An ultra-stable PHOS-100(Hf) is reported as an ideal MOF platform for proton conductivity test loading with various guest molecules/ions, as it has excellent chemical and thermal stability.

The material for managing and monitoring waste made from the waste itself is an excellent example of cyclic utilization, which could reduce issues and be more sustainable. A three-dimensional porous uranyl phosphonate MOF (UPF-105) was synthesized via a hydrothermal method. UPF-105 is stable in aqueous solution with pH in the range of 1−11 and maintains crystallinity below 215 °C. The uncoordinated phosphonate groups in the channels act as functional anchors to selectively capture uranyl ions, with a maximum uranium adsorption capacity of 170.23 mg g −1 . The fluorescence of UPF-105 makes it a good candidate for a uranyl ion sensor in uranium-contaminated solutions with concentrations in the range of 5−90 ppm.

Regulating the porosity of metal phosphonate frameworks is still challenging, even though this is not an issue for carboxylate-based metal−organic frameworks (MOFs). Quaternary ammonium cations are common template reagents widely used for structure control. However, it is not successful for uranyl phosphonate frameworks (UPFs) because the large volume sizes of templates make it challenging to enter the channels constructed by phosphonate ligands with small pore sizes and low dimensions. In this work, three new porous three-dimensional UPFs were synthesized using the phosphonate ligand and template reagents with the same geometry, namely, (TEA) 2 (UO 2 ) 3 (TppmH 4 ) 2 • 2H 2 O (UPF-106), (TPA) 2 (UO 2 ) 3 (TppmH 4 ) 2 (UPF-107), and (TBA) 2 (UO 2 ) 5 (TppmH 2 ) 2 (H 2 O) 2 •4H 2 O (UPF-108). The porosity of the UPFs in this work showed a positive relation with the sizes of the template ammonium cations. Thermogravimetric analysis and infrared and ultraviolet spectroscopy were performed. The variable-temperature fluorescence spectra of the three compounds showed that the fluorescence intensity has an excellent relation to temperature with a potential application as fluorescence temperature sensors.

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