Due to significantly tackling the problems of aggregation-caused quenching and water insolubility, aggregationinduced emission electrochemiluminescence (AIE-ECL) has emerged as a research highlight in aqueous detection and sensing. Herein, we reported a series of cyclopentadienols featuring excellent AIE-ECL properties on the basis of an enhanced aromaticity strategy. In detail, substituents profoundly determined ECL emission by affecting the characteristic absorption peak intensity ratio in UV−vis spectra and lowest unoccupied molecular orbital (LUMO)−highest occupied molecular orbital (HOMO) energies. It was found that 1,2,3,4,5-pentafluorophenyl cyclopentadienol (PFCD) containing an electron-withdrawing fluorine substituent, the maximum R/B band ratio, and a smaller LUMO−HOMO band gap demonstrated the best ECL performance. Meanwhile, such an AIE-ECL system displayed a wide response range toward pH (4−12) with a good linear relationship. Our research not only enriched polycyclic aromatic hydrocarbon-based AIE-ECL systems but also established an efficient pH sensor in the aqueous phase.
The development of superior probes is highly desirable
and valuable
for viscosity measurement. Herein, we designed and reported a series
of diphenylbenzofulvene (DPBF)-based organic luminophores according
to the molecular regulation strategy. There are two free-rotating
phenyl groups attached to the rigid fluorene skeleton in the DPBF,
enabling its unique propeller-like noncoplanar chemical structure.
Benefiting from this, DPBFs could feature outstanding PL and ECL emissions
with intriguing aggregation-induced characteristics. Experimental
and theoretical investigations revealed that substituent, spatial
structure, and molecular orbital energy profoundly affected their
luminescent behaviors. It was disclosed that fluoro-substituted DPBF(F)2 with a smaller LUMO–HOMO band gap demonstrated the
strongest ECL emission and was selected as the optimal ECL emitter.
Finally, DPBF(F)2 featured a linear response to the viscosity
and VC content with lower limits of detection (LOD) of 5.69 μcP
and 38.2 nM, respectively. This study represents the first example
of the ECL probe toward viscosity and will be of great significance
for both ECL application and viscosity measurement.
The
intriguing aggregation-induced emission has recently
been applied
in the electrochemiluminescence, called aggregation-induced electrochemiluminescence
(AIE-ECL), which is conducive to solving the water insolubility and
aggregation-caused quenching for most organic luminescence probes.
However, AIE-ECL still has the problems of low luminous efficiency
and limited practical application. In this work, we disclosed the
AIE-ECL properties of 1,2,3-triaryl-substituted indenes containing
rigid structures. Experimental and theoretical investigations demonstrated
that such a rigid structure could significantly enhance the aromaticity
and stability and thereby the luminescence performance of these indenes.
Moreover, according to the finding of hydrogen/deuterium exchange
for active hydrogen in indene under electrical excitation, ultrasensitive
detection for D2O in H2O was realized by such
an indene-based AIE-ECL system. Our research not only provided an
attractive strategy to enhance the luminescence property for an AIE-active
luminophore but also established a superior sensor toward D2O.
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