Structure–Property–Energetics Relationship of Organosulfide Capture Using Cu(I)/Cu(II)-BTC Edited by Valence Engineering

Mixed-valence metal-organic frameworks: concepts, opportunities, and prospects

Owing to increasing global demand for the development of multifunctional advanced materials with various practical applications, great attention has been paid to metal-organic frameworks due to their unique properties, such as structural, chemical, and functional diversity. Several strategies have been developed to promote the applicability of these materials in practical fields. The induction of mixed-valency is a promising strategy, contributing to exceptional features in these porous materials such as enhanced charge delocalization, conductivity, magnetism, etc. The current review provides a detailed study of mixed-valence MOFs, including their fundamental properties, synthesis challenges, and characterization methods. The outstanding applicability of these materials in diverse fields such as energy storage, catalysis, sensing, gas sorption, separation, etc. is also discussed, providing a roadmap for future design strategies to exploit mixed valency in advanced materials. Interestingly, mixed-valence MOFs have demonstrated fascinating features in practical fields compared to their homo-valence MOFs, resulting from an enhanced synergy between mixed-valence states within the framework.

Enhanced water-resistant performance of Cu-BTC through polyvinylpyrrolidone protection and its capture ability evaluation of methylene blue

Water instability issues greatly restrict the application of Cu-BTC for cationic dye (e.g. methylene blue (MB)) capture from wastewater.

Thermochemical Investigation of Oxyanion Coordination in a Zirconium-Based Metal-Organic Framework

Porous materials possess high internal surface areas and void fractions that make them valuable in several applications, including gas storage, heterogeneous catalysis, and water purification. Despite the plentiful effort allocated to porous materials research annually, few methods exist to directly monitor and characterize chemical events occurring within a pore's confines. The crystalline nature of zeolites, covalent organic frameworks (COFs), and metal-organic frameworks (MOFs) permit structural characterization by X-ray diffraction; yet, quantifying the thermodynamics of chemical processes and transformations remains tedious and error ridden. Herein, we employ isothermal titration calorimetry (ITC) to determine the full thermodynamic profile of oxyanion adsorption in a zirconium-based MOF, NU-1000. To further validate this method, which we recently introduced to the field, we replicated ITC experiments as bulk adsorption measurements to demonstrate the correlation between the extracted stoichiometric parameter from ITC thermograms and the MOF uptake capacity. Moreover, based on the calculated association constants, we accurately predicted which analytes might be able to displace others. For example, dihydrogen phosphate can displace selenate and sulfate because of its higher association constant (ΔGphosphate = -5.41 kcal/mol; ΔGselenate = -4.98 kcal/mol; ΔGsulfate = -4.77 kcal/mol). We monitored the exchange processes by titrating oxyanion-functionalized MOF samples with a more strongly binding analyte.