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.

Novel Highly Selective Fluorescent Chemosensors for Hg（Ⅱ）

Based on Rhodamine,two novel fluorescent Hg2＋ chemosensors（R1,R2） were synthesized from inexpensive starting materials.They were designed and synthesized with o-aminophenol and o-phenylenediamine derivatives as the Hg2＋ chelator,the comparison between the photophysical properties of two chemosensor molecules was made.The chemosensors were designed with a photoinduced electron transfer（PET） mechanism.After binding to Hg2＋ which blocks the PET process,the fluorescence intensity of the chemosensors was enhanced by up to 15-fold.They exhibit very strong fluorescence responses to Hg2＋ and have remarkably higher selectivity for Hg2＋ than for other metal ions including K＋,Na＋,Ca2＋,Mg2＋,Cd2＋,Mn2＋,Ni2＋,Co2＋,Zn2＋,Cu2＋,Cr3＋,Fe3＋,pb2＋,Ag＋,Al3＋,Fe2＋ and Sn2＋ in Tris-HC1/sodium phosphate buffer.The fluorescence enhancement of R2 towards Hg2＋ maintains stable in wide pH span（6.4-8.8） aqueous solutions.

Hg2＋-Selective Fluorescent Chemosensor Based on Cation-π Interaction

Two sulphur-containing 4-aminonaphthalimide derivatives were investigated as Hg2＋ fluorescent chemosensors. In CH3CN, both sensors present a remarkable fluorescence enhancement to Cu2＋ and Fe3＋, but a selective fluorescence quenching to Hg2＋ among the other metal ions. A cation-π interaction between Hg〉 and the naphthalimide moiety was proposed and confirmed By the density tunetional theory（DFT）.

A fluorescent probe for fluoride ion based on 2-aminopyridyl-bridged calix[6]arene

An 2-anfinopyddyl-bddged calix[6]arene on the upper rim fixed in cone conformation （3） was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and 1H NMR titration experiments.

Detection of Picric Acid by Terpy-Based Metallo- Supramolecular Fluorescent Coordination Polymers in Aqueous Media

The synthesis of two linear terpy-based metallo-supramolecular fluorescent coordination polymers through 1 ： 1 complexation of Zn^2＋ and Cd^2＋ ions with ditopic terpyridine ligand was reported. The dispersibility of P1 and P2 was significantly improved in organic solvent and water through the introduction of hydrophilic oligo-ethyoxy side chain. Two polymers displayed yellow light emission both in solution and the solid state due to the intra-ligand charge transfer （ILCT） between the d^10 metal ions and the conjugated spacer unit. These coordination polymers were explored as fluorescent chemosensors for detecting picric acid in aqueous media, displaying high sensitivity and good selectivity. In addition, test strips were prepared from these polymers and exhibited the practical potential of detecting the NACs pollutants in the outdoor water for public safety and security.

Naphthalimide as Highly Selective Fluorescent Sensor for Ag^＋ Ions

The naphthalimide derivative. NA1 was synthesized, which consists of a bis（2-（ethylthio）ethyl）amine group binding cations and naphthalimide unit as chromogenic and fluorogenic signaling subunit. Absorption and emission spectra and the effect of polarity of solvents and pH values were studied. The photo-induced electron transfer （PET） occurred from the donor of bis（2-（ethylthio）ethyl）amine group to the naphthalimide fluorophore. The present study demonstrates that NA1 is a viable candidate as a fluorescent receptor for a new Ag^＋ ion sensor. This silver ion chemosensor can discriminate Ag^＋ ion well among heavy metal ions by an enhancement of the fluorescence intensity in ethanol-water （1 ： 9, V ： V）. And NA1 is also a pH-sensor because the fluorescence of the compound varies with the pH values.

A New Biphenylcarbonitrile Based Fluorescent Sensor for Zn2＋ Ions and Application in Living Ceils

A new and efficient fluorescent sensor 4＇-hydroxy-3＇-[（4-antipyrineimino）methyl]-4-biphenylcarboni- trile（L） was prepared for the selective detection of Zn2＋ in aqueous ethanol medium. When excited at 419 nm, the fluorescent intensity of sensor L at 507 nm was remarkably increased more than 54-fold after adding Zn2＋ ions. The strong green emission of the solution can be easily identified by naked eye tinder UV light. Thus, sensor L behaves as a naked eye fluorescent ＂turn on＂ detector for Zn2＋ ions. The fluorescence enhancement might be attributed to the in- hibition of excited state intramolecular proton transfer（ESIPT） and C==N isomerization as well as the chelation en- hanced fluorescence（CHEF） effect. The complex solution of sensor L with Zn2＋ ions exhibited reversibility with ethylene diamine tetraacetic acid（EDTA） and the probe could be recycled for further use. Notably, sensor L could clearly distinguish Zn2＋ from Cd2＋. The interaction of sensor L with zinc ions was investigated by means of FTIR, 1H NMR and HRMS spectroscopy. Furthermore, sensor L has been applied for cell imaging studies.

Highly selective and sensitive colorimetric chemosensor based on tricarboyanine for detection of Ag^(+) in industrial wastewater

An efficient fluorescent probe 1 based on tricarbocyanine derivative was designed and synthesized,which can detect Ag^(+) in real industrial wastewater.UV-V is absorption and fluorescent emission spectra of probe 1 were carried out and indicated this probe can bind Ag^(+) via complexation reaction,then leading to a remarkable color change from blue to light red.Furthermore,probe 1 showed high sensitive performance and excellent selectivity toward Ag^(+) over other common metal ions in neutral pH.The sensing mechanism was proposed and further confirmed by ^(1)H NMR,which demonstrate analyte-induced destruction of the π-electron system could be shorten by the disruption of the pull-push π-conjugation system in probe 1.Moreover,a test strip was prepared by filter paper immersing in probe 1 solution,which further provide its potential application for trace Ag^(+) detection in real industrial wastewater.

Structure-property relationship on aggregation-induced emission properties of simple azine-based AIEgens and its application in metal ions detection

In recent twenty years,aggregation-induced emission(AIE),due to its excellent application prospect,has aroused widespread interests.The development of novel and easy to make AIE luminogens(AIEgens)is an attractive subject.For this purpose,it is very important to study the structure-property relationship of AIEgens.Because azine derivatives are easy to synthesis and some of them have nice AIE properties,herein,a series of azine derivatives(ADs)were employed as models to study the influence of different functional groups,electronic effects and structures on the AIE properties of azine derivatives.The AIE mechanism were studied by single crystal analysis,density functional theory(DFT)calculations and so on.The results indicated that the o-hydroxyl aryl substituted azine compounds could show good AIE properties.Meanwhile,the AIE properties of o-hydroxyl aryl substituted azine compounds were also influenced by the electronic effects of the aryl groups in the azine compounds.The o-hydroxyl groups could form intramolecular hydrogen bond with imine group,which play key role to restrict the intramolecular rotation of the aryl groups and act as base stone for the AIE process of this kind compounds.The HOMO-LUMO energy gaps of o-hydroxyl substituted azine are smaller than other homologous compounds,which is agree with the proposed AIE mechanism.Finally,thanks to the AIE properties,the o-hydroxy-substituted azines could be used as efficient Al^(3+)and Cu^(2+)fluorescent chemosensors in different conditions.In addition,test strips based on AD10 has been prepared,which can conveniently detect Cu^(2+)in industrial wastewater.This research supplied a way for the design of novel easy to make AIEgens through simple azine derivatives.