Metal ion complexation in acetonitrile by upper-rim allyl-substituted, di-ionized calix[4]arenes bearing two dansyl fluorophores

A single probe for solvent dependent optical recognition of iron(II/III) and arsenite: discrimination between iron redox states with single crystal X-ray structure evidence

The detection and discrimination of Fe2+ and Fe3+ ions have been investigated using a simple probe (L), produced by the condensation of ethylenediamine and 3-ethoxysalicyaldehyde. Single crystal X-ray structures demonstrate that L interacts with Fe2+ and Fe3+. In aqueous-DMSO media, the L recognises AsO2- by fluorescence and colorimetry techniques. The AsO2- aided PET inhibition and H-bond assisted chelation enhanced fluorescence (CHEF) boost fluorescence by 91-fold. The L can detect 0.354 ppb Fe2+, 0.22 ppb Fe3+ and 0.235 ppt AsO2-.

Calix[4]arene Based Highly Efficient Fluorescent Sensor for Au(3+) and I(.)

This approach disclose the selective fluorogenic ion sensing ability of 5,11,17,23-tetratertbutyl-25,27-bis((2hydroxynaphthylimino)1,2-ethylenediaminecarbonylmethoxy)-26,28 dihydroxycalix[4]arene (C4NSB). Binding property of receptor probed by using selected various cations and anions with conferring of results that demonstrates 'turn-off' fluorescence response and significantly high chromogenic selectivity toward Au(3+) and I(-). Furthermore, selective nature of receptor was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) for Au(3+) and I(-) was determined as 1.5 × 10(-5) and 4.5 × 10(-6) M respectively. Receptor C4NSB form (1:1) stoichiometric complex with both ions and their binding constants were calculated as 8.0 × 10(2) for Au(3+) and 15.6 × 10(2) M(-1) for I(-). Complexes were also characterized through FT-IR spectroscopy.

An insight into the extraction of transition metal ions by picolinamides associated with intramolecular hydrogen bonding and rotational isomerization

Disruption of intramolecular H-bonding via N-substitution leads to rotational isomerization and much improvement in extraction of Hg²⁺.

Quinoline driven fluorescence turn on 1,3-bis-calix[4]arene conjugate-based receptor to discriminate Fe3+ from Fe2+

The synthesis and characterization of a triazole linked quinoline appended calix[4]arene conjugate, L, and its fluorescence turn on receptor property for Fe(3+) have been demonstrated. The selective and sensitive discrimination of Fe(3+) has been shown using fluorescence and absorption titration experiments. The Fe(3+) binding to L has been further shown by ITC and ESI MS. The mode of binding of Fe(3+) by calix[4]arene conjugate has been shown by absorption, (1)H NMR and visual color change and the species were modeled based on DFT computations. The {L + Fe(3+)} has been shown to label cells with fluorescence imaging. Moreover the utility of this conjugate has been demonstrated by the combination logic gate system.

A Novel Fluorescent Sensor for Fe3+ and Cr3+ based on a calix[4]arene bearing two coumarin units

A novel turn-on fluorescent sensor based on a calix[4]arene with two coumarin units as fluorophores and iminogroups as ionophores on the upper rim has been synthesised. Its recognition properties towards heavy and transition metal ions have been studied by UV-Vis and fluorescence spectrometry. The compound showed an enhanced fluorescent intensity in the presence of Fe3+ or Cr3+ ion, a high selectivity to Fe3+ or Cr3+ ions and a complexation ratio towards Fe3+ or Cr3+ of 1:1. The association constant for Fe3+ was 5.37×105 M−1 and for Cr3+ was 9.18×105 M−1.