Picomolar detection of As(III) ions by using hydrothermal synthesis of functionalized polymer dots as a highly selective fluorescence sensor

Arsenic is a toxic and ubiquitous metalloid that leads to a widespread health risk to human beings and other living organisms. In this paper, a novel water-soluble fluorescent probe based on functionalized polypyrrole dots (FPPyDots) was designed and applied to determine As(III) selectively and sensitively in aqueous media. FPPyDots probe was synthesized by using a hydrothermal method, via the facile chemical polymerization of pyrrole (Py) and cysteamine (Cys) and then functionalized with ditheritheritol (DTT). To investigate the chemical composition, morphology, and optical properties of the resultant fluorescence probe various characterization techniques including FTIR, EDC, TEM, Zeta potential, UV-vis, and fluorescence spectroscopies were used. The Stern-Volmer equation was used for calibration curves and show a negative deviation with the two linear concentration ranges of 270-2200 pM and 2.5-22.5 nM with an excellent limit of detection (LOD) of 110 pM. FPPyDots exhibit high selectivity to As(III) ions over various transition and heavy metal ions interferences. The performance of the probe has also been perused concerning the pH effect. Finally, to illustrate the applicability and reliability of the FPPyDots probe, the As(III) traces were identified in water real samples and compared with ICP-OES analysis.

Terbium-based metal-organic frameworks: highly selective and fast respond sensor for styrene detection and construction of molecular logic gate

Volatile organic compounds (VOCs) are extremely harmful to the human body and environment, thus it is greatly meaningful and urgent to detect VOCs. In this work, terbium-based metal-organic frameworks (Tb-MOFs) have been prepared successfully via a facile and efficient route. These well-constructed Tb-MOFs architectures exhibit characteristic green emission of Tb³⁺ ion upon excitation of UV light. It is noteworthy that the Tb-MOFs can act as a convenient and efficient luminescent sensor for VOCs. Especially, the Tb-MOFs displayed high selectivity and superior sensitivity towards the sensing of styrene solution and vapor through fluorescence quenching mechanism. The Tb-MOFs can realize fast detection for styrene vapor with a response time of 30 s. The mechanism of fluorescence quenching of Tb-MOFs induced by styrene was also discussed. More importantly, we have designed a logic gate operation with the combination of the sensor for the intelligent detection of styrene. This developed type of lanthanide luminescent metal-organic frameworks (Ln-MOFs) based on the combination of fluorescence sensor and logic gate has a great application prospect in the detection of VOCs in daily life.

Assembly, Structure, and Properties of Six Coordination Polymers Based on 1,3,5-Tri-4-pyridyl-1,2-ethenylbenzene

Six coordination polymers including [Cd(tpeb)X2]n (1: X=Br, 2: X=I), [Cu(tpeb)I]n (3), [Cd2I2(tpeb)2(1,4-bdc)]n (4), {[Co(tpeb)(dpa)]·MeCN}n (5), and {[Ni2(tpeb)3(oba)2]·solvent}n (6) were prepared from solvothermal reactions of 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene (tpeb) with CdII, CuI, CoII, or NiII salts in the absence or presence of 1,4-benzenedicarboxylic acid (1,4-H2bdc), 2,2′-biphenyldicarboxylic acid (H2dpa), and 4,4′-oxybisbenzoic acid (H2oba). Compounds 1–3 have 1D chain structures while 4 holds a 2D wave-like network. Compound 5 adopts a 3D (3,5)-connected net with a Schläfli symbol of 33.48.513.63.7 and 6 possesses a 3D 5-connected net with a Schläfli symbol of 42.65.7.82. Compound 2 as a representative photocatalyst shows efficient degradation of rhodamine B in water while 5 displays highly selective sensing of p-nitrophenol in water through fluorescence quenching.

A facile strategy for achieving high selective Zn(II) fluorescence probe by regulating the solvent polarity

A simple Schiff base comprised of tris(2-aminoethyl)amine and salicylaldehyde was designed and synthesized by one-step reaction. Although this compound has poor selectivity for metal ions in acetonitrile, it shows high selectivity and sensitivity detection for Zn(II) ions through adjusting the solvent polarity (the volume ratio of CH₃CN/H₂O). In other words, this work provides a facile way to realize a transformation from poor to excellent feature for fluorescent probes. The bonding mode of this probe with Zn(II) ions was verified by ¹H NMR and MS assays. The stoichiometric ratio of the probe with Zn(II) is 1:1 (mole), which matches with the Job-plot assay. The detection limitation of the probe for Zn(II) is up to 1 × 10^-8 mol/L. The electrochemical property of the probe combined with Zn(II) was investigated by cyclic voltammetry method, and the result agreed with the theoretical calculation by the Gaussian 09 software. The probe for Zn(II) could be applied in practical samples and biological systems. The main contribution of this work lies in providing a very simple method to realize the selectivity transformation for poor selective probes. The providing way is a simple, easy and low-cost method for obtaining high selectively fluorescence probes.

Luminescent Functionalised Supramolecular Coordination Polymers Based on an Aromatic Carboxylic Acid Ligand for Sensing Hg2+ Ions

Two luminescent functionalised supramolecular coordination polymers, namely, [Zn(TPDC-2CH3)(H2O)2]·H2O (1) and [Cd(TPDC-2CH3)(H2O)4]·H2O (2), were successfully synthesised by the reaction of 2′,5′-dimethyl-[1,1′:4′,1″-terphenyl]-4,4″-dicarboxylic acid (H2TPDC-2CH3) with Zn2+ and Cd2+ ions, respectively. X-Ray crystallographic analysis reveals that both compounds 1 and 2 exhibit fascinating 3D supramolecular networks, in which metal ions are linked by ligands to form a 1D chain which further extends to a 3D structure through the interaction of hydrogen bonding. The use of 1 and 2 as luminescent sensors for the optical detection of metal ions: Na+, K+, Hg2+, Ag+, Ca2+, Co2+, Ni2+, Mn2+, Cu2+, Zn2+, Cd2+, Pb2+, Mg2+, Al3+, Fe3+, Fe2+, In3+, Bi3+, and Cr3+ was carried out in aqueous solution, and the results indicated that compound 1 could effectively detect Hg2+ ions among various cations at room temperature, with a detection limit of 3.6 × 10−15 M.

Selective chemiluminescence method for the determination of trinitrotoluene based on molecularly imprinted polymer-capped ZnO quantum dots

A novel molecularly imprinted polymer (MIP) based chemiluminescence (CL) assay is described for the determination of TNT in environmental samples.