Cu₃(BTC)₂ with an incorporated Keggin polyoxometalate was demonstrated to be stable under steaming conditions up to 483 K, while the isostructural HKUST-1 degrades and transforms into [Cu₂OH(BTC)(H₂O)]_n·2nH₂O from 343 K onwards.

HKUST-1 is one of the popular metal–organic frameworks (MOFs). The formation of this MOF is significantly accelerated by adding Keggin polyoxometalate anions to the synthesis solution. In this paper the chemistry behind this observation was investigated. Upon addition of Keggin type H₃PW₁₂O₄₀ heteropolyacid the speciation of Cu²⁺ cations in ethanol : H₂O mixture drastically changes. Combining EPR and XANES measurements with accurate pH measurements and prediction of Cu²⁺ hydrolysis provides strong evidence for surface induced hydrolysis and consequent dimerisation of monomeric Cu²⁺ species on Keggin ions in acidic conditions. This enables paddle wheel formation, hence explaining the instantaneous precipitation of Cu₃(BTC)₂ at room temperature and the systematic encapsulation of Keggin ions in its pores.

Self-supported oligo-layered ZnAlEu LDH nanotubes (∅ 20 nm) self-assemble upon controlled hydrolysis of the metal ions (Zn²⁺, Al³⁺, Eu³⁺) in the presence of 1,3,5-benzenetricarboxylate anions and non-ionic worm-like micelles. Their high surface area and easily accessible cylindrical mesopores (175 m² g⁻¹; 0.75 cm³ g⁻¹) facilitate interaction with 5 nm CdTe quantum dots, enhancing the overall luminescence behavior.

Layered double hydroxides (LDHs) containing Eu³⁺ activators were synthesized by coprecipitation of Zn²⁺, Al³⁺, and Eu³⁺ in alkaline NO₃⁻-rich aqueous solution. Upon calcination, these materials transform into a crystalline ZnO solid solution containing Al and Eu. For suitably low calcination temperatures, this phase can be restored to LDH by rehydration in water, a feature known as the memory effect. During rehydration of an LDH, new anionic species can be intercalated and functionalized, obtaining desired physicochemical properties. This work explores the memory effect as a route to produce luminescent LDHs intercalated with 1,3,5-benzenetricarboxylic acid (BTC), a known anionic photosensitizer for Eu³⁺. Time-dependent hydration of calcined LDHs in a BTC-rich aqueous solution resulted in the recovery of the lamellar phase and in the intercalation with BTC. The interaction of this photosensitizer with Eu³⁺ in the recovered hydroxide layers gave rise to efficient energy transfer from the BTC antennae to the Eu³⁺ ions, providing a useful tool to monitor the rehydration process of the calcined LDHs.