Development of the Smartphone-Assisted Colorimetric Detection of Thorium by Using New Schiff’s Base and Its Applications to Real Time Samples

Abstract

In this paper, a new Th 4+ ion-selective chromogenic sensor (L) was developed by reacting 1,10phenanthroline-2,9-dicarbohydrazide with 2-hydroxy naphthaldehyde. The sensing ability of L toward Th 4+ was investigated in solution and paper strips loaded with L using spectrophotometric and colorimetric methods. The selective interaction of L was examined with various f-metal ions and other selected metal ions from s-block and d-block elements. Results show that by the colorimetric method in solutionphase dimethyl sulfoxide/H 2 O (7:3, v/v) and paper strip methods, the naked-eye detectable color change of L occurred from colorless solution to yellow-orange and pale yellow colour upon interacting with Th 4+ and Al 3+ , respectively, whereas other metal ions did not interfere. The ligand L exhibits two absorbance bands at 320 and 375 nm because of ligand-toligand charge transfer. Upon interaction with Th 4+ , L undergoes red shift of both absorption bands and the formation of a new UV−vis band at 335 and 440 nm. The UV−visible spectral studies indicate the formation of a 1:1 host−guest complex between L and Th 4+ with an association constant of 4.7 × 10 3 M −1 . The limit of quantification and limit of detection of L for the analysis of Th 4+ are found to be 167 and 50 nM, respectively. The visually detectable color change of L has been well integrated with a smartphone RGB color value to make it an analytical signal for real-time analysis of Th 4+ with the detection limit down to 116 nM. Besides, L was applied for the analysis of Th 4+ content present in various real water samples, monazite, and lantern mantle samples by spectrophotometry and RGB color values. The binding mode of L with Th 4+ is investigated by 1 H NMR, electrospray ionization-mass, and theoretical studies.

Screening of Scaffolds for the Design of G-Quadruplex Ligands

“…The mixture was filtered through celite in a hot condition and dioxane was removed under reduced pressure. The residue was purified by column chromatography using silica gel (0.060-0.200 mm, 60 A) and MeOH:CHCl 3 (v/v; 95:5) solvent mixture [19]. After complete separation, the solution was evaporated under vacuum conditions to give a pale yellow solid with a 50% yield (2.3 g, 9.7 mmol); 1 2,9-Dicarbaldehyde-1,10-phenanthroline (0.6 g, 2.4 mmol) was added into HNO 3 (2 mL; 65 wt %).…”

“…After complete separation, the solution was evaporated under vacuum conditions to give a pale yellow solid with a 50% yield (2.3 g, 9.7 mmol); 1 2,9-Dicarbaldehyde-1,10-phenanthroline (0.6 g, 2.4 mmol) was added into HNO 3 (2 mL; 65 wt %). The mixture was refluxed over 6 h, and then the content was poured into cursed ice [19]. The solid was filtered to give a light yellow final product with an 89% yield (0.6 g, 2.2 mmol); 1 1,10-Phenanthroline-2,9-dicarboxylic acid (0.6 g, 2.1 mmol) was suspended in MeOH (150 mL) and conc.…”

“…H 2 SO 4 (15 mL) was added to this solution. The reaction mixture was refluxed overnight [19]. After that, the mixture was poured into crushed ice and allowed to cool.…”

Multifactor colorimetric analysis on pH-indicator papers: an optimized approach for direct determination of ambient aerosol pH

“…As aforementioned, besides the RGB model used by Craig et al (2018), other models have also been adopted to create a linear correlation between RGB and concentrations of the chemicals of interest in previous colorimetric analyses (Su et al, 2008;Yadav et al, 2010;Wan et al, 2017;Selva Kumar et al, 2018). However, few comparisons have been made regarding the goodness of the established linearity using these RGB models.…”

Multifactor colorimetric analysis on pH-indicator papers: an optimized approach for direct determination of ambient aerosol pH

“…Considering that the pH values of ambient aerosols can cover a wide range (up to ∼ 6) (von Glasow and Sander, 2001;Pszenny et al, 2004;Song et al, 2018;Shi et al, 2019), the goal of the present study is to optimize the RGBbased colorimetric analysis on pH-indicator papers for direct determination of ambient aerosol pH in a wider detection range (pH ∼ 0 to 6). We thus propose a new way to analyze the RGB values and establish the relationship between RGB and pH.…”