Stimulus-Responsive Lanthanide MOF Materials Encapsulated with Viologen Derivatives: Characterization, Photophysical Properties and Sensing on Nitrophenols.

Viologens (1,1'-disubstituted 4,4'-bipyridyls) possessing electron-deficient properties and redox activity are a class of suitable chromophores to assemble metal-organic hybrid photochromic materials. Thus, viologen-functionalized metal-organic frameworks (MOFs) have attracted much attention for their photochromic properties; however, the syntheses of lanthanide-viologen hybrid crystalline photochromic materials still face many challenges. For example, the structures and properties of the final products are difficult to predict and are limited by molecular configurations. In this work, host-guest composite-material Ln-NH2 BDC-pbpy MOFs were constructed by encapsulating viologen derivative pbpyCl2 . The pbpy2+ moieties are uniformly embed by their π-π conjugation in the pores of the 3D structure by electrostatic interactions. Due to the encapsulation of the chromophore pbpy2+ moieties, Ln-NH2 BDC-pbpy MOFs have reversible photochromic properties: they can change color after irradiation and can return to the original color after being protected from light or heating. Interestingly, the fluorescence intensity decreases with illumination time and recovers in the dark. As a result, Ln-NH2 BDC-pbpy MOFs show both photochromic and photomodulated fluorescence. Based on the outstanding fluorescence performance of the Ln-NH2 BDC-pbpy MOFs, they also show a wonderful effect for detecting nitrophenols, especially TNP.

Multi-emitter metal-organic frameworks as ratiometric luminescent sensors for food contamination and spoilage detection.

Food contamination and spoilage is a worldwide concern considering its adverse effect on public health and food security. Real time monitoring food quality can reduce the risk of foodborne disease to consumers. Particularly, the emergence of multi-emitter luminescent metal-organic frameworks (LMOFs) as ratiometric sensory materials has provided the possibility for food quality and safety detection with high sensitivity and selectivity taking advantage of specific host-guest interactions, pre-concentrating and molecule-sieving effects of MOFs. Furthermore, the excellent sensing performance of multi-emitter MOF-based ratiometric sensors including self-calibration, multi-dimensional recognition and visual signal readout is able to meet the increasing rigor requirement of food safety evaluation. Multi-emitter MOF-based ratiometric sensors have become the focus of food safety detection. This review focuses on design strategies for different multiple emission sources assembly to construct multi-emitter MOFs materials based on at least two emitting centers. The design strategies for creating multi-emitter MOFs can be mainly classified into three categories: (1) multiple emission building blocks assembly in a single MOF phase; (2) single non-luminescent MOF or LMOF phase as a matrix for chromophore guest(s); (3) heterostructured hybrids of LMOF with other luminescent materials. In addition, the sensing signal output modes of multi-emitter MOF-based ratiometric sensors have critically discussed. Next, we highlight the recent progress for the development of multi-emitter MOF as ratiometric sensors in food contamination and spoilage detection. Their future improvement and advancing direction potential for their practical application is finally discussed.

Capture and Separation of SO2 Traces in Metal-Organic Frameworks via Pre-Synthetic Pore Environment Tailoring by Methyl Groups.

Herein, we report a pre-synthetic pore environment design strategy to achieve stable methyl-functionalized metal-organic frameworks (MOFs) for preferential SO2 binding and thus enhanced low (partial) pressure SO2 adsorption and SO2 /CO2 separation. The enhanced sorption performance is for the first time attributed to an optimal pore size by increasing methyl group densities at the benzenedicarboxylate linker in [Ni2 (BDC-X)2 DABCO] (BDC-X=mono-, di-, and tetramethyl-1,4-benzenedicarboxylate/terephthalate; DABCO=1,4-diazabicyclo[2,2,2]octane). Monte Carlo simulations and first-principles density functional theory (DFT) calculations demonstrate the key role of methyl groups within the pore surface on the preferential SO2 affinity over the parent MOF. The SO2 separation potential by methyl-functionalized MOFs has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, simulated and experimental breakthrough curves, and DFT calculations.

Cucurbituril-Encapsulating Metal-Organic Framework via Mechanochemistry: Adsorbents with Enhanced Performance.

The first examples of monolithic crystalline host-guest hybrid materials are described. The reaction of 1,3,5-benzenetricarboxylic acid (H3 BTC) and Fe(NO3 )3 ⋅9 H2 O in the presence of decamethylcucurbit[5]uril ammonium chloride (MC5⋅2 NH4 Cl⋅4 H2 O) directly affords MC5@MIL-100(Fe) hybrid monoliths featuring hierarchical micro-, meso- and macropores. Particularly, this "bottle-around-ship" synthesis and one-pot shaping are facilitated by a newly discovered Fe-MC5 flowing gel formed by mechanochemistry. The designed MC5@MIL-100(Fe) hybrid material with MC5 as active domains shows enhanced CH4 and lead(II) uptake performance, and selective capture of lead(II) cations at low concentrations. This shows that host-guest hybrid materials can exhibit synergic properties that out-perform materials based on individual components.

One-Pot Synthesis of High-Quality AgGaS2/ZnS-based Photoluminescent Nanocrystals with Widely Tunable Band Gap.

Herein, we present a facile colloidal method to synthesize the high-quality AgGaS2 nanocrystals (NCs) within 2 min via exploiting the high-reactivity S precursor and then extend this synthetic strategy to the preparation of AgGaS2/ZnS core-shell NCs by a one-pot method without prior purification of AgGaS2 core. The as-synthesized samples were structurally characterized to confrim the formation of AgGaS2/ZnS core-shell NCs. The energy band gap of the AgGaS2/ZnS NCs can be effectively tunable from 2.98 to 2.83 eV by the control of their nonstoichiometry and further continuously decreases to 1.90 eV by the preparation of alloyed AgGaxIn1-xS2/ZnS NCs (1 ≤ x ≤ 0). Benefitting from the efficient band gap modulations, the photoluminescence (PL) colors of the AgGaS2-based NCs can cover almost the whole visible region from blue (460 nm) to red (671 nm). Our work demonstrates the one-pot synthesis of AgGaS2/ZnS core-shell NCs and their band gap engineering, which is of crucial in scalability toward industrial application and in tailoring optical characteristics of I-III-VI2 materials.

Stable Lanthanide-Organic Framework Materials Constructed by a Triazolyl Carboxylate Ligand: Multifunction Detection and White Luminescence Tuning.

Under hydrothermal conditions, we have successfully synthesized six isostructural lanthanide coordination polymers, [LnL1.5(H2O)2]·1.75H2O (1-6; Ln = Eu, La, Pr, Nd, Sm, Gd), by the reaction of 5-methyl-1-(4-carboxylphenyl)-1 H-1,2,3-triazole-4-carboxylic acid (H2L) and Ln(NO3)3·6H2O. Structural analysis shows that polymers 1-6 show novel three-dimensional supramolecular network structures. The luminescent properties for polymer 1 have been investigated at room temperature. The results have shown that polymer 1 can be used as a chemical sensor for multifunctional testing such as UO22+, Fe3+ ion detection, and small organic molecule detection because of its strong fluorescence properties. In particular, polymer 1 exhibits extremely high selectivity and sensitivity for the detection of Fe3+ ions. In addition, white-light emission is achieved through a reasonable tuning proportion by mixing Gd3+ and Eu3+.

The Uncommon Channel-Based Ln-MOFs for Highly Selective Fe3+ Detection and Superior Rhodamine†B Adsorption.

Two new isostructural 3D lanthanide-organic frameworks [H2 N(Me)2 ] [Ln3 (OH)(bpt)3 (H2 O)3 ] (DMF)2 ⋅(H2 O)4 (1-Ln; Ln=Sm and Eu) with a 1D channel (25 Å) have been successfully assembled from the rare trinuclear [Ln3 (OH)(COO)9 ] clusters and biphenyl-3,4',5-tricarboxylic acid (H3 bpt) and exhibit high stability towards water in the pH range 3-10. MOF 1-Eu is a promising luminescent probe for sensing Fe3+ in aqueous solution and is also selective towards rhodamine B (RhB) with a superior adsorption capacity of 735 mg g-1 , which is the highest among the reported Ln-MOFs for RhB removal so far. Periodic DFT calculations further confirmed the selective adsorption of rhodamine B over other dyes.

3d-4f Metal-Organic Framework with Dual Luminescent Centers That Efficiently Discriminates the Isomer and Homologues of Small Organic Molecules.

A 3d-4f luminescent metal-organic framework (MOF), [Tb2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (4), and three analogues {[La2(Cu8I8)(C12H8NO2)6(C4H8O2)2(H2O)2]·3C4H8O2·2H2O (1), [Ce2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (2), and [Eu2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (3)}, were self-assembled from copper(I) halide clusters and lanthanide metal ions with an organic linker [3-(pyridin-4-yl)benzoic acid] under solvothermal conditions. Compound 4 with high quantum yield (Φ = 68%) exhibits reversible luminescence behavior, accompanying the removal and recovery of guest molecules (1,4-dioxane). Because of the unique porous structure and dual luminescent centers of compound 4, it can efficiently differentiate benzene series with different sizes and provide readouts in corresponding optical signals. Furthermore, it also can unambiguously discriminate the isomers, homologues, and other small molecules with similar structural motifs from one another. The luminescent color of the MOF sensor in different guest solvents has obvious changes that can be clearly distinguished by the naked eye. This multicolor luminescence originates from emissions of the dual luminescent centers, and the emissions have shifted, enhanced, weakened, or quenched to different degrees.

Green synthesis of Zn2+ nanocarriers from Auricularia auricula fermentation broth with excellent antioxidant activity.

Nanoparticles (NPs) possessing nanoscale dimensions and remarkable antioxidant activity were synthesized via a green hydrothermal method utilizing Auricularia auricula fermentation broth, referred to as AFNPs. The functional groups on the surface of the AFNPs significantly contributed to the formation of AFNPs-Zn2+. The AFNPs-Zn2+ appeared a zinc retention rate of 40.80 % after gastrointestinal digestion. When compared to typical zinc supplements, AFNPs-Zn2+ did not exhibit visible cytotoxicity or hemolysis. Furthermore, AFNPs-Zn2+ demonstrated the ability to mitigate cell damage resulting from zinc deficiency. In vivo experiments showed that AFNPs-Zn2+ were mainly observed in the stomach, intestine, kidney, and testis after oral administration. In vivo distribution experiments indicated predominant presence of AFNPs-Zn2+ in the stomach, intestine, kidney, and testis following oral administration. This study highlights the potential for Auricularia auricula NPs to serve as the efficient, stable, and safe nanocarriers for Zn2+.

Enhanced stability of anthocyanins by cyclodextrin-metal organic frameworks: Encapsulation mechanism and application as protecting agent for grape preservation.

Anthocyanins are promising naturally occurring food preservatives for enhancing the quality of food products due to their excellent antioxidant properties. However, their low stability hinders their food packaging application. Here, we propose a facile strategy to achieve the improved stability of anthocyanins encapsulated in γ-cyclodextrin metal-organic frameworks (CD-MOFs) with an in-depth exploration of their structure-property relationships. The adsorbed anthocyanins in CD-MOFs are stabilized by multiple cooperative non-covalent interactions including hydrogen bonding and van der Waals (vdW) interactions as demonstrated by density functional theory (DFT) calculations and spectroscopy analysis. Particularly, by ion-exchange of acetate ions into the pores of CD-MOFs, the resulting CD-MOFs (CD-MOF_OAc) shows a higher anthocyanins adsorption rate with a maximum loading capacity of 83.7 % at 1 min. Besides, CD-MOF_OAc possesses the more effective protecting effect on anthocyanins with at least two-fold enhancement of stability in comparison of free anthocyanins under heating and light irradiation. The anthocyanins encapsulated CD-MOFs films for fruit freshness was validated by the Kyoho experiment. This novel encapsulation system provides a new possibility for the potential use of CD-MOFs as the encapsulating material for anthocyanins in fruit preservation.

Bi-functional astaxanthin macromolecular nanocarriers to alleviate dextran sodium sulfate-induced inflammatory bowel disease.

Dextran sulfate sodium is one of the important members in the field of polysaccharide biotechnology, which can induce inflammatory bowel disease (IBD) in the gastrointestinal tract. Nevertheless, the application of astaxanthin (AST) and epigallocatechin-3-gallate (EGCG), known for their pronounced antioxidant and anti-inflammatory properties, is encumbered by limited stability and bioavailability. To surmount this challenge, dual nutritional macromolecular nanoparticles were provided for alleviating IBD. The forementioned strategy entailed the utilization of EGCG as a wall material via the Mannich reaction, resulting in the creation of specialized nanocarriers capable of mitochondrial targeting and glutathione-responsive AST delivery. In vitro investigations, these nanocarriers demonstrated an enhanced propensity for mitochondrial accumulation, leading to proficient elimination of reactive oxygen species and preservation of optimal mitochondrial membrane potential about 1.5 times stronger than free AST and EGCG. Crucially, in vivo experiments showed that the colon length of IBD mice treated with these nanocarriers increased by 51.29 % and facilitated the polarization of M2 macrophages. Moreover, the assimilation of these nanocarriers exerted a favorable impact on the composition of gut microbiota. These findings underscore the immense potential of dual nutrition nanocarriers in contemporaneously delivering hydrophobic biological activators through oral absorption, thereby presenting a highly promising avenue for combating IBD.

Development of a fluorometric and colorimetric dual-mode sensing platform for acid phosphatase assay based on Fe3+ functionalized CuInS2/ZnS quantum dots.

BACKGROUND: The spectral dual-mode response towards analyte has been attracted much attention, benefiting from the higher detection accuracy of such strategy in comparison to single signal readout. However, the currently reported dual-mode sensors for acid phosphatase (ACP) activity are still limited, and most of them more or less exist some deficiencies, such as complicated construction procedure, high-cost, poor biocompatibility, aggregation-caused quenching and limited emission capacity. RESULTS: Herein, we employed Fe3+ functionalized CuInS2/ZnS quantum dots (CIS/ZnS QDs) as nanosensor to develop a novel fluorometric and colorimetric dual-mode assay for ACP activity, combing with ACP-triggered hydrolysis of ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA). The Fe3+ binding to CIS/ZnS QDs can be reduced into Fe2+ during the determination, resulting in the dramatically weakened photoinduced electron transfer (PET) effect and the disappearance of competition absorption. Thus, a highly sensitive ACP assay in the range of 0.22-12.5 U L-1 through fluorescence "turn-on" mode has been achieved with a detection of limit (LOD) of 0.064 U L-1. Meanwhile, the ACP activity can also be quantified by spectrophotometry based on the chromogenic reaction of the formed Fe2+ with 1,10-phenanthroline (Phen). Moreover, the designed nanosensor with good biocompatibility was successfully applied to image and monitor the ACP levels in living cells. SIGNIFICANCE: We believe that the proposed method has remarkable advantages and potential application for ACP assay in terms of the high accuracy, simplicity, low cost, as well as its adequate sensitivity.

Hepatic parenchymal cell and mitochondrial-targeted astaxanthin nanocarriers for relief of high fat diet-induced nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is a metabolic syndrome disorder. Here, hepatic parenchymal cell and mitochondrial-targeted nanocarriers were constructed to deliver astaxanthin (AST) to liver tissue to maximize AST intervention efficiency. The hepatic parenchymal cell-targeting was achieved using galactose (Gal) conjugated onto whey protein isolate (WPI) through the Maillard reaction by recognizing asialoglycoprotein receptors specifically expressed in hepatocytes. Grafting triphenylphosphonium (TPP) onto glycosylated WPI by an amidation reaction enabled the nanocarriers (AST@TPP-WPI-Gal) to achieve dual targeting capability. The AST@TPP-WPI-Gal nanocarriers could target mitochondria in steatotic HepG2 cells with an enhanced anti-oxidative and anti-adipogenesis effect. The ability of AST@TPP-WPI-Gal to target liver tissue was verified by an NAFLD mice model, and the results showed that AST@TPP-WPI-Gal could regulate blood lipid disorders, protect liver function, and remarkably reduce liver lipid accumulation (40%) compared with that of free AST. Therefore, AST@TPP-WPI-Gal might have potential as a dual targeting hepatic agent for nutritional intervention for NAFLD.

ROS-triggered self-disintegrating and pH-responsive astaxanthin nanoparticles for regulating the intestinal barrier and colitis.

Smart delivery systems with stimuli-responsive capability are able to improve the bioaccessibility through increasing the solubility, physicochemical stability and biocompatibility of bioactive compounds. In this study, the astaxanthin nanoparticles with reactive oxygen species (ROS) and pH dual-response function were design and constructed using poly (propylene sulfide) covalently modified sodium alginate as carriers based on ultrasonic assisted self-assembly strategy. Atomic force microscope and scanning electron microscope analysis showed that the nanoparticles were spherical in shape with a size of around 260 nm. Meanwhile, the astaxanthin nanoparticles showed both pH and ROS stimuli-responsive release characteristics. In vitro cell experiments showed that astaxanthin nanoparticles significantly inhibited the production of ROS and mitochondrial depolarization induced by oxidative stress. In vivo colitis experiment of mice revealed that astaxanthin nanoparticles could significantly relieve colitis, protect the integrity of colon tissue and restore the expression of tight junction proteins ZO-1 and occludin. The abundance of Lactobacillus and Lachnospiraceae, and the ratio of Firmicutes/Bacteroidota of gut microbiota were significantly improved after intervention of the stimuli-responsive astaxanthin nanoparticles. This work provided a simple strategy for constructing ROS/pH dual response delivery system, which provided an experimental basis for improving the oral bioavailability of hydrophobic active compounds.

Luminescent AgGaSe2/ZnSe nanocrystals: rapid synthesis, color tunability, aqueous phase transfer, and bio-labeling application.

The unique optoelectronic properties of I-III-VI2 nanocrystals (NCs) have attracted extensive attention. Herein, element Se in oleylamine reduced by alkythiol, which has been demonstrated to generate highly reactive alkylammonium selenide, was selected as the Se precursor by us to successfully synthesize high-quality tetragonal AgGaSe2 NCs via a facile colloidal method in just 2 minutes. Further, the photoluminescence (PL) properties of the as-synthesized AgGaSe2 NCs were systematically optimized through utilizing one Zn precursor to integrate shell coating and anionic/cationic alloying strategies into our reactive system, resulting in not only the obvious improvement of PL intensity but also tunable PL color from blue to red. Furthermore, the ligand exchange approach was adopted for the aqueous phase transfer of the oleophilic AgGaSe2/ZnSe NCs. Our data suggest that either metalated mercaptopropionic acid (Zn-MPA) short- or 11-mercaptoundecanoic acid long-chain ligand exchanged NCs all could maintain the original high crystallinity, present good water solubility, and retain up to nearly 95% and 70% of the initial PL intensity, respectively. Benefiting from the low cytotoxicity, the water-soluble AgGaSe2/ZnSe NCs can be applied as a fluorescent probe in cell imaging and signal labels for the fluoroimmunoassay of prostate-specific antigen, implying their potential in biological application.

Sea bass protein-polyphenol complex stabilized high internal phase of algal oil Pickering emulsions to stabilize astaxanthin for 3D food printing.

The protective effect of sea bass protein (SBP)-(-)-epigallocatechin-3-gallate (EGCG) covalent complex-stabilized high internal phase (algal oil) Pickering emulsions (HIPPEs) on astaxanthin and algal oils was demonstrated in this study. The SBP-EGCG complex with better wettability and antioxidant activity was formed by the free radical-induced reaction to stabilize HIPPEs. Our results show that the SBP-EGCG complex formed dense particle shells surrounding the oil droplets, and the shells were crosslinked with the complex in the continuous phase to produce a network structure. The rheological analysis demonstrated that the SBP-EGCG complex endowed HIPPEs with high viscoelasticity, high thixotropic recovery, and good thermal stability, which were beneficial for three-dimensional (3D) printing applications. HIPPEs stabilized by SBP-EGCG complex were applied to improve the stability and bioaccessibility of astaxanthin and to delay algal oil lipid oxidation. The HIPPEs might become a food-grade 3D printing material served as a delivery system for functional foods.

On-Chip Precisely Controlled Preparation of Uniform Core-Shell Salmon Byproduct Protein/Polysaccharide Microcapsules for Enhancing Probiotic Survivability in Fruit Juice.

The increasing demand for probiotic-fortified fruit juices stems from the dietary requirements of individuals with dairy allergies, lactose intolerance, and vegetarian diets. However, a notable obstacle arises from the degradation of probiotics in fruit juices due to their low pH levels and harsh gastrointestinal conditions. In response, this study proposes an innovative approach utilizing a microfluidic chip to create core-shell microcapsules that contain Lactobacillus plantarum Lp90. This method, based on internal-external gelation, forms highly uniform microcapsules that fully enclose the core, which consists of oil-in-water Pickering emulsions stabilized by salmon byproduct protein and sodium alginate. These emulsions remain stable for up to 72 h at a 1% sodium alginate concentration. The shell layer incorporates kelp nanocellulose and sodium alginate, thus improving the thermal properties. Furthermore, compared to free probiotics, the multilayer structure of the core-shell microcapsules provides a robust barrier, resulting in significantly enhanced probiotic stability. These findings introduce a novel strategy for augmenting probiotic delivery in functional fruit juice beverages, promising solutions to the challenges encountered during their development.

The Complexity of Comparative Adsorption of C6 Hydrocarbons (Benzene, Cyclohexane, n-Hexane) at Metal-Organic Frameworks.

The relatively stable MOFs Alfum, MIL-160, DUT-4, DUT-5, MIL-53-TDC, MIL-53, UiO-66, UiO-66-NH2, UiO-66(F)4, UiO-67, DUT-67, NH2-MIL-125, MIL-125, MIL-101(Cr), ZIF-8, ZIF-11 and ZIF-7 were studied for their C6 sorption properties. An understanding of the uptake of the larger C6 molecules cannot simply be achieved with surface area and pore volume (from N2 sorption) but involves the complex micropore structure of the MOF. The maximum adsorption capacity at p p0-1 = 0.9 was shown by DUT-4 for benzene, MIL-101(Cr) for cyclohexane and DUT-5 for n-hexane. In the low-pressure range from p p0-1 = 0.1 down to 0.05 the highest benzene uptake is given by DUT-5, DUT-67/UiO-67 and MIL-101(Cr), for cyclohexane and n-hexane by DUT-5, UiO-67 and MIL-101(Cr). The highest uptake capacity at p p0-1 = 0.02 was seen with MIL-53 for benzene, MIL-125 for cyclohexane and DUT-5 for n-hexane. DUT-5 and MIL-101(Cr) are the MOFs with the widest pore window openings/cross sections but the low-pressure uptake seems to be controlled by a complex combination of ligand and pore-size effect. IAST selectivities between the three binary mixtures show a finely tuned and difficult to predict interplay of pore window size with (critical) adsorptive size and possibly a role of electrostatics through functional groups such as NH2.

Biphenyl-Based Covalent Triazine Framework/Matrimid® Mixed-Matrix Membranes for CO2/CH4 Separation.

Processes, such as biogas upgrading and natural gas sweetening, make CO2/CH4 separation an environmentally relevant and current topic. One way to overcome this separation issue is the application of membranes. An increase in separation efficiency can be achieved by applying mixed-matrix membranes, in which filler materials are introduced into polymer matrices. In this work, we report the covalent triazine framework CTF-biphenyl as filler material in a matrix of the glassy polyimide Matrimid®. MMMs with 8, 16, and 24 wt% of the filler material are applied for CO2/CH4 mixed-gas separation measurements. With a CTF-biphenyl loading of only 16 wt%, the CO2 permeability is more than doubled compared to the pure polymer membrane, while maintaining the high CO2/CH4 selectivity of Matrimid®.

Zirconium and Aluminum MOFs for Low-Pressure SO2 Adsorption and Potential Separation: Elucidating the Effect of Small Pores and NH2 Groups.

Finding new adsorbents for the desulfurization of flue gases is a challenging task but is of current interest, as even low SO2 emissions impair the environment and health. Four Zr- and eight Al-MOFs (Zr-Fum, DUT-67(Zr), NU-1000, MOF-808, Al-Fum, MIL-53(Al), NH2-MIL-53(Al), MIL-53(tdc)(Al), CAU-10-H, MIL-96(Al), MIL-100(Al), NH2-MIL-101(Al)) were examined toward their SO2 sorption capability. Pore sizes in the range of about 4-8 Å are optimal for SO2 uptake in the low-pressure range (up to 0.1 bar). Pore widths that are only slightly larger than the kinetic diameter of 4.1 Å of the SO2 molecules allow for multi-side-dispersive interactions, which translate into high affinity at low pressure. Frameworks NH2-MIL-53(Al) and NH2-MIL-101(Al) with an NH2-group at the linker tend to show enhanced SO2 affinity. Moreover, from single-gas adsorption isotherms, ideal adsorbed solution theory (IAST) selectivities toward binary SO2/CO2 gas mixtures were determined with selectivity values between 35 and 53 at a molar fraction of 0.01 SO2 (10.000 ppm) and 1 bar for the frameworks Zr-Fum, MOF-808, NH2-MIL-53(Al), and Al-Fum. Stability tests with exposure to dry SO2 during ≤10 h and humid SO2 during 5 h showed full retention of crystallinity and porosity for Zr-Fum and DUT-67(Zr). However, NU-1000, MOF-808, Al-Fum, MIL-53(tdc), CAU-10-H, and MIL-100(Al) exhibited ≥50-90% retained Brunauer-Emmett-Teller (BET)-surface area and pore volume; while NH2-MIL-100(Al) and MIL-96(Al) demonstrated a major loss of porosity under dry SO2 and MIL-53(Al) and NH2-MIL-53(Al) under humid SO2. SO2 binding sites were revealed by density functional theory (DFT) simulation calculations with adsorption energies of -40 to -50 kJ·mol-1 for Zr-Fum and Al-Fum and even above -50 kJ·mol-1 for NH2-MIL-53(Al), in agreement with the isosteric heat of adsorption near zero coverage (ΔHads0). The predominant, highest binding energy noncovalent binding modes in both Zr-Fum and Al-Fum feature µ-OHδ+···Î´-OSO hydrogen bonding interactions. The small pores of Al-Fum allow the interaction of two µ-OH bridges from opposite pore walls with the same SO2 molecule via OHδ+···Î´-OSOδ-···Î´+HO hydrogen bonds. For NH2-MIL-53(Al), the DFT high-energy binding sites involve NHδ+···Î´-OS together with the also present Al-µ-OHδ+···Î´-OS hydrogen bonding interactions and C6-πδ-···Î´+SO2, Nδ-···Î´+SO2 interactions.