Formate Research Articles

Back-decay of the muonic molecular ion (αμt)012+ resonantly formed in (tμ)1s+4HeH+ collision

Abstract Resonant formation of the muonic molecular ion ( α μ t ) 01 2 + in the collision of the muonic tritium atom with the helium hydride ion, ( t μ ) 1 s + 4 HeH + → [ ( α μ t ) 01 2 + , p , e e ] + , is proposed. The ( α μ t ) 01 2 + ion is formed in the rotational-vibrational state (0,1) as one of the two nuclei of the final complex. Back-decay process [ ( α μ t ) 01 2 + , p , e e ] K n + → ( t μ ) 1 s + 4 HeH K ′ n ′ + , where K and n ( K ′ and n ′ ) is the rotational and vibrational quantum number, respectively, is considered in detail and the corresponding decay widths for all possible rotational-vibrational ( K , n ) → ( K ′ , n ′ ) transitions are calculated. Numerous inelastic decay channels of ( α μ t ) 01 2 + are also presented and discussed. The possible fast resonant formation of the ( α μ t ) 01 2 + ion may provide an interesting tool for experimental studies of t ( α , γ ) 7 Li nuclear fusion, which is one of the most important reactions in Big-Bang nucleosynthesis models. Studying this reaction may prove important for solving the lithium problem.

Determining the evaporation and evolution of surface water in a large catchment using isotopes and multiple models

The evolution and formation mechanisms of chemical components in surface water can reflect changes in the geological background of a basin and the extent of human interference. The Yangtze River basin is the largest water source area in China, yet its main ion sources and formation mechanisms are not fully understood. This study uses a combination of hydrochemistry, stable isotopes (δ18O, δD), the Craig-Gordon model, and the APCS-MLR model to quantitatively assess the water source replenishment and evaporation intensity of surface water in the Yangtze River. The study reveals the primary ion sources and controlling factors of surface water in the Yangtze River. The results show that the hydrochemical type in the upstream is mainly HCO3−-Ca2+ and Na+-K+, while in the midstream and downstream it is primarily HCO3−-Ca2+ and SO42−-Ca2+. The evolution of hydrochemical types is mainly controlled by rock weathering and human inputs. The surface water sources in the Yangtze River are directly replenished by precipitation, with the evaporation ratio in the upstream (0.66) being higher than in the midstream (0.63) and downstream (0.47). The lc-excess in the upstream (−0.32 ‰) is lower than in the midstream (1.21 ‰) and downstream (−0.27 ‰), indicating more intense evaporation in the upstream. The hydrochemical composition of the Yangtze River surface water mainly comes from geological factors (80.5 %), industrial factors (11.1 %), agricultural factors (6.4 %), and unknown factors (2.0 %). This study enhances the understanding of the chemical composition, water source replenishment, ion sources, and evolution mechanisms of the Yangtze River surface water, providing a basis for maintaining water quality and sustainable development in the Yangtze River basin.

Copper and Colorectal Cancer

Minerals constitute only 5% of the typical human diet but are vital for health and functionality. Copper, a trace element, is absorbed by the human gut at 30–40% from diets typical of industrialized countries. The liver produces metallothioneins, which store copper. Copper is crucial for mitochondrial respiration, pigmentation, iron transport, antioxidant defense, hormone production, and extracellular matrix biosynthesis. Copper deficiency, often caused by mutations in the ATP7A gene, results in Menkes disease, an X-linked recessive disorder. On the contrary, Wilson disease is characterized by toxic copper accumulation. Cuproptosis, a unique form of cell death regulated by copper, is a subtype of necrosis induced by enhanced mitochondrial metabolism and intracellular copper accumulation. This process can reduce the malignant potential of tumor cells by inhibiting glucose metabolism. Therapeutically, copper and its complexes have shown efficacy in malignancy treatments. The disruption of copper homeostasis and excessive cuproplasia are significant in colorectal cancer development and metastasis. Therefore, manipulating copper status presents a potential therapeutic target for colorectal cancer, using copper chelators to inhibit copper formation or copper ion carriers to promote cuproptosis. This review highlights the role of copper in human physiology and pathology, emphasizing its impact on colorectal cancer and potential therapeutic strategies. Future AI-based approaches are anticipated to accelerate the development of new compounds targeting cuproptosis and copper disruption in colorectal cancer.

The Operando Nature of Isobutene Adsorbed in Zeolite H-SSZ-13 Unraveled by Machine Learning Potentials Beyond DFT Accuracy.

Unraveling the nature of adsorbed olefins in zeolites is crucial to understand numerous zeolite-catalyzed processes. A well-grounded theoretical description critically depends on both an accurate determination of the potential energy surface (PES) and a reliable account of entropic effects at operating conditions. Herein, we propose a transfer learning approach to perform random phase approximation (RPA) quality enhanced sampling molecular dynamics simulations, thereby approaching chemical accuracy on both the determination and exploration of the PES. The proposed methodology is used to investigate isobutene adsorption in H-SSZ-13 as prototypical system to estimate the relative stability of physisorbed olefins, carbenium ions and surface alkoxide species (SAS) in Brönsted-acidic zeolites. We show that the tert-butyl carbenium ion formation is highly endothermic and no entropic stabilization is observed compared to the physisorbed complex within H-SSZ-13. Hence, its predicted concentration and lifetime are negligible, making a direct experimental observation unlikely. Yet, it remains a shallow minimum on the free energy surface over the whole considered temperature range (273--873 K), being therefore a short-lived reaction intermediate rather than a transition state species.

The Operando Nature of Isobutene Adsorbed in Zeolite H‐SSZ‐13 Unraveled by Machine Learning Potentials Beyond DFT Accuracy

Unraveling the nature of adsorbed olefins in zeolites is crucial to understand numerous zeolite‐catalyzed processes. A well‐grounded theoretical description critically depends on both an accurate determination of the potential energy surface (PES) and a reliable account of entropic effects at operating conditions. Herein, we propose a transfer learning approach to perform random phase approximation (RPA) quality enhanced sampling molecular dynamics simulations, thereby approaching chemical accuracy on both the determination and exploration of the PES. The proposed methodology is used to investigate isobutene adsorption in H‐SSZ‐13 as prototypical system to estimate the relative stability of physisorbed olefins, carbenium ions and surface alkoxide species (SAS) in Brönsted‐acidic zeolites. We show that the tert‐butyl carbenium ion formation is highly endothermic and no entropic stabilization is observed compared to the physisorbed complex within H‐SSZ‐13. Hence, its predicted concentration and lifetime are negligible, making a direct experimental observation unlikely. Yet, it remains a shallow minimum on the free energy surface over the whole considered temperature range (273‐‐873 K), being therefore a short‐lived reaction intermediate rather than a transition state species.

Comprehensive Analysis of a Chloride‐Rich Topographic Depression in Terra Sirenum, Mars: A Possible Lost Basin With Astrobiological Significance

AbstractThe hygroscopic nature of chlorides gives them the potential to provide a harbor for microbes to adapt and survive in extreme conditions, which is pertinent to Mars, given its evolution of climatic conditions. Moreover, observations of secondary hydrous minerals in chloride‐rich regions have opened the case for a diverse geological environment on the Martian surface. Therefore, through comprehensive analysis, we aim to reconstruct the geological evolution of a chloride‐rich basin within Terra Sirenum. We conducted morphological, morphometric, and mineralogical analyses of the basin and its surrounding area to determine its geological evolution, longevity, and environmental condi5tions during its activity. Subsequently, we carried out a discharge analysis of the surrounding valley networks and determined the water activity using ionic forms of the associated mineralogy. We observed bright‐toned polygonal cracks within the basin as well as its surrounding terrain, suggesting that the basin extended beyond its present boundary. Mineralogical diversity and age dating of the basin and the surrounding area indicated different geochemical environments and cycles of wetting and drying until the late Hesperian. Whereas, sediment transport modeling suggests that the basin was hydrologically active for more than ten thousand years. Our results show a tell‐tale signature of a large sedimentary basin and a large‐scale geological process within the Terra Sirenum. The water activity modeling show that the geochemical composition of the basin was favorable to support the origin of life forms and/or sustain them and suggest promising aspects of the basin for future landing missions.

Revealing the Reaction Pathway of Anodic Hydrogen Evolution at Magnesium Surfaces in Aqueous Electrolytes.

Aqueous metal corrosion is a major economic concern in modern society. A phenomenon that has puzzled generations of scientists in this field is the so-called anomalous hydrogen evolution: the violent dissolution of magnesium under electron-deficient (anodic) conditions, accompanied by strong hydrogen evolution and a key mechanism hampering Mg technology. Experimental studies have indicated the presence of univalent Mg+ in solution, but these findings have been largely ignored because they defy our common chemical understanding and evaded direct experimental observation. Using recent advances in the ab initio description of solid-liquid electrochemical interfaces under controlled potential conditions, we describe the full reaction path of Mg atom dissolution from a kinked Mg surface under anodic conditions. Our study reveals the formation of a solvated [Mg2+(OH)-]+ ion complex, challenging the conventional assumption of Mg2+ ion formation. This insight provides an intuitive explanation for the postulated presence of (Coulombically) univalent Mg+ ions, and the absence of protective oxide/hydroxide layers normally formed under anodic/oxidizing conditions. The discovery of this unexpected and unconventional reaction mechanism is crucial for identifying new strategies for corrosion prevention and can be transferred to other metals.

Synergistic Anion and Solvent-Derived Interphases Enable Lithium-Ion Batteries under Extreme Conditions.

Lithium-ion batteries (LIBs) face increasingly stringent demands as their application expands into new areas, including extreme temperatures and fast charging. To meet these demands, the electrolyte should enable fast lithium-ion transport and form stable interphases on electrodes simultaneously. In practice, however, improving one aspect often compromises another. For instance, the trend toward electrolytes forming anion-derived interphases typically reduces transport efficiency due to weak-solvating solvents. We propose that instead of relying on anions to form the interphase, leveraging both solvents and anions to form interphases can potentially lead to a balancing point between robust interphase formation and effective ion transport. Guided by this design principle, 2,2-difluoroethyl ethyl carbonate (DFDEC) was identified as the promising solvent. With the new electrolyte using DFDEC as the major solvent and lithium bis(fluorosulfonyl) imide (LiFSI) as the salt, graphite||LiNi0.8Mn0.1Co0.1O2 (NMC811) full cells are capable of fast charging and demonstrate long-term cycling stability with a cutoff voltage of 4.5 V. Notably, the battery shows a capacity retention of 84.3% after 500 cycles with an average Coulombic efficiency (CE) as high as 99.93%. This new electrolyte also enables stable battery cycling across a wide temperature range (-20 to 60 °C), with excellent capacity retention.

Quantum Chemical Analysis of the Molecular and Fragment Ion Formation of Butyrophenone by High-Electric Field Tunnel Ionization at Atmospheric Pressure.

The molecular ion M+· was observed when the liquid sample of butyrophenone was supplied using atmospheric pressure corona discharge (APCD). In contrast, the vapor supply resulted in the formation of the protonated molecule [M+H]+. The mass spectrum obtained with the liquid supply showed two distinctive fragment ions at m/z 105 and 120, resulting from α-cleavage and McLafferty rearrangement (McLR), respectively. The APCD spectrum showed peaks of M+· and the characteristic two fragment ions that were the same as the field ionization mass spectra of butyrophenone as reported by Chait et al. and Beckey et al. The formation of the molecular and fragment ions strongly indicated that high-electric field tunnel ionization (HEFTI) occurs by the HEF strength exceeding 108 V/m at the tip of the corona needle in APCD. The charge and spin density distributions of the molecular and fragment ions were analyzed by quantum chemical calculations using time-dependent density functional theory (TDDFT) and natural bond orbital (NBO) analysis.

Enhancing Aromaticity of Alkenylbenzenes May Decrease Their Metabolic Activation and Reduce Their Potential Cytotoxicity: Lessons Learnt from the Investigation of Myristicin and Elemicin.

Metabolic activation studies of lead compounds are a crucial step in drug development and offer a key consideration during rational drug design. Myristicin (MRS) and elemicin (ELM), natural products belonging to alkenylbenzenes, share the backbone of 1-allyl-3-methoxybenzene. The backbone fuses with a methylenedioxy five-membered ring in MRS, while ELM is connected with two adjacent methoxy groups. ELM displayed powerful ability to induce cytotoxicity in cultured primary hepatocytes relative to MRS. Additionally, ELM exhibited superior efficiency in metabolic activation by CYP3A4, resulting in the formation of reactive metabolites carbonium ion, epoxides, and α,β-unsaturated ketone. Quantum chemical calculation and molecular dynamic studies revealed that the fused methylenedioxy 5-membered ring enhances the aromaticity of MRS, which affects the interaction between the allyl side chain and the heme for metabolic activation by the π-π stacking interaction with the aromatic amino acid residues of the host enzyme.

Ferrates (VI) ; Alternative products in water treatment : their electrochemical synthesis

This study focuses on determining the optimum conditions for the electrochemical generation of ferrates in concentrated NaOH solution. Various operating parameters, including electrolyte concentration, current density, temperature, electrolysis duration, and the composition and form of the anode, were investigated to enhance the yield of electrochemical ferrate (VI) ion production. The synthesized ferrates were characterized using UV-visible and FTIR spectroscopic techniques. Experimental results confirmed the formation of ferrate ions, with optimal synthesis conditions identified as follows: a current density of 11.96 mA/cm², NaOH concentration of 16 M, electrolysis time of 1 hour, temperature of 25°C, and the use of white cast iron as the anode material. These conditions were found to yield the highest efficiency for sodium ferrate production. The spectroscopic analysis effectively verified the presence of ferrate (VI) ions, providing valuable insights into the electrochemical synthesis process. This study contributes to the advancement of ferrate synthesis techniques, potentially offering an efficient route for large-scale production.

Effects of Hydrogen Dissociation During Gas Flooding on Formation of Metal Hydride Cluster Ions in Secondary Ion Mass Spectrometry

The application of hydrogen flooding was recently shown to be a simple and effective approach for improved layer differentiation and interface determination during secondary ion mass spectrometry (SIMS) depth profiling of thin films, as well as an approach with potential in the field of quantitative SIMS analyses. To study the effects of hydrogen further, flooding of H2 molecules was compared to reactions with atomic H on samples of pure metals and their alloys. H2 was introduced into the analytical chamber via a capillary, which was heated to approximately 2200 K to achieve dissociation. Dissociation of H2 up to 30% resulted in a significant increase in the intensity of the metal hydride cluster secondary ions originating from the metallic samples. Comparison of the time scales of possible processes provided insight into the mechanism of hydride cluster secondary ion formation. Cluster ions presumably form during the recombination of the atoms and molecules from the sample and atoms and molecules adsorbed from the gas. This process occurs on the surface or just above it during the sputtering process. These findings coincide with those of previous mechanistic and computational studies.

Triflic Acid-Catalyzed Dehydrative Amination of 2-Arylethanols with Weak N-Nucleophiles in Hexafluoroisopropanol.

The catalytic deoxyamination of readily available 2-arylethanols offers an appealing, simple, and straightforward means of accessing β-(hetero)arylethylamines of biological interest. Yet, it currently represents a great challenge to synthetic chemistry. In most cases, the alcohol has to be either pre-activated in situ or converted into a reactive carbonyl intermediate, limiting the substrate scope for some methods. Examples of direct dehydrative amination of 2-arylethanols are still scarce. Here, we describe a catalytic protocol based on the synergy of triflic acid and hexafluoroisopropanol, which enables the direct and stereospecific amination of a broad array of 2-arylethanols, and does not require any pre-activation of the alcohol. This approach yields high value-added products incorporating sulfonamide, amide, urea, and aniline functionalities. In addition, this approach was applied to the sulfidation of 2-arylethanols. Mechanistic experiments and DFT computations indicate the formation of phenonium ions as key intermediates in the reaction.

Triflic Acid‐Catalyzed Dehydrative Amination of 2‐Arylethanols with Weak N‐Nucleophiles in Hexafluoroisopropanol

The catalytic deoxyamination of readily available 2‐arylethanols offers an appealing, simple, and straightforward means of accessing β‐(hetero)arylethylamines of biological interest. Yet, it currently represents a great challenge to synthetic chemistry. In most cases, the alcohol has to be either pre‐activated in situ or converted into a reactive carbonyl intermediate, limiting the substrate scope for some methods. Examples of direct dehydrative amination of 2‐arylethanols are still scarce. Here, we describe a catalytic protocol based on the synergy of triflic acid and hexafluoroisopropanol, which enables the direct and stereospecific amination of a broad array of 2‐arylethanols, and does not require any pre‐activation of the alcohol. This approach yields high value‐added products incorporating sulfonamide, amide, urea, and aniline functionalities. In addition, this approach was applied to the sulfidation of 2‐arylethanols. Mechanistic experiments and DFT computations indicate the formation of phenonium ions as key intermediates in the reaction.

UV light promoted dihydrolipoic acid and its alanine derivative directed rapid synthesis of stable gold nanoparticles and their catalytic activity

In general, colloidal gold nanoparticles (AuNPs) have been synthesized in heated or boiling water containing HAuCl4 precursor with sodium citrate as reducing stabilizing reagent. Although temperature plays a driving for synthesis of AuNPs, elevated temperature in thermal reduction method causes aggregation of the AuNPs. The preferential, rapid and strong binding of dihydro-lipoic acid and its derivatives on surface of AuNPs via thiol − Au chemistry promote the production of very stable AuNPs. In this study, we have developed citric acid (CA), dihydrolipoic acid (DHLA) and DHLA-Alanine (DHLA-Ala) directed rapid synthesis of ultra-stable AuNPs, DHLA@AuNPs and DHLA-Ala@AuNPs, under the UV (311 nm) irradiation at room temperature (RT: 25 °C) in around 10 min (min). CA is used as a potential reducing agent to expedite both reduction of Au3+ ion and AuNP formation, DHLA and DHLA-Ala act as stabilizing agents by replacing CA molecules on surface of AuNPs in order to produce quite stable AuNP. It is worthy to mention that reduction of Au3+ ion, formation and surface stabilization of AuNPs are consequently occurred in one step. We also investigated how experimental parameters including reaction time and temperature, pH of reaction solution, affect formation of the AuNPs. The effects of salt concentration and storage temperature were studied to show stability of the AuNPs. The synthesized DHLA@AuNPs and DHLA-Alanine@AuNPs were characterized via UV-Vis spectrophotometer (UV-Vis), scanning transmission electron microscope (STEM), dynamic light scattering (DLS) and Zeta potential (ZT) devices. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was efficiently catalyzed by the AuNPs in the presence of sodium borohydride in aqueous solution.

Meloxicam-amino acids salts/ion pair complexes with advanced solubility, dissolution, and gastric safety

Amino acids have attracted attention as a potential functional excipient for optimizing biopharmaceutics characteristics of poorly soluble drugs. The amino acids are a diverse class with many functional groups, natural compounds, biocompatible and low molecular weight substances. Two amino acids serine and arginine were investigated with meloxicam. Meloxicam has extremely low solubility; being NSAIDs, gastric upset and ulcer are common side effects. Solid dispersions were produced by precipitation and physical mixing techniques. The produced combinations underwent in vitro dissolution, docking, DSC, FTIR, XRD, solubility and gastric ulcer formation studies. Docking indicated formation of ion pair/salt between the basic amino acid arginine and meloxicam. Both solubility and dissolution rates were increased by up to 3000- and 12-fold, respectively. DSC, FTIR an XRD supported these findings. Rats treated with meloxicam showed loss of surface gastric epithelium integrity and ulceration. The animal group received meloxicam: arginine showed intact gastric mucosa with the surface epithelium and gastric glands well organized and nearly similar to the untreated control. Arginine with the guanidine group that was capable of preserving gastric mucosa after repeated administration for 10 days. This study highlighted the role of arginine as a functional excipient that did not only improve solubility and dissolution rates but ameliorated the long-standing gastric side effects attributed to meloxicam.

Quantitative Determination of Volatile N-Nitrosamines in Meat Products Using Gas Chromatography Coupled to an Ion Mobility Spectrometer with an Ammonia Dopant.

Herein, we develop a novel method using gas chromatography-ion mobility spectrometry (IMS) with an ammonia dopant for the determination of volatile N-nitrosamines in meat products. The IMS system was implemented with Fourier deconvolution multiplexing to simultaneously improve the resolving power and sensitivity. The ammonia dopant mitigated the formation of N-nitrosamine dimer ions, suppressing the ionization of interferents and shifting the reactant peak from hydrated protons to hydrated ammonium ions. The ammonium adduct product ions of N-nitrosamines were confirmed using time-of-flight mass spectrometry. The instrument limits of detection and quantitation for nitrosamines were 0.78-1.79 and 2.60-5.82 ng/mL, respectively, with recoveries between 71.39% and 110.59% using a simple water distillation method. The developed method showed satisfactory performance when applied to the detection of nitrosamines in various meat products.

Effect of the concentration and ionic form of nitrogen (N) on photosynthesis, growth and fruit production of blueberry (Vaccinium corymbosum L.)

The aim of this work was to evaluate the main effects and the interactions of nitrogen (N) concentration and ammonium (NH4+): nitrate (NO3-) proportion in the nutrient solution, on net photosynthesis, plant growth, production and quality of fruits on blueberry (Vaccinium corimbosum L.) plants. The studied factors were N concentration (0.6 and 6.0 mM) and NH4+: NO3- proportion (100 % NH4+, 50 % NH4+ - 50 % NO3- and 100 % NO3-). 243 days after the experiment establishment net photosynthesis (PN) was measured and a day after, leaf area (LA), shoots fresh weight (SFW) and roots fresh weight (RFW) were determined. Fruit yield (FY), fruit diameter (FD) and Brix degrees (oBrix) were evaluated in four harvests along fruit production period. The results showed higher values on PN, LA, SFW, FY and FD in plants that received 6.0 mM N as NH4+; nevertheless, N concentration altered the NH4+: NO3- proportion effects and at 0.6 mM N only FY and FD maintained such a pattern. It is concluded that N concentration modifies the effect of NH4+: NO3- proportion and it is proposed that the effects of both factors on photosynthesis, growth and fruit production of blueberry were mediated by their interaction with plant carbohydrates availability.

Selective removal of organic dyes via polymer inclusion membrane containing a perbenzylated β-cyclodextrin derivative

Organic dyes threaten aquatic ecosystems due to carcino/mutagenic properties, and their removal from wastewater is a crucial issue. The novel PIM (Polymer Inclusion Membrane) containing perbenzylated β-cyclodextrin (CD) derivative was designed as an effective material for the selective removal of organic dyes because the CD characterizes strong affinity to these compounds via inclusion complex formation. The PIM was obtained through standard solvent casting from CTA as a matrix, o-NPOE as a plasticizer, and perbenzylated β-CD as the carrier. The membrane transport was evaluated towards two different types of dyes, cationic (Methylene Blue) and anionic (Acid Orange 7), where the optimal concentration for dye removal was 50 and 75 mg/L, respectively. The efficiency of this process was around 83–90 % after 8 h, when the pH of the source/receiving phase induced the formation of non−/ionic forms of dyes, respectively. The optimal membrane composition based on mass ratio was 11.1:72.2:16.7 for CD:o-NPOE:CTA with a membrane thickness of 0.053 mm. The PIM was characterized by high selectivity dependent on both the pH of each phase used in the transport and the chemical character of the dyes. The molecular mechanism of the removal process was mostly based on the complex inclusion of dyes inside the CD cavity. The activation energies were 8.73 and 13.93 kJ/mol for MB and AO7, respectively. The dyes transport was limited by diffusion. This study provides information about novel PIM with an effective and selective carrier, the perbenzylated β-CD derivative, towards organic dyes.

FTIR traced modification of defect-engineered UiO-66 for enhanced accessibility of zirconium sites

This research focuses on identifying the accessibility of active sites within the defect-engineered UiO-66 framework. The task is particularly challenging due to reversible changes in the framework during dehydroxylation: the loss of μ3-OH groups with simultaneous reduction of the Zr coordination number and the possible creation of Zr4+ Lewis acid sites in defect MOFs. We used in-situ FTIR and XANES analyses, as well as interaction with probe molecules, to monitor the changes in Zr coordination and the host-guest interaction. The defects were introduced using benzoic acid as a modulator, which coordinated to Zr4+ in defective pores. Our results showed that the UiO-66 sample synthesized with benzoic acid contained defects, but these were concealed under benzoate residues and thus inaccessible. Standard washing and heating did not remove benzoate anions. Dehydroxylation of the sample leads to the development of “hidden” Lewis acidity: some Zr4+ sites were not able to form complexes with the weak base CO, but they interact with the stronger bases acetonitrile. Additionally, in-situ XANES analysis revealed that the effect of acetonitrile adsorption is similar to that of water rehydration. Treatment of the sample with HCl and DMF led to the replacement of benzoates with formate ions, exposing the bare Zr4+ sites within the defective pores. These cationic sites acted as true Lewis acids and were able to coordinate both CO and acetonitrile. Our findings emphasize that the active sites in UiO-66 highly depend on synthesis conditions and post-synthetic treatments. Comprehensive site-specific methods are crucial for accurately predicting and identifying these active sites.