am5b08402_si_001.pdf (1.29 MB)
Tunable and Switchable Control of Luminescence through Multiple Physical Stimulations in Aggregation-Based Monocomponent Systems
journal contribution
posted on 2015-11-04, 00:00 authored by Xudong Yu, Xiaoting Ge, Haichuang Lan, Yajuan Li, Lijun Geng, Xiaoli Zhen, Tao YiThis
report describes how the luminescence of naphthalimide could
be tuned by various physical stimuli, including heat, sonication,
and grinding. Herein, instant and switchable control of color and
fluorescent emissions has been achieved by the sonication-triggered
gelation of an organic liquid with naphthalimide-based organogelators
(N3–N7). Green emissive suspensions
of the gelators in organic liquids are transformed into orange emissive
gels upon brief irradiation with ultrasound with an emission wavelength
red-shift of approximately 60 nm and fluorescence intensity quenching
by a factor of 20, which can subsequently be reversed by heating.
When sonication-triggered S-gels are evaporated to S-xerogels, the
solid state xerogels (N3, N4, N6, N7) exhibit mechanochromism, the color of which changes
from red to yellow and the emission color of which changes from orange
to green with enhanced intensity by grinding. This mechanochromic
property can be reversed through a regelation process. The mechanochromic
character of the S-xerogel of N3 is thus applied to quantitatively
sense the mechanical pressure range from 2 to 40 MPa through fluorescence
changes, reflecting a new type of application for gelation assembly.
The physical stimuli triggered fluorescence changes of these compounds
strongly depend on the molecular structure and solvent. The results
demonstrate that the different aggregation modes and long-range order
arrangement of the molecules regulated by the stimulus may affect
the internal charge transfer (ICT) process of the naphthalimide groups,
resulting in the tunability of the photophysical properties of the
gelators. This report provides a new strategy for tunable and switchable
control of luminescence through nonchemical stimuli in aggregation-based
monocomponent systems.