Small Molecules Research Articles

A Water Channel-like Structure Self-Assembled by Nucleosides.

As artificial water channels have received widespread attention, various types of artificial water channels have been reported. However, apart from I-quartet channels, the development of 1D water channels with water wires constructed from small molecules has rarely been reported, because of the difficulty in precisely tuning the dipolar water molecules. Inspired by G-quartet functionalization strategies, this study explored C8 modifications of our previously reported molecule, 2-amino-2'-fluoro-2'-deoxyadenosine (2FA), known for its strong hydration properties and self-assembly capabilities, and investigated its potential for constructing nucleoside-based water channel-like structures. Among all derivatives, 2-amino-8-(4-aminophenyl)-2'-deoxy-2'-fluoro-D-adenosine can form an S-shaped channel as a tetramer, incorporating water wire arrays in the solid state. Such water channel-like structures in nucleoside self-assemblies provide new insights into the development of novel nucleoside-based supramolecular water channel materials.

The role of loading-induced convection versus diffusion on the transport of small molecules into the intervertebral disc.

Limited nutrient transport is hypothesized to be involved in intervertebral disc (IVD) degeneration. It is widely recognized that the dominant mode of transport of small molecules such as glucose is via diffusion, rather than convection. However, recent findings suggest a role for convection-induced by fast (motion-related) and slow (diurnal) dynamic loading in molecular transport of even such small solutes. The aim of this study was to investigate whether fluid exchange induced by simulated physiological loading (composed of both fast cyclic or slower diurnal loading) can influence the molecular transport of a small molecule through the cartilage endplate (CEP) into the nucleus pulposus (NP) of IVDs. The molecular transport of fluorescein through the CEP and into the NP was studied in a bovine CEP/NP explant model and loading was applied by an axial compression bioreactor. The loaded explants (convection and diffusion) were compared to unloaded explants (diffusion alone). In the initial 24h, there were no differences between loaded and unloaded explants, indicating that convection did not enhance molecular transport of small solutes over diffusion alone. Notably, after 48h which corresponds to two complete diurnal cycles of tissue compression, fluid exudation/imbibing and redistribution, the fluorescein concentration was significantly increased in the top and bottom layer of the explant, when compared to the unloaded explant. Slower diurnal cyclic compression of the IVD might enhance the transport of small molecules into the IVD although it could not be discerned whether this was due to diffusion/convection or a combination.

Efficient Selection of the 2,4-Dichlorophenoxyacetic Acid Nanobody Gene from the Phage Library Constructed with Sorted Specific Cells and Expression in Plants to Confer Herbicide Resistance.

Immunomodulation in biotechnological processes requires an adequate level of specific, high-affinity recombinant antibodies expressed in the affected cells. Here, we report a new strategy to obtain a sensitive nanobody against the 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide. Unlike the previous methods that used total peripheral blood lymphocytes, specific peripheral lymphocytes stained with a fluorescein isothiocyanate-labeled 2,4-D coating antigen were isolated via fluorescence-activated cell sorting and used for phage display library construction. This strategy significantly reduced interference of anticarrier protein nanobody phages to small-molecule nanobody development and required only two cycles of panning to obtain the desired positive clones. Nb4-11, one of the most sensitive phage clones, showed good sensitivity and specificity against 2,4-D. Compared with previously reported 2,4-D nanobodies, the sequence of Nb4-11 exhibited completely different complementarity-determining regions (CDRs). The half-maximum inhibition concentration of the Nb4-11-based ic-ELISA was 29.3 ± 1.9 ng/mL. The Nb4-11 gene was subsequently transferred into Arabidopsis thaliana to confer herbicide resistance, and homozygous transgenic T3 lines were obtained. Stable expression of the 2,4-D nanobody in the model plant was confirmed via PCR, ic-ELISA, and Western blot analysis. In the dose-response bioassay, the transgenic T3 lines were resistant to 2 g of 2,4-D ai/ha. This work offers a new way to sort specific peripheral lymphocytes, efficiently develop nanobodies against small molecules, and create a novel mechanism for herbicide resistance based on the expression of nanobodies in plants.

Smad1 Promotes Tumorigenicity and Chemoresistance of Glioblastoma by Sequestering p300 From p53.

Acetylation is critically required for p53 activation, though it remains poorly understood how p53 acetylation is regulated in glioblastoma (GBM). This study reveals that p53 acetylation is a favorable prognostic marker for GBM, regardless of p53 status, and that Smad1, a key negative regulator of p53 acetylation, is involved in this process. Smad1 forms a complex with p53 and p300, inhibiting p300's interaction with p53 and leading to reduced p53 acetylation and increased Smad1 acetylation in GBM. This results in enhanced tumor growth and resistance to chemotherapy, particularly in tumors with missense mutant p53. Acetylation of K373 is found to be essential for Smad1's oncogenic function but does not confer chemoresistance in the absence of p53. Through molecular docking, it is discovered that Smad1 and p53 both interact with the acetyltransferase domain of p300, but at different amino acid sites. Disturbing the interface of Smad1 through amino acid mutations abolishes the Smad1-p300 complex and promotes p53 acetylation. Therefore, a small molecule is identified through virtual screening that specifically disrupts the Smad1-p300 interaction, offering a promising strategy for inhibiting GBM and increasing chemosensitivity by inhibiting Smad1 acetylation and restoring p53 acetylation.

Effect of Confinement on the Translational Diffusivity of Small Dye Molecules in Thin Polystyrene Films and Its Connection to Tg-Confinement and Fragility-Confinement Effects.

Using fluorescence, we study the impact of nanoscale confinement on the translational diffusivity (D) of trace levels of a small-molecule dye, 9,10-bis(phenylethynyl)anthracene (BPEA), in supported polystyrene (PS) films via Förster resonance energy transfer (FRET). Reductions in BPEA diffusivity are observed in films thinner than ∼200 nm, with D decreasing by 80-90% in 100 nm-thick films compared to bulk. The activation energy of BPEA diffusivity increases from ∼210 kJ/mol in bulk films to ∼370 kJ/mol in 130 nm-thick films. BPEA exhibits a greater diffusivity-confinement effect than a larger dye, decacyclene, in terms of the length scale at which the effects of confinement become evident and the percentage reduction in diffusivity. For both BPEA and decacyclene, the diffusivity-confinement effect in supported PS films occurs at a length scale much larger than that for the glass transition temperature (Tg)-confinement effect and somewhat larger than that for the fragility-confinement effect. This difference in confinement-effect length scales can be rationalized as follows: small-molecule dye diffusivity relates predominantly to short times in the α-relaxation distribution, whereas Tg relates to long times in the α-relaxation distribution, and fragility reflects the overall breadth of this relaxation time distribution. If confinement results in a narrower relaxation time distribution in PS films with the short-time relaxations being shifted to longer times and the longest-time relaxation regimes being shifted to shorter times, then Tg, diffusivity, and fragility all decrease at sufficient levels of confinement. If the narrowing with confinement begins with the shortest relaxation time regimes, then fragility and small-molecule dye diffusivity are influenced by confinement at larger length scales than Tg.

Combining crystallographic and binding affinity data towards a novel dataset of small molecule overlays

Although small molecule superposition is a standard technique in drug discovery, a rigorous performance assessment of the corresponding methods is currently challenging. Datasets in this field are sparse, small, tailored to specific applications, unavailable, or outdated. The newly developed LOBSTER set described herein offers a publicly available and method-independent dataset for benchmarking and method optimization. LOBSTER stands for “Ligand Overlays from Binding SiTe Ensemble Representatives”. All ligands were derived from the PDB in a fully automated workflow, including a ligand efficiency filter. So-called ligand ensembles were assembled by aligning identical binding sites. Thus, the ligands within the ensembles are superimposed according to their experimentally determined binding orientation and conformation. Overall, 671 representative ligand ensembles comprise 3583 ligands from 3521 proteins. Altogether, 72,734 ligand pairs based on the ensembles were grouped into ten distinct subsets based on their volume overlap, for the benefit of introducing different degrees of difficulty for evaluating superposition methods. Statistics on the physicochemical properties of the compounds indicate that the dataset represents drug-like compounds. Consensus Diversity Plots show predominantly high Bemis–Murcko scaffold diversity and low median MACCS fingerprint similarity for each ensemble. An analysis of the underlying protein classes further demonstrates the heterogeneity within our dataset. The LOBSTER set offers a variety of applications like benchmarking multiple as well as pairwise alignments, generating training and test sets, for example based on time splits, or empirical software performance evaluation studies. The LOBSTER set is publicly available at https://doi.org/10.5281/zenodo.12658320, representing a stable and versioned data resource. The Python scripts are available at https://github.com/rareylab/LOBSTER, open-source, and allow for updating or recreating superposition sets with different data sources. Graphical abstractSimplified illustration of the LOBSTER dataset generation.

Macromolecular crowding and bicarbonate enhance the hydrogen peroxide-induced inactivation of glyceraldehyde-3-phosphate dehydrogenase.

The active site Cys residue in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is sensitive to oxidation by hydrogen peroxide (H2O2), with this resulting in enzyme inactivation. This re-routes the carbon flux from glycolysis to the pentose phosphate pathway favoring the formation of NADPH and synthetic intermediates required for antioxidant defense and repair systems. Consequently, GAPDH inactivation serves as a redox switch for metabolic adaptation under conditions of oxidative stress. However, there is a major knowledge gap as to how GAPDH is efficiently oxidized and inactivated, when the increase in intracellular H2O2 is modest, and there is a high concentration of alternative (non-signaling) thiols and efficient peroxide removing systems. We have therefore explored whether GAPDH inactivation is enhanced by two factors of in vivo relevance: macromolecular crowding, an inherent property of biological environments, and the presence of bicarbonate, an abundant biological buffer. Bicarbonate is already known to modulate H2O2 metabolism via formation of peroxymonocarbonate. GAPDH activity was assessed in experiments with low doses of H2O2 under both dilute and crowded conditions (induced by inert high molecular mass polymers and small molecules), in both the absence and presence of 25 mM sodium bicarbonate. H2O2-induced inactivation of GAPDH was observed to be significantly enhanced under macromolecular crowding conditions, with bicarbonate having an additional effect. These data strongly suggest that these two factors are of major importance in redox switch mechanisms involving GAPDH (and possibly other thiol-dependent systems) within the cellular environment.

Photothermal Laser Printing of Sub-Micrometer Crystalline ZnO Structures.

During light-driven 3D additive manufacturing, an object represented in digital form is initially translated into a spatial distribution of light intensity (sequentially or in parallel), which then results in a spatial material distribution. To date, this process typically proceeds by photoexcitation of small functional molecules, leading to photochemically induced crosslinking of soft materials. Alternatively, thermal triggers can be employed, yet thermal processes are often slow and provide only low spatial localization. Nevertheless, sub-micrometer ZnO structures for functional microelectronic devices have recently been laser-printed. Herein, the photothermal laser-printing of ZnO is advanced by i) introducing single-crystalline rather than amorphous sub-micrometer ZnO shapes that crystallize in the hexagonal ZnO wurtzite structure, ii) employing dimethyl sulfoxide (DMSO) instead of water, enabling higher local process temperatures without micro-bubble formation, and iii) using substrates tailored for light absorption and heat management, resolving the challenge of light to heat conversion. Finally, the herein-demonstrated ZnO printing requires no post-processing and is a cleanroom-free technique for the fabrication of crystalline semiconductors.

Chromosome 1 Alterations in Multiple Myeloma: Considerations for Precision Therapy.

Multiple myeloma (MM) is an incurable blood malignancy characterized by the clonal expansion of plasma cells and the secretion of monoclonal immunoglobulins. High-risk MM, defined by specific cytogenetic abnormalities, poses significant therapeutic challenges and is associated with inferior survival outcomes compared to standard-risk disease. Although molecularly targeted therapies have shown efficacy in other hematologic malignancies, currently venetoclax is the only targeted therapy approved for MM (t(11;14)). However, chromosome 1q gains, amplifications, and 1p deletions are frequently observed in MM, and have been linked to drug resistance and poor patient prognosis. Accordingly, this review focuses on emerging MM precision therapies capable of targeting dysregulated genes within these regions. It addresses gene therapies, small molecule inhibitors and monoclonal antibodies currently under investigation to antagonize oncogenic drivers including MCL-1, BCL9, F11R, and CKS1B, all of which are implicated in cell survival, proliferation or drug resistance. In conclusion, the link between chromosome 1 abnormalities and high-risk disease in MM patients offers a compelling rationale to identify and explore therapeutic targeting of chromosome 1 gene products as a novel precision medicine approach for a poorly served patient population.

Imidazole Encapsulation Enabled by Confinement for I2 and CH3I Coremoval.

Nitrogen-rich small molecules are frequently doped into porous materials to enhance their iodine adsorption properties. To explore how imidazole confinement in metal-organic frameworks (MOFs) affects iodine adsorption, we obtained a UiO-66-based composite by embedding imidazole in UiO-66 pores via solid-phase adsorption (Im@UiO-66). Characterization confirmed that imidazole was successfully confined within the UiO-66 pores, with each unit of UiO-66 accommodating up to 27 imidazole molecules. The density functional theory (DFT) calculations suggested that the octahedral cages of UiO-66 are the primary sites for iodine capture. The adsorption studies revealed that Im@UiO-66 achieved maximum adsorption capacities for I2 and CH3I that were 12 and 7.9 times higher than those of UiO-66, respectively, reaching 6.42 g/g for I2 and 553 mg/g for CH3I. The spectroscopic analysis indicated that Im@UiO-66 absorbed iodine vapor and methyl iodide via charge-transfer interactions and N-methylation reactions. This study demonstrates that imidazole confinement can effectively enhance the adsorption performance of MOF-based materials, offering valuable insights for the design of iodine adsorbents.

Atomic-Scale Tailoring C-N Coupling Sites for Efficient Acetamide Electrosynthesis over Cu-Anchored Boron Nitride Nanosheets.

Electrochemical conversion of carbon and nitrogen sources into valuable chemicals provides a promising strategy for mitigating CO2 emissions and tackling pollutants. However, efficiently scaling up C-N products beyond basic compounds like urea remains a significant challenge. Herein, we upgrade the C-N coupling for acetamide synthesis through coreducing CO and nitrate (NO3-) on atomic-scale Cu dispersed on boron nitride (Cu/BN) nanosheets. The specific form of Cu, such as single atom, nanocluster, and nanoparticles, endows Cu/BN different adsorption capacity for CO and NO3-, thereby dictating the catalytic activity and selectivity for acetamide formation. The Cu nanocluster-anchored BN (Cu NCs/BN) catalyst achieves an industrial-level current density of 178 mA cm-2 for the C-N coupling reaction and an average acetamide yield rate of 137.0 mmol h-1 gcat.-1 at -1.6 V versus the reversible hydrogen electrode. Experimental and theoretical analyses uncover the pivotal role of the strong electronic interaction between Cu nanoclusters and BN, which activates CO and NO3-, facilitates the formation of key *CCO and *NH2 intermediates, and expedites the C-N coupling pathway to acetamide. This work propels the development of atomic structure catalysts for the efficient conversion of small molecules to high-value chemicals through electrochemical processes.

Renally Excretable Molybdenum Disulfide Nanoparticles as Contrast Agents for Dual-Energy Mammography and Computed Tomography.

Compared with conventional mammography, contrast-enhanced dual-energy mammography (DEM) can improve tumor detection for people with dense breasts. However, currently available iodine-based contrast agents have several drawbacks such as their contraindication for use with renal insufficiency, high-dose requirement, and suboptimal contrast production. Molybdenum disulfide nanoparticles (MoS2 NPs) have been shown to attenuate X-rays due to molybdenum's relatively high atomic number while having good biocompatibility. However, work exploring their use as X-ray contrast agents has been limited. In this study, we have developed a novel aqueous synthesis yielding ultrasmall, 2 nm MoS2 NPs with various small molecule coatings, including glutathione (GSH), penicillamine, and 2-mercaptopropionic acid (2MPA). These nanoparticles were shown to have low in vitro cytotoxicity when tested with various cell lines at concentrations up to 1 mg/mL. For the first time, these particles were shown to generate clinically relevant contrast in DEM. In DEM, MoS2 NPs generated higher contrast than iopamidol, a commercially available X-ray contrast agent, while also generating substantial contrast in CT. Moreover, MoS2 NPs demonstrated rapid elimination in vivo, mitigating long-term toxicity concerns. Together, the results presented here suggest the potential utility of MoS2 NPs as a dual-modality X-ray contrast agent for DEM and CT.

The promising role of proteomes and metabolomes in defining the single-cell landscapes of plants.

The plant community has a strong track record of RNA sequencing technology deployment, which combined with the recent advent of spatial platforms (e.g. 10× genomics) has resulted in an explosion of single-cell and nuclei datasets that can be positioned in an in situ context within tissues (e.g. a cell atlas). In the genomics era, application of proteomics technologies in the plant sciences has always trailed behind that of RNA sequencing technologies, largely due in part to upfront cost, ease-of-use, and access to expertise. Conversely, the use of early analytical tools for characterizing small molecules (metabolites) from plant systems predates nucleic acid sequencing and proteomics analysis, as the search for plant-based natural products has played a significant role in improving human health throughout history. As the plant sciences field now aims to fully define cell states, cell-specific regulatory networks, metabolic asymmetry and phenotypes, the measurement of proteins and metabolites at the single-cell level will be paramount. As a result of these efforts, the plant community will unlock exciting opportunities to accelerate discovery and drive toward meaningful translational outcomes.

Biochemical basis and therapeutic potential of mitochondrial uncoupling in cardiometabolic syndrome.

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria, allowing for adjustments in cellular energy metabolism to maintain metabolic homeostasis. Small molecule uncouplers have been extensively studied for their potential to increase metabolic rate, and recent research has focused on developing safe and effective mitochondrial uncoupling agents for the treatment of obesity and cardiometabolic syndrome (CMS). Here, we provide a brief overview of CMS and cover the recent mechanisms by which chemical uncouplers regulate CMS-associated risk-factors and comorbidities, including dyslipidemia, insulin resistance, steatotic liver disease, type 2 diabetes, and atherosclerosis. Additionally, we review the current landscape of uncoupling agents, focusing on repurposed FDA-approved drugs and compounds in advanced preclinical or early-stage clinical development. Lastly, we discuss recent molecular insights by which chemical uncouplers enhance cellular energy expenditure, highlighting their potential as a new addition to the current CMS drug landscape, and outline several limitations that need to be addressed before these agents can successfully be introduced into clinical practice.

Development and In-Vitro Evaluation of Doxorubicin-Loaded Methacrylate Gelatin (GelMa)-Acrylamide Hydrogels for the Treatment of Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) is the most prevalent subtype of malignant mesothelioma that affects the pleural lining of the lungs. Conventionally, chemotherapy via systemic injections has shown limited efficacy due to off-target effects, and inefficacious deposition at the disease site. In our previous study, we reported the development and optimization of UV-initiated methacrylate gelatin (GelMa)-acrylamide based hydrogel formulation for local intracavitary administration of therapies. The current study utilizes a pre-established GelMa formulation for delivering a small molecule chemotherapeutic agent, Doxorubicin (Dox), against in-vitro MPM models. Dox-loaded hydrogel (DLH) precursor solution was prepared by dissolving Dox in the precursor solution. The gels were characterized for physical properties such as gelling time, swelling index, bio adhesion, and injectability and were compared to blank hydrogels. Dox-loaded hydrogels were also tested for therapeutic efficacy in MPM cells in various 2D and 3D cell culture models. It was revealed that Dox-loaded hydrogels retained similar physical properties, including gelling time (< 25s), swelling index (~ 1,200%), bio-adhesion (> 20g detachment force), and injectability (< 2N force for injecting precursor), compared to blank hydrogels. Moreover, the gel formulation effectively sustained the release of hydrophilic Dox HCl over a period of 12days by increasing the degree of crosslinking between GelMa and its crosslinkers. Further, the therapeutic efficacy of Dox was retained even after loading into hydrogels, indicating that no chemical interactions took place between gel excipients and the drug. Studies in MPM cell-based models revealed that DLH showed excellent potential in inhibiting 2D and 3D cell growth, with DLH being more effective than plain Dox in suppressing tumor growth in 3D spheroid models. Overall, the results of the present study suggest that Dox-loaded hydrogels (DLH) may be a good candidate for efficacy study in preclinical mesothelioma models, with strong potential for clinical translation.

Changes in the small-molecule fingerprints of rice planted near an industrial explosion site in Taiwan.

A fire and explosion accident at a petrochemical complex sparked concerns over the rice health and production in nearby paddy fields. To unveil the potential effects, this study investigated small molecule changes in rice harvested in nearby counties using non-target analysis. Rice grains were harvested three, eight, 15, and 20months after the accident from a total of ten townships. Small-molecule (m/z 70-1100) data in brown rice (n = 27) were acquired using high-resolution mass spectrometry (HRMS). Partial least squares discriminant analysis (PLS-DA) models were constructed to illustrate the temporal and spatial trends of rice's small-molecule fingerprints, and markers of production locations were identified. The small-molecule fingerprint in the rice directly exposed to the accident and harvested three months after the explosion differed significantly from those planted after the accident (PLS-DA model Q2 = 0.943, Q2/R2Y = 0.962), probably indicating the exclusion of long-term effects. Besides, in the rice directly exposed to the accident, the rice collected from near the explosion site (< 15km) exhibited reduced jasmonic acid and increased imidacloprid levels (log2 fold change: -1.53 and 5.46, respectively), compared to that from farther locations. The result would suggest compromised disease defence in rice grown under the stress of explosion. In addition, lipid and amino acid metabolism perturbations are deemed relevant to plant development.

Assessing Exchange-Correlation Functionals for Accurate Densities of Solids.

The success of Kohn-Sham density functional theory in predicting electronic properties from first-principles is key to its ubiquitous presence in condensed matter research. Central to this theory is the exchange-correlation functional, which can only be written in an approximate form using a handful of exact constraints. A recent criticism of these approximations is that they are designed to give an accurate description of the energy at the expense of a poor representation of the density, which is contrary to the spirit of density functional theory. These conclusions are drawn from studies of atoms or small molecules, where exact results are available. To shed light on this issue, we use the almost exact densities and energies of three prototypical solids (a semiconductor, silicon, an insulator, sodium chloride, and a metal, copper) to compare the performance of exchange-correlation functionals from all rungs of Jacob's ladder. By examining their errors in reproducing both energy and density, we show that several hybrids and semilocal functionals perform consistently well. Furthermore, functionals built to reproduce exact constraints tend to be among the top performers for all tested material classes, strengthening the argument for using these constraints in functional construction. On average, functionals published up to the early 2000s simultaneously improve the prediction of both densities and energies. This is often not the case for more recent functionals, although errors in energy and density continue to evolve in a correlated manner.

Rings of Power: Controlling SOD Mimic Activity by the Addition of Pyridine Rings within the Pyridinophane Scaffold.

Superoxide dismutase enzymes are a major defense against superoxide, which is a potent reactive oxygen species. Misregulation of reactive oxygen species and subsequent neuronal damage are etiological hallmarks of neurodegenerative disease. Macrocyclic small molecules have offered inroads toward functional SOD1 mimics. Herein, we report a series of five tetra-aza macrocyclic RPy2N2 ligands, varied by 4-position substitution of the pyridine ring with both electron-donating (R = OMe) and withdrawing groups (R = Cl, I, and CF3) to offer the first comparison to well-studied RPyN3 congeners and other mimics in the literature. New ligands have been characterized by NMR, mass spectrometry, elemental analysis, and potentiometric titrations (pKa). Cyclic voltammetry and X-ray diffraction analysis of the copper(II) complexes (CuII(RPy2N2)2+) demonstrate how pyridine substitution impacts the metal center. This data, and evaluation of the log βCu(II) and log βCu(I) within the series, indicates significant improvement to the binding affinity for Cu(I) without sacrifice of Cu(II) binding. The CuII(RPy2N2)2+ series yield the highest kcat for any Cu(II)-based small molecule functional SOD1 mimic (kcat = 45.36 M-1 s-1). Furthermore, the CuII(OMePy2N2)2+ and CuII(CF3Py2N2)2+ complexes were studied in FRDA cells to determine cell toxicity as a first step toward the application of these mimics as therapeutics for neurological disease.

Enhancing Permanence of Corrosion Inhibitors Within Acrylic Protective Coatings for Outdoor Bronze Using Green Nanocontainers

Outdoor bronze statues are constantly exposed to weather conditions and reactive compounds in the atmosphere that can interact with their surfaces. To avoid these interactions, a commonly used method is the application of coatings with corrosion inhibitors. However, a significant limitation of these inhibitors is their gradual loss over time. In this study, we aimed to improve the durability of 5-ethyl-1,3,4-thiadiazol-2-amine (AEDTA), the inhibitor chosen to formulate new acrylic coatings for outdoor bronzes. Methyl-β-cyclodextrin (Me-β-CD) was selected to host the inhibitor due to the capability of cyclodextrins to form complexes incorporating small organic molecules. The complexes of Me-β-CD and AEDTA were prepared and the inclusion of AEDTA was proved by Fourier-transform infrared spectroscopy, X-ray diffraction and nuclear magnetic resonance spectroscopy. Then, acrylic coatings were prepared at different concentrations of the Me-β-CD/AEDTA system. They were thermally aged and monitored every 24 h. To evaluate the volatilization of the corrosion inhibitor, solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) and thermal desorption-GC/MS (TD-GC/MS) analyses were performed during the first 72 h. The results were compared to those of pure AEDTA films and Incralac®. The outcomes showed that Me-β-CD/AEDTA complexes are promising candidates for developing coatings with improved stability and longer retention of AEDTA.

Selective Gas Adsorption in Permanently Microporous Coordination Cages with Exposed Metal Sites.

Porous coordination cages (PCCs), molecular analogs of metal-organic frameworks, offer modular platforms for studying the adsorption properties of small molecules, with coordinatively unsaturated metal centers playing a pivotal role in tuning these behaviors. In this work, we present the synthesis, activation, and detailed gas adsorption studies of second-row transition metal-based M24L24 cuboctahedral cages, specifically Mo24(bdc)24, Rh24(bdc)24, and [Ru24(bdc)24]Cl12. These materials represent rare examples of Mo-, Rh-, and Ru-based hybrid porous solids. The synthesis and activation of these cages were optimized to maximize porosity, yielding BET surface areas of up to 832 m2/g. Gas adsorption studies with CO2 and CO reveal distinctive uptake behaviors linked to the metal cations, with Mo24(bdc)24 demonstrating the highest gravimetric CO2 uptake (2.12 mmol/g at 298 K) and [Ru24(bdc)24]Cl12 exhibiting the strongest CO binding (-75 kJ/mol). Additionally, we explore the selective adsorption of unsaturated hydrocarbons, such as ethylene and propylene, revealing strong binding interactions at low pressures as a result of strong metal-hydrocarbon interactions based on pi-backbonding interactions.