Ultrasensitive fluorescence detection of glutaraldehyde in water samples with bovine serum albumin-Au nanoclusters

Based on the cross-linking nature of BSA in the presence of glutaraldehyde (GA), the fluorescence of BSA-stabilized Au nanoclusters was effectively quenched by GA. A new method for ultrasensitive GA detection in water samples was thus developed with fluorescent BSA-stabilized Au nanoclusters. The fluorescence quenching of BSA-stabilized Au nanoclusters in the presence of GA fitted to Stern-Volmer equation. In the GA concentration range of 0.8–6 μM, a linear relationship of F₀/F versus GA concentration was obtained with a limit of detection (LOD) of 0.2 μM. The relative standard deviation of 5 replicate measurements of 4 μM GA is 1.3%. This method shows good selectivity over other organics in water samples. The feasibility of the new sensor for GA in different water samples was demonstrated.     

Polycyclic aromatic hydrocarbons (PAHs) pollution recorded in annual rings of gingko (Gingko biloba L.): Determination of PAHs by GC/MS after accelerated solvent extraction

Retrospective monitoring of polycyclic aromatic hydrocarbons (PAHs) pollution levels was demonstrated by analyzing the annual rings of gingko (Gingko biloba L.) sampled from the Chengdu plain of southwest China. The samples of gingko trunk section, leaf, bark and its host soil were analyzed for PAHs by gas chromatography/mass spectrometry (GC/MS) after optimized accelerated solvent extraction (ASE). Compared to ultrasonic or soxhlet, ASE has high extraction efficiency thus meaningful contamination information contained in trunk tissue. The distribution of PAHs in gingko trunk, leaf and its host soil indicates that the main uptake pathway might be gaseous and particles-bound deposition via foliage with the exception of two-ring compounds from root, such as Nap and 2-methyl-Nap. PAHs in gingko trunk could be used to reveal the regional and historical contamination information, which is consistent with the environmental history of events (straw incineration) in Chengdu.     

A potential visual fluorescence probe for ultratrace arsenic (III) detection by using glutathione-capped CdTe quantum dots

The interaction between mercaptoacetic acid (MA)-capped CdTe QDs, MA-capped CdTe/ZnS QDs or glutathione (GSH)-capped CdTe QDs with As(III) was studied using fluorescence spectrometry. As (III) has a high-affinity to reduced-GSH to form As(SG)₃, and the emission of the GSH-capped CdTe QDs (λ_em. = 612 nm) is quenched effectively. Thus, a novel fluorescence spectrometric method was developed for As (III) determination by using GSH-CdTe QDs. Under optimal conditions, the quenched fluorescence intensity (F₀/F) increased linearly with the concentration of As (III) ranging from 5.0 × 10⁻⁶ to 25 × 10⁻⁵ mol L⁻¹. The limit of detection (3σ) for As (III) was found to be 2 × 10⁻⁸ mol L⁻¹. This method is potentially useful in visual detection of As (III) under irradiation of the ultraviolet light.     

Synthesis and antiproliferative activity of multisubstituted N-fused heterocycles against the Hep-G2 cancer cell line

Abstract  

Pyrrolo[1,2-a]imidazole and pyrrolo[2,1-b]thiazole derivatives were synthesized in a one-pot procedure by [3 + 2] cycloaddition reactions of the corresponding imidazolium ylides and thiazolium ylides with an alkene followed by oxidative aromatization of the primary cycloadducts under the action of the mild oxidant tetrakispyridinecobalt(II) dichromate. Antiproliferative activity of 14 new bicyclic N-fused heterocycles against the human hepatocellular liver carcinoma (Hep-G2) cell line were examined by the MTT method. Some of the compounds showed favorable antiproliferative activity, especially compound 3i displayed potent antiproliferative activities with an IC₅₀ value of 0.36 μg/cm³.     

Polycyclic aromatic hydrocarbons (PAHs) pollution recorded in annual rings of gingko (Gingko biloba L.): Regression analysis and comparison to other pollutants

Further interesting information about contamination recorded in gingko annual rings is revealed in this paper. The degradation degrees of varied PAHs in gingko trunk, range 2.4 to 3.4%, are evaluated by using regression analysis and confirmed to depend upon their molecular sizes and chemical properties. For other lipophilic compounds, the translocation and diffusion behaviors conform to our donut model of PAHs in previous work, while for hydrophilic contaminants, the translocation and diffusion are more complicated owing to the second uptake pathways by roots. Further, the gingko tree exhibits selective absorption to heavy metals, such as Cu, Cd, Zn, Cr, Pb, Ni, Fe, and Mn. The relative accumulation degrees of these heavy metals are estimated by comparing to Fe in the soil and the gingko tree, and the result suggests that the gingko accumulates Cr, Cd and Pb from the soil. However, the metals in annual rings might not reflect historical environment changes for their diffusive nature in water-sapwood.     

Regioselective addition of thiophenol to α,β-unsaturated N-acylbenzotriazoles

Regioselective addition of thiophenol to α,β-unsaturated N-acylbenzotriazoles has been achieved by controlling the conditions. Thus, three types of products, namely α,β-unsaturated thioesters, β-thiophenoxy substituted N-acylbenzotriazoles, and β-thiophenoxy substituted thioesters were selectively obtained in good to excellent yields.     

Supramolecular Architectures with Open Frameworks Constructed by Transitional Metal Ions,Linear Dicarboxylic Acid,and 2,2′‐Bipyridine

Four new transitional metal supramolecular architectures, [Zn(cca)(2,2′‐bpy)]_n · n(2,2′‐bpy) ( 1 ), [Cu(cca)(2,2′‐bpy)]_n ( 2 ), [Zn(bpdc)(2,2′‐bpy)(H₂O)]_n · 0.5nDMF · 1.5nH₂O ( 3 ), and [Co(bpdc)(2,2′‐bpy)(H₂O)]_n · nH₂O ( 4 ) (H₂cca = p‐carboxycinnamic acid; H₂bpdc = 4,4′‐biphenyldicarboxylic acid; 2,2′‐bpy = 2,2′‐bipyridine) were synthesized by hydrothermal reactions and characterized by single crystal X‐ray diffraction, elemental analyses, and IR spectroscopy. Although the metal ions in these four compounds are bridged by linear dicarboxylic acid into 1D infinite chains, there are different π–π stacking interactions between the chains, which results in the formation of different 3D supramolecular networks. Compound 1 is of a 3D open‐framework with free 2,2′‐bpy molecules in the channels, whereas compound 2 is of a complicated 3D supramolecular network. Compounds 3 and 4 are isostructural. Both compounds have open‐frameworks.     

Solvothermal synthesis, crystal structure, and properties of lanthanide-organic frameworks based on thiophene-2,5-dicarboxylic acid

A series of lanthanide-organic framework coordination polymers, {[La(2)(TDC)(2)(NO(3))(H(2)O)(4)](OH)·5H(2)O}(n) (1) and [Ln(TDC)(NO(3))(H(2)O)](n) (TDC = thiophene- 2, 5- dicarboxylic acid; Ln = Nd(2), Sm(3), Eu(4), Gd(5), Tb(6), Dy(7), Ho(8), Er(9), Yb(10)) have been synthesized by solvothermal reaction and characterized by elemental analysis, FT-IR, TG analysis, single-crystal X-ray diffraction and power X-ray diffraction. The single-crystal X-ray diffraction analysis results show that 1 displays a 3-D porous framework with (3,7)-connected {4(10).6(11)}{4(3)} topology. The compounds 2-10 crystallized in the same P2(1)/c space group and exhibits a (3,6)-connected {4.6(2)}(2){4(2).6(10).8(3)} topology, Right-handed and left-handed helical chains coexist in the 2-D layer structure. The luminescence properties of 2-10 and the magnetic properties of 5,7,8,9 were investigated.     

A short synthesis of bisabolane sesquiterpenes

A facile total synthesis of three members of the bisabolane sesquiterpene family, namely (±)-curcumene, (±)-xanthorrhizol and (±)-curcuhydroquinone had been achieved in high overall yield. The synthesis used bromobenzene derivatives as starting materials. The halogen-lithium exchange followed by addition of isoprenylacetone and reduction of the obtained carbinols are the key steps of the synthetic pathway. This synthetic approach provides a new route to the bisabolane sesquiterpenes.