Chromogenic and fluorogenic Schiff base chemosensor for nano scale level fluoride detection with logical interpretation

Coumarin functionalized molecular scaffolds for the effectual detection of hazardous fluoride and cyanide

Fluoride and cyanide contamination in drinking water imposes detrimental impacts on human health above their permissible limits. Hence, the quantitative detection of these colourless water-soluble toxins has attracted attention. Even though a plethora of chemosensors have been reported so far for the detection of fluoride and cyanide from various matrices, still their applicability is limited to a few examples. Nevertheless, recent advances in the syntheses of coumarin derivatives have shown significant impact on fluoride and cyanide detection. Therefore, this present review provides a brief overview of the application of coumarin-coupled molecular scaffolds towards the detection of perilous fluoride and cyanide along with their sensing mechanisms in order to develop more innovative, simple, sensitive, real-time responsive and cost-effective coumarin-based supramolecular chemosensors to promote next generation approaches towards the ultra-trace quantitative detection of these toxic anions.

Detection of toxic fluoride ion via chromogenic and fluorogenic sensing. A comprehensive review of the year 2015-2019

Fluoride ion (F^-) contamination can be accumulated along the water and the food chain and cause serious risk to public health. It is of the greatest importance that selects the suitable chromophores and fluorophores for the design and synthesis of outstanding selective, sensitive chromogenic and fluorogenic probes for detection of fluoride ion. In this review is mainly focused on the current progress of fluoride ion detection according to their receptors into several categories like anthracene, azo, benzothiazole, BODIPY, calixarene, coumarin, imidazole, diketopyrrolopyrrole, hydrazone, imidazole, naphthalene, naphthalimide, quantum dots, Schiff base and urea group sensing in the year 2015-2019.

Engineering bio-molecular device with biocompatible sensor via symmetric encryption–decryption of spectroscopic signals towards F− detection and Zn2+ recognition by the imine hydrolysis pathway

A small molecular probe was synthesized and its response towards biologically significant ions Zn²⁺ and F⁻ with low detection threshold (Zn²⁺: 50 nM & F⁻: 3 μM) was investigated as well as Bio-molecular device designing was performed.

A simple urea-based multianalyte and multichannel chemosensor for the selective detection of F−, Hg2+ and Cu2+ in solution and cells and the extraction of Hg2+ and Cu2+ from real water sources: a logic gate mimic ensemble

Herein, a hydrazine-based chromogenic, fluorogenic and electrochemical chemosensor BCC [1,5-bis(4-cyanophenyl) carbonohydrazide] was reported.

A reversible fluoride chemosensor for the development of multi-input molecular logic gates

A reversible chemosensor for the development of a multi-input molecular logic gate was shown.

Toxic organic solvent adsorption by a hydrophobic covalent polymer

A hydrophobic needle-shaped novel covalent polymer has been synthesized at ambient temperature for adsorption of toxic organics.

A Journey towards Salivary Fluoride Level Detection by Suitable Low Cost Chemosensor: From Molecule to Product

Fluoride is a ubiquitous anion and essential for us owing to its ability to protect human body from several health related issues. The safe limit of Fluoride ion for human body is 1.5 ppm, above it the ion becomes toxic and can cause dental-skeletal fluorosis or urolithiasis. Several countries are facing such health hazard owing to the naturally abundant excess fluoride in ground water. As a consequence, habitants of such fluoride enriched zone needs to monitor the concentration of fluoride in their body by periodic analysis. In this regard, development of a chemosensor which can detect fluoride from human body fluid at easy-instant-economic way is an obvious mandate. For the first time, our group has developed a sensor kit and sensor station device as a deliverable product for individual and batch scale detection of salivary fluoride level by colorimetric method. The sensor station is the first device made by interfacing chemical output with electronics and the encrypted signal in digital version could be used as a level of fluoride in saliva. Our journey towards the development of suitable chemosensor for recognition of fluoride from human body fluid is summarized in this account.

A complicated biocomputing system based on multi-responsive P(NIPAM-co-APBA) copolymer film electrodes and electrocatalysis of NADH

In this paper, poly(N-isopropylacrylamide-co-3-aminophenylboronic acid) (P(NIPAM-co-APBA)) copolymer films were successfully electropolymerized on the Au electrode surface. The electroactive probe ferrocene carboxylic acid (FCA) in solution showed reversible thermal-, glucose- and pH-responsive on-off cyclic voltammetric (CV) behaviors at the film electrodes. The comparative experiments demonstrated that the thermo-responsive property of the film electrode was ascribed to the PNIPAM component of the films, whereas the glucose- and pH-sensitive behaviors came from the PAPBA constituent. The reduced form of nicotinamide adenine dinucleotide (NADH) could be electrocatalytically oxidized by FCA at the film electrodes, which would greatly amplify the multi-responsive CV signal difference between the on and off states. On the basis of these results, a binary 4-input/4-output logic circuit was fabricated with temperature, glucose, pH and NADH as inputs and the CV responses at 4 different levels as outputs. Moreover, a ternary CONSENSUS logic circuit was established on the same platform, which was the first report on the combination of ternary logic gate and bioelectrocatalysis without using enzymes. This work provided a novel idea for constructing complicated biocomputing systems by increasing the number of inputs/outputs with multi-sensitive interfaces and by designing new types of multi-valued logic gates on the basis of bioelectrocatalysis.

Nanomolar-level selective dual channel sensing of Cu2+and CN−from an aqueous medium by an opto-electronic chemoreceptor

A novel chromogenic and fluorogenic chemoreceptor exhibiting a proclivity towards Cu²⁺and CN⁻, with applications in bioimaging and molecular electronics, was developed.

Small molecular probe as selective tritopic sensor of Al3+, F- and TNP: Fabrication of portable prototype for onsite detection of explosive TNP

Schiff base organic compound (SOC) has been prepared as a tritopic chemosensor for selective sensing by fluorescence signalling towards ions like Al³⁺, F^- and explosive molecule like TNP. In general, fluorescence like photophysical property has been used for selective detection of analyte where Al³⁺ and F^- show turn-on fluorescence signal at different wavelengths (nm) however, quenching was found with TNP. As a consequence, the chemosensor has become a selective sensor for Al³⁺, F^- and TNP. Reversibility of fluorescence responses for Al³⁺ and F^- are observed in presence of ammonium nitrate and H⁺ respectively. Similar to the detection of TNP, the detection of explosive like NO₃^- salts is also essential from homeland security point of view. In the present work, the finding of reversible sequential fluorescence response can be promoted for fabrication of next generation AND-NOT-OR-NAND-XOR-XNOR-NOR based complex logic circuit which is applicable in photonics, security and other fields including inorganic and material science. In the case of TNP recognition, the pathway mainly depends on non-covalent interaction (quenching constant: 4.4 × 10⁵ M^-1) which is even better than the recently reported materials. Detection limit for Al³⁺, F^- and TNP is 1 μM, 3 μM and 500 nM respectively. DFT-D3 has been carried out to explore the host⋯guest interaction along with the structure-property correlation of the present host-guest system. All three guest analytes have been detected inside the living cell at a certain level and in its consequence, the successful in vitro recognition ability of the SOCs inside human cell line HeLa has been explored too. In real time stepping, an easy to operate and an economically affordable pocket prototype has also been fabricated for on spot detection of TNP like explosive.

Hydrazine functionalized probes for chromogenic and fluorescent ratiometric sensing of pH and F−: experimental and DFT studies

Two novel hydrazine based sensors, BPPIH (N¹,N³-bis(perfluorophenyl)isophthalohydrazide) and BPBIH (N^1′,N^3′-bis(perfluorobenzylidene)isophthalohydrazide), are presented here.

Rational Design of Azo-Azomethine Receptors for Sensing of Inorganic Fluoride: Construction of Molecular Logic Gates and DFT Study

New azo-azomethine receptors, HLn (n = 1–3), have been synthesised via condensation reaction of 5-(4-X-phenyl)-azo-salicylaldehyde (X = NO2, Cl and CH3) with (4-nitrobenzylidene)hydrazine. The receptor with a p-NO2 substituent on the aromatic ring of the azo moiety (HL1) has excellent sensitivity and selectivity towards basic anions with proper discrimination between F− and AcO− or H2PO4− in DMSO–water (4 : 1). A Job’s plot displays a 1 : 1 stoichiometry between HL1 and F− alone with a detection limit of 0.737 μM for fluoride ions. The solvatochromic behaviour of HL1 was probed by studying its UV-vis spectra in four pure organic solvents of different polarities and a meaningful correlation was observed. Furthermore, HL1 was used for detection of inorganic fluoride in toothpaste. The systematic density functional theory (DFT) and time dependent-DFT calculations have been carried out to investigate the mechanism of colourimetric sensing of fluoride ion by HL1 in the gas phase and in solution. Moreover, by using F− and H+ as chemical inputs, and the absorbance as output, a INHIBIT logic gate was constructed, which exhibits ‘Write–Read–Erase–Read’ ability without obvious degradation in its optical output.