Hydrazone Based Dual - Responsive Colorimetric and Ratiometric Chemosensor for the Detection of Cu2+/F- Ions: DNA Tracking, Practical Performance in Environmental Samples and Tooth Paste

2-hydroxy-1- Naphthaldehyde Based Colorimetric Probe for the Simultaneous Detection of Bivalent Copper and Nickel with High Sensitivity and Selectivity

A neoteric colorimetric probe based on 2-hydroxy-1-naphthaldehyde (PMB3) was designed and synthesized for the real-time as well as on-site naked-eye detection of Cu2+/Ni2+ ions. Various physicochemical methods were employed to characterize the probe, and its colorimetric response to different metal ions was meticulously investigated. The probe, PMB3, exhibited a sensitive colorimetric response to Cu2+/Ni2+ ions among other competing metal ions, culminating in a prominent colour change from colourless to yellow. The stoichiometry of the ligand metal complexes was ascertained to be in a 1:1 ratio using Job's plot analysis, which was further corroborated by ESI-MS data. With detection limits of 4.56 µM for Cu2+ and 2.68 µM for Ni2+, the method was effectively extended to real sample analysis, ensuring propitious results that closely aligned with the actual values.

Vitamin B6-based fluorescence chemosensor for selective detection of F- ions: design, synthesis, and characterization

The present paper reports on the synthesis and characterization of a new chemosensor for fluoride ions, a hydrazone derived from pyridoxal 5'-phosphate and benzothiazole. The structure of the chemosensor was confirmed using 1H and 13C NMR, FT-IR and mass spectroscopy. The conformational diversity of the chemosensor influencing the sensor activity was studied by the quantum chemistry methods on the B3LYP/6-311++G(d, p) (H, C, N, O, P, S) level, and the optimal structure of the chemosensor was chosen. The selective capability of detecting F- in the aqueous solution, which also contains Cl-, Br-, I-, NCS-, ClO4-, HSO4-, and NO3- was demonstrated. The detection limit (LOD) for fluoride ions was 0.22 µM as determined by the 3σ method. The turn-on effect in the presence of fluoride ions is based on the deprotonation of the chemosensor and its subsequent aggregation in DMSO. In addition, the chemosensor was used for the detection and estimation of F- in real samples using fluorescence spectroscopy.

A Fluorimetric Method Based On Magnetic Molecularly Imprinted Polymer For Selective Detection Of Chlorferon

In the present work, reusable magnetic molecularly imprinted polymers have been used for the first time as an adsorbent for the determination of chlorferon. Magnetic molecularly imprinted polymers have been used for the selective separation of chlorferon from the solution and sensitive fluorimetric determination has been performed using the native fluorescence of chlorferon. The developed method is rapid and determination of chlorferon was completed in an hour. Limit of detection (LOD) of the method was found to be 0.0027 µM and the linearity of the calibration graph was observed within the range of 0.01-0.36 µM (2.5 - 75 µg L^-1). Adsorption isotherms point out the multilayer adsorption and the heterogeneous distribution of binding sites for imprinted polymer and homogeneous binding site for non-imprinted polymer. The adsorption capacities of imprinted polymer and non-imprinted polymer were calculated as 2.03 μmol g^-1 and 0.96 μmol g^-1, respectively and the imprinting factor was found to be 2.11. The interference effects of some organic compounds and characterization studies were also evaluated. The method has been applied to honey and tap water samples and the recoveries were found to be in the range of 91.3 and 101.1 %.

Quantum Dots Based Fluorescent Probe for the Selective Detection of Heavy Metal Ions

Heavy metal ions are one of the primary causes of environmental pollution. A marshal effect of heavy metal ions is a paramount ultimatum to humans, aquatic animals and other organisms present in nature. Multitude arrays of materials have been proclaimed for sensing of heavy metal ions and also many methodologies are applied for heavy metal ion sensing. Due to their toxicity and non-biodegradability, it is required to be perceived immediately prior to its manifestation of harmful effects. Quantum Dots (QDs) are zero-dimensional nanomaterial particles and owing to their distinctive optical and electronic properties, they are utilized as nanosensors. QDs have enriched fluorescence properties which includes broad excitation spectrum, narrow emission spectrum and photostability. QDs offer eclectic and sensitive detection of heavy metal ions due to presence of discrete capping agents and different functional groups present on the surface of the QDs. These capping layers and functional groups attune the sensing capability of the QDs, which leverages the interactions of QDs with various analytes by different mechanisms. This review, comprising of papers from 2011 to 2020,focuses on heavy metal ions sensing potential of various quantum dots and its applicability as a nanosensor for on field heavy metal ions detection in water. Quantum Dots (QDs) based Heavy Metal Detection.

A New Reversible Colorimetric Chemosensor Based on Julolidine Moiety for Detecting F. J Fluoresc 2021;31:1675-1682. [PMID: 34387807 DOI: 10.1007/s10895-021-02801-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

We synthesized an original reversible colorimetric chemosensor PDJ ((E)-9-((2-(6-chloropyridazin-3-yl)hydrazono)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol) for the detection of F^-. PDJ displayed a selective colorimetric detection to F^- with a variation of color from colorless to yellow. Limit of detection of PDJ for F^- was calculated as 12.1 µM. The binding mode of PDJ and F^- turned out to be a 1:1 ratio using Job plot. Sensing process of F^- by PDJ was demonstrated by ¹H NMR titration and DFT calculation studies that suggested hydrogen bond interactions followed by deprotonation. Moreover, the practicality of PDJ was demonstrated via a reversible test with TFA (trifluoroacetic acid).

Exploiting the unique specialty of hydrazone functionality: Synthesis of a highly sensitive UV-Vis active solvatochromic probe

The unique physico-chemical attributes of the hydrazone functionality have been extensively studied for a diverse range of chemical, biological and analytical applications. The synthesis of a highly sensitive hydrazone based UV-Vis active solvatochromic probe that exhibits excellent sensitivity toward sensing of solvent polarity, microstructural changes and onset of micellization in aqueous systems was carried out. Specifically, synthesis of 2,4-dinitrophenyl-2-(2-nitrobenzylidene)hydrazone (DNPNBH), through an easy to carry, atom economical, one-pot single step approach via use of low-cost precursors viz. ortho-nitrobenzaldehyde and 2,4-dinitrophenyl hydrazine is presented. The UV-Vis absorption features of the synthesized hydrazone exhibit excellent sensitivity toward the polarity of its immediate microenvironment. The microenvironment polarity sensing potential of DNPNBH is demonstrated for some single solvent systems and DMF-Water mixture as a model binary solvent system and the results are supported by quantum mechanical calculations. Use of the DNPNBH as a probe (at concentrations many orders lower than required for conventional probes) to precisely reflect the onset of micellization and estimation of critical micelle concentration (CMC) of amphiphilic molecules (5.25 mM for SDS, 1.53 mM for CTAB and 0.055 mM for Brij56) in aqueous solutions is also demonstrated. The results clearly qualify the synthesized hydrazone as a highly sensitive UV-Vis probe that can be employed for reliable sensing of solvent polarity, composition dependence of physicochemical attributes in mixed solvent systems and the estimation of CMC of surfactant systems via spectrophotometry.

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.

A New bis(rhodamine)-Based Colorimetric Chemosensor for Cu2

A novel sensor (RD) bearing rhodamine B and 4-tert-Butyl phenol unit have been designed and synthesized using microwave irradiation. The sensor allows selective detection of Cu2+ by forming absorptive complex and trigger the formation of highly colored ring-open spirolactam. The recognition ability of the sensor was investigated by absorbance, Job's plot, infrared (IR) and time dependent-density functional theory (TD-DFT) calculations.