An efficient ICT-based ratio/colorimetric tripodal azobenzene probe for the recognition/discrimination of F−, AcO− and H2PO4− anions

Abstract

The tripodal probe L was readily prepared via introducing rhodamine and azobenzene groups in a two-step procedure. Studies of the recognition properties indicated that probe L exhibited high sensitivity and selectivity towards F -, AcOand H2PO4through a ratiometric colorimetric response with low detection limits of the order of 10 -7 M. The complexation behaviour was fully investigated by spectral titration, 1 H NMR spectroscopic titration and mass spectrometry. Probe L not only recognizes F -, AcOand H2PO4 -, but can also distinguish between these three anions via the different ratiometric behaviour in their UV-vis spectra (387/505 nm for L-H2PO4 -, 387/530 nm for L-AcOand 387/575 nm for L-Fcomplex) or via different colour changes (light coral for L-H2PO4 -, light pink for L-AcOand violet for the L-Fcomplex). Additionally, given the presence of NH and OH groups in probe L, which can be protonated and deprotonated, probe L further exhibited an excellent pH response over a wide pH range (pH 3 to pH 12).

Synthesis and application of hypochlorite mediated acylhydrazone fluorescence probes

“…To date, hydrazone and acylhydrazone based fluorescent probes have been reported to exhibit specific recognition of metal ions [4–6], anions [7–9], and reactive oxygen species (ROS) [10, 11] as well as strong chromogenic properties, have played an important role in the field of molecular recognition. Acylhydrazone derivatives can complex with metal ions (Cu 2+ , Zn 2+ ) utilizing nitrogen and oxygen atoms [12–14]; or interact with anions (such as AcO − , F − , CN − , H 2 PO 4 − ) via electrophilic central nitrogen atoms in carbon–nitrogen double bonds [15–18], thereby hindering the charge transfer or structural deformation of the probe itself. In addition, compared to simple Schiff base probes, hydrazone and acylhydrazone based fluorescent probes are more sensitive to strong oxides (such as ONOO − or HClO/ClO − ) and more easily break bonds by oxidation under mild conditions, generating aldehydes and carboxylic acids [19–21].…”

“…) via electrophilic central nitrogen atoms in carbon-nitrogen double bonds [15][16][17][18], thereby hindering the charge transfer or structural deformation of the probe itself. In addition, compared to simple Schiff base probes, hydrazone and acylhydrazone based fluorescent probes are more sensitive to strong oxides (such as ONOO À or HClO/ClO À ) and more easily break bonds by oxidation under mild conditions, generating aldehydes and carboxylic acids [19][20][21].…”

Thiadiazole-based turn-on fluorescent chemosensor for AcO− and its application in environmental systems and in bioimaging

“…Anion detection has become one of the most active areas of supramolecular chemistry because many anios play vital role in health, biological, medical, environmental, industrial and chemical processes [1][2][3][4][5][6]. Among the different anions, acetate anion (AcO − ) plays an enormous role in our life, such as human metabolic process, protein synthesis [7][8][9][10][11]. For example, the abnormal rise of AcO − in the body could be the exogenous cause of urinary calculi [7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

A Novel ‘On‐Off’ Rhodamine Based Sensor for Colorimetric Detection of CN−and Its Application as Encoder‐Decoder and Molecular Keypad Lock

“…A number of ratiometric donor-acceptor models has been designed based upon various phenomena such as RET (Resonance Energy Transfer), [1,2] ESIPT (Excited State Intramolecular Proton Transfer), [3] TBET (Through Bond Energy Transfer), [4,5] FRET (Fluorescence Resonance Energy Transfer), [6,7] PET (Photo-induced Electron Transfer) [8,9] and ICT (Intramolecular Charge Transfer). [10,11] ICT process leads to change in charge distribution in the fluorophores and is investigated to understand the factors that affect charge recombination and separation. It generally occurs in the probes having electron-withdrawing and -donating groups and the photophysical properties of the probes are dependent on the strength of donor and acceptor parts.…”

“…The ratiometric sensing permits the detection of ions by measuring ratio of emission intensities at two different wavelengths. A number of ratiometric donor‐acceptor models has been designed based upon various phenomena such as RET (Resonance Energy Transfer), [1,2] ESIPT (Excited State Intramolecular Proton Transfer), [3] TBET (Through Bond Energy Transfer), [4,5] FRET (Fluorescence Resonance Energy Transfer), [6,7] PET (Photo‐induced Electron Transfer) [8,9] and ICT (Intramolecular Charge Transfer) [10,11] …”