Recent advances in click-derived macrocycles for ions recognition

The Cu（I）-catalyzed azide-alkyne 1,3-dipolar cycloaddition（CuAAC） reaction, popularly known as the ＂click reaction＂, have been widely used in chemosensor field. This reaction gives a mild and efficient coupling reaction between the binding site and the reporter. In addition, the formation 1,4-disubstituted1,2,3-triazole linker shows a high binding affinity toward both anions and metal ions. Recently researches revealed this reaction is also an efficient tool to form rigid or shape-persistent, preorganized macrocyclic species. This review summarized the recent advances in click derived macrocyclic receptors for recognition of anion, metal ion and ions pair.

6-(N,N-Dimethylamino)-2-naphthoylacryl Acid:a Highly Selective and Sensitive Fluorescent Sensor of Copper(Ⅱ)

A novel fluorescent probe,6-（N,N-dimethylamino）-2-naphthoylacryl acid（ACADAN） was designed and synthesized as a fluorescent sensor for Cu^2＋ in aqueous media.Significant amplification of fluorescence signals without causing any discernible change of maximum fluorescence emission wavelength（λ max） was observed upon the addition of Cu^2＋.Importantly,ACADAN is capable of recognizing Cu^2＋ selectively in aqueous media in the presence of various biologically relevant metal ions and the prevalent toxic metal ions in the environment with high sensitivity（detection limit was 0.1 μmol/L）.

Synthesis of Novel Amphiphilic Poly(ester-amine) Dendrimers and Their Recognition of Hg^(2+) at the Air/Water Interface

Two novel amphiphilic poly(ester amine) dendrimers were synthesized and characterized by 1H NMR, 13 C NMR and IR spectra. Their properties of Langmuir film were investigated at the air/water interface. The relationship between the surface pressure and area isotherms of the dendrimers was found to be dependent on the nature of subphases. Interaction between HgCl 2 and the dendrimers was observed, indicating that the amphiphilic dendrimers could act as a sensor for Hg 2+ .

Proton-anion Ion-pair Recognition by a Hexaazatri- phenylene-Hexaurea Receptor

Recognition behavior of a hexaazatriphenylene （HAT） derivative toward different acids in THF solution was investigated through EH NMR, UV-vis and fluorescence spectroscopic experiments, as well as SEM image and semi-empirical calculations, which revealed that this propeller-like HAT receptor could co-assemble into a layered complex by sandwiching protons and halogen （chloride or bromide） anions synergistically between the receptor molecules. What＇s more, reversible and remarkable color changes visible to the naked eye could be observed, when the halogen acid and base were introduced alternatively.

UREA-BASED POLYACETYLENES AS AN OPTICAL SENSOR FOR FLUORIDE IONS

Novel acetylenes carrying urea groups, 1-（4-ethynylphenyl）-3-（4-nitrophenyl） urea （1）, 1-（4-propargyl）-3-（4- nitrophenyl） urea （2）, were synthesized and polymerized with rhodium catalyst. Polymers [poly（1） and poly（2）] with moderate molecular weights were obtained in good yields. The anion sensing ability of poly（1） and poly（2） was estimated using the tetra-n-butylammonium （TBA） salts of a series of anions in DMF. Upon the addition of F, the color of the DMF solution of poly（1） and poly（2） immediately turned to a different color, while the color of solution changed slightly upon addition of C1, HSO4-, Br-, and NO3-, indicating the F- sensing ability of poly（1） and poly（2）. The 1H-NMR titrations of poly（1） revealed that the colorimetric response of poly（1） was triggered by the urea/F interaction through the hydrogen bonding and/or deprotonation process. The absorption spectra titration and Hill plot analysis were carried out to measure the F binding ability, and the Hill coefficient in the poly（1）/F complexation was found to be 5.8. This result clearly indicated that this binding mode between poly（1） and F was based on a positive homotropic allosterism.

Synthesis and Characterization of Novel Schiff Base Macrocyclic Compounds Containing Thiophene

Several novel Schiff base macrocyclic compounds containing thiophene were synthesized from d/ethyl 3,4-dialkoxythiophene-2,5-dicarboxylate, cyanuric chloride, diethylarnine and p-nitrophenol by reduction, oxidation, substitution and cyclization, and their structures were characterized by IR, NMR and electrospray ionization-rnass spectrorneter（ESI-MS）. The studies on their UV-Vis absorption spectra show that Schiff base rnacrocycles 6-10 have selective recognition for Fe^3＋.

Synthesis of a crescent aromatic oligothioamide and its high selectivity in recognizing copper(II) ions

Functionalization of shape-persistent aromatic oligoamides still represents a difficult task nowadays. A crescent aromatic oligothioamide was synthesized by simple thionation of the corresponding oligoamide with the Lawesson＇s reagent. The results from UV-vis spectra of the molecule upon metal ion complexation demonstrated its higher selectivity in recognizing Cu2~ ions compared to the oligoamide precursor. The stoichiometry of the complex formed between the thioamide and Cu2＋ was found to be 1：1 with a binding constant of （4.3 ± 0.9） × 104 mol/L.