1,3-Di-amidoquinoline conjugate of calix[4]arene (L) as a ratiometric and colorimetric sensor for Zn²⁺: Spectroscopy, microscopy and computational studies

Abstract

Carboxamidoquinoline appended calix[4]arene-1,3-di-conjugate (L) has been synthesized and characterized and its single crystal XRD structure has been established. L has been shown to act as selective ratiometric turn-on fluorescence sensor for Zn(2+) up to a lowest concentration of 183 ± 18 ppb (2.82 μM) with a nine-fold enhancement by exhibiting blue-green emission. The coordination features of the species of recognition have been computationally evaluated by DFT methods and found to have distorted tetrahedral Zn(2+) center in an N(4) core. The spherical nano-structural features observed for L in TEM are being transformed into the Koosh nano-flower like structure when complexed with Zn(2+) and hence these two can be easily differentiated. Even the features observed in AFM can distinctly differentiate L from its Zn(2+) complex.

Hydroxyquinoline–Calix[4]arene Conjugates as Ligands for Polynuclear Lanthanide Complexes: Preparation, Characterization, and Properties of a Dinuclear EuIII Complex

“…(3) The calix[4]arenes often confer solubility on the compounds, and their coordination chemistry is more specific (and controllable) than that of their unmodified parents , , . (4) There are only a few examples in the literature in which quinoline or 8‐hydroxyquinoline units are tethered to a calix[4]arene backbone,, and none of these have been structurally characterized . (5) The macrocyclic platform can be used for preorganization of multicoordinate and chelating groups in two‐phase solvent extraction for the separation of rare earth elements …”

Zn2+‐Ion Sensing by Fluorescent Schiff Base Calix[4]arene Macrocycles

“…The fluorescencei ntensity was found to be linear between 1 10 À6 and 6 10 À8 m Zn 2 + (Figure 4), the LOD value being 0.147 (6) ppb. [24] However,u pon cyclization, the minimum detection limit appeared to drop further down to about 12 ppb. [24] However,u pon cyclization, the minimum detection limit appeared to drop further down to about 12 ppb.…”

A 1,3‐Capped Calix[4] Conjugate Possessing an Amine Moiety as an Anion Receptor: Reversible Anion Sensing Detected by Spectroscopy and Characterization of the Supramolecular Features by Microscopy

“…Calixarenes are known to show distinctive supramolecular features in the presence of different cations, anions, or molecules when placed on surfaces and studied by microscopy . The supramolecular characteristics of L amino and its anion adducts were studied by SEM.…”

“…Calixarenes are known to show distinctive supramolecular features in the presence of different cations, anions, or molecules when placed on surfaces and studied by microscopy. [58][59][60][61] The supramolecular characteristics of L amino and its anion adducts were studied by SEM. The L amino sample shows discrete spherical particles of 200-500 nm (Figure 7a,b ,o ,a nd p), and the features are the same, regardless of whether the molecule was taken in acetonitrile or ethanol.…”