In Situ Observation of Solvent-Mediated Cyclic Intermediates during the Alkene Epoxidation/Hydration over a Ti-Beta/H2O2 System.

Solvent effects in catalytic reactions have received widespread attention as they can promote reaction rates and product selectivities by orders of magnitude. It is well accepted that the stable five-membered cyclic intermediates formed between the solvent molecules and Ti species are crucial to the alkene epoxidation in a heterogeneous Ti(IV)-H2O2 system. However, the direct spectroscopic evidence of these intermediates is still missing and the corresponding reaction pathway for the alkene epoxidation remains unclear. By combining in situ 13C MAS NMR, two-dimensional (2D) 1H-13C heteronuclear correlation (HETCOR) NMR spectroscopy and theoretical calculations, the five-membered ring structures, where the protic solvents (ROH), and aprotic solvent (acetone), coordinate and stabilize the active Ti species, are identified for the first time over Ti-Beta/H2O2 system. Moreover, the role of these cyclic intermediates in the alkene epoxidation/hydration conversion is clarified. These results provide new insights into the solvent effect in liquid-phase epoxidation/hydration reactions over Ti(IV)-H2O2 system.

Insight into the Alkali Resistance Mechanism of FeMoTiOx Catalysts for NH3 Selective Catalytic Reduction of NO: Self-Defense Effects of MoOx for Alkali Capture.

The deactivation of selective catalytic reduction (SCR) catalysts caused by alkali metal poisoning remains an insurmountable challenge. In this study, we examined the impact of Na poisoning on the performance of Fe and Mo co-doped TiO2 (FeaMobTiOx) catalysts in the SCR reaction and revealed the related alkali resistance mechanism. On the obtained Fe1Mo2.6TiOx catalyst, the synergistic catalytic effect of uniformly dispersed FeOx and MoOx species leads to remarkable catalytic activity, with over 90% NO conversion achieved in a wide temperature range of 210-410 °C. During the Na poisoning process, Na ions predominantly adsorb on the MoOx species, which exhibit stronger alkali resistance, effectively safeguarding the FeOx species. This preferential adsorption minimizes the negative effect of Na poisoning on Fe1Mo2.6TiOx. Moreover, Na poisoning has little influence on the Eley-Rideal reaction pathway involving adsorbed NHx reacting with gaseous NOx. After Na poisoning, the Lewis acid sites were deteriorated, while the abundant Brønsted acid sites ensured sufficient NHx adsorption. As a benefit from the self-defense effects of active MoOx species for alkali capture, FeaMobTiOx exhibits exceptional alkali resistance in the SCR reaction. This research provides valuable insights for the design of highly efficient and alkali-resistant SCR catalysts.

Zeolite-encaged mononuclear copper centers catalyze CO2 selective hydrogenation to methanol.

The selective hydrogenation of CO2 to methanol by renewable hydrogen source represents an attractive route for CO2 recycling and is carbon neutral. Stable catalysts with high activity and methanol selectivity are being vigorously pursued, and current debates on the active site and reaction pathway need to be clarified. Here, we report a design of faujasite-encaged mononuclear Cu centers, namely Cu@FAU, for this challenging reaction. Stable methanol space-time-yield (STY) of 12.8 mmol gcat-1 h-1 and methanol selectivity of 89.5% are simultaneously achieved at a relatively low reaction temperature of 513 K, making Cu@FAU a potential methanol synthesis catalyst from CO2 hydrogenation. With zeolite-encaged mononuclear Cu centers as the destined active sites, the unique reaction pathway of stepwise CO2 hydrogenation over Cu@FAU is illustrated. This work provides a clear example of catalytic reaction with explicit structure-activity relationship and highlights the power of zeolite catalysis in complex chemical transformations.

Co engineered CoP catalyst for photochemical CO2 reduction with accelerated electron transfer endowed by the space-charge region.

Photocatalytic CO2 reduction has been regarded as an ideal method to simulate photosynthesis for achieving carbon neutralization. However, poor charge transfer efficiency limits its development. Herein, an efficient Co/CoP@C catalyst was prepared with compact contact of Co and CoP layer by using MOF as precursor. At the interface of Co/CoP, the difference in functionality between the two phases may result in uneven distribution of electrons, thus forming a self-driven space-chare region. In this region, spontaneous electron transfer is guaranteed, thus facilitating the effective separation of photogenerated carriers as well as boosting the utilization of solar energy. Furthermore, the electron density of active site Co in CoP is increased and more active sites are exposed, which promotes the adsorption and activation of CO2 molecules. Together with suitable redox potential, low energy barrier for *COOH formation and easy desorption of CO, the reduction rate of CO2 catalyzed by Co/CoP@C is 4 times higher than that of CoP@C.

The myo-inositol biosynthesis rate-limiting enzyme ISYNA1 suppresses the stemness of ovarian cancer via Notch1 pathway.

Cancer stem cells (CSCs) play a central role in ovarian cancer (OC), understanding regulatory mechanisms governing their stemness is critical. Here, we report ISYNA1, the rate-limiting enzyme in myo-inositol biosynthesis, as a suppressor of OC regulating cancer stemness. We identified ISYNA1 as a differentially expressed gene in normal ovary and ovarian cancer tissues, as well as OC cells and OCSCs. Low ISYNA1 expression correlated with poor prognosis in OC patients. In addition, ISYNA1 was negatively correlated with cancer stem cell (CSC) markers, and ISYNA1-related pathways were enriched in Wnt, Notch, and other critical cancer pathways. ISYNA1 deficiency promoted OC cell growth, migration, and invasion ability in vitro and in vivo. Knockdown of ISYNA1 increased stemness of OC cells, including self-renewal, CSC markers expression, ALDH activity, and proportion of CD44+/CD117+ CSCs. Conversely, ectopic overexpression of ISYNA1 suppresses cell proliferation, migration, invasion and stemness of OC cells. Mechanistically, ISYNA1 inhibits OC stemness by regulating myo-inositol to suppress Notch1 signaling. In summary, these data provide evidence that ISYNA1 act as a tumor suppressor in OC and a regulator of stemness, providing insight into potentially targetable pathways for ovarian cancer therapy.

JDHY3 Inhibits Hypopharyngeal Carcinoma Cell Proliferation and Promotes Apoptosis by Inhibiting the PI3K/AKT Pathway.

BACKGROUND: Jieduhuayu No.3 (JDHY3) is a modified Chinese herbal formula beneficial for treating hypopharyngeal carcinoma (HC), but its pharmacological mechanism is unknown. OBJECTIVE: This study aimed to explore the mechanism of the herbal formula JDHY3 in inhibiting cell proliferation and promoting apoptosis in HC in vitro and in vivo. METHODS: In this study, HC cells were treated with cisplatin and different concentrations of JDHY3. The apoptosis rate was detected by flow cytometry. Western blotting was used to detect the proteins related to cell proliferation and apoptosis. Afterward, the xenograft mouse model was established and treated with cisplatin and JDHY3. Mouse tumour volume was measured, and the tumour tissues were assessed by HE staining and immunohistochemistry. RESULTS: JDHY3 significantly inhibited the proliferation of FaDu and Detroit-562 cells. In addition, JDHY3 significantly increased the apoptosis rate of HC cells and downregulated p-PI3K and p-Akt. In addition, JDHY3 upregulated the expression of the apoptosis-promoting proteins Bax, P53, and cleaved caspase-3. In addition, the expression of the antiapoptotic protein Bcl-2 was downregulated. Coincubation with SC79 attenuated the decrease in cell proliferation induced by JDHY3, further confirming that the proapoptotic effect of JDHY3 is associated with the inhibition of PI3K/Akt pathway activation. CONCLUSIONS: The results of in vivo experiments showed that JDHY3 could effectively inhibit the proliferation of HC cells, and HE staining showed that JDHY3 reduced the invasion of HC cells. Immunohistochemistry showed that the expression of P53 and cleaved caspase-3 was significantly increased in the tissues of the JDHY3-treated group.

Effect of Triangle hierarchical management among community patients with hypertension / 预防医学

Objective@#To evaluate the effect of Triangle hierarchical management among community patients with hypertension, so as to provide insights into the improvements of standardized hypertension management.@*Methods@#Patients with newly diagnosed hypertension from 2 community health service centers in Qiantang District of Hangzhou City by the end of 2020 were randomly assigned to the conventional group and the Triangle group. Patients in the conventional group were given health management services according to the requirements of basic public health service standard for one year, while patients in the Triangle group were given Triangle hierarchical management. The blood pressure, self-management behaviors, treatment compliance, smoking, alcohol consumption and exercise were collected using the self-management behavior scale, treatment compliance scale and self-designed questionnaires, and were compared before and after intervention with analysis of covariance and generalized estimation equations.@*Results@#Totally 200 patients with hypertension were recruited, including 100 patients in the conventional group and 100 patients in the Triangle group. There were no significant differences between the two groups before implementation of interventions in terms of gender, age, educational level or occupation (P>0.05). The reduction in blood pressure, increase in the score of treatment, diet, exercise and living habitat management and the total score of self-management behaviors, increase in the score of adherence to medication regimens, daily living management behaviors, smoking and alcohol consumption preference and the total score of treatment compliance, and increase in the number of patients with normal standard of quitting smoking, quitting alcohol consumption, exercise and blood pressure were significantly higher in the Triangle group than in the conventional group after intervention (P<0.05). @*Conclusions @#Triangle hierarchical management may increase the treatment compliance, improve the self-management behavior and facilitate hypertension control among hypertensive patients, which may be popularized for health management among community patients with hypertension.

Effect of momethasone furoate combined with loratadine and montelukast sodium on inflammatory factors and pulmonary function in children with allergic rhinitis.

OBJECTIVE: To compare the effects of mometasone furoate in combination with loratadine and montelukast sodium on inflammatory factors and pulmonary function in children with allergic rhinitis (AR). METHODS: In this retrospective study, a total of 89 children with AR admitted to our hospital from March 2020 to October 2021 were enrolled. Among them, 47 children who received mometasone furoate combined with loratadine were designated group A, while the other 42 with mometasone furoate combined with montelukast sodium were group B. The clinical efficacy of both groups was compared, and the levels of inflammatory factors IL-6 and TNF-α as well as the changes of pulmonary function levels were tested during the treatment. Adverse reactions during treatment were recorded. Finally, children were followed up for 3 months to record rhinitis recurrence after discontinuation of the treatment. RESULTS: There was no statistical difference in clinical treatment efficacy between both groups (P>0.05), while the levels of IL-6, TNF-α, and IgE were lower in children in group A than in group B at 2 weeks of treatment. Group A's lung function indexes, including forced expiratory volume in one second (FEV1%), forced expiratory volume in one second/forced vital capacity (FEV1/FVC) and peak expiratory flow (PEF), were higher than in group B (all P<0.05). The total incidence of adverse reactions was dramatically lower in group A than group B (P<0.05). Follow-up demonstrated no difference in the recurrence rate of rhinitis between both groups of children (P>0.05). Higher TNF-α after treatment, history of allergy, family history of rhinitis, combined asthma, and parental history of smoking were independent risk factors for relapse after discontinuation of the drug in children. CONCLUSION: Both mometasone furoate combined with either loratadine or montelukast sodium had good effects in AR, while the first option had a faster inhibitory effect on inflammatory factors and a better protection of lung function in children.

Directional Construction of Active Naphthalenic Species within SAPO-34 Crystals toward More Efficient Methanol-to-Olefin Conversion.

Olefin selectivity and catalyst lifetime are two key metrics for industrial methanol-to-olefin catalysts. Currently, it is very difficult to obtain high olefin selectivity and long catalyst lifetime at the same time. Herein, a feasible strategy combining precoking and steaming to directionally construct the active naphthalenic species within the crystal center of the SAPO-34 catalyst has been developed, which can not only promote the lower olefin selectivity to ∼89% (ethylene and propylene) but also prolong the catalyst lifetime by ∼3.7-fold in the methanol-to-olefin conversion. Structured illumination microscopy, in situ ultraviolet-visible spectroscopy, and online mass spectrometry elucidate the spatiotemporal distribution and evolution of the naphthalenic species during the precoking and steaming processes. This one-stone-two-birds strategy is applicable to a commercial SAPO-34 catalyst containing a binder, demonstrating its bright prospect in the methanol-to-olefin industry.

Z-Scheme Heterojunction of SnS2/Bi2WO6 for Photoreduction of CO2 to 100% Alcohol Products by Promoting the Separation of Photogenerated Charges.

Using sunlight to convert CO2 into solar fuel is an ideal solution to both global warming and the energy crisis. The construction of direct Z-scheme heterojunctions is an effective method to overcome the shortcomings of single-component or conventional heterogeneous photocatalysts for photocatalytic CO2 (carbon dioxide) reduction. In this work, a composite photocatalyst of narrow-gap SnS2 and stable oxide Bi2WO6 were prepared by a simple hydrothermal method. The combination of Bi2WO6 and SnS2 narrows the bandgap, thereby broadening the absorption edge and increasing the absorption intensity of visible light. Photoluminescence, transient photocurrent, and electrochemical impedance showed that the coupling of SnS2 and Bi2WO6 enhanced the efficiency of photogenerated charge separation. The experimental results show that the electron transfer in the Z-scheme heterojunction of SnS2/Bi2WO6 enables the CO2 reduction reactions to take place. The photocatalytic reduction of CO2 is carried out in pure water phase without electron donor, and the products are only methanol and ethanol. By constructing a Z-scheme heterojunction, the photocatalytic activity of the SnS2/Bi2WO6 composite was improved to 3.3 times that of pure SnS2.

In2S3 nanoflakes grounded in Bi2WO6 nanoplates: A novel hierarchical heterojunction catalyst anchored on W mesh for efficient elimination of toluene.

Toxic toluene can be completely oxidized in CO2 and H2O with novel three-dimensional (3D) In2S3@Bi2WO6 hierarchical crystals under visible light. Dense and uniform In2S3 nanoflakes are rooted in Bi2WO6 nanoplates which intercross with each other and are anchored on a pliable tungsten mesh. This leads to the construction of a stable and porous interface for adsorbing and decomposing target gaseous toluene. The firm contact between In2S3 and Bi2WO6 initiates the formation of a built-in electric field that helps in channeling the photogenerated electrons in Bi2WO6 CB to quench the holes in2S3 VB. This results in highly capable electrons and holes, as well as notable increase in the yields of •O2- and •OH. 99.7% of toluene is removed and 93.4% is converted to CO2 when it is degraded in simulated air. This validates its remarkable efficacy in detoxifying toluene.

Zeolitic imidazolate framework-8 for ratiometric fluorescence sensing tetracyclines in environmental water based on AIE effects.

A ratiometric fluorimetric sensing strategy with Zeolitic imidazolate framework-8 (ZIF-8) has been developed for the analysis of tetracycline (TC) in environmental water samples. ZIF-8 with polyhedral structure was synthesized at room temperature exhibiting blue fluorescence at 445 nm. Especially, the as-prepared ZIF-8 could conduct the aggregation-induced emission (AIE) effect in the presence of TC through electrostatic, hydrogen bond, π-π stacking, and coordination interactions. As a result, a strong yellow-green fluorescence appeared and a new fluorescence peak at 505 nm was observed, although the initial fluorescence peak at 445 nm of ZIF-8 was almost unchanged. A ZIF-8-based fluorimetric platform was thereby designed for sensing TC by using ZIF-8 as the fluorescent probe with the peak at 445 nm as the reference and the one at 505 nm as the changing signal, which should increase with the increasing concentrations of TC. Moreover, the quantitative analysis of TC could be carried out through the ratiometric peak intensities of F505/F445, with a detection limit as low as 14.7 nM. Additionally, the ratiometric fluorescent analysis method was successfully employed to detect TC in environmental water samples, indicating that ZIF-8 might be a good luminescent sensor for probing the pollutants in the environmental water.

High-throughput lateral and basal interface in CeO2@Ti3C2TX: Reverse and synergistic migration of carrier for enhanced photocatalytic CO2 reduction.

Rational construction of heterogeneous interfaces that maximize carrier flux and allow carrier separation for achieving efficient photocatalytic CO2 reduction still remain a challenge. In this work, high-throughput and intimate interfaces that allow efficient carrier separation and flux are designed by depositing high-density CeO2 nanoparticles on large-area Ti3C2TX (T = terminal group) nanosheets. Oxygen-containing functional groups of Ti3C2TX nanosheets facilitate the anchoring of CeO2 nanoparticles on the nanosheets via the formation of interfacial Ce-O-Ti bonds, which serve as effective channels for reverse and synergistic migration of electrons and holes to achieve spatial separation. The light absorption of the CeO2@Ti3C2TX composites is extended to the infrared (IR) region due to narrow bandgaps of Ti3C2TX. High-density lateral and basal interfaces enhance carrier migration, which ultimately aids the CeO2@Ti3C2TX composites to exhibit excellent activity for reducing CO2 to alcohols (i.e., methanol and ethanol) under both visible (vis) and IR irradiations. The total amount of produced alcohol under visible irradiation is 109.9 µmol•gcatal-1 (methanol and ethanol: 76.2 and 33.7 µmol•gcatal-1, respectively), which is 4.3 times higher than that obtained using CeO2 (methanol and ethanol: 19.8 and 6 µmol•gcatal-1, respectively). The yields of methanol and ethanol using the optimized CeO2@Ti3C2TX were 102.24 and 59.21 µmol•gcatal-1, respectively, after 4 h under the vis-IR irradiation.

Characterization of AMA1-RON2L complex with native gel electrophoresis and capillary isoelectric focusing.

Rhoptry neck protein 2 (RON2) binds to the hydrophobic groove of apical membrane antigen 1 (AMA1), an interaction essential for invasion of red blood cells (RBCs) by Plasmodium falciparum (Pf) parasites. Vaccination with AMA1 alone has been shown to be immunogenic, but unprotective even against homologous challenge in human trials. However, the AMA1-RON2L (L is referred to as the loop region of RON2 peptide) complex is a promising candidate, as preclinical studies with Freund's adjuvant have indicated complete protection against lethal challenge in mice and superior protection against virulent infection in Aotus monkeys. To prepare for clinical trials of the AMA1-RON2L complex, identity and integrity of the candidate vaccine must be assessed, and characterization methods must be carefully designed to not dissociate the delicate complex during evaluation. In this study, we developed a native Tris-glycine gel method to separate and identify the AMA1-RON2L complex, which was further identified and confirmed by Western blotting using anti-AMA1 monoclonal antibodies (mAbs 4G2 and 2C2) and anti-RON2L polyclonal Ab coupled with mass spectrometry. The formation of complex was also confirmed by Capillary Isoelectric Focusing (cIEF). A short-term (48 h and 72 h at 4°C) stability study of AMA1-RON2L complex was also performed. The results indicate that the complex was stable for 72 h at 4°C. Our research demonstrates that the native Tris-glycine gel separation/Western blotting coupled with mass spectrometry and cIEF can fully characterize the identity and integrity of the AMA1-RON2L complex and provide useful quality control data for the subsequent clinical trials.

Zeolite-Encaged Isolated Platinum Ions Enable Heterolytic Dihydrogen Activation and Selective Hydrogenations.

Understanding the unique behaviors of atomically dispersed catalysts and the origin thereof is a challenging topic. Herein, we demonstrate a facile strategy to encapsulate Ptδ+ species within Y zeolite and reveal the nature of selective hydrogenation over a Pt@Y model catalyst. The unique configuration of Pt@Y, namely atomically dispersed Ptδ+ stabilized by the surrounding oxygen atoms of six-membered rings shared by sodalite cages and supercages, enables the exclusive heterolytic activation of dihydrogen over Ptδ+···O2- units, resembling the well-known classical Lewis pairs. The charged hydrogen species, i.e., H+ and Hδ-, are active reagents for selective hydrogenations, and therefore, the Pt@Y catalyst exhibits remarkable performance in the selective hydrogenation of α,ß-unsaturated aldehydes to unsaturated alcohols and of nitroarenes to arylamines.

Gradient Hydrogen Migration Modulated with Self-Adapting S Vacancy in Copper-Doped ZnIn2S4 Nanosheet for Photocatalytic Hydrogen Evolution.

It is a challenge to regulate charge flow synergistically at the atomic level to modulate gradient hydrogen migration (H migration) for boosting photocatalytic hydrogen evolution. Herein, a self-adapting S vacancy (Vs) induced with atomic Cu introduction into ZnIn2S4 nanosheets was fabricated elaborately, which can tune charge separation and construct a gradient channel for H migration. Detailed experimental results and theoretical simulations uncover the behavior mechanism of Vs generation with Cu introduction after substituting a Zn atom tendentiously. Cu-S bond shrinkage and Zn-S bond distortion are presented around Vs areas. Besides, Vs induced by Cu introduction lowers the internal electric field to restrain electron transmission between layers, which are enriched on the Vs area because of the lower surface electrostatic potential. Atomic Cu and Vs show a synergistic effect for regulating regional charge separation due to the Cu dopant being a hole trap and Vs being an electron trap. The channels for H migration with gradient ΔGH0 are constructed by different S atom sites, which are modulated by Vs. Gradient H migration driven by a photothermal effect occurs on an identical surface without striding across a heterogeneous interface, which is a valid pathway with lower resistance for boosting H2 release. Ultimately, 5 mol % Cu confined in ZnIn2S4 nanosheets achieves an optimum photocatalytic hydrogen evolution activity of 9.8647 mmol g-1 h-1, which is 14.8 times higher than 0.6640 mmol g-1 h-1 for ZnIn2S4, and apparent quantum efficiency reaches 37.11% at 420 nm. This work demonstrates the behavior mechanism of atomic substitution and provides cognition for hydrogen evolution mechanism deeply.

Stabilizing the framework of SAPO-34 zeolite toward long-term methanol-to-olefins conversion.

As a commercial MTO catalyst, SAPO-34 zeolite exhibits excellent recyclability probably due to its intrinsic good hydrothermal stability. However, the structural dynamic changes of SAPO-34 catalyst induced by hydrocarbon pool (HP) species and the water formed during the MTO conversion as well as its long-term stability after continuous regenerations are rarely investigated and poorly understood. Herein, the dynamic changes of SAPO-34 framework during the MTO conversion were identified by 1D 27Al, 31P MAS NMR, and 2D 31P-27Al HETCOR NMR spectroscopy. The breakage of T-O-T bonds in SAPO-34 catalyst during long-term continuous regenerations in the MTO conversion could be efficiently suppressed by pre-coking. The combination of catalyst pre-coking and water co-feeding is established to be an efficient strategy to promote the catalytic efficiency and long-term stability of SAPO-34 catalysts in the commercial MTO processes, also sheds light on the development of other high stable zeolite catalyst in the commercial catalysis.

Plasmodium Preerythrocytic Vaccine Antigens Enhance Sterile Protection in Mice Induced by Circumsporozoite Protein.

Preerythrocytic vaccines prevent malaria by targeting parasites in the clinically silent sporozoite and liver stages and preventing progression to the virulent blood stages. The leading preerythrocytic vaccine, RTS,S/AS01E (Mosquirix), entered implementation programs in 2019 and targets the major sporozoite surface antigen, circumsporozoite protein (CSP). However, in phase III clinical trials, RTS,S conferred partial protection with limited durability, indicating a need to improve CSP-based vaccination. Previously, we identified highly expressed liver-stage proteins that could potentially be used in combination with CSP; they are referred to as preerythrocytic vaccine antigens (PEVAs). Here, we developed heterologous prime-boost CSP vaccination models to confer partial sterilizing immunity against Plasmodium yoelii (protein prime-adenovirus 5 [Ad5] boost) and Plasmodium berghei (DNA prime-Ad5 boost) in mice. When combined as individual antigens with P. yoelii CSP (PyCSP), three of eight P. yoelii PEVAs significantly enhanced sterile protection against sporozoite challenge, compared to PyCSP alone. Similar results were obtained when three P. berghei PEVAs and P. berghei CSP were combined in a single vaccine regimen. In general, PyCSP antibody responses were similar after CSP alone versus CSP plus PEVA vaccinations. Both P. yoelii and P. berghei CSP plus PEVA combination vaccines induced robust CD8+ T cell responses, including signature gamma interferon (IFN-γ) increases. In the P. berghei model system, IFN-γ responses were significantly higher in hepatic versus splenic CD8+ T cells. The addition of novel antigens may enhance the degree and duration of sterile protective immunity conferred by a human vaccine such as RTS,S.

Confinement in a Zeolite and Zeolite Catalysis.

ConspectusZeolites, accompanied by their initial discovery as natural mines and the subsequent large-scale commercial production, have played indispensable roles in various fields such as petroleum refining and the chemical industry. Understanding the characteristics of zeolites, in contrast to their counterparts with similar chemical compositions and the origin thereof, is always a hot and challenging topic. Zeolites are known as intrinsic confined systems with ordered channels on the molecular scale, and structural confinement has been proposed to explain the unique chemical behaviors of zeolites. Generally, the channels of zeolites can regulate the diffusion of molecules, leading to a visible difference in molecular transportation and the ultimate shape-selective catalysis. On the other hand, the local electric field within the zeolite channels or cages can act on the guest molecules and change their energy levels. Confinement can be simply interpreted from both spatial and electronic issues; however, the nature of zeolite confinement is ambiguous and needs to be clarified.In this Account, we make a concise summary and analysis of the topics of confinement in a zeolite and zeolite catalysis from two specific views of spatial constraint and a local electric field to answer two basic questions of why zeolites and what else can we do with zeolites. First, it is shown how to construct functional sites including Brønsted acid sites, Lewis acid sites, extraframework cation sites, and entrapped metal or oxide aggregates in zeolites via confinement and how to understand the specific role of confinement in their reactivity. Second, the multiple impacts of confinement in zeolite-catalyzed reactions are discussed, which rationally lead to several unique processes, namely, Brønsted acid catalysis confined in zeolites, Lewis acid catalysis confined in zeolites, catalysis by zeolite-confined coordinatively unsaturated cation sites, and a cascade reaction within the confined space of zeolites. Overall, confinement effects do exist in zeolite systems and have already played extremely important roles in adsorption and catalysis. Although confinement might exist in many systems, the confinement by zeolites is more straightforward thanks to their well-ordered and rigid structure, deriving unique chemical behaviors within the confined space of zeolites. A zeolite is a fantastic scaffold for constructing isolated sites spatially and electrostatically confined in its matrix. Furthermore, zeolites containing well-defined transition-metal sites can be treated as inorganometallic complexes (i.e., a zeolite framework as the ligand of transition-metal ions) and can catalyze reactions resembling organometallic complexes or even metalloenzymes. The local electric field within the confined space of zeolites is strong enough to induce or assist the activation of small molecules, following the working fashion of frustrated Lewis pairs. The tactful utilization of structural confinement, both spatially and electronically, becomes the key to robust zeolites for adsorption and catalysis.

Experimental and Theoretical Evidence for the Promotional Effect of Acid Sites on the Diffusion of Alkenes through Small-Pore Zeolites.

The diffusion of saturated and unsaturated hydrocarbons is of fundamental importance for many zeolite-catalyzed processes. Transport of small alkenes in the confined zeolite pores can become hindered, resulting in a significant impact on the ultimate product selectivity and separation. Herein, intracrystalline light olefin/paraffin diffusion through the 8-ring windows of zeolite SAPO-34 is characterized by a complementary set of first-principle molecular dynamics simulations, PFG-NMR experiments, and pulse-response temporal analysis of products measurements, yielding information at different length and time scales. Our results clearly show a promotional effect of the presence of Brønsted acid sites on the diffusion rate of ethene and propene, whereas transport of alkanes is found to be insensitive to the presence of acid sites. The enhanced diffusivity of unsaturated hydrocarbons is ascribed to the formation of favorable π-H interactions with acid protons, as confirmed by IR spectroscopy measurements. The acid site distribution is proven to be an important design parameter for optimizing product distributions and separations.