fluorescence (TADF) due to the intrinsically
spin-forbidden transition. Meanwhile, those reported TADF organic
molecules have difficulty to be directly applied in the field of biological
and medical imaging because they usually have no water solubility.
Here, a water-soluble TADF organic molecule DCF-BXJ was developed
by introducing a flexible propenyl group into the commercial traditional
fluorophore DCF (2,7-dichlorofluorescein). The flexible group provides
nonradiative rotational motion, which causes an efficient energy level
cross between the S1 state and the T2 state
of DCF-BXJ. Results of transient absorption spectra and theoretical
calculations supported that nonradiative rotational motion of the
flexible group can enhance intersystem crossing (ISC) and bring out
TADF. This work provides a new mechanism explanation for TADF existing
in organic molecules.