Invisible Silver Guests Boost Order in a Framework That Cyclizes and Deposits Ag3Sb Nanodots.

The infusion of metal guests into (i.e., metalating) the porous medium of metal-organic frameworks (MOFs) is a topical approach to wide-ranging functionalization purposes. We report the notable interactions of AgSbF6 guests with the designer MOF host ZrL1 [Zr6O4(OH)7(L1)4.5(H2O)4]. (1) The heavy-atom guests of AgSbF6 induce order in the MOF host to allow the movable alkyne side arm to be fully located by X-ray diffraction, but they themselves curiously remain highly disordered and absent in the strucutral model. The enhanced order of the framework can be generally ascribed to interaction of the silver guests with the host alkyne and thioether functions, while the invisible heavy-atom guest represents a new phenomenon in the metalation of open framework materials. (2) The AgSbF6 guests also participate in the thermocyclization of the vicinal alkyne units of the L1 linker (at 450 °C) and form the rare nanoparticle of Ag3Sb supported on the concomitantly formed nanographene network. The resulted composite exhibits high electrical conductivity (1.0 S/cm) as well as useful, mitigated catalytic activity for selectively converting nitroarenes into the industrially important azo compounds, i.e., without overshooting to form the amine side products. The heterogeneous/cyclable catalysis entails only the cheap reducing reagents of NaBH4, ethanol, and water, with yields being generally close to 90%.

Crystallinity after decarboxylation of a metal-carboxylate framework: indestructible porosity for catalysis.

We report a curious case study of a Zr(iv)-carboxylate framework, which retains significant crystalline order after cascade thermocyclization of its linker components, and - more notably - after the crucial carboxylate links were severed by heat. Vigorous heat treatment (e.g., 450 °C and above) benzannulates the multiple alkyne groups on the linker to generate linked nanographene blocks and to afford real stability. The resultant Zr oxide/nanographene hybrid solid is stable in saturated NaOH and concentrated H3PO4, allowing a convenient anchoring of H3PO4 into its porous matrix to enable size-selective heterogeneous acid catalysis. The Zr oxide components can also be removed by strong hydrofluoric acid to further enhance the surface area (up to 650 m2 g-1), without collapsing the nanographene scaffold. The crystallinity order and the extensive thermal transformations were characterized by X-ray diffraction, scanning transmission electron microscopy (STEM), IR, solid state NMR and other instrumental methods.

Soil washing remediation of heavy metal from contaminated soil with EDTMP and PAA: Properties, optimization, and risk assessment.

Soil washing is a rapid and efficient remediation technique for soil contaminated by heavy metals. In this study, Cd, Pb, and Zn were removed from contaminated soil by ethylenediamine tetra (methylene phosphonic acid) (EDTMP) and polyacrylic acid (PAA). We then investigated the effect of varying the concentration, pH and duration of the washing processes. Single-factor experiments suggest that the PAA washing process may be dominated by electrostatic adsorption, and is suitable for remediation under weak acid and neutral conditions. Meanwhile, EDTMP remediation might be dominated by chelation, which is favorable in strong acid and alkaline environments. In a quadratic saturation D-optimization design (QSDD), we optimized the washing parameters and further explored the washing mechanism including primary factor, principal effect, interaction effect, and the optimal washing conditions, with simultaneously changing multiple influencing factors. The optimum efficiencies of Cd, Pb, and Zn removal were 92.74%, 96.14%, and 50.76% respectively in EDTMP remediation, and 84.62, 79.24, and 41.66% respectively in PAA remediation. The washing processes effectively reduced the availability of Cd, Pb, and Zn in contaminated soil, without noticeably affecting soil chemical properties. Therefore, the washing incurred little ecological risk. EDTMP and PAA are suitable remediation agents of soil contaminated by heavy metals.

Photoluminescence and labelling for microcrack bone of N-salicylidene-3-amino-1,2,4-triazole.

A new Schiff base of N-salicylidene-3-amino-1,2,4-triazole (SAT) was synthesized and its photoluminescent, photochromic and thermochromic properties were characterized and demonstrated. The fluorescence lifetime and quantum yield of SAT were measured and the microcrack bone imaging using SAT as a fluorescent label was observed by laser scanning confocal microscope (LSCM). The absorption spectrum of SAT was demonstrated using DFT/TD-DFT calculation.