Metal-organic Frameworks Research Articles

Combining nanocrystalline NiCo with MOFs-derived carbon fibers skeleton: A dual confinement strategy to efficient electrocatalysts for oxygen evolution reaction

A dual-confinement strategy was developed to design efficient electrocatalysts for oxygen evolution reaction (OER). NiCo alloy nanoparticles (NPs) were synthesized and embedded in N-doped carbon fibers (NCF) by electrospinning and carbonization techniques. Dual effects of size confinement by the metal–organic frameworks (MOFs) derived carbon skeleton companied with spatial confinement by polyacrylonitrile (PAN) derived carbon fibers (CFs) for the NiCo NPs were executed to improve the electrocatalytic activity. In an alkaline solution, the prepared NiCo-C@CF exhibits significant advantages over the commercial RuO2 catalyst i.e., a 61 mV lower overpotential of 363 mV under 50 mA cm−2, and excellent durability of 87.5 % current density retention after 60 h of continuous OER polarization.

Plasma Metabolic Profiles via p-p Heterojunction-Assisted Laser Desorption/Ionization Mass Spectrometry for Advanced Warning and Diagnosis of Epidural-Related Maternal Fever.

Epidural-related maternal fever (ERMF) heightens the risk of intrapartum fever, whereas effective prevention and treatment in clinical practice are currently lacking. Rapid and sensitive screening tools for ERMF are urgently needed to advance relevant research. In response to this challenge, we devise and craft porous Co3O4/CuO hollow polyhedral nanocages with p-p heterojunctions derived from metal-organic frameworks. We employ these p-p heterojunctions in conjunction with high-throughput mass spectrometry to conduct metabolic analysis of substantial plasma samples, with only about 0.03 μL per sample. Leveraging these p-p heterojunctions, metabolic signals from complex plasma can be amplified, with great reproducibility. By harnessing the power of machine learning on these metabolic signals, we are able to achieve advanced warning of ERMF with an area under the curve (AUC) of 0.887-0.975 by the differentially metabolic analysis of plasma samples collected upon admission. Furthermore, we can accurately diagnose ERMF with an AUC of 0.850-1.000 by analyzing plasma samples collected at the time of delivery from individuals who have received epidural analgesia. These breakthroughs offer invaluable insights for clinical decision making during labor and have the potential to significantly reduce the incidence of ERMF.

2D-to-1D Conversion of a Layered Sodium Titanate via Rational Framework Splitting for Highly Efficient Cation Exchange.

Demand on high-performance ion exchangers is ever-increasing in energy and environment applications. Among many cation exchangers, layered alkali titanates generally show larger cation exchange capacity, but slower cation exchange rate due to their 2D micrometer-size particle morphologies, which limits their practical applications. Here, a rational conversion of a layered sodium titanate, Na2Ti3O7, is reported to the corresponding 1D ultra-narrow nanowires via hydrothermal treatment under basic conditions. The formation of nanowires is thought to involve the partial exfoliation of Na2Ti3O7 to form thin plate-like particles that subsequently split into nanowires along a crystallographically defined, chemically selective weakness in the Na2Ti3O7 crystals. This process is similar to a recently burgeoning materials design using atomic-level weakness in solids, such as zeolites and metal-organic frameworks. The proposed formation scheme is further supported by comparative experiments performed on another layered alkali titanate, K0.8Ti1.73Li0.27O4, which possesses randomly distributed defects at the Ti sites. Thanks to the shortening of diffusion path lengths of the interlayer cations, the resulting Na2Ti3O7 nanowires show an excellent cation exchange performance toward Cd2+ in aqueous solution, exceeding several existing cation exchangers such as zeolites and organic resins.

A Review on Chemistry and Methods of Synthesis of 1,2,4-Triazole Derivatives.

This review provides a comprehensive overview of research on 1,2,4-triazoles conducted over the last fifteen years. 1,2,4-Triazoles are highly significant in the pharmaceutical industry, with numerous compounds from this class used clinically as antifungal, antiviral, antibacterial, anti-inflammatory, and antitubercular agents. Beyond their pharmaceutical relevance, this review also explores their role in material science and agriculture. In material science, 1,2,4-triazoles are gaining prominence, particularly in the development of energetic materials (EMs), due to their exceptional properties such as thermal stability, coordination ability, and performance comparable to well-known explosives. Their applications extend to polymers, corrosion inhibitors, and metal-organic frameworks (MOFs), and they play a significant role in the development of functional materials for sensors, catalysis, and energy storage. Additionally, the review addresses general aspects and synthetic methodologies for the functionalization and construction of the 1,2,4-triazole ring. Synthetic methods discussed include metalation synthesis, cyclization of hydrazine derivatives, multicomponent reactions, cyclization of amides and amidines, and microwave-assisted synthesis. Given the significance of the triazole scaffold, its synthesis has garnered considerable attention due to its wide-ranging applications across various industrial sectors.

Abstract A025: RNA-Based Therapeutics to target the p53 pathway in high-grade serous ovarian cancer: TAp63-Regulated Oncogenic LncRNAs (TROLLs) as novel therapeutic targets in cancer

Abstract High-grade serous ovarian cancer (HGSOC) is the most common and malignant type of ovarian cancer with a high frequency of p53 mutation and hyperactivation of the AKT pathway. Even though roughly 85% of patients achieve remission after initial surgical debulking and chemotherapy, four out of five HGSOC patients will experience disease recurrence, resulting in a 5-year survival rate of 43%. We have identified and characterized two TAp63 Regulated Oncogenic Long non-coding RNAs (TROLL-2 and TROLL-3) whose transcription is induced by mutant p53 and high expression level correlate with a more aggressive ovarian cancer grade and phosphorylation of AKT. In-depth analysis demonstrated that TROLL-2 and TROLL-3 directly activate AKT in tumor cells, thus linking p53 alterations to AKT activity. The use of AKT inhibitors in the clinic is limited because of frequent adverse effects, likely due to the constitutive expression of AKT in all cells. TROLL-2 and TROLL-3 expression is limited to tumor cells and provides a more specific target for decreasing AKT activation, potentially minimizing off-target effects. We have optimized reduction of TROLL-2 and TROLL-3 expression using antisense oligonucleotides (ASOs) in an ex vivo perfusion platform for 3D culture of microtumors from primary patient derived tumors. Samples show maximum reduction of proliferation (EdU) and phosphorylation of AKT when TROLL-2 and TROLL-3 ASOs are used concurrently. We also performed phospho-proteomics and single cell RNAseq to compare individual ASO-mediated knockdown of each lncRNA to combined targeted ASO treatments. We have developed primary patient derived xenograft models using ovarian tumors orthotopically implanted into NSG mice generating a relevant preclinical model to determine the efficacy of ASO treatment. To reduce the rapid degradation and clearance of ASOs in circulation, ASOs were encapsulated into lipid nanoparticles and metal-organic frameworks (MOFs) and we are currently testing these in vivo. Since AKT activation is associated with increased staging and resistance to platinum and targeted therapies in ovarian cancer patients, our data provides preclinical rationale for the implementation of ASOs and the use of new delivery methods as a relevant translational therapy and novel method to exploit the specificity of TROLL-2 and TROLL-3 expression in HGSOC. Citation Format: Ashley Lui, Marco Napoli, Jaden R Baldwin, Christina L Carr, Angie Rivera, Duy Nguyen, W. Gregory Sawyer, Michael R Dunne, Erin George, Omar K Farha, Michelle Teplensky, Elsa R Flores. RNA-Based Therapeutics to target the p53 pathway in high-grade serous ovarian cancer: TAp63-Regulated Oncogenic LncRNAs (TROLLs) as novel therapeutic targets in cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A025.

Organic-Inorganic Hybrid Solid Composite Electrolytes for High Energy Density Lithium Batteries: Combining Manufacturability, Conductivity, and Stability.

The deployment of solid and quasi-solid electrolytes in lithium metal batteries is envisioned to push their energy densities to even higher levels, in addition to providing enhanced safety. This article discusses a set of hybrid solid composite electrolytes which combine functional properties with electrode compatibility and manufacturability. Their anodic stability >5V versus Li+/Li and compatibility with lithium metal stem from the incorporated ionic liquid electrolyte, whereas the organic-inorganic hybrid host structure boosts their conductivity up to 2.7mScm-1 at room temperature. The absence of strong acids enables compatibility with porous NMC811 electrodes. Liquid precursor solutions can be readily impregnated into porous electrodes, facilitating cell assembly. Electrolytes containing TFSI- as the only anion have a superior compatibility toward high-voltage positive electrode materials, whereas electrolytes containing both FSI- and TFSI- have a better compatibility toward lithium metal. Using the former as catholyte and the latter as anolyte, NMC811/Li coin cells retain up to 100% of their initial capacity after 100 cycles (0.2C, 3.0-4.4V vs Li+/Li). Because of their unprecedented combination of functional properties, electrode compatibility, and manufacturability, these hybrid solid composite electrolytes are potential candidates for the further development of lithium metal battery technology.

Rigid shell and flexible pore for highly efficient and reversible sulfur-carbon co-adsorption by hierarchical porous Mg-gallate@Poly(acrylate)

The flue gas from coal combustion emits mass CO2 and trace SO2, which are harmful to the environment. To address the aforementioned issues, the development of a high-performance sulfur-carbon co-adsorption material is essential for the simultaneous capture of CO2 and SO2. A special hierarchical pore structure of Mg-gallate@Poly(acrylate) is synthesized here by self-nanocrystallization flexible metal–organic frameworks (MOFs) load a rigid and hydrophobic polymer macroporous surface. Adsorption results indicate that this material exhibits more pronounced characteristics, with an equivalent CO2 adsorption capacity to Mg-gallate powder and a 25 % increase in SO2 adsorption capacity. Dynamic gas adsorption data show that Mg-gallate@Poly(acrylate) has a fast adsorption rate and easy regeneration. Moreover, the adsorption performance of Mg-gallate@Poly(acrylate) in 2000 ppm SO2 slightly rises to that in a non-sulfur environment. The adsorption capacity of CO2 and SO2 can reach 76.5 and 45 mL/g, respectively. The reason for the sulfur-carbon co-adsorption of this material is further demonstrated by theoretical calculations. Additionally, Mg-gallate@Poly(acrylate) shows excellent hydrothermal stability and cyclic regenerability of SO2 and CO2. Thus, these results indicate that Mg-gallate@Poly(acrylate) satisfies the process requirements for sulfur-carbon co-adsorption.

Synergistic Catalytic Sites in High-Entropy Metal Hydroxide Organic Framework for Oxygen Evolution Reaction.

The integration of multiple elements in a high-entropy state is crucial in the design of high-performance, durable electrocatalysts. High-entropy metal hydroxide organic frameworks (HE-MHOFs) are synthesized under mild solvothermal conditions. This novel crystalline metal-organic framework (MOF) features a random, homogeneous distribution of cations within high-entropy hydroxide layers. HE-MHOF exhibits excellent electrocatalytic performance for the oxygen evolution reaction (OER), reaching a current density of 100mA cm-2 at ≈1.64 VRHE, and demonstrates remarkable durability, maintaining a current density of 10mA cm-2 for over 100 h. Notably, HE-MHOF outperforms precious metal-based electrocatalysts despite containing only ≈60% OER active metals. Ab initio calculations and operando X-ray absorption spectroscopy (XAS) demonstrate that the high-entropy catalyst contains active sites that facilitate a multifaceted OER mechanism. This study highlights the benefits of high-entropy MOFs in developing noble metal-free electrocatalysts, reducing reliance on precious metals, lowering metal loading (especially for Ni, Co, and Mn), and ultimately reducing costs for sustainable water electrolysis technologies.

Iron-based MOF with Catalase-like activity improves the synergistic therapeutic effect of PDT/ferroptosis/starvation therapy by reversing the tumor hypoxic microenvironment

Reversing the hypoxic microenvironment of tumors is an important method to enhance the synergistic effect of tumor treatment. In this work, we developed the nanoparticles called Ce6@HGMOF, which consists of a photosensitizer (Ce6), glucose oxidase (GOX), chemotherapy drugs (HCPT) and an iron-based metal-organic framework (MOF). Ce6@HGMOF can consume glucose in tumor cells through “starvation therapy”, cut off their nutrition source, and produce gluconic acid and hydrogen peroxide (H2O2). Utilizing this feature, Ce6@HGMOF can produce oxygen through catalase-like catalytic activity, thereby reversing the hypoxic microenvironment of tumors. This strategy of changing the hypoxic environment can help to slow down the growth of tumor blood vessels and improve the drug-resistant microenvironment to some extent. Meanwhile, increasing the supply of oxygen can enhance the effect of photodynamic therapy (PDT) and enhance the oxidative stress damage caused by reactive oxygen species (ROS) in tumor cells. On the other hand, cancer cells usually produce higher levels of glutathione (GSH) to adapt to high oxidative stress and protect themselves. The Ce6@HGMOF we designed can also consume GSH and induce ferroptosis of tumor cells through Fenton reaction with H2O2, while enhancing the effect of PDT. This innovative synergistic strategy, the combination of PDT/ferroptosis /starvation therapy, can complement each other and enhance each other. It has great potential as a powerful new anti-tumor paradigm in the future.

A Sodium Metal-Organic Framework with Deep Blue Room-Temperature Phosphorescence.

It is a great challenge to manufacture room-temperature blue long afterglow phosphorescent materials adapted to environmental conditions. Herein, an Na-based metal-organic framework (MOF) was constructed using Na+ and 1H-1,2,4-triazole-3,5-dicarboxylic acid, which exhibits long-lived of 378.9 ms, deep blue and room-temperature phosphorescence, meanwhile possesses the visible blue afterglow for 3~6 seconds after removing excitation light source. The three-dimensional coordination bonds network provided by Na-based MOF protects the organic ligands intrinsic hydrogen bond network, resulting in the phosphor lifetime and residual color remaining unchanged in different gas atmospheres. Furthermore, first-principles time-dependent density functional theory reveals that the rigid Na-based MOF structure can limit the rotation and vibration of the room-temperature phosphorescent organic ligands. This limitation results in the suppression of non-radiative decay for both singlet and triplet excitons, promotes intersystem crossing, and increases the rate of radiative decay, ultimately achieving long-lived room-temperature phosphorescence.

Preprocessed Monomer Interfacial Polymerization for Scalable Fabrication of High-Valent Cluster-Based Metal-Organic Framework Membranes.

Current research on emergent membrane materials with ordered and stable nanoporous structures often overlooks the vital facet of manufacturing scalability. We propose the preprocessed monomer interfacial polymerization (PMIP) strategy for the scalable fabrication of high-valent cluster-based metal-organic framework (MOF) membranes with robust structures. Using a roll-to-roll device on commercial polymer supports, Zr-fum-MOF membranes are continuously processed at room temperature through the PMIP approach. These large-area membranes demonstrate the preeminent hydrogen separation capabilities, boasting an order of magnitude of permeance and a thrice-enhanced selectivity when juxtaposed with conventional polymeric membranes. The obtained PMIP-Zr-fum-MOF membranes possess superior stability in water compared with interfacial polymerization (IP)-processed low-valent metal-ion-based ZIF-8 membranes. Moreover, we have implemented the PMIP strategy's universality to process the other four diverse MOF membranes. The proposal of PMIP significantly advances the scalable fabrication of water-stable high-valent cluster MOF membranes.

Ferrocene‐Based Nickel Metal–Organic Framework Nanosheets as Efficient, Long‐Cycle Cathode Catalyst for Li‐CO2 Battery

AbstractLi‐CO2 batteries, as a novel type of secondary battery, show great potential for energy conversion and storage. However, challenges such as large electrode polarization and poor cycling performance, stemming from difficulties in decomposing discharge products, limit their practical application. Here, Ferrocene‐based nickel metal–organic framework (Ni‐Fc) nanosheets structure to act as cathode catalysts, prepared via a one‐pot solvothermal reaction. X‐ray absorption fine structure (XAFS) analysis shows that Ni metal forms abundant catalytic active centers with O coordination of carboxylic acid groups in ferrocene units. The Ni‐Fc‐based battery demonstrates a high discharge capacity of 18636 mAh g−1 and exhibits a cycle life exceeding 2000 h at a current of 200 mA g−1. Density functional theory (DFT) calculations indicate that the stronger interaction of Ni‐Fc with discharge intermediates and enhanced Li adsorption accelerate battery reaction kinetics. This study introduces novel catalyst design concepts aimed at achieving high‐performance CO2 reduction and oxidation, thereby advancing Li‐CO2 batteries toward practical application.

Optimizing supramolecular interactions within metal–organic frameworks for ultra‐high purity propylene purification

Optimizing supramolecular interactions within metal–organic frameworks for ultra‐high purity propylene purification

Synthesis of zirconium-based metal-organic framework under mild conditions and its application to the removal of cationic and anionic dyes from wastewater

Water resources contaminated by industrial dyes can pose a significant threat to the environment and human health. Herein, we conducted a study on the removal of cationic and anionic dyes, such as methylene blue (MB) and methyl orange (MO), using MIL-140A, a zirconium-based metal-organic framework. MIL-140A is synthesized in a Schlenk flask at 120 °C, whereas its conventional synthesis route involves a teflon-sealed autoclave at 220 °C, highlighting the cost reduction and lower equipment requirements of the low-temperature synthesis. The structure of MIL-140A is characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and nitrogen adsorption techniques. The optimal pH for the adsorption of two dyes by MIL-140A is pH 5–8 for MB and pH 3 for MO. The adsorption equilibrium can be reached within 60 min at room temperature, and the adsorption of both dyes on MIL-140A follows pseudo-second-order kinetics and Langmuir isotherm, and the maximum adsorption capacity of MO and MB by MIL-140A were 163.6 and 89.2 mg/g, respectively. Thermodynamic studies indicate an entropy-driven spontaneous process. The adsorption mechanism of MO and MB on MIL-140A is investigated using FT-IR and X-ray photoelectron spectroscopy. The adsorption of MO involves coordination between Zr and sulfonate, while MB adsorption occurs via π-π interactions. Additionally, MIL-140A exhibits better removal efficiency for MO from lithium battery wastewater compared to MB, primarily due to stronger coordination interactions than π-π interactions. These findings demonstrate that MIL-140A is a promising adsorbent for effectively removing both anionic and cationic dyes from water resources.

Fine-Tuning Porous Structure of Zirconium-Based Metal-Organic Frameworks for Efficient Separation and Purification of Astaxanthin by Defect Engineering.

Efficient separation of bioactive compounds from nature source, particularly that of astaxanthin (AXT), remains challenging due to their low content in complicated matrix and readily degradable structure. Herein, a modulator-induced defect engineering is presented on the stable zirconium-based metal-organic frameworks (Zr-MOFs) to optimize pore size and pore chemistry for the efficient separation and purification of AXT for the first time. High adsorption capacity of 26.21mgg-1 is achieved on the best-performing defect Zr-MOF (d-UiO-67-4), superior over the other reported adsorbent for AXT. Meanwhile, d-UiO-67-4 exhibits the selective adsorption of AXT over other carotenoids analogues with similar structure and properties. This is attributed to the preferential non-covalent interactions between defect framework and AXT revealed by the spectroscopy analysis and density functional theory (DFT) calculations. High purity of AXT with 89.0%±2.3% extraction efficiency can be realized after the purification of AXT by d-UiO-67-4. The practical separation performance of d-UiO-67-4 for AXT extracted from Haematococcus pluvialis is demonstrated by fixed-bed column-based dynamic adsorption and desorption experiments. This work broadens the preparation methods for thermosensitive active substances and provided new research ideas for the controlled adsorption of functional food factors.

Rapid Preparation of a Self-Luminous Cd-Based Metal-Organic Framework Using AIEgen Ligands for High-Performance Electrochemiluminescence.

The design and synthesis of high-efficiency electrochemiluminescence (ECL) emitters hold great promise for a wide range of analytical applications. In this study, we developed a rapid and straightforward strategy to fabricate a self-luminous Cd-based metal-organic framework (Cd-MOF) using individual aggregation-induced emission ligands, specifically 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethane (TPPE), within a few seconds. The rigid and directionally enriched metal node of Cd, along with the organic ligands, is formed within the Cd-MOF via coordination, effectively constraining the intramolecular free motions of TPPE and suppressing nonradiative relaxation. Additionally, the unique porous structure combined with the catalytic activity resulting from the incorporation of Cd2+, endow the Cd-MOF with 90-fold ECL enhancement compared to individual TPPE as more chromophores are electro-excited and more coreactants are catalyzed to produce luminescence. The as-made Cd-MOF amplifies the ECL performance by integrating ECL emitters and coreactant accelerators into a single entity, simplifying the sensing process. Leveraging the excellent ECL performance, we constructed a sensitive ECL sensor for hydroquinone based on competitive reactions, with a wide linear range from 200 nM to 1 mM and a satisfying detection limit as low as 80 nM.

Exceptional proton conduction in two robust zirconium(IV)/hafnium(IV)-organic frameworks constructed by tetratopic carboxylate

The fabrication of metal-organic frameworks based on zirconium and hafnium with high structural rigidity using multifunctional carboxylate and the examination of their possible uses have gained significant attention in recent times. The structural features of these porous MOFs, such as their abundant Lewy acid sites and hydroxyl groups, which are appropriate for building effective proton transport channels, have also drawn much attention in the proton conduction field. Herein, two highly stable Zr(IV)/Hf(IV) MOFs, [M6(μ3-O)4(μ3-OH)4(bptc)3]·2DMF (M = Zr (Zr-bptc) or Hf (Hf-bptc)) were solvothermally prepared by employing the tetratopic ligand, 3,3′,5,5′-biphenyltetracarboxylic acid (H4bptc), in which M6(μ3-O)4(μ3-OH)4(COO)12 clusters are linked by bptc3- anions to form an ftw type framework with 12-connected M6 cluster. X-ray powder diffraction, infrared spectroscopy, scanning electron microscopy, and thermogravimetric analyses proved that the two MOFs had remarkable water, chemical, and thermal stability. The alternating current (AC) impedance determinations manifested that the two MOFs have high proton conductivities under 100 °C and 98 % relative humidity (RH) of 0.89 × 10−3 and 1.37 × 10−3 S/cm, respectively, which are among the described MOFs with high proton conductivity. Furthermore, the two MOFs demonstrated excellent electrochemical determination durability. In addition, the activation energy estimates at high or low RHs fully illustrated the significant influence of water molecules in the environment on proton transport within the framework. This investigation again confirms that Zr/Hf-based MOFs have unparalleled structural and performance advantages in energy chemistry.

Synthesis, crystal structure, Hirshfeld surface analyses and antibacterial activity of 2-fluorobenzylpyridinium tetrabromidocuprate(II)

In this article, novel organic-inorganic hybrid material, 2-fluorobenzylpyridinium tetrabromidocuprate(II) [2FBzPy]2[CuBr4], has been obtained by using a slow evaporation solution-growth method and was characterized by powder X-ray diffraction, infrared spectroscopy, scanning electron microscopy, UV–visible diffuse reflectance spectrum. The compound crystallizes in the monoclinic space group P21 /c, and the packing is governed by C − H···Br hydrogen bonding interactions, which was confirmed by the Hirshfeld surface analysis. The results of antimicrobial experiments showed that the compound possessed excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. RESEARCH HIGHLIGHTS An inorganic-organic hybrid salt [2FBzPy]2[CuBr4] was synthesized and characterized. The main intermolecular interaction in [2FBzPy]2[CuBr4] crystals have been studied and analyzed. The interactions between different molecules in[2FBzPy]2 [CuBr4] were examined by Hirshfeld surface analyses. [2FBzPy]2[CuBr4] had an optical band gap of 1.69 eV, was a typical semiconductor material with good optical property. The as-synthesized salts exhibits good antibacterial activities against S. aureus and E. coli.

Formamidinium Incorporates into Rb-based Non-Perovskite Phases in Solar Cell Formulations.

Organic-inorganic hybrid perovskite materials, such as formamidinium lead iodide (FAPbI3), are among the most promising emerging photovoltaic materials. However, the spontaneous phase transition from the photoactive perovskite phase to an inactive non-perovskite phase complicates the application of FAPbI3 in solar cells. To remedy this, alkali metal cations, most often Cs+, Rb+ or K+, are included during perovskite synthesis to stabilize the photoactive phase. The atomic-level mechanisms of stabilization are complex. While Cs+ dopes directly into the perovskite lattice, Rb+ does not, but instead forms an additional non-perovskite phase, and the mechanism by which Rb confers increased stability remains unclear. Here, we use 1H-87Rb double resonance NMR experiments to show that FA+ incorporates into the Rb-based non-perovskite phases (FAyRb1-yPb2Br5 and δ-FAyRb1-yPbI3) for both bromide and iodide perovskite formulations. This is demonstrated by changes in the 1H and 87Rb chemical shifts, 1H-87Rb heteronuclear correlation spectra, and 87Rb{1H} REDOR spectra. Simulation of the REDOR dephasing curves suggests up to ~60 % FA+ incorporation into the inorganic Rb-based phase for the bromide system. In light of these results, we hypothesize that the substitution of FA+ into the non-perovskite phase may contribute to the greater stability conferred by Rb salts in the synthesis of FA-based perovskites.

Microfluidic Precision Manufacture of High Performance Liquid Chromatographic Microspheres.

A key bottleneck in developing chromatographic material is the chemically entangled control of morphology, pore structure, and material chemistry, which holds back precision material manufacture in order to pursue advanced separation performance. In this work, a precision manufacture strategy based on droplet microfluidics was developed, for production of highly efficient chromatographic microspheres with independent control over particle morphology, pore structure and material chemistry. The droplet-synthesized microspheres display extremely narrow particle size distribution (CV<3 %), enabling a 100 % production yield due to complete elimination of sieving steps. More importantly, the size of the droplet-synthesized microspheres is freely adjustable without the need for re-optimizing chemical recipes or reaction conditions. The resulting materials exhibit excellent separation efficiencies, achieving a reduced plate height of hmin=1.67. This precision manufacture strategy also allows for flexible pore design and continuous pore size adjustment across three orders of magnitudes, providing a novel vehicle for resolution fine-tuning targeting protein separation. Besides traditional silica, organic-inorganic hybrid silica, zirconia, and titania microspheres can also be precisely synthesized on the same platform, supporting various separation applications and operating conditions. Powered by precision manufacture, super-throughput production, and versatile chemistry, the high-performance droplet-synthesized separation material will pave the way towards green and precision chromatographic industry.