A single probe to sense Al(iii) colorimetrically and Cd(ii) by turn-on fluorescence in physiological conditions and live cells, corroborated by X-ray crystallographic and theoretical studies

Abstract

A pyridine-2-carbohydrazide functionalized conjugated fluorophoric Schiff base ligand (L₁) specifically senses Al(3+) and Cd(2+) ions through significant changes in its absorption and emission spectral behavior, respectively, in physiological conditions. The spectral changes are in the visible region of the spectrum and thus facilitate naked eye detection. Apart from the visible changes, an in-field device application was demonstrated by sensing these ions in paper strips coated with L₁. The crystal structure of the L₁-Cd complex provided additional insight of the metal coordination attributes of L₁. Interestingly, fluorescence microscopic studies demonstrated that the ligand L₁ could also be used as an effective probe in imaging experiments for the detection of intracellular Cd(2+) ions in HeLa cells, without any toxicity to these model human cells.

Crystal structure of bis{2-hydroxy-N′-[1-(pyrazin-2-yl)ethylidene]benzohydrazidato}cadmium(II)

“…Aroylhydrazones synthesized from arylhydrazides and aromatic aldehydes/ketones with a nitrogen or oxygen atom in the ortho position can coordinate to metals in a tridentate chelating mode (Cindrić et al, 2017;Patel et al, 2018;You et al, 2018), and they have been used as probes and chemosensors for various metal ions. For example, the aroylhydrazone ligand containing a 4-(dimethylamino)phenylpropenyl or benzamide substituent specifically senses Al 3+ , Cd 2+ (Kar et al, 2015) and Ni 2+ ions (Manna et al, 2019) through significant changes in their absorption and emission spectroscopic behaviour after complexation with the metal ions. Here, we study the coordination attributes of an aroylhydrazone with cadmium.…”

Colorimetric Detection of Copper(II) Ions Using Schiff‐Base Derivatives

“…[30] Nowadays, Schiff base derivatives are increasingly used as colorimetric sensors due to their simple synthesis steps and high selectivity. In particular, cinnamaldehyde-based Schiff base derivatives have been developed for the detection of metal ions such as Ag + , [31] Al 3 + , [32,33] Cu 2 + /Hg 2 + [34] and Ni 2 + . [35] However, simple, rapid, high-selective, and sensitive colorimetric sensors for Cu 2 + are still rare and needed to be developed.…”

Colorimetric cadmium ion detection in aqueous solutions by newly synthesized Schiff bases

“…Nowadays, Schiff base derivatives have been increasingly used as colorimetric sensors due to having simple synthesis steps and high selectivity. Especially, cinnamaldehydebased and benzaldehyde-based Schiff base derivatives have been developed for the detection of metal ions such as Ni 2+ [26], Ag + [27], Al 3+ [28,29] Cu 2+ /Hg 2+ [30]. However, simple, rapid, highly selective, and sensitive colorimetric sensors for Cd 2+ are still rare and needed to be developed.…”