Colorimetric and fluorimetric response of Schiff base molecules towards fluoride anion, solution test kit fabrication, logical interpretations and DFT-D3 study

Abstract

Two newly synthesized Schiff base molecules are herein reported as anion sensors. -NO2 substituted receptor (P1) is comparatively more acidic and can sense F(-), OAc(-) and H2PO4(-), whereas -CN substituted receptor (P2) is less acidic and is selective for F(-) only. Reversible UV-Vis response for both receptors with F(-) can mimic multiple logic gate functions, and several complex electronic circuits based on XNOR, XOR, OR, AND, NOT and NOR logic operations with 'Write-Read-Erase-Read' options have been executed. Interesting 'turn on and off' fluorescence responses were noticed for the receptors with F(-). Intracellular F(-) detection as a diagnosis of non-skeletal fluorosis was successful using a fluorescence microscope with Candida albicans (prokaryotic cell, a diploid fungus) and pollen grains of Tecoma stans (eukaryotic cell) incubated in 10(-6) M fluoride-contaminated hand-pump water collected from Bankura, West Bengal, India. Furthermore, a solution test kit was fabricated for easy and selective detection of F(-) in an aqueous solvent.

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

“…The enhancement of the ICT transition could be ascribed to a push–pull nature between the electron withdrawing –CN substituent and the conjugated system [39]. The appearance of a clear isosbestic point at 443 nm indicates the existence of a host–guest complex in the system.…”

A new Schiff base as a turn‐off fluorescent sensor for Cu2+ and its photophysical properties

“…Receptor 1 studied here upon complexation Cu 2+ showed selective fluorescence quenching when compared with other tested metal ions. Compared with receptors based on imidazole, amide, urea and thiourea possessing multiple –NH groups preferred mainly to detect anions . The use of Schiff bases is advantageous due to their easy one‐step synthesis; the presence of conjugated bonds gave excellent optical properties that could be tuned to develop chemosensors for different metal ions.…”

A Coumarin–based Colorimetric and Fluorescent Chemosensor for the “Naked–eye” Detection of Fluoride ion in 100 % Natural Water Medium Using Coated Chromatography Plates

“…However, the downside of this type of chemosensor is that other anions, such as AcO – and H 2 PO 4 – may cause significant interference . It is reported that the selectivity if an anion chemosensor in related to the structure of the hydrogen bond complex and the basicity of the anions . Therefore, the higher basicity of F – compared to other anions is commonly exploited as the basis for the construction of F – ‐specific chemosensors …”