Supramolecular Interactions Induce Dynamics in Metal-Organic Layers to Selectively Separate Acetylene from Carbon Dioxide.

We report the synthesis and structural characterization of a 2D metal-organic framework with AB-packing layers, [Co2(pybz)2(CH3COO)2]·DMF (Co2, pybz= 4-(4-pyridyl)benzoate), containing a stable (4,4)-grid network fabricated by paddle-wheel nodes, ditopic pybz, and acetate ligands. After removal of the guest, the layer structure is retained but reorganized into an ABCD packing mode in the activated phase (Co2a). Consequently, the intralayer square windows (7.2 × 5.0 Å2) close, while the interlayer separation is decreased slightly from 3.69 to 3.45 Å, leaving a narrow gap. Importantly, the dangling methyl group of the acetate with H-bonds to the adjacent layers and also the well-distributed π-π interactions between the aromatic rings of neighboring layers facilitate the structural stability. These weak supramolecular interactions further allow for favorable dynamic exfoliation of the layers, which promotes efficient adsorption of C2H2 (41.6 cm3 g-1) over CO2 with an adsorption ratio of 6.3 (0.5 bar, 298 K). The effective separation performance of equimolar C2H2/CO2 was verified by cycling breakthrough experiments and was even tolerable to moisture (R.H = 52%). DFT calculations, in situ PXRD, and PDF characterization reveal that the favorable retention of C2H2 rather than that of CO2 is due to its H-bond formation with the paddle-wheel oxygen atoms that triggers the increase in interlayer separation during C2H2 adsorption.

Highly Enantioselective Catalysis by Enzyme Encapsulated in Metal Azolate Frameworks with Micelle-Controlled Pore Sizes.

Encapsulating enzymes within metal-organic frameworks has enhanced their structural stability and interface tunability for catalysis. However, the small apertures of the frameworks restrict their effectiveness to small organic molecules. Herein, we present a green strategy directed by visible linker micelles for the aqueous synthesis of MAF-6 that enables enzymes for the catalytic asymmetric synthesis of chiral molecules. Due to the large pore aperture (7.6 Å), double the aperture size of benchmark ZIF-8 (3.4 Å), MAF-6 allows encapsulated enzyme BCL to access larger substrates and do so faster. Through the optimization of surfactants' effect during synthesis, BCL@MAF-6-SDS (SDS = sodium dodecyl sulfate) displayed a catalytic efficiency (Kcat/Km) that was 420 times greater than that of BCL@ZIF-8. This biocomposite efficiently catalyzed the synthesis of drug precursor molecules with 94-99% enantioselectivity and nearly quantitative yields. These findings represent a deeper understanding of de novo synthetic encapsulation of enzyme in MOFs, thereby unfolding the great potential of enzyme@MAF catalysts for asymmetric synthesis of organics and pharmaceuticals.

Oligogenic basis of premature ovarian insufficiency: an observational study.

BACKGROUND: The etiology of premature ovarian insufficiency, that is, the loss of ovarian activity before 40 years of age, is complex. Studies suggest that genetic factors are involved in 20-25% of cases. The aim of this study was to explore the oligogenic basis of premature ovarian insufficiency. RESULTS: Whole-exome sequencing of 93 patients with POI and whole-genome sequencing of 465 controls were performed. In the gene-burden analysis, multiple genetic variants, including those associated with DNA damage repair and meiosis, were more common in participants with premature ovarian insufficiency than in controls. The ORVAL-platform analysis confirmed the pathogenicity of the RAD52 and MSH6 combination. CONCLUSIONS: The results of this study indicate that oligogenic inheritance is an important cause of premature ovarian insufficiency and provide insights into the biological mechanisms underlying premature ovarian insufficiency.

Mn(II) Promoted Divergent-Convergent Domino Reaction Giving Dinuclear Tetrasubstituted Pyrrole Complex.

Domino reaction of benzo[d]thiazole-2-methylamine (S1) has been developed in the presence of MnCl2 ⋅ 4H2O, leading to tetrasubstituted pyrrole coordinated dinuclear Mn(II) complex 1 ([MnClP]2, P-=2,3,4,5-tetrakis(benzo[d]thiazol-2-yl)pyrrol-1-ide). The reaction process has been studied by assigning a series of intermediates based on time-dependent mass spectrometry, control experiments, crystallography, and density functional theory (DFT) theoretical calculation. A plausible mechanism involving an unprecedented divergent-convergent domino sequence has been proposed. Compound S1 could be activated by MnCl2 ⋅ 4H2O via coordination, which divergently produces two intermediates imine II (1-(benzo[d]thiazol-2-yl)-N-(benzo[d]thiazol-2-ylmethyl)methanimine) and alkene C (1,2-bis(benzo[d]thiazol-2-yl)ethene) through oxidative self-condensation and free radical coupling followed by elimination, respectively. They could then react with each other convergently via formal [3+2] cycloaddition to give deprotonated tetrasubstituted pyrrole coordinated intermediate [MnClP] after aromatization. Dimerization of [MnClP] produces the final product 1. Three C-C bonds and one C-N bond are formed through this six-step domino sequence. The corresponding organic skeleton (HP: 2,2',2'',2'''-(1H-pyrrole-2,3,4,5-tetrayl)tetrakis(benzo[d]thiazole)) has been obtained from 1 and shows a higher fluorescent quantum yield (52 %) than the reported 3,4-diphenyl substituted analogue 2,2'-(3,4-diphenyl-1H-pyrrole-2,5-diyl)bis(benzo[d]thiazole) (DPB) (42 %).

Mechanistic insights into an NH4OAc-promoted imine dance in Rh-catalysed multicomponent double C-H annulations through an N-retention/exchange dual channel.

Developing new and understanding multicomponent reactions (MCRs) is an appealing but challenging task. Herein, Rh(iii)-catalyzed multicomponent double C-H annulations of cyclic diimines (or diketones and acetone), alkynes, and ammonium acetate to assemble functionalized 1,1'-biisoquinolines and C-bridged 1,1'-bisisoquinolines with controllable 14N/15N editing in one shot has been developed. Through a combination of isotopic-labeling (2H, 18O, and 15N) experiments, crystallography, and time-dependent ESI-MS, the reaction process was studied in detail. Ammonium acetate accounts for two rounds of Hofmann elimination and iminization, thus leading to an unprecedented imine dance, cyclic imine → N-alkenyl imine → NH imine. The N-alkenyl imine can immediately guide a C-H annulation (N-retention channel), and some of it is converted into NH-imine to trigger another annulation (N-exchange channel). The channels and 15N ratios can be regulated by the reaction mode and acidity. Moreover, the resulting 1,1'-biisoquinolines are a privileged ligand scaffold which is exemplified herein by a hydrazine-iodine exchange reaction to form drug-like benzo[c]cinnolines.

Pipsqueak family genes dan/danr antagonize nuclear Pros to prevent neural stem cell aging in Drosophila larval brains.

Neural stem cell aging is a fundamental question in neurogenesis. Premature nuclear Pros is considered as an indicator of early neural stem cell aging in Drosophila. The underlying mechanism of how neural stem cells prevent premature nuclear Pros remains largely unknown. Here we identified that two pipsqueak family genes, distal antenna (dan) and distal antenna-related (danr), promote the proliferation of neural stem cells (also called neuroblasts, NBs) in third instar larval brains. In the absence of Dan and Danr (dan/danr), the NBs produce fewer daughter cells with smaller lineage sizes. The larval brain NBs in dan/danr clones show premature accumulation of nuclear Prospero (Pros), which usually appears in the terminating NBs at early pupal stage. The premature nuclear Pros leads to NBs cell cycle defects and NB identities loss. Removal of Pros from dan/danr MARCM clones prevents lineage size shrinkage and rescues the loss of NB markers. We propose that the timing of nuclear Pros is after the downregulation of dan/danr in the wt terminating NBs. dan/danr and nuclear Pros are mutually exclusive in NBs. In addition, dan/danr are also required for the late temporal regulator, Grainyhead (Grh), in third instar larval brains. Our study uncovers the novel function of dan/danr in NBs cell fate maintenance. dan/danr antagonize nuclear Pros to prevent NBs aging in Drosophila larval brains.

Multi-stage Transformations of a Cluster-Based Metal-Organic Framework: Perturbing Crystals to Glass-Forming Liquids that Re-Crystallize at High Temperature.

Glassy and liquid state metal-organic frameworks (MOFs) are emerging type of materials subjected to intense research for their rich physical and chemical properties. In this report, we obtained the first glassy MOF that involves metal-carboxylate cluster building units via multi-stage structural transformations. This MOF is composed of linear [Mn3 (COO)6 ] node and flexible pyridyl-ethenylbenzoic linker. The crystalline MOF was first perturbed by vapor hydration and thermal dehydration to give an amorphous state, which can go through a glass transition at 505 K into a super-cooled liquid. The super-cooled liquid state is stable through a wide temperature range of 40 K and has the largest fragility index of 105, giving a broad processing window. Remarkably, the super-cooled liquid can not only be quenched into glass, but also recrystallize into the initial MOF when heated to a higher temperature above 558 K. The mechanism of the multi-stage structural transformations was studied by systematic characterizations of in situ X-ray diffraction, calorimetry, rheological, spectroscopic and pair-distribution function analysis. These multi-stage transformations not only represent a rare example of high temperature coordinative recognition and self-assembly, but also provide new MOF processing strategy through crystal-amorphous-liquid-crystal transformations.

Supramolecular Gel-to-Gel Transition Induced by Nanoscale Structural Perturbation via the Rotary Motion of Feringa's Motor.

Supramolecular rather than covalent molecular engineering on Feringa motors can provide an alternative toolkit for tuning the properties of motorized materials through appropriate supramolecular structural perturbations, which are underexplored. Herein, a multicomponent supramolecular gel system is successfully prepared by employing an ultra-low molecular weight gelator and a modulator-Feringa motor. The electron microscopic, spectroscopic, and rheological data revealed that the morphology and mechanical properties of the gel can be tuned via a crystallographic mismatch branching (CMB) mechanism simply by adding varied amounts of motor modulators. Notably, the rotary motion of the motor is preserved in such a multicomponent gel system, and the morphology and rheology of the gel can be further altered by the motor's rotary motion that promotes the structural perturbation, resulting in seldomly seen gel-to-gel transition events. The work shown here offers prospects to utilize a supramolecular perturbation strategy to deliver responsiveness from molecular motors to the corresponding bulk materials.

Hydrazine-Halogen Exchange Strategy Toward N═N-Containing Compounds and Process Tracking for Mechanistic Insight.

An anhydride-promoted traceless hydrazine-I/Br exchange strategy is reported, where hydrazine hydrate and cyclic/linear iodonium, including rarely explored cyclic bromonium, are converted to benzo[c]cinnolines/azobenzenes in one pot. The reaction proceeds through diacylation (first and second C─N formation), N,N'-diarylation (third and fourth C─N formation), and deacylation/oxidation (2 C─N cleavages and 1 N═N formation). The reaction mechanism is investigated by isolating multiple intermediates and kinetic studies. Furthermore, time-dependent electrospray ionization mass spectrometry (TD ESI-MS) was applied to track the process by detecting most intermediates. The complex [CuIII(iodobiphenyl)(bipy)I]+ (Int-C) was detected for the first time, giving evidence for oxidative addition of cyclic iodonium to Cu catalyst. Another complex [CuI(PHA)(bipy)] (Int-B) via ligand-exchange between the hydrazide and Cu catalyst was also detected, indicating a two-path initial activation process.

Monolithic Titanium Alkoxide Networks for Lithium-Ion Conductive All-Solid-State Electrolytes.

Reticular chemistry provides opportunities to design solid-state electrolytes (SSEs) with modular tunability. However, SSEs based on modularly designed crystalline metal-organic frameworks (MOFs) often require liquid electrolytes for interfacial contact. Monolithic glassy MOFs can have liquid processability and uniform lithium conduction, which is promising for the reticular design of SSE without liquid electrolytes. Here, we develop a generalizable strategy for the modular design of noncrystalline SSEs based on a bottom-up synthesis of glassy MOFs. We demonstrate such a strategy by linking polyethylene glycol (PEG) struts and nanosized titanium-oxo clusters into network structures termed titanium alkoxide networks (TANs). The modular design allows the incorporation of PEG linkers with different molecular weights, which give optimal chain flexibility for high ionic conductivity, and the reticular coordinative network provides a controlled degree of cross-linking that gives adequate mechanical strength. This research shows the power of reticular design in noncrystalline molecular framework materials for SSEs.

The sequential structural transformation of a heptanuclear zinc cluster towards hierarchical porous carbon for supercapacitor applications.

The peripheral N/O chelating of Schiff base ligands, inner bridges, counterions, and metal centers gave rise to a brucite disk cluster [Zn7L6(OCH3)6](NO3)2 (Zn7, (HL = 2-methoxy-6-((methylimino)-methyl)phenolate)) which crystallized into hexagonal prismatic plates. The combination of crystallographic studies, in situ TG-MS, and other characterization techniques showed that with a fixed metal and ligand composition in the precursors, weak correlative interactions (e.g., electrostatic interactions) and shape matching between the cluster core and counterions determine the cluster packing modes in the crystals and affect their phase and morphological changes during pyrolysis. The tracking of the pyrolysis process showed that the peripheral ligands, inner bridge, and counterion decompose first, followed by the Zn7O6 core merging with cubic ZnO, which was then reduced by carbon and eventually evaporated, leaving behind a porous carbon structure. In this process, the solid material composition change was in the sequence {Zn7}-{Zn-O core@C}-{ZnO@C}-{Zn@C}-{C}, which was accompanied by a porosity change from micropores to hierarchical pores, and then to micropores again. The core structure and packing modes of Zn7 evolved into micropores and mesopores, respectively. Micro-mesoporous carbon Zn7-1000 featured a capacitance of 1797 F g-1 at 1 A g-1, where the BET specific surface area was 3119.18 m2 g-1, which, to the best of our knowledge, is the highest value reported for a porous carbon electrode. This work represents an important benchmark for the analysis of dynamic chemical processes involving coordination clusters at high temperatures, and it could lead to important applications in high-performance devices.

Vibration assisted glass-formation in zeolitic imidazolate framework.

A new glass forming method is essential for broadening the scope of liquid and glassy metal-organic frameworks due to the limitations of the conventional melt-quenching method. Herein, we show that in situ mechanical vibration can facilitate the framework melting at a lower temperature and produce glassy metal-organic frameworks (MOFs) with unique properties. Using zeolitic imidazolate framework (ZIF)-62 as a concept-proofing material, in situ mechanical vibration enables low-temperature melting at 653 K, far below its melting point (713 K). The resultant vibrated ZIF-62 glass exhibited a lower glass transition temperature of 545 K, improved gas accessible porosity, and pronounced short-to-medium range structures compared to the corresponding melt-quenched glass. We propose that vibration-facilitated surface reconstruction facilitates pre-melting, which could be the cause of the lowered melting temperature. The vibration assisted method represents a new general method to produce MOF glasses without thermal decomposition.

Short stature and melanocytic nevi in a girl with ARID1B-related Coffin-Siris syndrome: a case report.

BACKGROUND: Coffin-Siris syndrome (CSS) is a rare autosomal dominant disorder characterized by intellectual disability, developmental delay, and characteristic facial features. Few patients with cutaneous phenotype in this rare syndrome have been reported. CASE PRESENTATION: Herein, we describe a 12-year-old Chinese girl diagnosed with CSS, who was referred to our hospital because of intellectual disability and short stature. Prominent characteristics of the cutaneous system were observed: (1) A congenital giant nevus from the left frontal and temporal regions to the entire left scalp; and (2) multiple melanocytic nevi on the face and trunk. Whole exome sequencing revealed a novel heterozygous variant in the ARID1B gene. Recombinant human growth hormone (rhGH) was given for short stature, and resulted in significantly improved height. No enlargement or malignant transformation of nevi occurred within 4 years of follow-up. CONCLUSION: The symptoms in cutaneous system is noteworthy,which may be a neglected phenotype in CSS.The therapeutic response of growth hormone is effective in this patient and no tumor related signs were found.

Construction of Photo-Responsive Pd2 L4 -Type Nanocages based on Feringa's Second-Generation Motor and Its Guest Binding Ability for C60.

We present the construction of a M2 L4 -type metal-organic nanocage featuring four endohedral Feringa's motor motifs and its adaptive encapsulation towards a C60 guest molecule. The structure of the cage, though complicated on the 1 H NMR spectrum due to the adoption of mixed ligands, was unambiguously characterized with a combination of ESI-MS, 2D DOSY, 13 C NMR and particularly the SAXS technique. The molecular motor within the cage demonstrated similar photophysical properties to the uncoordinated one, indicating the motor's function was not compromised when it was anchored in such a confined nanospace. Furthermore, the nanocage showed good guest encapsulation ability towards C60 , and a guest induced-fit behavior of the cage was revealed based on the extensive SAXS analysis and molecular dynamics simulation. The adaptive motorized nanocage reported here represents one of the very few examples of integrating individual motors into a discrete nanoconfined system and offers prospects to achieve its non-equilibrium functions.

Ru(II)-catalyzed P(III)-assisted C8-alkylation of naphthphosphines.

We report a phosphine-directed ruthenium-catalyzed C8-selective alkylation of naphthalenes with alkenes. This protocol provides straightforward access to a large library of electron-rich C8-alkyl substituent 1-naphthphosphines, which outperformed common commercial phosphines and their precursors in the Pd-catalyzed Suzuki-Miyaura coupling of aryl bromides with alkylboronic acid.

Synergistic Stimulation of Metal-Organic Frameworks for Stable Super-cooled Liquid and Quenched Glass.

Metal-organic framework (MOF) glasses are a fascinating new class of materials, yet their prosperity has been impeded by the scarcity of known examples and limited vitrification methods. In the work described in this report, we applied synergistic stimuli of vapor hydration and thermal dehydration to introduce structural disorders in interpenetrated dia-net MOF, which facilitate the formation of stable super-cooled liquid and quenched glass. The material after stimulus has a glass transition temperature (Tg) of 560 K, far below the decomposition temperature of 695 K. When heated, the perturbed MOF enters a super-cooled liquid phase that is stable for a long period of time (>104 s), across a broad temperature range (26 K), and has a large fragility index of 83. Quenching the super-cooled liquid gives rise to porous MOF glass with maintained framework connectivity, confirmed by EXAFS and PDF analysis. This method provides a fundamentally new route to obtain glassy materials from MOFs that cannot be melted without causing decomposition.

Electronic structures of hydroxylated low index surfaces of rutile and anatase-type titanium dioxide.

Different surface planes of various types of titanium dioxide (TiO2) crystals have diverse catalysis effects on the splitting of H2O and H2 and the electronic structures of the formed hydroxylated TiO2 vary significantly. A series of sixteen types of hydroxylated TiO2 surfaces containing two types of hydroxyls (OH1 and OH2) on four kinds of low index surfaces [(001), (100), (101), and (110)] of two types of crystals [anatase (A) and rutile (R)] are studied using first-principles density functional theory calculations. The catalyzed splitting of H2O and H2 on the eight low index surfaces is compared using Gibbs free energy. The geometries and electronic structures including the total and partial density of states and the charge density distribution of the sixteen hydroxylated surfaces are systematically described. The electronic structures of R-101, R-001, A-110, A-100, and A-001 surfaces are more significantly influenced by hydroxylation than other surfaces and the effects of OH2 are larger than those of OH1. In particular, the band gap values decrease and a new electronic energy state appears in R-001-OH2 and A-100-OH2. A new electronic state appears in the middle of the bands of R-101 and A-110 surfaces upon hydroxylation. The electron spin balance at the edge of the conduction band minimum of A-001-OH2 is disturbed. This research can provide theoretical guidance for experimental researchers to design surface hydroxylated TiO2 materials with tunable electronic structures and high catalytic performance.

PC Splice-Site Variant c.1825+5G>A Caused Intron Retention in a Patient With Pyruvate Carboxylase Deficiency: A Case Report.

Background: Pyruvate carboxylase deficiency (PCD; MIM#266150) is a rare autosomal recessive disorder characterized by a wide range of clinical features, including delayed neurodevelopment, elevated pyruvate levels, lactic acidosis, elevated ketone levels, and hyperammonemia. The pyruvate carboxylase (PC) gene was identified to be the disease-causing gene for PCD. A novel homozygous splice variant in the PC gene was identified in a Chinese boy, but the pathogenicity is still unclear. The objective of the present study was to determine the effect of this splice-site variant by reverse transcription analysis. Methods: We reported the clinical course of a 20-month-old Chinese pediatric patient who was diagnosed with PCD using whole-exome sequencing (WES). The effects of the variant on mRNA splicing were analyzed through the transcript analysis in vivo. Results: The results of metabolic blood and urine screening suggested PCD by employing tandem mass spectrometry. WES revealed a novel homozygous splice-site variant (c.1825+5G>A) in the PC gene. in vivo transcript analysis indicated that the splice-site variant caused the retention of 192 bp of the intron. Conclusion: Thus, c.1825+5G>A was established as a pathogenic variant, thereby enriching the mutational spectrum of the PC gene and providing a basis for the genetic diagnosis of PCD.

Heterozygous FMN2 missense variant found in a family case of premature ovarian insufficiency.

BACKGROUND: Premature ovarian insufficiency (POI) plagues 1% of women under 40, while quite a few remain an unknown cause. The development of sequencing has helped find pathogenic genes and reveal the relationship between DNA repair and ovarian reserve. Through the exome sequencing, our study targets screening out the possible POI pathogenic gene and variants in a Chinese family and 20 sporadic POI patients, preliminarily exploring the functional impact and finding out potential linkages between the gene and POI. RESULTS: The whole exome sequencing suggested a novel FMN2 heterozygous variant c.1949C > T (p.Ser650Leu) carried by all three patients in a Chinese family and another c.1967G > A(p.Arg656His) variant in a sporadic case. Since no FMN2 missense mutation is reported for causing human POI, we preliminarily assessed p.Ser650Leu variant via cross-species alignment and 3D modeling and found it possibly deleterious. A series of functional evidence was consistent with our hypothesis. We proved the expression of FMN2 in different stages of oocytes and observed a statistical difference of chromosomal breakages between the POI patient carrying p.Arg656His variant and the health control (p = 0.0013). Western Blot also suggested a decrease in FMN2 and P21 in the mutant type and an associated increase in H2AX. The p.Arg656His variant with an extremely low frequency also indicated that the gene FMN2 might play an essential role in the genetic etiology of POI. To the best of our knowledge, this is the first POI report on missense variants of FMN2. CONCLUSION: This finding indicates a novel gene possibly related to POI and sheds lights on the study of FMN2.

Single-Atom Pt Boosting Electrochemical Nonenzymatic Glucose Sensing on Ni(OH)2/N-Doped Graphene.

Conventional nanomaterials in electrochemical nonenzymatic sensing face huge challenge due to their complex size-, surface-, and composition-dependent catalytic properties and low active site density. In this work, we designed a single-atom Pt supported on Ni(OH)2 nanoplates/nitrogen-doped graphene (Pt1/Ni(OH)2/NG) as the first example for constructing a single-atom catalyst based electrochemical nonenzymatic glucose sensor. The resulting Pt1/Ni(OH)2/NG exhibited a low anode peak potential of 0.48 V and high sensitivity of 220.75 µA mM-1 cm-2 toward glucose, which are 45 mV lower and 12 times higher than those of Ni(OH)2, respectively. The catalyst also showed excellent selectivity for several important interferences, short response time of 4.6 s, and high stability over 4 weeks. Experimental and density functional theory (DFT) calculated results reveal that the improved performance of Pt1/Ni(OH)2/NG could be attributed to stronger binding strength of glucose on single-atom Pt active centers and their surrounding Ni atoms, combined with fast electron transfer ability by the adding of the highly conductive NG. This research sheds light on the applications of SACs in the field of electrochemical nonenzymatic sensing.