Selective Fluorescent Chemosensor Research Articles

A selective colorimetric and fluorescence chemosensing sensor for Cr3+ based on a rhodamine base derivative

A rhodamine-conjugated coumarin (L) was used in designing a selective fluorescence chemosensor for the determination of trace amounts of Cr3+ ions in acetonitrile–water (MeCN/H2O (90:10, %v/v) solutions. The intensity of the fluoresce emission of the chemosensor is intensified upon addition of Cr3+ ions in MeCN/H2O (90:10, %v/v) solutions, due to the formation of a selective 1:1 complex between L and Cr3+ ions. The fluorescence enhancement versus Cr3+ concentration has been found to be linear from 1.0 × 10−7 to 1.8 × 10−5 M and a detection limit of 7.5 × 10−8 M. The proposed fluorescent probe proved to be highly selective towards Cr3+ ions as compared to other common metal ions and could be successfully applied to the determination of Cr3+ concentrations in some water and wastewater samples.

A highly selective two-photon fluorescent chemosensor for tracking homocysteine via situ reaction

A new sensitive and selective two-photon fluorescent chemosensor L bearing triphenylamine skeleton was conveniently prepared for detecting homocysteine (Hcy) through Cu2+ displaced method in situ system generated from the pre-prepared L-Cu2+. Furthermore, Cu2+ of the polluted water can also be monitored conveniently in range from 10−8 to 10−2 M by naked eye with test strips coated with L. What's more, L having low cytotoxicity and good biocompatibility were successfully applied to imaging for endogenously and exogenously tracking Hcy in HeLa cell by two-photon fluorescence microscopy.

Electron-deficient tripodal amide based receptor: An exclusive turn-on fluorescent and colorimetric chemo sensor for cyanide ion

Here in, we have designed, synthesized and isolated sensor L, as an exclusive selective turn-on fluorescent chemo sensor for cyanide ion. The acetonitrile solution contains L with tetrabutyl ammonium cyanide, results sudden color change from colorless to yellowish-brown. Chemosensor L produced a strong fluorescence response with an enhancement of very high fluorescence intensity while addition of CN− ion and the strength of the chemosensor L towards cyanide binding is found to be 3.9813×104M−1. In order to use this sensor in practical application, we also prepared a cassette which is fabricated with sensor L and we succeeded to sense cyanide ion.

New hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates as highly selective and sensitive fluorescent chemosensor for Co2+ ions

In the study, the new hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) have been successfully synthesized and characterized by using general spectroscopic techniques such as 1H, 13C and 31P NMR spectroscopies. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) were investigated by UV–Vis and fluorescence spectroscopies in dilute tetrahydrofuran solutions. These dendrimers showed strong absorption bands 501 and 641nm at low concentration with high molar extinction coefficients. In addition, the stoichiometry of the complex between the conjugate (HBCP 2) and Co2+ ions were determined by a Job's plot obtained from fluorescence titrations. The metal sensing data showed that the hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugate (HBCP 2) is a candidate for fluorescent chemosensor for Co2+ ions due to showing high selectivity with a low limit of detection.

Highly sensitive and selective chemosensor for Cu2+ and H2PO4− based on coumarin fluorophore

In this study, a highly selective fluorescence chemosensor N-(2-(bis(2-((4-methylphenyl)sulfonamido)ethyl)amino)ethyl)-7-(diethylamino)-2-oxo-2H-chromene-3-carboxamide(1) was synthesized and characterized by 1H NMR, 13C NMR and ESI-MS. This tren-based chemosensor 1 showed an “on-off-on” fluorescence response toward Cu2+ and H2PO4− with a 1:1 binding stoichiometry in CH3CN/HEPES buffer medium (9:1 v/v) by UV/vis and fluorescence spectroscopies. The detection limits of sensor 1 to Cu2+ was determined to be 0.37 μM, while that of 1-Cu2+ complex to H2PO4− was 1.6 μM, respectively. The sequential recognition behavior can be repeated four times with little fluorescence efficiency loss using Cu2+ and H2PO4−. The stable pH range for Cu2+ and H2PO4− determination was from 4 to 7.5.

Ratiometric Fluorescent Chemosensor for Selective Detection Cr3+ based on Carbazole and Benzimidazole

A novel Cr3+‐selective ratiometric fluorescent chemosensor 1‐substitued‐2‐carbazoleylbenzoimidazole (L) based on benzimidazole and carbazole was synthesized and characterized by nuclear magnetic resonance (1H/13C NMR), Fourier transform infrared spectrometry (FTIR), and mass spectroscopy. L could selectively detect Cr3+ over other metal ions by UV–vis absorption and fluorescence emission spectroscopic methods in CH3CN. L showed ratiometric fluorescent recognition of Cr3+; the fluorescent responses could be observed by naked eye under a UV lamp. The binding stoichiometry ratio of the L–Cr3+ complex was found to be 1:1 according to Job’s plot and MALDI‐TOF MS analysis. The results of DFT calculation supported this conclusion.

A highly sensitive and selective chemosensor for Pb2+ based on quinoline-coumarin.

In this study, a highly sensitive and selective fluorescent chemosensor, ethyl(E)-2-((2-((2-(7-(diethylamino)-2-oxo-2H-chromene-3-carbonyl)hydrazono)methyl)quinolin-8-yl)oxy)acetate (1), was synthesized and characterized by 1H NMR, 13C NMR and ESI-MS. Sensor 1 showed an “on–off” fluorescence response to Pb2+ with a 1 : 1 binding stoichiometry in CH3CN/HEPES buffer medium (9 : 1 v/v). The detection limit of sensor 1 to Pb2+ was determined to be 0.5 μM, and the stable pH range for Pb2+ detection was from 4 to 8.

Studies on a multifunctional chromo-fluorogenic sensor for dual channel recognition of Zn2+ and CN− ions in aqueous media: mimicking multiple molecular logic gates and memory devices

A new effectual naphthalene-based azomethine receptor has been systematically designed and synthesized as a selective colorimetric and fluorescent chemosensor for dual channel detection of cations and anions in aqueous environments.

A highly selective and sensitive fluorescent chemosensor for distinguishing cadmium(ii) from zinc(ii) based on amide tautomerization

A naphthalimide-derived fluorescent sensor termed L2 was designed and synthesized.

A fluorescence-enhanced chemosensor based on multifarene[2,2] and its recognition of metal cations.

A selective and sensitive fluorescent chemosensor based on an anthracene-functionalized triazole-linked multifarene[2,2] was successfully synthesized and investigated with regard to the recognition of metal ions using fluorescence spectroscopy, 1H NMR titration, and IR spectroscopy. The proposed sensor exhibited desirable properties for potential fluorescence enhanced chemosensor applications, including selective affinity and low Zn2+ and Cd2+ detection limits compared with other metal ions. Quantum chemical calculations described the synthesized chemosensor's static structure and its coordination to Zn2+ and Cd2+. Frontier molecular orbital distribution and energy changes suggested a possible mechanism for increased receptor fluorescence intensity with Zn2+ and Cd2+ addition.

Synthesis and spectroscopic investigation of a novel sensitive and selective fluorescent chemosensor for Ag+ based on a BINOL-glucose derivative.

Based on a versatile 2,2′-binaphthol (BINOL) backbone, a novel BINOL–glucose derivative fluorescent sensor was synthesized using a click reaction. The fluorescence responses of the BINOL–glucose derivative (S,β-d)-1 conclude that it can be used as a specific fluorescent chemical sensor for Ag+ in the presence of a large number of competing metal ions without any obvious interference from other metal ions. Mass spectrometric and NMR spectroscopic data were used to study the mechanism, and implied the formation of a 1 + 1 complex between BINOL–glucose 1 and Ag+. Both the oxygen atoms of S-BINOL and two nitrogen atoms of triazole were involved in coordinating the silver ion.

A water-soluble Fe3+ selective fluorescent turn-on chemosensor: Preparation, theoretical study and its optical vitro imaging

A rhodamine derivative bearing a thiazole receptor (probe 1) was developed and characterized. Probe 1 rendered a prominently chromogenic and turn-on fluorescent signal toward Fe3+ ion in aqueous media based on coordination reaction. Probe 1 also showed high sensitivity toward Fe3+ ion with the detection limit as low as 92nM. By means of the Job's plot, 2:1 binding mode of 1-Fe3+ complex was determined and a possible sensing mechanism was further proposed based on the changes in the Fourier Transform Infrared (FT-IR) and mass spectra. The turn-on fluorescence and sensing mechanism for 1-Fe3+ complex were well demonstrated by theoretical calculations. Importantly, probe 1 has been tested highly suitable for mapping Fe3+ ion in human colon cancer cells SW480, providing a wonderful candidate for tracking Fe3+ in biological processes.

A highly selective and sensitive fluorescent chemosensor and its application for rapid on-site detection of Al3 +

In this paper, a simple naphthalene-based derivative (HL) has been designed and synthesized as a Al3+-selective fluorescent chemosensor based on the PET mechanism. HL exhibited high selectivity and sensitivity towards Al3+ over other commonly coexisting metal ions in ethanol with a detection limit of 2.72nM. The 1:1 binding stoichiometry of the complex (HL-Al3+) was determined from the Job's plot based on fluorescence titrations and the ESI-MS spectrum data. Moreover, the binding site of HL with Al3+ was assured by the 1H NMR titration experiment. The binding constant (Ka) of the complex (HL-Al3+) was calculated to be 5.06×104M−1 according to the Benesi-Hildebrand equation. In addition, the recognizing process of HL towards Al3+ was chemically reversible by adding Na2EDTA. Importantly, HL could directly and rapidly detect aluminum ion through the filter paper without resorting to additional instrumental analysis.

A porous zinc(II) metal–organic framework exhibiting high sensing ability for ferric and nitroaromatics as well as photocatalytic degradation activities against organic dyes

A NbO-type Zn(II) metal–organic framework of {[Zn2(HL)(H2O)2]∙H2O}n (1) has been developed using a pentacarboxylate 2,5-bis(3′,5′-dicarboxylphenyl)-benzoic acid (H5L) ligand and characterized. The single-crystal X-ray diffraction studies indicate that 1 comprises free –COOH groups and Zn(II) centers bridged by four carboxylate groups to form a paddle wheel SBU which is further connected by L5− ligands to build a 3-D porous network with two types of cages. The chemically stable MOF 1 behaves as a highly selective and sensitive fluorescent chemosensor for the detection of Fe3+ ions, 2,4,6-trinitrophenol (TNP), which is known to be an extremely hazardous and strong explosive. Furthermore, the photocatalytic properties of 1 for degradation of methyl violet (MV) and Rhodamine B (RhB) have been explored. The possible emission quenching mechanism in the presence of nitro-aromatics (NACs) has been addressed by theoretical calculations and photocatalytic activity of 1 against organic dyes has been supported using density of states (DOS) calculations.

Naphthalene-derived Al3+-selective fluorescent chemosensor based on PET and ESIPT in aqueous solution

A simple fluorescent chemosensor HL based on naphthalene with high selectivity and sensitivity towards Al3+ over other commonly coexisting metal cations in fully aqueous solution to enhance the potential applications of the fluorescent chemosensor was developed. HL exhibited a significant fluorescence enhancement at 475 nm in the presence of Al3+ over other competitive metal ions with a low detection limit of 0.43 μM due to the inhibition of the photo induced electron transfer (PET) and the excited-state intramolecular proton transfer (ESIPT). The 1:1 binding stoichiometry between HL and Al3+ was corroborated by the Job plot and the ESI-MS spectrum. Importantly, the reversible recognition process of HL to Al3+ will make HL could be used circularly and repeatedly in practical applications by addition of Na2EDTA. In addition, the binding behavior and sensing mechanism of HL to Al3+ were illustrated in detail by the 1H NMR titration experiment.

A selective colorimetric fluorescent chemosensor for Hg2+ in aqueous medium and in the solid state

A simple colorimetric and turn-on fluorescence receptor RN (Rhodamine-based derivative) was prepared and its cation-sensing properties were investigated. Receptor RN displayed a selective sensing of Hg2+ and showed an obvious colorimetric changing in aqueous solution (from colorless to pink color) and in the solid state (from red to pink color), respectively. The association constant of RN-Hg2+ complex was calculated to be 8.25×109 M−2, and the detection limit for Hg2+ was found to be 27 ppb.

Highly sensitive and selective turn-on fluorescent chemosensors for Hg2+ based on thioacetal modified pyrene

This work reports a facile strategy for the synthesis of water-soluble fluorescent probes Pyr1 and Pyr2, which have carboxyl and hydroxyl group in the side chain of thioacetal moiety, respectively. Pyr1-2 exhibit exclusively selective turn-on fluorescence response towards Hg2+ over other cations, based on intramolecular charge transfer (ICT) mechanism. Upon addition of Hg2+, the thioacetal moiety in Pyr1-2 can be converted to aldehyde group, which is confirmed by 1H NMR titrations. The detection limits for Pyr1-2 are less than 1.80nM in aqueous media, lower than the maximum allowable level of Hg2+ in drinking water by EPA. Moreover, Pyr2 have been successfully used for fluorescence imaging of Hg2+ in living cells, demonstrating potential application in biological science.

A highly sensitive and selective fluorescent chemosensor for the sequential recognition of Zn2+ and S2− in living cells and aqueous media

Abstract A new highly selective chemosensor 1 ( E )-5-((2-hydroxybenzylidene)amino)-1H-imidazole-4-carboxamide was designed and synthesized for the sequential recognition of Zn 2+ and S 2− in a near-perfect aqueous media. The sensor 1 exhibited a green color fluorescence in the presence of Zn 2+ . The detection limit (1.18 μM) of 1 for Zn 2+ is much lower than World Health Organization guideline (76 μM) in drinking water. 1 can detect and quantify Zn 2+ in real water samples and the sensing mechanism of Zn 2+ by 1 was explained by DFT calculations. Moreover, resulting 1 -Zn 2+ complex can detect hydrogen sulfide through turn-off fluorescent change, without any anion interference. The detection limit (2.60 μM) of 1 -Zn 2+ complex for S 2− was much lower than EPA guideline (7.8 mM) by odor in drinking water. Furthermore, sensor 1 could detect sequentially Zn 2+ and S 2− in living cells.

A highly selective fluorescent chemosensor for CN− based on a novel bis(salamo)-type tetraoxime ligand

The optical properties of a novel chemosensor for cyanide anions based on a symmetric bis(salamo)-type ligand (H3L) were investigated by UV–Vis and fluorescence spectroscopy in MeOH/H2O (1:1 v/v) solution. Sensor H3L can selectively sense CN− based on prominent color changes among other anions. The chemosensor exhibits an apparent fluorescence enhancement at 482nm to CN− which because cyanide ions interact with CN bonds. Combining the corrected Benesi-Hildebrand formula, the binding constant of the formed host-guest complex was calculated as 2.42×105M−1. Meanwhile, the detection limit of the sensor toward CN− was 8.91×10−7M. It is worth noting that the designed sensor can be used for rapid detection of cyanide anions in basic pH range, and has great practical value.

A highly selective colorimetric and fluorescent turn-on chemosensor for Zn2+and its logic gate behavior

A novel quinoline-based fluorescent chemosensor L was synthesized and characterized by 1H NMR, 13C NMR, HRMS and X-ray Crystallography. L showed a significant fluorescent enhancement (120-fold) and color change upon the addition of Zn2+ attributed to the joint contribution of the PET and CHEF processes. The binding ratio of the L–Zn2+ complex was 1:1 confirmed by the 1 HNMR, mass-spectral analysis and Job plot, and the detection limit for Zn2+ was as low as 5.2×10−7M. L was successfully applied to the determination of Zn2+ in real water samples. Moreover, the fluorescent signals of L were utilized to built an INHIBIT logic gate.