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The therapeutic application of drugs often faces challenges due to non-specific distribution, inadequate dosification and degradation, which limits their efficacy. Two primary strategies are employed to overcome these issues: the use of derivatives of the active substances and incorporation of those into porous materials. The latter, involving materials such as zeolites, metal–organic frameworks (MOFs), and hydrogels, has shown promising results in protecting the active ingredients from degradation and enabling a controlled release. This study focuses on supramolecular metal–organic frameworks (SMOFs), which leverage supramolecular interactions for enhanced pore size control. [Cu6Cr(μ-adeninato-κN3:κN9)6(μ3-OH)6(μ-OH2)6](SO4)1.5·nH2O (Cu6Cr) was chosen for its flexible porous structure, water-stability, and paramagnetic properties. Magnetic sustentation studies showed that this compound was able to capture several drug molecules: 5-fluorouracil (5-FU), 5-aminosalicylic acid (5-ASA), 4-aminosalicylic acid (4-ASA) and theophylline (THEO). Their release follows a pseudo-first-order kinetics with desorption half-lives ranging from 2.2 to 4.7 hours. In this sense, a novel approach is proposed using bulkier raffinose and cholesterol as pore-blocking molecules. Cholesterol exhibited the best performance as a blocking molecule increasing the desorption half-life up to 8.2 hours. Cytotoxicity and RNA-seq transcriptomic assays carried out on human colorectal cancer cell cultures showed, on one hand, that the Cu6Cr porous material exhibits a proliferative effect, probably coming from the over-expression of MIR1248 and SUMO2 genes, and on the other hand, that there is a delay in the emergence of the cytotoxicity of 5-FU as expected for a slower release. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and photocatalytic hydrogen evolution reaction (HER) performance of a series of metal–organic gels (MOGs) constructed from titanium(IV)-oxo clusters and dicarboxylato linkers (benzene-1,4-dicarboxylato and 2-aminobenzene-1,4-dicarboxylato) are described. All the MOGs exhibit a microstructure comprised of metal–organic nanoparticles intertwined into a highly meso-/macroporous structure, as demonstrated by cryogenic transmission electron microscopy and gas adsorption isotherms. Comprehensive chemical characterization enabled the estimation of the complex formula for these defective materials, which exhibit low crystallinity and linker vacancies. To gain deeper insights into the local structure, X-ray absorption fine structure (XAFS) spectroscopy experiments were performed and compared to that of the analogous crystalline metal–organic framework. Additionally, the ultraviolet–visible absorption properties and optical band gaps were determined from diffuse reflectance spectroscopy data. The MOGs were studied as light absorbers for the sacrificial photocatalytic HER under simulated solar light irradiation using a platinum co-catalyst by either (1) in situ photodeposition or (2) ex situ doping process, through a post-synthetic metalation of the MOG structure. The chemical analysis of the metalation, along with high-angle annular dark-field scanning transmission electron microscopy, revealed that although the in situ addition of the co-catalyst led to greater HER rates (227 vs. 110 μmolH2 gMOG−1 h−1 for in situ and ex situ, respectively), the ex situ modification provided a finer distribution of platinum nanoparticles along the porous microstructure and, as a result, it led to a more efficient utilization of the co-catalyst (45 vs. 110 mmolH2 gPt−1 h−1). [ABSTRACT FROM AUTHOR]

The present study explores the effect of local symmetry breaking of globular cations on the formation and properties of hybrid organic–inorganic materials based on tetrahalometallate anions. To this end, a crystal engineering approach was employed to design and synthesize three novel compounds, namely (quinuclidinium)2[CoCl4] (A), ((R,S)-3-aminoquinuclidinium)[CoCl4] (B) and ((R)-(−)-3-hydroxyquinuclidinium)2[CoCl4] (C). The thermal, structural, magnetic and electrical properties of these compounds were investigated using a comprehensive array of characterization techniques, including differential scanning calorimetry, single crystal X-ray diffraction, variable temperature synchrotron X-ray powder diffraction, and powder and single crystal neutron diffraction. Our results demonstrate that compounds A and C exhibit a structural phase transition above 322 and 340 K, respectively, resulting in a mesophase-like state featured by a sharp dielectric anomaly, which is attributed to the molecular dynamics of the organic cations in their rotational state. Moreover, compound C also displays an additional crystal phase transition at around 200 K as a result of the formation of a superstructure along the c-axis direction. On the other hand, compound B shows a possible diffusion phenomenon around 350 K related to dielectric permittivity changes. In terms of magnetic behaviour, all the compounds present antiferromagnetic interactions between tetrachloridocobaltate anions without long-range magnetic ordering down to 2 K. Overall, this study provides valuable insights at the molecular level into the impact of local symmetry breaking of the quinuclidinium cation in combination with the synergistic effect of the tetrachloridocobaltate anion on the structural, magnetic and dielectric properties, thus contributing to the progress of cutting-edge functional hybrid organic–inorganic materials. [ABSTRACT FROM AUTHOR]

The recovery of alcohols from low-concentration aqueous solutions is of great interest due to the wide use of alcohols in industrial processes. In this regard, adsorption-based separation is considered a green and cost-effective alternative towards high-energy demanding processes, which have been traditionally used in the separation of alcohol/water mixtures. Therefore, in this work, the recovery of different alcohols (methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, and tert-butyl alcohol) from water has been studied based on the adsorptive separation properties of a very flexible metal–organic framework (MOF): MIL-88A(Fe). The adsorption capacity of the material has been studied for different alcohols by the magnetic sustentation technique taking advantage of the paramagnetic iron(III) metal centers in the structure. Interestingly, the competitive adsorption studies between different alcohols aqueous mixtures (methanol/tert-butyl alcohol, methanol/isopropyl alcohol and n-butyl alco-hol/tert-butyl alcohol) revealed the dominance of hydrophobicity of the alcohol over the size and shape factor, resulting in higher preference toward the alcohols with higher number of carbons. In addition, theoretical studies were carried out in order to have a deeper understanding of the adsorptive performance of MIL-88A(Fe), which demonstrated that framework flexibility and diffusion play a key role in alcohol adsorption. PVDF@MIL-88A(Fe) membranes with different MOF loadings were prepared to address the processability aspect of MOF powder. The synergetic contributions from PVDF and MIL-88A(Fe) resulted in a higher adsorption capacity of the composite material compared to the performance of each component, independently. Such systematic and strategic utilization of flexible MOFs can provide a promising platform for challenging alcohol separation from water and environmental remediation technologies. [ABSTRACT FROM AUTHOR]