Layered Dinitrostilbene-Based Molecular Solids with Tunable Micro/Nanostructures and the Reversible Fluorescent Response to Explosives

The
ability to modulate and control the fluorescence properties
of molecular solids at the micro/nanoscale is important to develop
high-performance optoelectronic materials and sensors. Here we report
the tunable one-photon and two-photon fluorescence as well as micro/nanostructures
of dinitrostilbene-based (DNS) chromophore by the formation of layered
multicomponent crystals with guanidinium cation (GD) through hydrogen-bonding
assembly. The as-prepared GD2DNS bulk crystal shows a red-shift
emission as well as enhanced photoluminescence quantum yield and fluorescence
lifetime compared with those of the Na2DNS sample, which
is related to the structural transfer of DNS from staggered arrangement
to parallel fashion within the crystal. Periodic density functional
theoretical calculations further show that the introduction of different
cationic units can modify the frontier orbital distribution and electronic
structure of DNS anions within the multicomponent crystals. Moreover,
one-dimensional GD2DNS nanobelts with well-aligned orientation
can be further obtained by a combined ultrasound and coprecipitation
method. The GD2DNS nanobelts undergo a blue-shift fluorescence
compared with its bulk crystal, and exhibit alternated photoresponse
(such as emission wavelength and intensity) upon interaction with
different nitroaromatic explosives (trinitrotoluene, picric acid and
m-dinitrobenzen). Therefore, this work gives a facile bottom-up self-assembly
rout to prepare organic multicomponent materials with tunable fluorescence
properties and micro/nanostructures, which can be potentially used
as luminescence detector for nitroaromatic explosives.