A Real-Time LSPR-Based Study of Metal-Organic Framework (MOF) Growth.

MOFs are known for their absorption properties and widely used for accumulation, filtering, sensorics, photothermal, catalytical and other applications. Their combination with plasmonic metal nanoparticles leads to hybrid structures that profit from the stabilizing effect and high porosity of the MOF as well as the optical and electronic properties of the nanoparticles. The growth of MOFs on plasmonic nanoparticles can be monitored in-situ using LSPR spectroscopy, simultaneously applying microfluidic reaction conditions for the fabrication of NP@MOF structures. Here, a systematic study is conducted using LSPR spectroscopy for the monitoring of the Layer-by-Layer deposition of twelve different MOFs, determining the suitability of LSPR spectroscopy for this purpose. In addition to some well-investigated materials like HKUST-1, other MOFs such as MIL-53, MIL-88 A and Cu-BDC are deposited successfully. For some MOFs such as Zn-Fum, the LSPR experiment indicates that no deposition had taken place. The results are confirmed with AFM, SEM and XPS measurements. This work shows that LSPR spectroscopy is suitable for the in-situ monitoring of LbL MOF growth and the microfluidic setup is a very promising method for the controlled manufacturing of NP@MOF hybrid structures. Further studies may include the optimization of the synthesis process or the transfer to other materials.

Heat Capacity Function, Enthalpy of Formation and Absolute Entropy of Mg(AlH4 )2.

In this investigation, we set out first to characterize the thermodynamics of Mg(AlH4 )2 and secondly to use the determined data to reevaluate and update existing estimation procedures for heat capacity functions, enthalpies of formation and absolute entropies of alanates. Within this study, we report the heat capacity function of Mg(AlH4 )2 in the temperature range from 2 K to 370 K and its enthalpy of formation and absolute entropy at 298.15 K, being - 70 . 6 ± 3 . 6 ${ - 70.6 \pm 3.6}$  kJ mol-1 and 133.06 J (K mol)-1 , respectively. Using these values, we updated and expanded methods for the estimation of thermodynamic data of alanates.

Interfacial Rearrangements of Block Copolymer Micelles Toward Gelled Liquid-Liquid Interfaces with Adjustable Viscoelasticity.

Though amphiphiles are ubiquitously used for altering interfaces, interfacial reorganization processes are in many cases obscure. For example, adsorption of micelles to liquid-liquid interfaces is often accompanied by rapid reorganizations toward monolayers. Then, the involved time scales are too short to be followed accurately. A block copolymer system, which comprises poly(ethylene oxide)110 -b-poly{[2-(methacryloyloxy)ethyl]diisopropylmethylammonium chloride}170 (i.e., PEO110 -b-qPDPAEMA170 with quaternized poly(diisopropylaminoethyl methacrylate)) is presented. Its reorganization kinetics at the water/n-decane interface is slowed down by electrostatic interactions with ferricyanide ([Fe(CN)6 ]3- ). This deceleration allows an observation of the restructuring of the adsorbed micelles not only by tracing the interfacial pressure, but also by analyzing the interfacial rheology and structure with help of atomic force microscopy. The observed micellar flattening and subsequent merging toward a physically interconnected monolayer lead to a viscoelastic interface well detectable by interfacial shear rheology (ISR). Furthermore, the "gelled" interface is redox-active, enabling a return to purely viscous interfaces and hence a manipulation of the rheological properties by redox reactions. Additionally, interfacial Prussian blue formation stiffens the interface. Such manipulation and in-depth knowledge of the rheology of complex interfaces can be beneficial for the development of emulsion formulations in industry or medicine, where colloidal stability or adapted permeability is crucial.

Study on the kinetics of the adsorption and desorption of NH3 on Fe/HBEA zeolite.

In this work, a Fe/HBEA zeolite (Si/Al: 12.5), representing an effective catalyst for the NH3-SCR process, was physico-chemically characterized and investigated regarding the kinetics of the adsorption and desorption of NH3. The sample was evaluated by N2 physisorption, 57Fe Möessbauer and DRUV-Vis spectroscopy, while the kinetics was investigated by temperature-programmed desorption of NH3 (TPD) including different adsorption temperatures. It was shown that the NH3 chemisorption results in weakly and strongly bonded molecular ammonia as well as ammonium species. A kinetic mean field model was developed implying two different types of adsorbates reflecting low (ca. 200 °C). Kinetic parameters and surface coverages were obtained from numeric fits of the TPD curves, whereas pre-exponential factors of adsorption were deduced from the kinetic gas theory. As a result, the activation energy for the NHx adsorbate decomposition in the low temperature regime, which is assigned to single and double bonded ammonium species was determined to be 106 kJ mol-1. The NH3 desorption at higher temperatures referred to an activation energy of 133 kJ mol-1 predominately related to NH3 coordinated to Lewis acid surface sites and to some extent to stabilized NH4+ species. For validation of the kinetic model, experiments were simulated including NH3 adsorption at different temperatures, subsequent flushing with N2 and final TPD. Additionally, the consistency of the activation energies with the thermodynamic data was checked using differential scanning calorimetry and a van't Hoff approach.

Electrochemical Stimulation of Water-Oil Interfaces by Nonionic-Cationic Block Copolymer Systems.

Variable interfacial tension could be desirable for many applications. Beyond classical stimuli like temperature, we introduce an electrochemical approach employing polymers. Hence, aqueous solutions of the nonionic-cationic block copolymer poly(ethylene oxide)114-b-poly{[2-(methacryloyloxy)ethyl]diisopropylmethylammonium chloride}171 (i.e., PEO114-b-PDPAEMA171 with a quaternized poly(diisopropylaminoethyl methacrylate) block) were investigated by emerging drop measurements and dynamic light scattering, analyzing the PEO114-b-qPDPAEMA171 impact on the interfacial tension between water and n-decane and its micellar formation in the aqueous bulk phase. Potassium hexacyanoferrates (HCFs) were used as electroactive complexants for the charged block, which convert the bishydrophilic copolymer into amphiphilic species. Interestingly, ferricyanides ([Fe(CN)6]3-) act as stronger complexants than ferrocyanides ([Fe(CN)6]4-), leading to an insoluble qPDPAEMA block in the presence of ferricyanides. Hence, bulk micellization was demonstrated by light scattering. Due to their addressability, in situ redox experiments were performed to trace the interfacial tension under electrochemical control, directly utilizing a drop shape analyzer. Here, the open-circuit potential (OCP) was changed by electrolysis to vary the ratio between ferricyanides and ferrocyanides in the aqueous solution. While a chemical oxidation/reduction is feasible, also an electrochemical oxidation leads to a significant change in the interfacial tension properties. In contrast, a corresponding electrochemical reduction showed only a slight response after converting ferricyanides to ferrocyanides. Atomic force microscopy (AFM) images of the liquid/liquid interface transferred to a solid substrate showed particles that are in accordance with the diameter from light scattering experiments of the bulk phase. In conclusion, the present results could be an important step toward economic switching of interfaces suitable, e.g., for emulsion breakage.

Direct Hydrogenation of Aluminum via Stabilization with Triethylenediamine: A Mechanochemical Approach to Synthesize the Triethylenediamine ⋠AlH3 Adduct.

Two approaches for the synthesis of the triethylenediamine (TEDA) ⋅ AlH3 adduct have been discovered. Both, the mechanochemical procedure and the wet chemical method lead to crystalline products. Starting from metallic Al powder and TEDA, ball milling under a pressure of 100 bar H2 facilitates a direct hydrogenation of aluminum with conversions up to 90 %. Structure determination from X-ray powder diffraction data revealed an 1-D-coordination polymer of the type [TEDA-AlH3 ]n . Furthermore, solid-state NMR techniques have been applied to analyze composition and structure of the products. Due to the polymeric arrangement, an enhanced stability of the material occurred which was investigated by thermal analysis showing a decomposition located above 200 °C. Overall, the stabilization of AlH3 by TEDA holds promise for hydrogen storage applications.

Direct determination of anaerobe contributions to the energy metabolism of Trypanosoma cruzi by chip calorimetry.

We describe a chip calorimetric technique that allows the investigation of biological material under anoxic conditions in a micro-scale and in real time. Due to the fast oxygen exchange through the sample flow channel wall, the oxygen concentration inside the samples could be switched between atmospheric oxygen partial pressure to an oxygen concentration of 0.5% within less than 2 h. Using this technique, anaerobic processes in the energy metabolism of Trypanosoma cruzi could be studied directly. The comparison of the calorimetric and respirometric response of T. cruzi cells to the treatment with the mitochondrial inhibitors oligomycin and antimycin A and the uncoupler FCCP revealed that the respiration-related heat rate is superimposed by strong anaerobic contributions. Calorimetric measurements under anoxic conditions and with glycolytic inhibitors showed that anaerobic metabolic processes contribute from 30 to 40% to the overall heat production rate. Similar basal and antimycin A heat rates with cells under anoxic conditions indicated that the glycolytic rates are independent of the oxygen concentration which confirms the absence of the "Pasteur effect" in Trypanosomes. Graphical abstract.

Kinetic modeling of the adsorption and desorption of CO2 on α-Fe2O3.

The present paper addresses the interaction of CO2 with polycrystalline α-Fe2O3 revealing considerable catalytic activity in CO oxidation to yield CO2. The mechanism of adsorption and desorption of CO2 was investigated by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), while the kinetics was examined by temperature-programmed desorption (CO2-TPD). For numeric modeling as well as simulation of the surface coverage, an elementary kinetic mean field model was constructed using Arrhenius-based rate expressions. The kinetic parameters of desorption were taken from fitting calculations (A2 = 3.01 × 10(5) mol (m(2) s)(-1), E2(0) = 112.8 kJ mol(-1), α2 = 70.2 kJ mol(-1)), whereas the adsorption was considered to be non-activated and the pre-exponential factor was estimated from kinetic gas theory (A1 = 0.0192 m s(-1), E1 = 0 kJ mol(-1)). For model validation, predicted and experimental CO2-TPD profiles were compared and thermodynamic consistency was evaluated by using differential scanning calorimetry (ΔadsH(250 °C) = -129 kJ mol(-1)) as well as literature data.

Methanol from CO2 by organo-cocatalysis: CO2 capture and hydrogenation in one process step.

Carbon dioxide chemically bound to alcohol-amines was hydrogenated to methanol under retrieval of these industrially used CO2 capturing reagents. The energetics of the process can be seen as a partial cancellation of the exothermic heat of reaction of the hydrogenation with the endothermic one of the CO2 release from the capturing reagent. The process provides a means to significantly improve the energy efficiency of CO2 to methanol conversions.

5,5'-(Ethyne-1,2-di-yl)diisophthalic acid dimethyl sulfoxide tetra-solvate.

In the title compound, C18H10O8·4C2H6OS, the mid-point of the triple bond of the main mol-ecule is located on a special position, i.e. about an inversion center. The carboxyl groups are twisted slightly out of the planes of the aromatic rings to which they are attached, making dihedral angles of 24.89 (1) and 7.40 (2)°. The cystal packing features strong O-H⋯O hydrogen bonds, weaker C-H⋯O inter-actions and O⋯S contacts [3.0981 (11) Å] and displays channel-like voids extending along the a-axis direction which contain the dimethyl sulfoxide solvent mol-ecules.

Hydrogen absorption and desorption in the V-Al-H system.

The presented work sets out to investigate the influence of aluminium on the hydrogenation of vanadium by first studying the hydrogenation properties of the V-H system in detail followed by the study of the V-Al-H system. Aluminium was found to have a stabilising effect on vanadium hydride phases. Presumably by functioning as an oxygen getter, aluminium lowers equilibrium pressures and increases hydrogen capacities in respect to the V/H ratio compared to the V-H system. Attempts of the synthesis of the hypothetical V(AlH4)x by metathesis and direct hydrogenation were not successful, suggesting its instability below room temperature at ambient pressure as well as up to 180 bar of hydrogen pressure in the temperature range of 30 to 100 °C.

Nonequilibrium Colloids: Temperature-Induced Bouquet Formation of Flower-like Micelles as a Time-Domain-Shifting Macromolecular Heat Alert.

Climate change requires enhanced autonomous temperature monitoring during logistics/transport. A cheap approach comprises the use of temperature-sensitive copolymers that undergo temperature-induced irreversible coagulation. The synthesis/characterization of pentablock copolymers (PBCP) starting from poloxamer PEO130-b-PPO44-b-PEO130 (poly(ethylene oxide)130-b-poly(propylene oxide)44-b-poly(ethylene oxide)130) and adding two terminal qPDMAEMA85 (quaternized poly[(2-dimethylamino)ethyl methacrylate]85) blocks is presented. Mixing of PBCP solutions with hexacyanoferrate(III)/ferricyanide solutions leads to a reduction of the decane/water interfacial tension accompanied by a co/self-assembly toward flower-like micelles in cold water because of the formation of an insoluble/hydrophobic qPDMAEMA/ferricyanide complex. In cold water, the PEO/PPO blocks provide colloidal stability over months. In hot water, the temperature-responsive PPO block is dehydrated, leading to a pronounced temperature dependence of the oil-water interfacial tension. In solution, the sticky PPO segments exposed at the micellar corona cause a colloidal clustering above a certain threshold temperature, which follows Smoluchowski-type kinetics. This coagulation remains for months even after cooling, indicating the presence of a kinetically trapped nonequilibrium state for at least one of the observed micellar structures. Therefore, the system memorizes a previous suffering of heat. This phenomenon is linked to an exchange of qPDMAEMA-blocks bridging the micellar cores after PPO-induced clustering. The addition of ferrous ions hampers the exchange, leading to the reversible coagulation of Prussian blue loaded micelles. Hence, the Fe2+ addition causes a shift from history monitoring to the sensing of the present temperature. Presumably, the system can be adapted for different temperatures in order to monitor transport and storage in a simple way. Hence, these polymeric "flowers" could contribute to preventing waste and sustaining the quality of goods (e.g., food) by temperature-induced bouquet formation, where an irreversible exchange of "tentacles" between the flowers stabilizes the bouquet at other temperatures as well.

2-Amino-terephthalic acid N,N-dimethyl-formamide disolvate.

The asymmetric unit of the title structure, C(8)H(7)NO(4)·2C(3)H(7)NO, contains one 2-amino-terephthalic acid and two N,N-dimethyl-formamide mol-ecules. Strong O-H⋯O hydrogen bonds between the acidic carb-oxy H atoms of 2-am-ino-terephthalic acid and the O atoms of both solvent mol-ecules form linear 1:2 complex units. One H atom of the amine group is involved in intra-molecular N-H⋯O hydrogen bonding, whereas the second one takes part in an inter-molecular N-H⋯O connection. Furthermore, the crystal is stabilized by weak C-H⋯O hydrogen bonds.

Synthesis and temperature-dependent NMR studies of monomeric and dimeric tris(dialkylamido)alanes.

After an introductory overview of all currently known tris(dialkylamido)alanes with the formula [Al(NR2)3]n (n = 1, 2), a simplified synthetic method based on the usage of is presented. The simplification results from the fact that the ether adduct can already be obtained during the necessary synthesis of the alane moiety and that the use of trimethylamine is no longer required. Current conflicts regarding the experimental data of tris(diethylamido)alane and their interpretation have been resolved by means of single crystal structure analysis. The N-methylpiperazine derivative was described for the first time and characterised by various analytical methods. In temperature-dependent NMR measurements ranging from -35 °C to 90 °C coalescence phenomena of 13C and 1H NMR signals of tris(N-methylpiperazino)alane as well as thermal migration of 1H NMR signals of tris(diethylamido)alane were observed.

High-separation performance of chromatographic capillaries coated with MOF-5 by the controlled SBU approach.

Recently developed MOF surface-coating techniques, the controlled SBU approach (CSA) for the generation of MOF-5, and the use of self-assembled monolayers have been combined to generate a wall-bonded, crosslinked stationary phase for gas chromatographic capillary columns displaying excellent performance in the separation of natural gas components. The chromatographic performance of this new type of column has been compared to the state-of-the-art solution for this separation problem, namely a coated silica column of the porous layer open tubular (PLOT) type. Chromatographic parameters such as separation, resolution, and tailing factors, as well as plate numbers and heights in the case of isothermal operation, have been determined. Kinetic and thermodynamic parameters characterizing the analyte-stationary phase interaction have been determined for various C1-C4 analytes.

Potentials and limitations of miniaturized calorimeters for bioprocess monitoring.

In theory, heat production rates are very well suited for analysing and controlling bioprocesses on different scales from a few nanolitres up to many cubic metres. Any bioconversion is accompanied by a production (exothermic) or consumption (endothermic) of heat. The heat is tightly connected with the stoichiometry of the bioprocess via the law of Hess, and its rate is connected to the kinetics of the process. Heat signals provide real-time information of bioprocesses. The combination of heat measurements with respirometry is theoretically suited for the quantification of the coupling between catabolic and anabolic reactions. Heat measurements have also practical advantages. Unlike most other biochemical sensors, thermal transducers can be mounted in a protected way that prevents fouling, thereby minimizing response drifts. Finally, calorimetry works in optically opaque solutions and does not require labelling or reactants. It is surprising to see that despite all these advantages, calorimetry has rarely been applied to monitor and control bioprocesses with intact cells in the laboratory, industrial bioreactors or ecosystems. This review article analyses the reasons for this omission, discusses the additional information calorimetry can provide in comparison with respirometry and presents miniaturization as a potential way to overcome some inherent weaknesses of conventional calorimetry. It will be discussed for which sample types and scientific question miniaturized calorimeter can be advantageously applied. A few examples from different fields of microbiological and biotechnological research will illustrate the potentials and limitations of chip calorimetry. Finally, the future of chip calorimetry is addressed in an outlook.

Poly[(µ4-2,5-dimethoxybenzene-1,4-dicarboxylato)manganese(II)] and its zinc(II) analogue: three-dimensional coordination polymers containing unusually coordinated metal centres.

The title compounds, [Mn(C(10)H(8)O(6))](n) and [Zn(C(10)H(8)O(6))](n), are isomorphous coordination polymers prepared from 2,5-dimethoxyterephthalic acid (H(2)dmt) and the respective metal(II) salts. Both complexes form three-dimensional metal-organic frameworks with each M(II) centre bridged by four 2,5-dimethoxyterephthalate (dmt(2-)) anions, resulting in the same type of network topology. The asymmetric unit consists of one M(II) cation on a twofold axis and one half of a dmt(2-) anion (located on a centre of inversion). In the crystal structure, the M(II) centres are coordinated in a rather unusual way, as there is a distorted tetrahedral inner coordination sphere formed by four carboxylate O atoms of four different dmt(2-) anions, and an additional outer coordination sphere formed by two methoxy and two carboxylate O atoms, with each of the O atoms belonging to one of the four different dmt(2-) anions forming the inner coordination sphere. Consideration of both coordination spheres results in a super-dodecahedral coordination geometry for the M(II) centres. Besides the numerous M(II)···O interactions, both structures are further stabilized by weak C-H···O contacts.

Little change but great effect: varying supramolecular interactions in 2,5-dimethoxyterephthalic acid and 2,5-diethoxyterephthalic acid.

The title terephthalic acid derivatives, namely 2,5-dimethoxyterephthalic acid, C(10)H(10)O(6), (I), and 2,5-diethoxyterephthalic acid, C(12)H(14)O(6), (II), exhibit nearly planar molecular structures, with maximum deviations from the least-squares planes calculated for all non-H atoms of 0.0418 (6) and 0.0902 (10) Å for (I) and (II), respectively. The molecules of both title compounds contain an inversion centre and thus the asymmetric unit of both crystal structures consists of only half a molecule. It is a remarkable fact that a comparatively small change in the substitution of the terephthalic acid [dimethoxy in (I) versus diethoxy in (II)] causes major differences in the dominating supramolecular interactions. While in (II) the packing structure is stabilized by typical intermolecular hydrogen-bonded carboxylic acid dimer interactions, the carboxyl group in (I) forms an unusual intramolecular hydrogen bond with the O atom of the neighbouring methoxy group.

Bis-(triphenylphosphane) Aluminum Hydride: A Simple Way to Provide, Store, and Use Non-Polymerized Alane for Synthesis.

AlH3 (PPh3 )2 was synthesized as a stable solid being the first known 1 : 2 alane arylphosphane adduct. Although only weakly intra-molecularly coordinated, it displays as a molecular crystal significant inertness against atmospheric humidity and oxygen due to strong steric screening of the alane unit. The compound readily dissociates PPh3 in solution allowing for its use as a Lewis acidic reducing agent. These features lead to an easy to store, easy to use reducing agent that may enable the quantitative investigation of aluminum hydride chemistry including reduction, complexation and hydroalumination reactions. The structure contains two non-equivalent penta-coordinated aluminum centers that despite long Al-P distances of ca. 2.7 Šdisplay unusually high quadrupolar coupling constants CQ of 25.1 and 26.5 in 27 Al solid state NMR measurements. The product was also tested as a reducing agent on a small set of selected compounds with various functional groups.

Main-group and transition-element IRMOF homologues.

A simple two-component procedure was developed to synthesize not only classical zinc-based IRMOFs represented by MOF-5 but also the cobalt and beryllium homologues of this most prominent MOF. The procedure is the first manifestation of mirroring the IRMOF series with other metal centers taken from main-group as well as transition-metal elements. Because of the existence of many suitable precursors, the procedure promises the generation of a large number of IRMOF homologues. Since the IRMOF series together with the MIL series is the MOF group with the largest number of representatives, the possibility of choosing the metal centers of the secondary building units from an extended set will tremendously expand the number of obtainable structures in a predictive, crystal-engineering-type way. Use of metal centers other than zinc will allow the addition of new features to the existing IRMOF structures, such as magnetic properties in the example of cobalt.