“Test kit” of chromogenic and ratiometric 1,10-phenanthroline based chemosensor for the recognition of F− and CN– ions

A Novel Naphthylidene-diimine Chemosensor for Selective Colorimetric and Fluorometric Detection of Al3+ and CN- Ions

A naphthylidene-diimine L2 was newly designed, and its structure was identified by elemental analysis and spectroscopic methods. The effect of temperature, acid-base and light on enol-keto tautomerism in this Schiff base was evaluated by colorimetry, UV-Vis and fluorescence spectroscopy. Under irradiation 365 nm, L2 emitted yellow, orange and strong green emission in pure, basic and aqueous DMSO media (v/v, 1/1), respectively. Its ionochromic behavior against various cations (Fe3+, Al3+, Cr3+, Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ba2+ and Ag+) and anions (F-, Cl-, CH3COO-, SO32-, S2O32-, HSO4-, H2PO4-, NO3-, CN-, and OH-) was investigated in aqueous DMSO media (v/v, 1/1) by UV-Vis and fluorescence experiments. Dark yellow color of L2 changed to colorless for Fe3+, Cr3+ and HSO4- ions, and turned to light yellow for Al3+ and Cu2+ ions, and to orange for CN- and OH- ions. According to UV-Vis data, the chemosensor displayed selective recognition towards Fe3+, Al3+, Cu2+, HSO4-, CN- and OH- with a 1:1 stoichiometric ratio. At the excitation wavelength of 365 nm, L2 gave strong yellowish white emission (λem = 445 and 539 nm) in the presence of Al3+, and the intensity increased about 12.5 times. On the other hand, the chemosensor displayed one emission band at 452 nm and 450 nm in the presence of CN- and OH- with 1.9 fold and 2.3 fold fluorescence enhancement, respectively.

A Handy Chemical Sensor Based on Benzaldehyde and Imidazo[1,2-a]pyridine Mixture for Naked-eye Colorimetric and Fluorescent Detection of F. J Fluoresc 2023;33:2381-2390. [PMID: 37071230 DOI: 10.1007/s10895-023-03195-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Upon the Schiff base condensation reaction of imidazo[1,2-a]pyridine-2-carbohydrazide and 2,5-dihydroxybenzaldehyde, a bimodal colorimetric and fluorescent chemosensor 1o for assaying fluoride (F-) in DMSO was synthesized. The characterization of 1o structure was obtained by 1H NMR, 13C NMR and MS.The structure of 1o was characterized by 1H NMR, 13C NMR and MS. Under the presence of various anions, 1o could be applied for naked-eye and fluorescent detection of F- (naked eye: colorless to yellow; fluorescence: dark to green) and displayed promising performance, such as high selectivity and sensitivity, as well as a low detection limit. Upon calculation, the detection limit of chemosensor 1o for F- was 193.5 nM, which is well below the allowed maximum value of F- (1.5 mg/L) by WHO. As the intermolecular proton transfer mechanism induced "turn-on" fluorescent signal and naked-eye color change of F- to 1o through deprotonation effect, which was confirmed by Job's plot curve, mass spectrometry and 1H NMR titration. Alternatively, the chemosensor 1o can be effectively manufactured into test strips to detect fluoride in solid state, which is user-friendly with no additional equipment required.

Preparation of a new fluorescence nanochemosensor for Sn(II) ions by a modified nanoprecipitation method

A new dialdehyde was designed and synthesized containing naphthalene groups, and then its macrocycle was prepared with 1,4-diaminobuthan. A modified nanoprecipitation method has been reported for the preparation of the nanoparticles. In this method, to obtain nanoparticles with small particle sizes, the nucleation rate was increased with decreasing of the mixing time. The organic nanoparticles were used for turn-off fluorescence response of low concentration of Sn²⁺ ions over cations such as Cs⁺, K⁺, Na⁺, Ba²⁺, Ca²⁺, Mg²⁺, Al³⁺, Pb^2+, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺, Ag⁺, Cd²⁺, and Hg²⁺ and ions in aqueous buffer solution. The limit of detection was 5.4 nM.

A Visual and Ratiometric Chemosensor Using Thiophene Functionalized Hydrazone for the Selective Sensing of Pb2+ and F- Ions

Herein, a simple, efficient ratiometric chemosensor was reported for the selective sensing of Pb²⁺ and F^- ions using thiophene functionalized hydrazone as a chemical probe. Hydrazone moiety was developed by utilizing thiophene/naphthalene as a platform for the particular recognition of cation and anion. The structures of the precursor (Z)-(1-(5-bromothiophen-2-yl)ethylidene)hydrazine (ABTH) and the final probe 1-((Z)-(((Z)-1-(5-bromothiophen-2-yl)ethylidene)hydrazono)methyl)naphthalen-2-ol (NAPABTH) were confirmed by ¹H, ¹³C-NMR and LC-MS spectroscopic methods. The interaction of NAPABTH with Pb²⁺ and F^- ions was visually observed by the formation of pink and dark yellow solutions, respectively. The detection limits were found to be very low for Pb²⁺ as 1.06 ppm and for F^- ions as 3.72 nM. This visual detection of Pb²⁺/F^- ions with satisfactory outcomes obtained from UV-Vis titrations. The sensing mechanistic pathways and stoichiometric ratios were obtained from DFT and Job's plot, respectively. The observed results are highly promising as highly selective chemosensor with lower detection limits for Pb²⁺ and F^- ions. This strategy could exhibit tremendous applications for the selective sensing of heavy metal cations with rapid sensitivity for the design of new devices.