New Fluorogenic Dansyl-Containing Calix[4]arene in the Partial Cone Conformation for Highly Sensitive and Selective Recognition of Lead(II)

Abstract

A new efficient and highly selective fluorescent chemosensor for determination of Pb (2+) has been obtained by covalent attachment of two pendent proton-ionizable dansylcarboxamide groups to the calix[4]arene preorganized in the partial cone conformation. This geometry of the calixarene moiety was chosen on the basis of the prior (1)H NMR study of conformations adopted by the flexible dansyl-containing prototype upon complexation with lead ion. In acidic MeCN-H2O (1:1 v/v) solutions, the partial cone fluoroionophore allowed for detection of Pb (2+) at the levels as low as 2.5 ppb, which is totally compatible with the regulations of the U.S. Environmental Protection Agency and the World Health Organization on the limiting content of this hazardous pollutant in drinking water.

A pyrene-containing fluorescent sensor with high selectivity for lead(II) ion in water with dual illustration of ground-state dimer

“…Lu and co-workers utilized gold nanoparticles and DNAzyme as a unique class of biosensors for Pb 2+ [8], while Kwon et al reported a new fluorescent sensor based on rhodamine B for Pb 2+ [9]. In addition, some fluorophore-appended macrocycles have also been reported [10,11].…”

Dansyl-containing fluorogenic calixarenes as optical chemosensors of hazardous metal ions: a mini-review

“…The preferred geometry in solution may be determined by NMR spectroscopy applied to the metal complex of the flexible ligand. In particular, in complexes with Hg 2þ , mobile calix [4]arene N-dansylcarboxamide 1 was found to prefer the cone (62) and, under different experimental conditions, 1,3-alternate conformation (44).…”

“…Known metal-sensing dansyl-containing fluorogenic calixarenes (as well as thiacalixarenes) vary in the fashion of the fluorophore attachment to the receptor moiety as HN-dansyl (37,(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54) and O-dansyl ligands (36,(55)(56)(57) (for the structural formulae, see Figures 1-4). In the former type, the anchor NH-group usually is a part of carbamoyl or aminoalkyl linker, or it may be bound directly to the aromatic ring of the calixarene; while in the latter type, the dansyl moiety is a substituent on the calixarene lower-rim phenolic oxygen.…”

“…Accordingly, the spectral response of the dansyl fluorophore to the ion recognition event consists of an increase in the fluorescence intensity accompanied by hypsochromic shift of the emission band, consistent with the enhancement of electron density on the 5-dimethylaminonaphthalene ring caused by ionisation of the adjacent NH-group. In particular, this allowed to use a ratiometric approach in monitoring the concentrations of such hazardous metal ions as Pb 2þ (43,44) and Cs þ (58) with the employment of HN-dansyl-containing calixarenes.…”

Synthesis and characterisation of p-diethylaminomethylthiacalix[4]arene for selective recovery of platinum from automotive catalyst residue

“…Consequently, thiacalix[n]arene and its functionalised derivatives behave as extractants for metal ions and can form host -guest complexes. Their aforementioned interactions make it possible to use them for sensing (10,11), solvent extraction (5, 6, 12 -20), gas adsorption and molecule storage (21 -24). In addition, thiacalix [n] arenes are superior to common calix[n]arenes because they possess higher molecular structure flexibility and metal ion affinity.…”