A highly selective and sensitive chemosensor for instant detection cyanide via different channels in aqueous solution

A highly selective probe for fluorometric sensing of cyanide in an aqueous solution and its application in quantitative determination and living cell imaging

A simple fluorescent probe (KS4) containing multiple reaction sites (phenolic -OH, imine and C = C bonds) is successfully synthesized and characterized using 1H NMR, 13C NMR, mass and single crystal XRD techniques. KS4 exhibits high selectivity towards CN- over a wide range of common anions in H2O:DMSO (1:1 v/v) leading to an amazing turn-on fluorescence at 505 nm via deprotonation of the phenolic -OH group. The limit of detection (1.3 µM) for CN- was much below the standard (1.9 µM) set by the World Health Organization (WHO). Stoichiometry of the interaction between KS4 and CN- was ascertained as 1:1 by the Job's plot method and the binding constant was determined to be 1.5x104 M-1. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) based theoretical insight has been appealed to understand the optical properties of KS4 before and after the addition of CN- ion. The probe shows respectable real-time applicability for qualitative detection of CN- in almond and cassava powder as well as quantification in real water samples with excellent recoveries (98.8 - 99.8%). In addition, KS4 is found to safe towards living HeLa cells and successfully applied to the detection of endogenous cyanide ions in HeLa cells.

Interference of nuclear wavepackets in a pair of proton transfer reactions

Quantum mechanics revolutionized chemists' understanding of molecular structure. In contrast, the kinetics of molecular reactions in solution are well described by classical, statistical theories. To reveal how the dynamics of chemical systems transition from quantum to classical, we study femtosecond proton transfer in a symmetric molecule with two identical reactant sites that are spatially apart. With the reaction launched from a superposition of two local basis states, we hypothesize that the ensuing motions of the electrons and nuclei will proceed, conceptually, in lockstep as a superposition of probability amplitudes until decoherence collapses the system to a product. Using ultrafast spectroscopy, we observe that the initial superposition state affects the reaction kinetics by an interference mechanism. With the aid of a quantum dynamics model, we propose how the evolution of nuclear wavepackets manifests the unusual intersite quantum correlations during the reaction.

Pyrene-Hydrazone-π···Hole Coupled Turn-on Fluorescent and Naked- Eye Colorimetric Sensor for Cyanide: Role of Homogeneous π-Hole Dispersion in Anion Selectivity

A pyrene based probe associated with π···hole - hydrazone as one of the recognizing elements is synthesized and its turn in to a selective colorimetric and turn-on fluorescent sensor, (L³) for cyanide anion. This chemo sensor show high selectivity towards cyanide anion through photo electron transfer (PET) mechanism. The binding strength and sensitivity of the chemo sensor L³ towards cyanide are found to be 2.0 X 10⁴, and 4.44 x 10^-4 respectively. We have compared this high selectivity of the receptor towards cyanide, with our previously reported receptors L¹ and L². The detailed UV-Vis, Emission, ¹H-NMR, IR spectroscopic and Molecular Electrostatic Potential (MEP) studies reveals that the homogeneous π···hole dispersion in the aromatic ring governing the selectivity of the receptor towards cyanide anion. Such a positive π···hole homogeneous dispersion is missing in the case of sensor L², instead we have polarized π···hole dispersion towards 2^nd and 4^th position of di-nitrophenyl chromophoric unit in L².

A molecular phototropic system for cyanide: Detection and sunlight driven harvesting of cyanide with molecular sunflower

We are reporting a simple, easy to prepare, and conformation switchable first molecular phototropic system L, "(E)-2-(2,4-dinitrophenyl)-1-((pyren-8-yl)methylene)hydrazine, for cyanide harvesting. This molecular phototropic system behaves as a molecular sunflower in which the conformation of this molecular sunflower can be altered in response to the sunlight. This molecular flower can sense and bind the cyanide anion colorimetrically through its transition state. Further, upon exposure of this transition state cyanide complex 1, under sunlight, this system is capable to release the bound cyanide via -C=N- free rotation to reach its lower energy stable conformation. Similar behaviors were observed for acetate and fluoride with L. The strength of the phototropic system L towards cyanide, acetate and fluoride is found to be 4.5 × 10⁵, 1.53 × 10² and 6.09 × 10² M^-1.

A new chromogenic and fluorescent chemosensor based on a naphthol-bisthiazolopyridine hybrid: a fast response and selective detection of multiple targets, silver, cyanide, sulfide, and hydrogen sulfide ions and gaseous H2S

A novel chemosensor 1 based on a naphthol-bisthiazolopyridine hybrid was synthesized and characterized. Among the various screened cations and anions, chemosensor 1 selectively recognized Ag+ and CN- ions by relying on the color change and distinct absorption and emission changes. Moreover, the probe 1·Ag+ was well operable for the selective monitoring of S2-, HS- and H2S as evidenced by the different color and optical changes. The selective detection of all the anions was simply based on the breakage of the intramolecular hydrogen bonding of 1, followed by the protonation or deprotonation mechanism. In general, chemosensor 1 is a promising indicator in terms of its ease-of-use, selectivity, sensitivity, and rapid response (<1 s). Moreover, the visual detection and concentration determination of these analytes by solution or solid kits are the advantages for the practical applications of this sensor.

A new ratiometric, colorimetric and ‘‘turn-on’’ fluorescent chemosensor for the detection of cyanide ions based on a phenol–bisthiazolopyridine hybrid

This optical probe recognizes CN⁻ over various anions and cations via the deprotonation mechanism as evidenced by ¹H NMR titration.

Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on Circularly Polarized Luminescence by Al3

We designed glutamide-derived amphiphilic Schiff bases containing three different aldehyde moieties for the fabrication of circularly polarized luminescence (CPL) emitting materials. Upon self-assembly in acetonitrile, Schiff bases featuring 4-(dimethylamino)-2-hydroxylbenzaldehyde and 1-hydroxy-2-naphthaldehyde groups form supramolecular gels with twist and fiber structures, respectively, whereas Schiff bases featuring 2-hydroxy-1-naphthaldehyde groups form precipitation with flake structures. Although emission and circular dichroism signals can be detected from the supramolecular gels formed by amphiphilic Schiff bases, none of them exhibits a circularly polarized luminescence (CPL). Although Mg²⁺, Zn²⁺, and Al³⁺ can significantly enhance the fluorescence of the Schiff bases, interestingly, only Al³⁺ ion is able to turn on the CPL emission. This study on the one hand provides a simple method for the fabrication of CPL-emitting supramolecular materials and on the other hand offers a novel way for the sensing of aluminum ion with supramolecular materials.

A novel colorimetric and "turn-on" fluorimetric chemosensor for selective recognition of CN- ions based on asymmetric azine derivatives in aqueous media

A novel chemosensor 2-((Z)-(((E)-quinolin-2-ylmethylene)hydrazono)methyl)phenol PX has been successfully designed and synthesized, which showed both colorimetric and "turn-on" fluorescence responses for CN^- in DMSO/H₂O (3:2, v/v; pH=7.20) solution. The sensor could respond effectively to the stimulation of CN^- ions via deprotonation and sensing mechanism of intramolecular charge transfer (ICT). Moreover, the sensor PX was successfully utilized to detect CN^- in bitter almond, and the detection limit on fluorescence response of PX towards CN^- was down to 4.5×10^-7M. Test strips containing PX were also prepared, which could act as a practical colorimetric tool to detect CN^- in aqueous media.

Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN^- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN^- on the vinyl CC bond has been successfully confirmed by the optical measurements, ¹H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19μM, which is much lower than the maximum permission concentration in drinking water (1.9μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN^- in field measurements.

A Mitochondria-Specific Fluorescent Probe for Visualizing Endogenous Hydrogen Cyanide Fluctuations in Neurons

An ability to visualize HCN in mitochondria in real time may permit additional insights into the critical toxicological and physiological roles this classic toxin plays in living organisms. Herein, we report a mitochondria-specific coumarin pyrrolidinium-derived fluorescence probe (MRP1) that permits the real-time ratiometric imaging of HCN in living cells. The response is specific, sensitive (detection limit is ca. 65.6 nM), rapid (within 1 s), and reversible. Probe MRP1 contains a benzyl chloride subunit designed to enhance retention within the mitochondria under conditions where the mitochondria membrane potential is eliminated. It has proved effective in visualizing different concentrations of exogenous HCN in the mitochondria of HepG2 cells, as well as the imaging of endogenous HCN in the mitochondria of PC12 cells and within neurons. Fluctuations in HCN levels arising from the intracellular generation of HCN could be readily detected.

A novel water soluble pillar[5]arene and phenazine derivative self-assembled pseudorotaxane sensor for the selective detection of Hg2+ and Ag+ with high selectivity and sensitivity

A bifunctional supramolecular pseudorotaxane chemosensor (G-WAP) based on pillar[5]arene and phenazine imidazole was constructed, which could detect Hg²⁺ and Ag⁺ in water.

A simple azoquinoline based highly selective colorimetric sensor for CN− anion in aqueous media

Azoquinoline based sensor AZQ was designed and synthesized as a new molecular ion sensor containing an azo group in its structure. The structural characterization of AZQ was carried out using FTIR, NMR, mass, and elemental analysis. Then, the interaction of AZQ with anions was observed visually and UV–vis measurements were made in EtOH/H2O (1:1, v/v) solvent mixture. As a result of this investigation, it was determined that AZQ is a fast and highly selective sensor for CN− ions. The solution colour of AZQ changed from light yellow to orange only in the presence of CN− ions. The limit of detection of AZQ was calculated as 2.6 μmol/L from anion titration experiments. Also, to identify the interaction mechanism of AZQ with CN− ions, 1H NMR spectra of AZQ in the presence of CN− anions were recorded and the structure was proposed for AZQ-CN− host–guest complex.

A novel dual-channel chemosensor for CN− based on rhodamine B hydrazide derivatives and its application in bitter almond

We successfully designed and synthesized a novel chemosensor PW bearing rhodamine B hydrazide and 8-formyl-7-hydroxyl-4-methylcoumarin, which displayed both colorimetric and “turn-on” fluorescence responses for CN⁻ in DMSO/H₂O (1 : 1, v/v, pH = 7.20) solution.

A turn-on fluorescent chemosensor based on acylhydrazone for sensing of Mg2+ with a low detection limit

A novel highly selective chemosensor for Mg²⁺ ions based on the naphthalene group as the fluorophore has been designed and synthesized, which shows a fluorescence turn-on response from colorless to green for Mg²⁺ ions in DMSO–H₂O solutions.

A highly selective colorimetric and "turn-on" fluorimetric chemosensor for detecting CN(-) based on unsymmetrical azine derivatives in aqueous media

A novel highly selective chemosensor S1 for cyanide based on unsymmetrical azine derivative was successfully designed and synthesized, which showed both colorimetric and fluorescence turn-on responses for cyanide ions in aqueous. This structurally simple chemosensor could detect CN(-) anion over other anions in aqueous solution DMSO/H2O (v/v=3:2) undergo deprotonation reaction. Results showed that the chemosensor S1 exhibited 50 fold enhancement in fluorescence at 530nm and showed an obvious change in color from colorless to yellow that could be detected by naked eye under the UV-lamp after the addition of CN(-) in aqueous solution. Moreover, the detection limit on fluorescence response of the sensor to CN(-) is down to 6.17×10(-8)M by titration method. Test strips based on S1 were obtain, which could be used as a convenient and efficient CN(-) test kit to detect CN(-) in aqueous solution.

Off–on fluorometric detection of cyanide anions in an aqueous mixture by an indane-based receptor

An indanedione–coumarin conjugate behaves as an off–on type fluorescent receptor for rapid, selective, and sensitive detection of cyanide anions in an aqueous mixture via a nucleophilic interaction with the electrophilic β-carbon of the receptor.

Benzoindolium–triarylborane conjugates: a ratiometric fluorescent chemodosimeter for the detection of cyanide ions in aqueous medium

A new ratiometric fluorescent chemodosimeter has been synthesized and characterized that exhibits high selectivity and sensitivity toward CN⁻ ions in aqueous medium.

A colorimetric and ratiometric fluorescent probe for the selective detection of cyanide anions in aqueous media and living cells

Based on the internal charge transfer (ICT) mechanism, a novel colorimetric and ratiometric fluorescent probe was developed for highly selective and sensitive detection of cyanide ion in aqueous media.

A simple chemosensor for the dual-channel detection of cyanide in water with high selectivity and sensitivity

By a deprotonated mechanism, the simple chemosensorHYshowed high sensitivity and selectivity for cyanide in aqueous media.

Multistimuli-Responsive Luminescence of Naphthalazine Based on Aggregation-Induced Emission

Stimuli-responsive luminescent materials, which are dependent on changes in physical molecular packing modes, have attracted more and more interest over the past ten years. In this study, 2,2-dihydroxy-1,1-naphthalazine was synthesized and shown to exhibit different fluorescence emission in solution and solid states with characteristic aggregation-induced emission (AIE) properties. A remarkable change in the fluorescence of 2,2-dihydroxy-1,1-naphthalazine occurred upon mechanical grinding, heating, or exposure to solvents. According to the characterization by solid-state fluorescence spectroscopy, X-ray crystallography, differential scanning calorimetry, and X-ray powder diffraction, the fluorescence change could be attributed to transitions between two structurally different polymorphs. These significant properties could also give 2,2-dihydroxy-1,1-naphthalazine more potential applications as a multifunctional material.

A coumarin-indole based colorimetric and "turn on" fluorescent probe for cyanide

A novel coumarin-indole based chemodosimeter with a simple structure was designed and prepared via a condensation reaction in high yield. The probe exhibited very high selectivity towards cyanide on both fluorescence and UV-vis spectra, which allowed it to quantitatively detect and imaging cyanide ions in organic-aqueous solution by either fluorescence enhancement or colorimetric changes. Confirmed by (1)H NMR and HRMS spectra, the detection mechanism was proved to be related with the Michael addition reaction induced by cyanide ions, which blocked the intramolecular charge transfer (ICT) of the probe. Moreover, the probe was able to be utilized efficiently in a wide pH range (7.5-10) with negligible interference from other anions and a low detection limit of 0.51μM. Application in 5 kinds of natural water source and accurate detection of cyanide in tap water solvent system also indicated the high practical significance of the probe.

Ratiometric fluorescent pH probes based on aggregation-induced emission-active salicylaldehyde azines

AIE-active salicylaldehyde azines (SAs) display strong blue, green, and red fluorescence with large Stokes shifts in MeCN–water and solid medium and can be used as ratiometric fluorescent pH probes in water and test paper.

A highly selective colorimetric and “Off–On” fluorescent chemosensor for fluoride ions and its application as a molecular-scale logic device

A new sensor based on phenolic hydroxy and imine groups was used as an efficient colorimetric and “turn on” fluorescent sensor, which exhibited high selectivity and sensitivity for F⁻.

Colorimetric probes designed to provide high sensitivity and single selectivity for CN− in aqueous solution

Easily-made probe L1 recognized CN⁻ by the deprotonation process and the detecting limit is 5 × 10⁻⁶ mol L⁻¹.

A new coumarin based chromo-fluorogenic probe for selective recognition of cyanide ions in an aqueous medium

The optical behavior of a simple intramolecular charge transfer (ICT) fluorescent probe, a coumarin-nitrobenzene conjugate (CNB), has been described to detect cyanide (CN⁻) selectively in buffered aqueous media.

Reaction-based fluorescent probe for detection of endogenous cyanide in real biological samples

Herein, two compounds (1 a and 1 b) were rationally constructed as novel reaction-based fluorescent probes for CN(-) by making use of the electron-withdrawing ability of the cyano group that was formed from the sensing reaction. Notably, this design strategy was first employed for the development of fluorescent CN(-) probes. The experimental details showed that probe 1 a exhibited a fluorescence turn-on response to CN(-), whereas other anions, biological thiols, and hydrogen sulfide gave almost no interference. The detection limit of probe 1 a for CN(-) was found to be 0.12 μM. The sensing reaction product of 1 a with CN(-) was characterized by NMR spectroscopy and mass spectrometry. TD-DFT calculations demonstrated that the formed cyano group drives the intramolecular charge transfer (ICT) process from coumarin dye to the cyano group and thus the original strong ICT from the coumarin dye to the 3-position pyridyl vinyl ketone substituent is weakened, which results in recovery of coumarin fluorescence. The practical utility of 1 a was also examined. By fabricating paper strips, probe 1 a can be used as a simple tool to detect CN(-) in field measurements. Moreover, probe 1 a has been successfully applied for quantitative detection of endogenous CN(-) from cassava root.