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While zeolitic imidazolate framework, ZIF-8, membranes show impressive propylene/propane separation, their throughput needs to be greatly improved for practical applications. A method is described that drastically reduces the effective thickness of ZIF-8 membranes, thereby substantially improving their propylene permeance (that is, flux). The new strategy is based on a controlled single-crystal to single-crystal linker exchange of 2-methylimidazole in ZIF-8 membrane grains with 2-imidazolecarboxaldehyde (ZIF-90 linker), thereby enlarging the effective aperture size of ZIF-8. The linker-exchanged ZIF-8 membranes showed a drastic increase in propylene permeance by about four times, with a negligible loss in propylene/propane separation factor when compared to as-prepared membranes. The linker-exchange effect depends on the membrane synthesis method.

Outside the box: A postsynthetic linker exchange approach is described for preparation of ultrathin propylene-selective ZIF-8 membranes. As-prepared ZIF-8 membranes were subjected to systematic linker exchange reactions with 2-imidazolecarboxaldehyde without compromising the grain boundary structure of the framework. The resulting membranes display the highest propylene permeance reported to date.

A new luminescent Zn^II-MOF with 1D triangular channels along the b axis, namely NUM-5, has been successfully assembled and well characterized, which features good stability, especially in aqueous solution. Interestingly, this compound exhibits a fast, sensitive and selective luminescence quenching response towards Cr^VI (Cr₂O₇²⁻/CrO₄²⁻) in aqueous solution. The detection limits towards Cr₂O₇²⁻ and CrO₄²⁻ ions are estimated to be 0.7 and 0.3 ppm, respectively, which are among the lowest detection limits reported for the MOF-based fluorescent probes that can simultaneously detect Cr₂O₇²⁻ and CrO₄²⁻ in aqueous environment. The possible detection mechanism has been discussed in detail. Moreover, it can be easily regenerated after detection experiments, indicative of excellent recyclability. All these results suggest NUM-5 to be a highly selective and recyclable luminescent sensing material for the quantitative detection of Cr^VI anions in aqueous solution.

Lights down on chromium: A novel luminescent Zn^II-MOF, (NUM-5) has been successfully assembled and investigated as a regenerable luminescent sensor with excellent sensitivity, selectivity and fast luminescence quenching response to Cr^VI anions in aqueous solution. The experiments exhibit NUM-5 can be a great candidate for quantitatively detecting Cr^VI anions in aqueous solution.

A novel organic–inorganic silica-based fluorescent probe was designed, synthesized and characterized by different techniques such as XRD, BET, TGA, and FT-IR. The fluorescence properties of the probe were studied in the presence of a variety of metal-ions in water. The results revealed that various metal-ions negligibly vary the emission intensity of the probe except for Hg²⁺, which quenched the intensity dramatically. The selectivity of the probe toward Hg²⁺ ion was further investigated in the presence of common competing metal-ions and the results demonstrated the high selectivity of the probe toward Hg²⁺ ion. The fluorescence emission of the probe was also studied as a function of the concentration of Hg²⁺ ion. A nanomolar limit of detection was estimated for Hg²⁺, indicating a high sensitivity. Furthermore, the probe showed INHIBIT-type logic behavior with Hg²⁺ and H⁺ as inputs. Also, the optimum pH range was studied in addition to reversibility and real world applicability of the probe.

A novel fluorescent probe based on functionalization of SBA-15 with a Schiff base was synthesized and displayed a high selectivity for Hg²⁺ over a variety of metal ions in water with a nanomolar limit of detection. Furthermore, the probe showed INHIBIT- type logic behavior with Hg²⁺ and H⁺ as inputs.

Activated carbon from lemon wood (AC) and ZnO nanoparticles loaded on activated carbon (ZnO-NP-AC) were prepared and their efficiency for effective acid yellow 199 (AY 199) removal under various operational conditions was investigated. The dependence of removal efficiency on variables such as AY 199 concentration, amount of adsorbent and contact time was optimized using response surface methodology and Design-Expert. ZnO nanoparticles and ZnO-NP-AC were studied using various techniques such as scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray analysis. The optimum pH was studied using one-at-a-time method to achieve maximum dye removal percentage. Small amounts of the proposed adsorbents (0.025 and 0.025 g) were sufficient for successful removal of AY 199 in short times (4.0 and 4.0 min) with high adsorption capacity (85.51 and 116.29 mg g⁻¹ for AC and ZnO-NPs-AC, respectively). Fitting the empirical equilibrium data to several conventional isotherm models at optimum conditions indicated the appropriateness of the Langmuir model with high correlation coefficient (0.999 and 0.978 for AC and ZnO-NPs-AC, respectively) for representation and explanation of experimental data. Kinetics evaluation of experiments at various time intervals revealed that adsorption processes can be well predicted and fitted by pseudo-second-order and Elovich models. This study revealed that the combination of ZnO nanoparticles and AC following simple loading led to significant improvement in the removal process in short adsorption time which was enhanced by mixing the media via sonication.

Activated carbon from lemon wood (AC) and ZnO nanoparticles loaded on activated carbon (ZnO-NP-AC) were synthesized and characterized. The influence of the operational parameters such as are pH, concentration of AY, amount of adsorbent and contact time on removal of AY by using of AC and ZnO-NPs-AC adsorbent was investigated.

In this work, a new Fe₃O₄/AlFe/Te nanocomposite was synthesized by a one-step sol–gel method. The Fe₃O₄ magnetic nanoparticles (MNPs) were prepared and then mixed with aluminum telluride (Al₂Te₃) in an alkali medium to produce the desired catalyst. After characterization of the Fe₃O₄/AlFe/Te nanocomposite by SEM, TEM, EDS, XRD, and ICP analyses, it was used in the esterification reaction. This heterogeneous catalyst showed high catalytic activity in the esterification of commercially available carboxylic acids with various alcohols to produce the desired esters at high conversions under neat conditions. The Fe₃O₄/AlFe/Te nanocomposites were separated from the reaction mixture via an external magnet and re-used 8 times without significant loss of catalytic activity.

In this study, a new nanocomposite of Fe₃O₄/AlFe/Te was prepared. This nanocomposite (Fe₃O₄/AlFe/Te) applied as a catalyst for synthesis a series of esters under neat condition with the magnetically and reusable property. It promotes the reaction with excellent yield, short time reaction and then separated from the reaction mixture via an external magnet and does not to require the use of column chromatography.

In this study, the imine-graphene hybrid material (HM) was used as an adsorbent for removal of Fe(III) and Cr(III) metal ions from the drinking waters. The adsorbent material (HM) was prepared at three steps. At the first step, the graphite was oxidized by Hummer's method for preparation of graphene oxide (GO), in the second step, the silanization derivative (GO-APTES) was obtained from the reaction of the 3-(trimethoxysilyl) propylamine and GO. In the final step, the hybrid material (HM) was synthesized from the reaction of the 3,5-diiodosalicylaldehyde and GO-APTES. The chemical structures of three materials GO, GO-APTES and HB were characterized by using the FT-IR, XRD, EDX, SEM, TEM and UV-vis methods. Thermal properties of the materials GO, GO-APTES and HB were investigated by TGA/DTA methods in the 25–1000°C temperature range. Adsorption and desorption studies of the hybrid material toward Fe(III) and Cr(III) metal ions were investigated using the Batch method. The effect of pH, contact time, temperature, concentration on the adsorption properties of the hybrid material were investigated by ICP-OES. The Fe(III) and Cr(III) ions have the maximum adsorption at the pH 7. The adsorption capacity decreases with the increase in pH values because above pH 9 the adsorption decreases due to the precipitation of metal hydroxide.

The imine-graphene hybrid material (HM) was used as an adsorbent for removal of Fe(III) and Cr(III) metal ions from the drinking waters.

A practical zinc acetate dihydrate-catalyzed reductive amination of various carbonyl compounds with N,N-dimethylformamide (DMF) as dimethylamino (Me₂N) source, reductant and solvent has been developed. This reaction shows broad substrate scope, good functional group tolerance, avoids the need for a pressure-proof reactor and column chromatographic isolation operations and gives up to 98% yield, to make it an attractive method for the preparation of tertiary N,N-dimethylamines.

The most important properties of self-healing polymers are efficient recovery at room temperature and prolonged durability. However, these two characteristics are contradictory, making it difficult to optimize them simultaneously. Herein, a transparent and easily processable thermoplastic polyurethane (TPU) with the highest reported tensile strength and toughness (6.8 MPa and 26.9 MJ m⁻³, respectively) is prepared. This TPU is superior to reported contemporary room-temperature self-healable materials and conveniently heals within 2 h through facile aromatic disulfide metathesis engineered by hard segment embedded aromatic disulfides. After the TPU film is cut in half and respliced, the mechanical properties recover to more than 75% of those of the virgin sample within 2 h. Hard segments with an asymmetric alicyclic structure are more effective than those with symmetric alicyclic, linear aliphatic, and aromatic structures. An asymmetric structure provides the optimal metathesis efficiency for the embedded aromatic disulfide while preserving the remarkable mechanical properties of TPU, as indicated by rheological and surface investigations. The demonstration of a scratch-detecting electrical sensor coated on a tough TPU film capable of auto-repair at room temperature suggests that this film has potential applications in the wearable electronics industry.

Remarkably tough and room-temperature self-healable thermoplastic polyurethane (TPU) elastomers are engineered by hard segment embedding aromatic disulfides. Hard segments with asymmetric alicyclic structure have adequate packing density to achieve efficient self-healing and to retain the remarkable mechanical properties of TPU. Their toughness value of 26.9 MJ m⁻³ doubles previous records. A scratch-detecting and auto-repairing electrical sensor application is demonstrated.