Design
and development of multifunctional materials have drawn
incredible attraction in recent years. Herein, we report the design
and construction of versatile star-shaped intramolecular charge transfer
(ICT)-coupled excited-state intramolecular proton transfer (ESIPT)-active
mechanoresponsive and aggregation-induced emissive (AIE) luminogen
triaminoguanidine-diethylaminophenol (
LH
3
)
conjugate from simple precursors triaminoguanidine hydrochloride and
4-(
N
,
N
-diethylamino)salicylaldehyde.
Solvent-dependent dual emission in nonpolar to polar protic solvents
implies the presence of ICT-coupled ESIPT features in the excited
state. Aggregation-enhanced emissive feature of
LH
3
was established in the CH
3
CN/water mixture. Furthermore,
this compound exhibits mechanochromic fluorescence behavior upon external
grinding. Fluorescence microscopy images of pristine, crystal, and
crushed crystals confirm the naked-eye mechanoresponsive characteristics
of
LH
3
. In addition,
LH
3
selectively sensed a Cu
2+
ion through a colorimetric
and fluorescence “turn-off” route, and subsequently,
the
LH
3
-Cu
2+
ensemble could act
as a selective and sensitive sensor for S
2–
in a
“turn-on” fluorescence manner via a metal displacement
approach. Reversible “turn-off–turn-on” features
of
LH
3
with Cu
2+
/S
2–
ions were efficiently demonstrated to construct the IMPLICATION
logic gate function. The Cu
2+
/S
2–
-responsive
sensing behavior of
LH
3
was established in
the paper strip experiment also, which can easily be characterized
by the naked eye under daylight as well as a UV lamp (λ = 365
nm).