Microwave-Assisted ultrafast Synthesis of Bimetallic Nickel-Cobalt Metal-Organic Frameworks for Application in the Oxygen Evolution Reaction.

A series of monometallic Ni-, Co- and Zn-MOFs and bimetallic NiCo-, NiZn- and CoZn-MOFs M2(BDC)2DABCO and (M,M')2(BDC)2DABCO, respectively, with the same pillar and layer linkers 4-diazabicyclo[2.2.2]octane (DABCO) and benzene-1,4-dicarboxylate (BDC) were prepared through a fast microwave-assisted thermal conversion synthesis method within only 12 min. In the bimetallic MOFs the ratio M:M' was 4:1. The mono- and bimetallic MOFs were selected to systematically explore the catalytic-activity of their derived metal oxide/hydroxides for the oxygen evolution reaction (OER). The NiCoMOF exhibits superior catalytic activity for the OER with the lowest overpotentials of 301 mV and Tafel slopes of 42 mV dec-1 on a glassy carbon electrode in 1 mol L-1 KOH electrolyte at a current density of 10 mA cm-2. In addition, NiCoMOF was in situ grown in just 25 min by the MW synthesis on the surface of nickel foam (NF) where overpotentials of 313 and 328 mV at current densities of 50 and 300 mA cm-2, respectively, were delivered and superior long-term stability for practical OER application. The low Tafel slope of 27 mV dec-1, as well as a low reaction resistance from electrochemical impedance spectroscopy measurement (Rfar = 2 Ω), confirm the excellent OER performance of this NiCoMOF/NF composite.

Exceptionally Stable And Super-Efficient Electrocatalysts Derived From Semiconducting Metal Phosphonate Frameworks.

Two new isostructural semiconducting metal-phosphonate frameworks are reported. Co2 [1,4-NDPA] and Zn2 [1,4-NDPA] (1,4-NDPA4- is 1,4-naphthalenediphosphonate) have optical bandgaps of 1.7 eV and 2.5 eV, respectively. The electrocatalyst derived from Co2 [1,4-NPDA] as a precatalyst generated a low overpotential of 374 mV in the oxygen evolution reaction (OER) with a Tafel slope of 43 mV dec-1 at a current density of 10 mA cm-2 in alkaline electrolyte (1 mol L-1 KOH), which is indicative of remarkably superior reaction kinetics. Benchmarking of the OER of Co2 [1,4-NPDA] material as a precatalyst coupled with nickel foam (NF) showed exceptional long-term stability at a current density of 50 mA cm-2 for water splitting compared to the state-of-the-art Pt/C/RuO2 @NF after 30 h in 1 mol L-1 KOH. In order to further understand the OER mechanism, the transformation of Co2 [1,4-NPDA] into its electrocatalytically active species was investigated.

Interfacial design for detection of a few molecules.

Major advances in molecular detection are being driven by goals associated with the development of methods that are amenable to miniaturization and automation, and that have high sensitivity and low interference. The new detection methods are confronted by many interfacial issues, which when properly addressed can lead to improved performance. One interfacial property, special wettability, can facilitate precise delivery and local enrichment of molecules to sensing elements. This review summarizes applications of unique features of special wettability in molecular detection including (1) chemical and electrochemical reactions in anchored microdroplets on superwetting surfaces, (2) enrichment of analytes and active materials at low contact areas between droplets and superwetting surfaces, (3) complete opposite affinities of superwetting surfaces toward nonpolar/polar solutes and oil/water phases, and (4) directional droplet transportation on asymmetric superwetting surfaces. The challenges and opportunities that exist in design and applications of special wettability in interfacial delivery and enrichment for detection of a few molecules are also discussed.

Fractal Design of Hierarchical PtPd with Enhanced Exposed Surface Atoms for Highly Catalytic Activity and Stability.

Hierarchical assembly of arc-like fractal nanostructures not only has its unique self-similarity feature for stability enhancement but also possesses the structural advantages of highly exposed surface-active sites for activity enhancement, remaining a great challenge for high-performance metallic nanocatalyst design. Herein, we report a facile strategy to synthesize a novel arc-like hierarchical fractal structure of PtPd bimetallic nanoparticles (h-PtPd) by using pyridinium-type ionic liquids as the structure-directing agent. Growth mechanisms of the arc-like nanostructured PtPd nanoparticles have been fully studied, and precise control of the particle sizes and pore sizes has been achieved. Due to the structural features, such as size control by self-similarity growth of subunits, structural stability by nanofusion of subunits, and increased numbers of exposed active atoms by the curved homoepitaxial growth, h-PtPd displays outstanding electrocatalytic activity toward oxygen reduction reaction and excellent stability during hydrothermal treatment and catalytic process.

A RuCoBO Nanocomposite for Highly Efficient and Stable Electrocatalytic Seawater Splitting.

Efficient and stable electrocatalysts are critically needed for the development of practical overall seawater splitting. The nanocomposite of RuCoBO has been rationally engineered to be an electrocatalyst that fits these criteria. The study has shown that a calcinated RuCoBO-based nanocomposite (Ru2Co1BO-350) exhibits an extremely high catalytic activity for H2 and O2 production in alkaline seawater (overpotentials of 14 mV for H2 evolution and 219 mV for O2 evolution) as well as a record low cell voltage (1.466 V@10 mA cm-2) and long-term stability (230 h @50 mA cm-2 and @100 mA cm-2) for seawater splitting. The results show that surface reconstruction of Ru2Co1BO-350 occurs during hydrogen evolution reaction and oxygen evolution reaction, which leads to the high activity and stability of the catalyst. The reconstructed surface is highly resistant to Cl- corrosion. The investigation suggests that a new strategy exists for the design of high-performance Ru-based electrocatalysts that resist anodic corrosion during seawater splitting.

Inverse Adsorption Separation of N2 O/CO2 in AgZK-5 Zeolite.

Nitrous oxide (N2 O), as the third largest greenhouse gas in the world, also has great applications in daily life and industrial production, like anesthetic, foaming agent, combustion supporting agent, N or O atomic donor. The capture of N2 O in adipic acid tail gas is of great significance but remains challenging due to the similarity with CO2 in molecular size and physical properties. Herein, the influence of cation types on CO2 -N2 O separation in zeolite was studied comprehensively. In particular, the inverse adsorption of CO2 -N2 O was achieved by AgZK-5, which preferentially adsorbs N2 O over CO2 , making it capable of trapping N2 O from an N2 O/CO2 mixture. AgZK-5 shows a recorded N2 O/CO2 selectivity of 2.2, and the breakthrough experiment indicates excellent performance for N2 O/CO2 separation. The density functional theory (DFT) calculation shows that Ag+ has stronger adsorption energy with N2 O, and the kinetics of N2 O is slightly faster than that of CO2 on AgZK-5.

A New Family of Layered Metal-Organic Semiconductors: Cu/V-Organophosphonates.

Herein, we report the design and synthesis of a layered redox-active, antiferromagnetic metal organic semiconductor crystals with the chemical formula [Cu(H2 O)2 V(µ-O)(PPA)2 ] (where PPA is phenylphosphonate). The crystal structure of [Cu(H2 O)2 V(µ-O)(PPA)2 ] shows that the metal phosphonate layers are separated by phenyl groups of the phenyl phosphonate linker. Tauc plotting of diffuse reflectance spectra indicates that [Cu(H2 O)2 V(µ-O)(PPA)2 ] has an indirect band gap of 2.19 eV. Photoluminescence (PL) spectra indicate a complex landscape of energy states with PL peaks at 1.8 and 2.2 eV. [Cu(H2 O)2 V(µ-O)(PPA)2 ] has estimated hybrid ionic and electronic conductivity values between 0.13 and 0.6 S m-1 . Temperature-dependent magnetization measurements show that [Cu(H2 O)2 V(µ-O)(PPA)2 ] exhibits short range antiferromagnetic order between Cu(II) and V(IV) ions. [Cu(H2 O)2 V(µ-O)(PPA)2 ] is also photoluminescent with photoluminescence quantum yield of 0.02%. [Cu(H2 O)2 V(µ-O)(PPA)2 ] shows high electrochemical, and thermal stability.

Indole Diketopiperazine Alkaloids from the Marine Sediment-Derived Fungus Aspergillus chevalieri against Pancreatic Ductal Adenocarcinoma.

A new prenylated indole diketopiperazine alkaloid, rubrumline P (1), was isolated along with six more analogues and characterized from the fermentation culture of a marine sediment-derived fungus, Aspergillus chevalieri, collected at a depth of 15 m near the lighthouse in Dahab, Red Sea, Egypt. In the current study, a bioassay-guided fractionation allowed for the identification of an active fraction displaying significant cytotoxic activity against the human pancreatic adenocarcinoma cell line PANC-1 from the EtOAc extract of the investigated fungus compared to the standard paclitaxel. The structures of the isolated compounds from the active fraction were established using 1D/2D NMR spectroscopy and mass spectrometry, together with comparisons with the literature. The absolute configuration of the obtained indole diketopiperazines was established based on single-crystal X-ray diffraction analyses of rubrumline I (2) and comparisons of optical rotations and NMR data, as well as on biogenetic considerations. Genome sequencing indicated the formation of prenyltransferases, which was subsequently confirmed by the isolation of mono-, di-, tri-, and tetraprenylated compounds. Compounds rubrumline P (1) and neoechinulin D (4) confirmed preferential cytotoxic activity against PANC-1 cancer cells with IC50 values of 25.8 and 23.4 µM, respectively. Although the underlying mechanism-of-action remains elusive in this study, cell cycle analysis indicated a slight increase in the sub-G1 peak after treatment with compounds 1 and 4.

Synthesis of Ketjenblack Decorated Pillared Ni(Fe) Metal-Organic Frameworks as Precursor Electrocatalysts for Enhancing the Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) have been investigated with regard to the oxygen evolution reaction (OER) due to their structure diversity, high specific surface area, adjustable pore size, and abundant active sites. However, the poor conductivity of most MOFs restricts this application. Herein, through a facile one-step solvothermal method, the Ni-based pillared metal-organic framework [Ni2(BDC)2DABCO] (BDC = 1,4-benzenedicarboxylate, DABCO = 1,4-diazabicyclo[2.2.2]octane), its bimetallic nickel-iron form [Ni(Fe)(BDC)2DABCO], and their modified Ketjenblack (mKB) composites were synthesized and tested toward OER in an alkaline medium (KOH 1 mol L-1). A synergistic effect of the bimetallic nickel-iron MOF and the conductive mKB additive enhanced the catalytic activity of the MOF/mKB composites. All MOF/mKB composite samples (7, 14, 22, and 34 wt.% mKB) indicated much higher OER performances than the MOFs and mKB alone. The Ni-MOF/mKB14 composite (14 wt.% of mKB) demonstrated an overpotential of 294 mV at a current density of 10 mA cm-2 and a Tafel slope of 32 mV dec-1, which is comparable with commercial RuO2, commonly used as a benchmark material for OER. The catalytic performance of Ni(Fe)MOF/mKB14 (0.57 wt.% Fe) was further improved to an overpotential of 279 mV at a current density of 10 mA cm-2. The low Tafel slope of 25 mV dec-1 as well as a low reaction resistance due to the electrochemical impedance spectroscopy (EIS) measurement confirmed the excellent OER performance of the Ni(Fe)MOF/mKB14 composite. For practical applications, the Ni(Fe)MOF/mKB14 electrocatalyst was impregnated into commercial nickel foam (NF), where overpotentials of 247 and 291 mV at current densities of 10 and 50 mA cm-2, respectively, were realized. The activity was maintained for 30 h at the applied current density of 50 mA cm-2. More importantly, this work adds to the fundamental understanding of the in situ transformation of Ni(Fe)DMOF into OER-active α/ß-Ni(OH)2, ß/γ-NiOOH, and FeOOH with residual porosity inherited from the MOF structure, as seen by powder X-ray diffractometry and N2 sorption analysis. Benefitting from the porosity structure of the MOF precursor, the nickel-iron catalysts outperformed the solely Ni-based catalysts due to their synergistic effects and exhibited superior catalytic activity and long-term stability in OER. In addition, by introducing mKB as a conductive carbon additive in the MOF structure, a homogeneous conductive network was constructed to improve the electronic conductivity of the MOF/mKB composites. The electrocatalytic system consisting of earth-abundant Ni and Fe metals only is attractive for the development of efficient, practical, and economical energy conversion materials for efficient OER activity.

Formation of Gold Nanoclusters from Goldcarbonyl Chloride inside the Metal-Organic Framework HKUST-1.

Gas-phase infiltration of the carbonylchloridogold(I), Au(CO)Cl precursor into the pores of HKUST-1 ([Cu3(BTC)2(H2O)2], Cu-BTC) SURMOFs (surface-mounted metal-organic frameworks; BTC = benzene-1,3,5-tricarboxylate) leads to Au(CO)Cl decomposition within the MOF through hydrolysis with the aqua ligands on Cu. Small Aux clusters with an average atom number of x ≈ 5 are formed in the medium-sized pores of the HKUST-1 matrix. These gold nanoclusters are homogeneously distributed and crystallographically ordered, which was supported by simulations of the powder X-ray diffractometric characterization. Aux@HKUST-1 was further characterized by scanning electron microscopy (SEM) and infrared reflection absorption (IRRA) as well as Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP-OES).

Electrochemical Determination of Epinephrine in Pharmaceutical Preparation Using Laponite Clay-Modified Graphene Inkjet-Printed Electrode.

Epinephrine (EP, also called adrenaline) is a compound belonging to the catecholamine neurotransmitter family. It can cause neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. This work describes an amperometric sensor for the electroanalytical detection of EP by using an inkjet-printed graphene electrode (IPGE) that has been chemically modified by a thin layer of a laponite (La) clay mineral. The ion exchange properties and permeability of the chemically modified electrode (denoted La/IPGE) were evaluated using multi-sweep cyclic voltammetry, while its charge transfer resistance was determined by electrochemical impedance spectroscopy. The results showed that La/IPGE exhibited higher sensitivity to EP compared to the bare IPGE. The developed sensor was directly applied for the determination of EP in aqueous solution using differential pulse voltammetry. Under optimized conditions, a linear calibration graph was obtained in the concentration range between 0.8 µM and 10 µM. The anodic peak current of EP was directly proportional to its concentration, leading to detection limits of 0.34 µM and 0.26 µM with bare IPGE and La/IPGE, respectively. The sensor was successfully applied for the determination of EP in pharmaceutical preparations. Recovery rates and the effects of interfering species on the detection of EP were evaluated to highlight the selectivity of the elaborated sensor.

Tunable Aryl Alkyl Ionic Liquid Supported Synthesis of Platinum Nanoparticles and Their Catalytic Activity in the Hydrogen Evolution Reaction and in Hydrosilylation.

Tunable aryl alkyl ionic liquids (TAAILs) are ionic liquids (ILs) with a 1-aryl-3-alkylimidazolium cation having differently substituted aryl groups. Herein, nine TAAILs with the bis(trifluoromethylsulfonyl)imide anion are utilized in combination with and without ethylene glycol (EG) as reaction media for the rapid microwave synthesis of platinum nanoparticles (Pt-NPs). TAAILs allow the synthesis of small NPs and are efficient solvents for microwave absorption. Transmission electron microscopy (TEM) shows that small primary NPs with sizes of 2 nm to 5 nm are obtained in TAAILs and EG/TAAIL mixtures. The Pt-NPs feature excellent activity as electrocatalysts in the hydrogen evolution reaction (HER) under acidic conditions, with an overpotential at a current density of 10 mA cm-2 as low as 32 mV vs the reversible hydrogen electrode (RHE), which is significantly lower than the standard Pt/C 20% with 42 mV. Pt-NPs obtained in TAAILs also achieved quantitative conversion in the hydrosilylation reaction of phenylacetylene with triethylsilane after just 5 min at 200 °C.

Enhanced Solid-State Fluorescence of Flavin Derivatives by Incorporation in the Metal-Organic Frameworks MIL-53(Al) and MOF-5.

The flavin derivatives 10-methyl-isoalloxazine (MIA) and 6-fluoro-10-methyl-isoalloxazine (6F-MIA) were incorporated in two alternative metal-organic frameworks, (MOFs) MIL-53(Al) and MOF-5. We used a post-synthetic, diffusion-based incorporation into microcrystalline MIL-53 powders with one-dimensional (1D) pores and an in-situ approach during the synthesis of MOF-5 with its 3D channel network. The maximum amount of flavin dye incorporation is 3.9 wt% for MIA@MIL-53(Al) and 1.5 wt% for 6F-MIA@MIL-53(Al), 0.85 wt% for MIA@MOF-5 and 5.2 wt% for 6F-MIA@MOF-5. For the high incorporation yields the probability to have more than one dye molecule in a pore volume is significant. As compared to the flavins in solution, the fluorescence spectrum of these flavin@MOF composites is broadened at the bathocromic side especially for MIA. Time-resolved spectroscopy showed that multi-exponential fluorescence lifetimes were needed to describe the decays. The fluorescence-weighted lifetime of flavin@MOF of 4 ± 1 ns also corresponds to those in solution but is significantly prolonged compared to the solid flavin dyes with less than 1 ns, thereby confirming the concept of "solid solutions" for dye@MOF composites. The fluorescence quantum yield (ΦF) of the flavin@MOF composites is about half of the solution but is significantly higher compared to the solid flavin dyes. Both the fluorescence lifetime and quantum yield of flavin@MOF decrease with the flavin loading in MIL-53 due to the formation of various J-aggregates. Theoretical calculations using plane-wave and QM/MM methods are in good correspondence with the experimental results and explain the electronic structures as well as the photophysical properties of crystalline MIA and the flavin@MOF composites. In the solid flavins, π-stacking interactions of the molecules lead to a charge transfer state with low oscillator strength resulting in aggregation-caused quenching (ACQ) with low lifetimes and quantum yields. In the MOF pores, single flavin molecules represent a major population and the computed MIA@MOF structures do not find π-stacking interactions with the pore walls but only weak van-der-Waals contacts which reasons the enhanced fluorescence lifetime and quantum yield of the flavins in the composites compared to their neat solid state. To analyze the orientation of flavins in MOFs, we measured fluorescence anisotropy images of single flavin@MOF-5 crystals and a static ensemble flavin@MIL53 microcrystals, respectively. Based on image information, anisotropy distributions and overall curve of the time-resolved anisotropy curves combined with theoretical calculations, we can prove that all fluorescent flavins species have a defined and rather homogeneous orientation in the MOF framework. In MIL-53, the transition dipole moments of flavins are orientated along the 1D channel axis, whereas in MOF-5 we resolved an average orientation that is tilted with respect to the cubic crystal lattice. Notably, the more hydrophobic 6F-MIA exhibits a higher degree order than MIA. The flexible MOF MIL-53(Al) was optimized essentially to the experimental large-pore form in the guest-free state with QuantumEspresso (QE) and with MIA molecules in the pores the structure contracted to close to the experimental narrow-pore form which was also confirmed by PXRD. In summary, the incorporation of flavins in MOFs yields solid-state materials with enhanced rigidity, stabilized conformation, defined orientation and reduced aggregations of the flavins, leading to increased fluorescence lifetime and quantum yield as controllable photo-luminescent and photo-physical properties.

Solid-State Emission and Aggregate Emission of Aroyl- S,N-Ketene Acetals Are Controlled and Tuned by Their Substitution Pattern.

Aroyl-S,N-ketene acetals are a novel highly diverse class of aggregation-induced emission fluorogens (AIEgens) with a plethora of interesting properties. An expanded compound library of more than 110 dyes set the stage for the first qualitative control and tuneability of all aspects of their photophysical properties. The interplay of substituents not only allows tuning and prediction of the emission color, but also of the intensity, and quantum yields both in solids and in the aggregated state; these can be rationalized by scrutinizing intermolecular interactions in the crystalline solid state.

Modulation of the Sorption Characteristics for an H-bonded porous Architecture by Varying the Chemical Functionalization of the Channel Walls.

Five isostructural microporous supramolecular architectures prepared by H-bonded assembly between the hexa-anionic complex [Zr2 (Ox)7 ]6- (Ox=oxalate, (C2 O4 )2- ) and tripodal cations (H3 -TripCH2 -R)3+ with R=H, CH3 , OH and OBn (Bn=CH2 Ph) are reported. The possibility to obtain the same structure using a mixture of tripodal cations with different R group (R=OH and R=CH3 ) has also been successfully explored, providing a unique example of three-component H-bonded porous framework. The resulting SPA-1(R) materials feature 1D pores decorated by R groups, with apparent pore diameters ranging from 3.0 to 8.5 Å. Influence of R groups on the sorption properties of these materials is evidenced through CO2 and H2 O vapor sorption/desorption experiments, as well as with I2 capture/release experiments in liquid media. This study is one of the first to demonstrate the possibility of tuning the porosity and exerting precise control over the chemical functionalization of the pores in a given H-bonded structure, without modifying the topology of the reference structure, and thus finely adjusting the sorption characteristics of the material.

Improvement of the Proton Conduction of Copper(II)-Mesoxalate Metal-Organic Frameworks by Strategic Selection of the Counterions.

Three copper(II)/mesoxalate-based MOFs with formulas (H3O)[Cu9(Hmesox)6(H2O)6Cl]·8H2O (1), (NH2Me2)0.4(H3O)0.6[Cu9(Hmesox)6(H2O)6Cl]·8H2O (2), and (enH2)0.25(enH)1.5[Cu6(Hmesox)3(mesox)(H2O)6Cl0.5]Cl0.5·5.25H2O (3) were synthesized (H4mesox = mesoxalic acid = 2,2-dihydroxypropanedioic acid, en = ethylenediamine). Essentially, all of the compounds display the same anionic network with a different arrangement of the cations, which have a remarkable effect on the proton conduction of the materials, ranging from 1.16 × 10-4 S cm-1 for 1 to 1.87 × 10-3 S cm-1 for 3 (at 80 °C and 95% RH). These compounds also display antiferromagnetic coupling among the copper(II) ions through both the carboxylate and alkoxido bridges. The values of the principal magnetic coupling constants were calculated by density functional theory (DFT), leading to congruent values that confirm the predominant antiferromagnetic nature of the interactions.

CD133-Functionalized Gold Nanoparticles as a Carrier Platform for Telaglenastat (CB-839) against Tumor Stem Cells.

The failure of a long-lasting curative therapeutic benefit of currently applied chemotherapies against malignant cancers is suggested to be caused by the ineffectiveness of such interventions on cancer stem cells (CSCs). CD133/AC133 is a cell surface protein previously shown to have potential to identify CSCs in various tumors, including brain tumors. Moreover, an increase in the rate of cellular metabolism of glutamine and glucose are contributors to the fast cellular proliferation of some high-grade malignancies. Inhibition of glutaminolysis by utilizing pharmacological inhibitors of the enzyme glutaminase 1 (GLS1) can be an effective anti-CSC strategy. In this study, the clinical-stage GLS1 inhibitor Telaglenastat (CB-839) was loaded into PEGylated gold nanoparticles equipped with the covalently conjugated CD133 aptamer (Au-PEG-CD133-CB-839) and exposed to a collection of CD133-positive brain tumor models in vitro. Our results show that Au-PEG-CD133-CB-839 significantly decreased the viability of CD133-postive cancer cells in a dose-dependent manner, which was higher as compared to the effects of treatment of the cells with the individual components of the assembled nanodrug. Interestingly, the treatment effect was observed in glioblastoma stem cells modeling different transcriptomic subtypes of the disease. The presented platform is the fundament for subsequent target specificity characterization and in vivo application.

Synthesis of pozzolan and sugarcane bagasse derived geopolymer-biochar composites for methylene blue sequestration from aqueous medium.

In this study, four pozzolan-based geopolymers GP0, GP5, GP10, and GP20 were synthesized by alkaline activation and by substituting 0, 5, 10, and 20% of the precursor with sugarcane bagasse-derived biochar, respectively. The composites were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM/EDX), and Brunauer-Emmett-Teller (BET) surface area analyses, and applied to sequester methylene blue (MB) dye in an aqueous medium in batch mode. The alkaline activation of pozzolan-biochar blends resulted in the formation of poly (Ferro-sialate-siloxo)-biochar chains. The adsorption capacity increased with an increase in biochar content from 24.44 to 455.46 mg/g (18-fold) for GP0 and GP10, respectively. The sorption kinetics of MB onto the composites followed pseudo-second-order kinetics while the equilibrium data were best described by the Sips isotherm model. The adsorption process was thermodynamically spontaneous, endothermic (ΔH = 14.32-32.20 kJ/mol), and physical. The amount of adsorbent required for the removal of 99% of a fixed amount of MB in different volumes of effluent was predicted. Cost-analysis indicates that the composites are efficient and cheaper eco-adsorbents than commercial activated carbon and are suitable alternative candidates for the removal of dyes from water.

Synthesis of a Chiral 3,6T22-Zn-MOF with a T-Shaped Bifunctional Pyrazole-Isophthalate Ligand Following the Principles of the Supramolecular Building Layer Approach.

The metal-organic framework (MOF) [Zn(Isa-az-tmpz)]·~1-1.5 DMF with the novel T-shaped bifunctional linker 5-(2-(1,3,5-trimethyl-1H-pyrazol-4-yl)azo)isophthalate (Isa-az-tmpz) was obtained as a conglomerate of crystals with varying degrees of enantiomeric excess in the chiral tetragonal space groups P43212 or P41212. A topological analysis of the compound resulted in the rare 3,6T22-topology, deviating from the expected rtl-topology, which has been found before in pyrazolate-isophthalate-functionalized MOFs using the supramolecular building layer (SBL) approach. 3,6T22-[Zn(Isa-az-tmpz)]·~1-1.5 DMF is a potentially porous, three-dimensional structure with DMF molecules included in the corrugated channels along the a and b-axis of the as synthesized material. The small trigonal cross-section of about 6 × 4 Å (considering the van der Waals surface) prevents the access of N2 and Ar under cryogenic conditions. After activation, only smaller H2 (at 87 K) and CO2 (at 195 K) are allowed for gas uptakes of 2 mmol g-1 and 5.4 mmol g-1, respectively, in the ultramicroporous material, for which a BET surface area of 496 m2·g-1 was calculated from CO2 adsorption. Thermogravimetric analysis of the compound shows a thermal stability of up to 400 °C.

Schiff Base in Ketoamine Form and Rh(η4-cod)-Schiff Base Complex with Z' = 2 Structure from Pairwise C-H···Metallochelate-π Contacts.

Condensation of 2-hydroxybenzaldehyde (salicylaldehyde) or 2-hydroxy-1-naphthaldehyde with 2-ethylaniline yields the Schiff base compound of (E)-2-(((2-ethylphenyl)imino)methyl)phenol (HL1) or (E)-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-ol (HL2), which in turn react with the dinuclear complex of [Rh(η4-cod)(µ-O2CCH3)]2 (cod = cycloocta-1,5-diene) to afford the mononuclear (η4-cod){(E)-2-(((2-ethylphenyl)imino)methyl)phenolato-κ2N,O}rhodium(I), [Rh(η4-cod)(L1)] (1) or (η4-cod){(E)-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-olato-κ2N,O}rhodium(I), [Rh(η4-cod)(L2)] (2) (L1 or L2 = deprotonated Schiff base ligand). The X-ray structure determination revealed that the HL2 exists in the solid state not as the usual (imine)N···H-O(phenol) form (enolamine form) but as the zwitterionic (imine)N-H+···-O(phenol) form (ketoamine form). 1H NMR spectra for HL2 in different solvents demonstrated the existence of keto-enol tautomerism (i.e., keto ⇆ enol equilibrium) in solution. The structure for 1 and 2 showed that the deprotonated Schiff base ligand coordinates to the Rh(η4-cod)-fragment as a six-membered N^O-chelate around the rhodium atom with a close-to-square-planar geometry. Two symmetry-independent molecules (with Rh1 and Rh2) were found in the asymmetric unit in 1 in a structure with Z' = 2. The supramolecular packing in HL2 was organized by π-π and C-H···π contacts, while only two recognized C-H···π contacts were revealed in 1 and 2. Remarkably, there were reciprocal or pairwise C-H···π contacts between a pair of each of the symmetry-independent molecules in 1. This pairwise C-H contact to the Rh-N^O chelate (metalloaromatic) ring may be a reason for the two symmetry-independent molecules in 1. Differential scanning calorimetry (DSC) analyses revealed an irreversible phase transformation from the crystalline-solid to the isotropic-liquid phase and subsequently confirmed the thermal stability of the compounds. Absorption spectra in solution were explained by excited state properties from DFT/TD-DFT calculations.