A novel salicylideneaniline-based fluorescent sensor, SB1, with a unique excited-state intramolecular charge transfer-excited-state intramolecular proton transfer (ESICT-ESIPT) coupled system was synthesized and demonstrated to fluorescently sense CN(-) with specific selectivity and high sensitivity in aqueous media based on ESICT-ESIPT switching. A large blue shift (96 nm) was also observed in the absorption spectra in response to CN(-). The bleaching of the color could be clearly observed by the naked eye. Moreover, SB1-based test strips were easily fabricated and low-cost, and could be used in practical and efficient CN(-) test kits. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations further support the cyanide-induced ESICT-ESIPT switching mechanism. The results provide the proof of concept that the colorimetric and ratiometric fluorescent cyanide-selective chemodosimeter can be created based on an ESICT-ESIPT coupled system.
A series
of new molecules bearing alkyl-substitutes on the parent
molecule 1-hydroxy-11H-benzo[b]fluoren-11-one
(HBF) has been designed and synthesized, which possesses
an intramolecular hydrogen bond (H-bond) between −OH proton
donor and carbonyl proton acceptor. All studied molecules present
an equilibrium type of excited-state intramolecular proton transfer
(ESIPT) at 298 K. The alkyl-substitutions at various positions subtly
alter the intramolecular H-bond strength, which then fine-tune the
excited-state equilibrium and hence thermodynamics between normal
and tautomer species. These, in combination with finite rates of ESIPT
resolved by femtosecond fluorescence upconversion techniques, lead
to the establishment of an empirical relationship among H-bond strengths,
ESIPT kinetics, and thermodynamics for HBF series of
molecules, in which the stronger H-bond is, the faster and more exergonic
ESIPT is. The intensity ratio for normal versus proton-transfer tautomer
emission can be systematically tuned, demonstrating the harness of
−OH type ESIPT reaction via facile alkyl-substituent perturbation.
A new series of molecules bearing 2,11-dihydro-1H-cyclopenta[de]indeno[1,2-b]quinoline (CPIQ) chromophore with N-H---N type of intramolecular hydrogen bond are strategically designed and synthesized, among which CPIQ-OH, CPIQ-NHAc and CPIQ-NHTs in solution exhibit...
An alkoxy-substituted 1,3-indanedione-based chemodosimeter 1 with an aggregation-induced emission (AIE) characteristic was rationally designed and synthesized for the ultrasensitive and selective sensing of cyanide in a wide pH range of 3.0−12.0. The nucleophilic addition of cyanide to the β-conjugated carbon of the 1,3-indanedione group obstructs intramolecular charge transfer (ICT) and causes a significant change in the absorption and fluorescence spectra, enabling colorimetric and ratiometric fluorescent detection of cyanide in a 90% aqueous solution. The cyanide-sensing mechanism is supported by singlecrystal X-ray diffraction analysis, time-dependent density functional theory (TD-DFT) calculations, and 1 H NMR titration experiments. Sensor 1 exhibits strong yellow fluorescence in the solid state due to the AIE effect, and the paper probes containing 1 can be conveniently used to sense cyanide by the naked eye. Furthermore, chemodosimeter 1 was successfully used for sensing cyanide in real environmental water samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.