Room-temperature synthesis of bimetallic ZnCu-MOF-74 as an adsorbent for tetracycline removal from an aqueous solution.

The novel bimetallic MOF, ZnCu-MOF-74, has been evaluated for the remediation of tetracycline-contaminated water. ZnCu-MOF-74 was obtained at room temperature, avoiding high pressure and temperature. ZnCu-MOF-74 exhibited chemical stability in the 4-8 pH range. The adsorption result analysis was described using the Elovich kinetic model and the Langmuir adsorption isotherm, suggesting a physicochemical process. The maximum adsorption capacity was estimated at 775.66 mg g-1. The pH of the solution and the presence of ions such as NO3-, SO42-, Na+, Mg2+, Cl-, and Ca2+ had no influence on the removal of tetracycline. In addition, π-interactions and metal complexation were proposed as possible adsorption mechanisms through FT-IR and XPS. ZnCu-MOF-74 showed outstanding cyclability performance, preserving its adsorption capacity after 4 adsorption-desorption cycles, besides exhibiting chemical stability, proving the benefits of applying ZnCu-MOF-74 in the water treatment process.

APTES functionalization in SBA-15: the effect on SO2 capture and detection applications.

The development of adsorbents for air pollutant remediation and effective monitoring is of interest. Then, the effect of the APTES functionalization ratio on the impact of the adsorption and detection of SO2 molecules was evaluated. The higher APTES functionalization material (SBA-15_6.1APTES) shows a high uptake of 1.15 mmol g-1 at 0.001 bar and 298 K. Fluorescence, time-resolved photoluminescence, and quantum yield experiments revealed a turn-on effect specifically for SO2 molecules, indicating high selectivity, suggesting host-to-guest energy transfer. Attractively, XPS measurement provided an understanding of the mechanism, suggesting hydrogen bonding and dipole-dipole interactions as the main interactions between SO2 molecules and SBA-15_6.1APTES. DFT calculations were performed to confirm these interactions. Furthermore, this study highlights the application of SBA-15 materials with different amino modifications for SO2 treatment and provides insight into the interaction mechanism using experimental techniques.

CYCU-3: an Al(III)-based MOF for SO2 capture and detection.

The Al(III)-based MOF CYCU-3 exhibits a relevant SO2 adsorption performance with a total uptake of 11.03 mmol g-1 at 1 bar and 298 K. CYCU-3 displays high chemical stability towards dry and wet SO2 exposure. DRIFTS experiments and computational calculations demonstrated that hydrogen bonding between SO2 molecules and bridging Al(III)-OH groups are the preferential adsorption sites. In addition, photoluminescence experiments demonstrated the relevance of CYCU-3 for application in SO2 detection with good selectivity for SO2 over CO2 and H2O. The change in fluorescence performance demonstrates a clear turn-on effect after SO2 interaction. Finally, the suppression of ligand-metal energy transfer along with the enhancement of ligand-centered π* → π electronic transition was proposed as a plausible fluorescence mechanism.

SU-101: a Bi(III)-based metal-organic framework as an efficient heterogeneous catalyst for the CO2 cycloaddition reaction.

A non-porous version of SU-101 (herein n-SU-101) was evaluated for the CO2 cycloaddition reaction. The findings revealed that open metal sites (Bi3+) are necessary for the reaction. n-SU-101 displays a high styrene oxide conversion of 96.6% under mild conditions (3 bar and 80 °C). The catalytic activity of n-SU-101 demonstrated its potential application for the cycloaddition of CO2 using styrene oxide.

MOF-based catalysts: insights into the chemical transformation of greenhouse and toxic gases.

Metal-organic framework (MOF)-based catalysts are outstanding alternative materials for the chemical transformation of greenhouse and toxic gases into high-add-value products. MOF catalysts exhibit remarkable properties to host different active sites. The combination of catalytic properties of MOFs is mentioned in order to understand their application. Furthermore, the main catalytic reactions, which involve the chemical transformation of CH4, CO2, NOx, fluorinated gases, O3, CO, VOCs, and H2S, are highlighted. The main active centers and reaction conditions for these reactions are presented and discussed to understand the reaction mechanisms. Interestingly, implementing MOF materials as catalysts for toxic gas-phase reactions is a great opportunity to provide new alternatives to enhance the air quality of our planet.

Gas-phase organometallic catalysis in MFM-300(Sc) provided by switchable dynamic metal sites.

MFM-300(Sc) was explored as a catalyst for the gas-phase hydrogenation of acetone. The catalysis results support the presence of non-permanent open Sc(III) sites within the structure due to the requirement of Lewis acid sites for the reaction to proceed. The open Sc(III) sites are generated in situ due to the presence of hemilabile Sc-O bonds. MFM-300(Sc) showed high mechanical and chemical stability, and the crystalline structure was maintained after the catalytic reaction. The catalytic activity of the material was quantified by performing a gas-phase reaction using a continuous flow reactor. The acetone conversion in MFM-300(Sc) was estimated to be 27.7% with no loss of activity after catalytic cycles.