A Quinoline Derivated Chemosensor for Cu^(2+) Recognition

A quinoline derivative N-（2-hydroxyl-naphthylmethyl）-N-（quinol-8-yl）amine（2） was synthesized and characterized, which can selectively recognize Cu^2＋ over other metal ions such as Zn^2＋, Cd^2＋, Sn^2＋, Pb^2＋, Hg^2＋, Ni^2＋, Mg^2＋, Cr^3＋, Mn^2＋, Sr^2＋, K^＋, Ca^2＋, Na^＋, Ba^2＋ in acetonitrile/water（volume ratio 99：1）. Cu^2＋ induced a new absorption peak at 464 nm in the absorption spectrum（ε=4.66×10^2 L·mol^-1·cm^-1） and quenched the fluorescence emission of quinoline derivative 2. The binding of quinoline derivative 2 to Cu^2＋ was in 1 ： 1 model and stable constant was esti- mated to be 2.48×10^5 L·mol^-1.

Novel fluorescent chemosensor for Ag^+ based on coumarin fluorophore

A novel chemosensor 1 （CS1） bearing one coumarin and two carbodithioate groups was synthesized and its fluorescent sensing behavior toward metal ions was investigated. Ag^＋ addition to a CH3COCH3/H2O （3：7, v：v） solution of CS1 gave a significantly quenched fluorescence. Other ions including Pb^2＋, Zn^2＋, Cu^2＋, Ca^2＋, Cd^2＋, Co^2＋, Mg^2＋, Mn^2＋, Hg^2＋, Ag^＋, Ni^2＋ induced no or much smaller spectral changes. This constitutes an ON-OFF Ag^＋-selective fluorescent chemosensor.

A highly selective and sensitive fluorescent chemosensor for Zn^(2+)

A new selective Zn^2＋ fluorescent chemosensor, o-vanillin-4-ethoxybenzoylhydrazone （1）, was designed and prepared. Free 1 mainly displayed very weak fluorescence at 480 nm upon excitation at 403 nm. It displayed high selectivity for Zn^2＋ and had a 518- fold fluorescent enhancement upon binding of Zn^2＋, while the other cation ions had only little influence on the fluorescence of 1. Mechanism of enhancement of l＇s fluorescence by Zn^2＋ was briefly discussed.

Phenanthroline-based Fluorescent Chemosensor for Selective Detection of Zn^(2+) in DMF Buffer Solution

A simple ＂off-on＂ fluorescent chemosensor with high selectivity to zinc ions based on 1,10-phenanthro-line receptor dipyrido[3,2-d：2＇,3＇-f]quinoxaline（L） was investigated.The selectivity response of receptor L to zinc ion was demonstrated by UV-Vis absorption and fluorescence spectroscopies in DMF buffer solution.The experiment results show that the fluorescent chemosensor L exhibits the optimum response behavior to Zn2＋ in the range of pH 8.0―9.0 and shows excellent selectivity to Zn2＋ over other cations tested.

A novel selective fluorescent chemosensor for Cu(Ⅱ)

A novel fluorescence enhancement Cu^2＋ chemosensor derived from coumarin was prepared. Emission study found that it exhibits evident Cu^2＋-arnplified fluorescence prior to Co^2＋, Pb^2＋, Mg^2＋, Mn^2＋, Ni^2＋, Zn^2＋, Fe^3＋, Ag^＋ and Cd^2＋, and the largest emission enhancement factor is about 9 at a ratio of 2：1 （chemosensor 1/Cu^2＋）.

Time-resolved Luminescence-based Chemosensor for Fluoride Anion

A new europium complex is descried as a time-resolved luminescence-based sensor for fluoride anion. The sensor is selective even in the presence of intensive background fluorescence.

Conjugated 8-Hydroxylquinoline-Based Fluorescent Chemosensor for Zn^(2+) and Cd^(2+) and Bioimaging Application in Living Cells

A conjugated 8-hydroxyquinoline( 8-HQ)-based fluorescent chemosensor( 1) for Zinc ion( Zn^(2+)) and Cadmium ion( Cd^(2+)) was developed in aqueous solution and used for Zinc ion living cells bioimaging. The probe 1 was weakly fluorescent,but displayed a strong fluorescence at 580 nm with a large Stokes shift of150 nm in the presence of Zn^(2+) or Cd^(2+). This probe allows the detections of Zn^(2+) in the range of 0. 8-10 μmol/L and Cd^(2+) in the range of 0. 8-8 μmol/L,with the limit of detections of 0. 2 and 0. 6μmol/L for Zn^(2+) and Cd^(2+),respectively. The present probe was successfully used for fluorescence bioimaging of Zn^(2+) or Cd^(2+) in the living cells.

Synthesis of Porphyrin-Appended Pyridine as a Fluorescent Chemosensor for Cd（Ⅱ） and Hg（Ⅱ）

In this research, specific molecular sensors are classified according to the type of receptor-cation interaction, that is ligand-metal interactions. Receptors are based on a multidentate protoporphyrin-appended pyridine platform, which leaves at least a vacant coordination site for the incoming metal ions. A protoporphyrin-appended pyridine, 2,5-pyridine dicarboxyamidyl-8,13-bis（vinyl）-3,7,18,17-tetramethyl-21 H, 23 H-porphyrin（P-PTP）, was designed and synthesized. Its application as potential fluoroionophore for recognition of cadmium and mercury ions is reported. P-PTP shows chelation-enhanced fluorescence effect with Cd（Ⅱ） and Hg（Ⅱ） via the interruption of photoinduced electron transfer （PET） process, which has been utilized as the basis of the fabrication of the metal ions-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd（Ⅱ）- and Hg（Ⅱ）- sensitive chemosensors were investigated. It shows a linear response toward Cd（Ⅱ） and Hg（Ⅱ） in the concentration range of 1.0×10-3 to 1.0×10-7 M with a limit of detection of 1.0×10-7 M and 0.5×10-7M for Cd（Ⅱ） and Hg（Ⅱ）, respectively. The chemosensor shows good selectivity for Cd（Ⅱ） over a large number of other transition metal ions, i.e., Cu（Ⅱ）, Zn（Ⅱ） and mixed metal ions.

A New Fluorescent Chemosensor for Selective and Sensitive Detection of Mn2+ in Acidic Medium

Recently, fluorescent sensors have attracted considerable attention in their sensitive and selective determination of heavy metal ions in the aqueous acidic medium due to their advantages such as low cost and easy handling. In this study, the bathocuproine (BCP) compound was used as a fluorescent chemosensor. The selectivity and sensitivity of BCP have been investigated against some metal ions of biological and environmental importance. The results obtained from the ultraviolet-visible region (UV-vis.) and the fluorescence spectroscopy experiments revealed that the BCP sensor showed selectivity and sensitivity only to Manganese (II) ions in the experimental conditions studied. In addition, the binding stoichiometry of BCP and Mn2+ was determined to be 1:1 by the Benesi-Hildebrand method.

A new tripodal rhodamine B derivative as a highly selective and sensitive fluorescence chemosensor for copper(Ⅱ)

A new tripodal rhodamine B derivative 2 was designed and synthesized by tripodal trialdehyde and rhodamine B hydrazide for the first time. This derivative could be used as a fluorescent chemosensor for the selective and sensitive determination of copper(II) in Tris-HCl buffer and ethanol aqueous mixed media. Under the optimum conditions described herein,fluorescence enhancement at 557/577 nm was linearly related to the concentration of copper(II) in the range of 0.10 to 10.00×10-5 mol·L-1,with a corre-lation coefficient of R2=0.9964 (n=15) and a detection limit of 1.129×10-7 mol·L-1 (the relative standard deviation for five repeated measurements at 4.00×10-5 mol·L-1 Cu(II) was 2.2%). The absorbance meas-urements at 557 nm were linearly related to the concentration of Cu(II) in the range of 0.50 to 25.00×10-5 mol·L-1,with a correlation coefficient of R2=0.9948 (n=13) and a detection limit of 3.338×10-7mol·L-1.

A new rhodamine-based fluorescent chemosensor for mercury in aqueous media

A new fluorescent ＂on-off＇ chemosensor for Hg2＋ initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2＋ over other commonly coexistent metal ions in aqueous media, Upon the addition of Hg2＋, the spirocyclic ring of probe is opened and a significant enhancement of visible color and fluorescence in the range of 500-600 nm is observed, The colorimetric and fluorescent response to Hg2＋ can be conveniently detected by the naked eye, which provides a facile method for visual detection of Hg2＋, From the molecular structure and spectral results of 1, an irreversible, hydrolysis, desulfurization reaction mechanism is proposed.

Novel Fluorescent Chemosensors Based on Tryptophan Unit for Cu2＋ and Fe3＋ in Aqueous Solution

We reported four fluorescent chemosensors containing tryptophan units.The fluorescence spectrum titration experiments suggest that chemosensors 1,2,3 and 4 are highly selective for Cu2＋ and Fe3＋ over Li＋,Na＋,K＋,Co2＋,Zn2＋,Ni2＋,Hg2＋ and Cr3＋ via forming complexes with Cu2＋ or Fe3＋,which is confirmed by dramatical quench of fluoreseence in aqueous solution at pH 7.4,thus making all the chemosensors suitable for Cu2＋ and Fe3＋ fluorescent sensors.

Fluorescence turn-on chemosensor for Hg^(2+) based on a rhodamine derivative and its application in bioimaging

A fluorescence turn-on chemosensor based on rhodamine B derivative (FD10) has been developed as a highly sensitive chemosensor for Hg2+. A prominent fluorescence enhancement was measured in the presence of Hg2+, which was in agreement with the changes in the absorption spectrum. Furthermore, by means of laser scanning fluorescence microscopy experiments, it was demonstrated that FD10 was cell-permeable and could be used as a fluorescent probe for monitoring Hg2+ in living cells.

A Turn-On Fluorescence Chemosensor for Cyanide in Aqueous Media Based on a Nucleophilic Addition Reaction

We synthesized a new cyanide （CN-） chemosensor CX based on a nucleophilic addition reaction prompted by cyanide ion, which could be used for highly selective and sensitive fluorescence turn-on detection of cyanide in aqueous media. The CX showed selective fluorescence recognition for CN-, the miscellaneous competitive anions （F-, Cl-, Br-, I-, AcO-, H2PO4, HSO4, ClO4, S2-, PO4^3-, CO3^2- and SCN- ） did not lead to any significant interference. The detection limit of the sensor towards CN is 1.15 × 10^-7 mol.L- 1. The sensor has been successfully applied to estimate the cyanide ion in seeds of cherries. Test strips based on CX were fabricated, which could be used as a convenient and efficient CN test kit to detect CN in aqueous solution for ＂in-the-field＂ measurement.

A minimized fluorescent chemosensor array utilizing carboxylate-attached polythiophenes on a chip for metal ions detection

Chemosensor arrays have a great potential for on-site applications in real-world scenarios.However,to fabricate on chemosensor array a number of chemosensors are required to obtain various optical patterns for multianalyte detection.Herein,we propose a minimized chemosensor array composed of only two types of carboxylate-functionalized polythiophene derivatives for the detection of eight types of metal ions.Upon recognition of the metal ions,the polythiophenes exhibited changes in their fluorescence intensity and various spectral shifts.Although both chemosensors have the same polymer backbone and recognition moiety,only the difference in the number of methylene groups contributed to the difference in the fluorescence response patterns.Consequently,the metal ions in aqueous media were successfully discriminated qualitatively and quantitatively by the chemosensor microarray on the glass chip.This study offers an approach for achieving a minimized chemosensor array just by changing the alkyl chain lengths without the necessity for many receptors and reporters.

A FUNCTIONAL CONJUGATED HYPERBRANCHED POLYMER DERIVED FROM TETRAPHENYLETHENE AND OXADIAZOLE MOIETIES:SYNTHESIS BY ONE-POT “A_4+B_2+C_2” POLYMERIZATION AND APPLICAION AS EXPLOSIVE CHEMOSENSOR AND PLED

A new conjugated hyperbranched polymer （hb-TFO） containing tetraphenylethylene （TPE） units, a famous aggregation-induced emission （AIE） active group, as the core, was synthesized successfully with modest yield via one-pot Suzuki polymerization reaction. Thanks to the introduction of TPE moieties, hb-TFO exhibited aggregation-enhanced emission （AEE） property, and could work as explosive chemosensor with high sensitivity. The polymeric light-emitting diode （PLED） device was fabricated to investigate its electroluminescent property, and hb-TFO demonstrated a maximum luminance efficiency of 0.22 cd/A and a maximum brightness of 545 cd/m2 at 15.9 V.

DDTC-Na-based colorimetric chemosensor for the sensing of cyanide in water

Sodium diethyldithiocarbamate (DDTC-Na) was demonstrated to be a new colorimetric cyanide chemosensor by utilizing an indirect trick. First, some copper ions were added to the colorless aque- ous solution of DDTC-Na. Then, the resultant brown solution was studied upon the addition of different anions, including Cl-, I-, IO3-, SO42-, NO-2, Br-, H2PO4-, F-, SCN-, HSO-4, ClO-4 and CN-. It was observed by naked eyes that the brown solution changed to colorless immediately after the addition of the trace cyanide, but there were no changes towards other anions, making DDTC-Na a good selective cyanide chemosensor in pure water.

A hydrophilic fluorescent polymer containing naphthalimide moiety as chemosensor for microbioreactors

A novel hydrophilic copolymer P(NI-HEMA) containing the pendant group of naphthalimide moiety has been prepared. In the aqueous buffer solution, its film on the glass substrate shows an obvious fluorescence change and excellent linear relevance in the pH range of 5.8-8.0. Specifically, using the isobestic point at 406 nm as excitation wavelength can avoid the UV irradiation and the tedious calibration process. The film stability and hydrophilicity of copolymer P(NI-HEMA) were studied. Because of the easy synthesis, low price and high linear relevance to pH, the hydrophilic chemosensor film of P(NI- HEMA) could be potentially applied as a low-cost pH indicator for high-throughput bioprocessing in microreactors.

Sensitive and Selective Fluorescent Chemosensors Combining Multiple PET Processes for Ag＋ Sensing

In this work, a novel fluorescent chemosensor combining multiple photoinduced electron transfer（PET） processes for the detection ofAg＋ ion was synthesized. The PET processes were derived from the lone electron pair of the selenium donors and the tertiary nitrogen atom of the coumarin fluorophore, which have not yet been used in the fluorescent chemosensor designed for Ag＋ ion. Interestingly, the chemosensors showed fluorescent responses to Ag＋ ion with a fluorescence enhancement factor of 3--5-fold by blocking the intramolecular PET quenching path- ways. Furthermore, the probe exhibited high selectivity and sensitivity for Ag＋ ion over other relevant species with detection limit down to 10 nmol/L level. The chemosensors also showed excellent performances in analyzing natural water samples. The chemosensors developed herein represent a new strategy for the PET fluorescent chemosensor design for the detection ofAg＋ ion.

Design and Synthesis of a Selective Chemosensor for Zn^2＋

A hydroxyl substituted phenolic Schiff base 1, used as sensor for detection of Zn^2＋, was synthesized and investigated. It was found that a strong fluorescence emission was observed when 1 bound to Zn^2＋ in acetonitrile, whereas no fluorescence emission was detected when 1 bound to other metal ions （Fe^2＋, Co^2＋, Ni^2＋, Cu^2＋, Cd^2＋, Hg^2＋, Mg^2＋, Pb^2＋, Ca^2＋, Ba^2＋, Sr^2＋） except for Mg^2＋, for which a weak fluorescence emission was detected in the same condition. Competition experiment showed that no obvious interference was observed in its fluorescence while 1 performed the titration with Zn^2＋ in the different mixtures of metal ions. To understand the site where Zn^2＋ coordinated to the ligand and the mechanism of binding, three other hydroxyl substituted phenolic Schiff bases 2-4 were synthesized and their binding reactions with Zn^2＋were also investigated.