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.

modified by several types of additives such as low molecular weight surfactants and proteins, [3][4][5] particles, [6][7][8][9] or polymers. [10][11][12][13][14][15][16] Hereby, the adsorption of surface-active entities can occur by adsorption of unimers to form eventually more or less homogeneous monolayers. However, amphiphiles are often present in colloidal form as micelles. Since other colloidal particles, e.g., nanoparticles and microgels, can adsorb to interfaces in a pickeringlike fashion, intact micelles might also be prone to adsorb to the interface. [10,17,18] However, little is known on the fate of such interfacially attached micelles. In most cases, the kinetics of the rearrangements toward a monolayer are hard to capture.Generally, the interfacial tension is regarded as a primary indicator of adsorption processes, often deemed sufficient to trace changes at liquid interfaces. However, the involvement of certain substances or combinations can lead to complex interfaces with additional rheological properties, completely different to the ones of the pure interface. [1,19,20] Examples could involve, e.g., interfacial polymerization [21] (including classical nylon thread fabrication) or even interfacial crosslinking (bubble tea preparation). In some of these cases, the interfacial film is rather thick. However, also monolayers of amphiphiles can exhibit viscoelastic properties being essential for the properties of the whole system. Hence, 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., PEO 110 -b-qPDPAEMA 170 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 permeabil...

The development of cyclic preparation techniques based on the application of an SBU (secondary building unit) precursor and a linker solution for the generation of MOF (metal-organic framework) coatings were used to prepare HKUST-1 (Hong Kong University of Science and Technology-1) coated capillary gas-chromatographic columns. As a prerequisite for the conducted preparation of the coatings some optimisation of the procedure for the generation of the MOF material at room temperature was carried out. Beside the demonstration of their general suitability for the separation of permanent gases, the capillaries were used to perform isothermal retention time measurements with analytes possessing electron donating capabilities, such as aromatic or oxygen containing compounds. Since HKUST-1 possesses SBUs with open metal sites, the heat of adsorption and the adsorption entropy were determined to address the question whether or not coordinative contributions may affect the analyte-MOF interaction.

Because of its multiresponsive behavior upon variation of pH value, temperature, and ionic strength, poly­(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) is an attractive candidate for adaptive surface coatings, especially in the field of biomedical sensors. In the presented article, PDMAEMA Guiselin brushes (5–12 nm, dry thickness) were prepared by the grafting-to approach, and the thermoresponsive UCST-type (upper critical solution temperature) behavior of the generated films, induced by [Fe­(CN)6]3–, was demonstrated for the first time. To clarify the specific mechanism of the temperature responsiveness, the molecular interactions between polymer chains and complex ions were studied by in situ infrared spectroscopy and in situ ellipsometry, showing wavenumber shifts of the ν­(CN) band due to ion pairing as well as changes of the ν­(OH) band intensity due to swelling. Conclusively, experimental data suggest that the electrostatic interaction between the two components plays a significant role in the thermoresponsive behavior of PDMAEMA films. Using this knowledge, the UCST of the PDMAEMA Guiselin brushes could be adjusted between 34.0 ± 1.2 °C at pH 8 and 40.7 ± 2.0 °C at pH 5.

An asymmetric synthesis of densely functionalized 7-11-membered carbocycles and 9-11-membered lactones has been developed. Its key steps are a modular assembly of sulfoximine-substituted C- and O-tethered trienes and C-tethered dienynes and their Ru-catalyzed ring-closing diene and enyne metathesis (RCDEM and RCEYM). The synthesis of the C-tethered trienes and dienynes includes the following steps: 1) hydroxyalkylation of enantiomerically pure titanated allylic sulfoximines with unsaturated aldehydes, 2) α-lithiation of alkenylsulfoximines, 3) alkylation, hydroxy-alkylation, formylation, and acylation of α-lithioalkenylsulfoximines, and 4) addition of Grignard reagents to α-formyl(acyl)alkenylsulfoximines. The sulfoximine group provided for high asymmetric induction in steps 1) and 4). RCDEM of the sulfoximine-substituted trienes with the second-generation Ru catalyst stereoselectively afforded the corresponding functionalized 7-11-membered carbocyles. RCDEM of diastereomeric silyloxy-substituted 1,6,12-trienes revealed an interesting difference in reactivity. While the (R)-diastereomer gave the 11-membered carbocyle, the (S)-diastereomer delivered in a cascade of cross metathesis and RCDEM 22-membered macrocycles. RCDEM of cyclic trienes furnished bicyclic carbocycles with a bicyclo[7.4.0]tridecane and bicyclo[9.4.0]pentadecane skeleton. Selective transformations of the sulfoximine- and bissilyloxy-substituted carbocycles were performed including deprotection, cross-coupling reaction and reduction of the sulfoximine moiety. Esterification of a sulfoximine-substituted homoallylic alcohol with unsaturated carboxylic acids gave the O-tethered trienes, RCDEM of which yielded the sulfoximine-substituted 9-11-membered lactones. RCEYM of a sulfoximine-substituted 1,7-dien-10-yne showed an unprecedented dichotomy in ring formation depending on the Ru catalyst. While the second-generation Ru catalyst gave the 9-membered exo 1,3-dienyl carbocycle, the first-generation Ru catalyst furnished a truncated 9-membered 1,3-dieny carbocycle having one CH(2) unit less than the dienyne.

Metal-organic frameworks (MOFs) have demonstrated great utilizability in separation applications, as in the separation of small volatile compounds via gas chromatography (GC). In the present work, HKUST-1 (Hong Kong University of Science and Technology), one of the best investigated MOFs, is used as a stationary phase for the gas chromatographic separation of various analytes possessing different modes of interaction due to their differences in polarity and the presence of free electron pairs. The system was investigated by inverse gas chromatography (IGC) to demonstrate in general how MOF materials can be quantitatively and qualitatively characterized in respect to their Lewis basic and acidic properties. Applying IGC theory, the investigation of the separation problem of benzene and its completely hydrogenated analogue cyclohexane was used to the determine the donor properties of the MOF linker benzene-1,3,5-tricarboxylic acid and the separation of diethyl ether, diisopropyl ether, tetrahydrofuran, and di-n-propyl ether to determine the acceptor properties of the coordinatively unsaturated sites of the copper(II)-secondary building unit (SBU), i.e. the nodal points of the MOF lattice.438 | CrystEngComm, 2015, 17, 438-447 This journal is

In the last years, the generation of multifunctional coatings has been moved into the focus of interface modifications to expand the spectrum of material applications and to introduce new smart properties. Herein a promising multifunctional and universally usable coating with simultaneous antifouling, easy‐to‐clean, and anti‐fog functionality is presented based on smart polymer films consisting of copolymers with 2‐methacryloyloxyethyl phosphorylcholine (MPC), realizing the function of the film and photoreactive 4‐benzophenyl methacrylate (BPO), which is responsible for stability and crosslinking. The easy‐to‐clean effect is demonstrated qualitatively and quantitatively by oil droplet detachment experiments. The antifouling behavior against different germs is investigated by cell adhesion experiments. Furthermore the anti‐fog performance is shown by breathing on the surfaces. To study the influence of the different amounts of copolymerized BPO, the grafted films are characterized by atomic force microscopy (AFM), infrared spectroscopy (ATR‐FTIR), as well as contact angle measurements. In situ spectroscopic ellipsometry is performed to investigate the swelling behavior of the thin films as a function of the time of UV‐irradiation. It is found that a degree of swelling of 15 and a water contact angle of less than 12° are the key parameters necessary for the generation of multifunctional coatings.

Poly­(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) is an attractive polymer for switchable surface coatings based on its multiresponsiveness toward environmental triggers (temperature, pH-value, ionic strength). In this in situ study, we present the complex and tunable thermoresponsiveness of PDMAEMA Guiselin brushes (9 nm, dry thickness), which were prepared via an efficient grafting-to approach. Combining in situ atomic force microscopy (AFM) visualizing the surface topography (x–y plane) and spectroscopic ellipsometry monitoring the swelling behavior of the polymer film (layer thickness, z-direction) offers for the first time a three-dimensional insight into thermoresponsive transitions on the nanoscale. While PDMAEMA films exhibit LCST behavior in the presence of monovalent counterions, it can easily be switched toward an UCST thermoresponsiveness via the addition of small quantities of multivalent ions. In both cases, the transition temperature as well as the sharpness and reversibility of the transition can be tuned via a second external trigger, the ionic strength. Whereas homogeneous surfaces were observed both below and above the LCST in monovalent salt solutions, the UCST transition was characterized by the in situ formation of a nanostructured surface of pinned PDMAEMA micelles with entrapped multivalent counterions. Moreover, it was demonstrated for the first time that the characteristic dimensions of the nanopattern (the diameter and height of the pinned micelles) could be tuned in situ by the pH- and induced UCST thermoresponsiveness of PDMAEMA. This approach therefore provides a novel bottom-up strategy to create and control polymeric nanostructures in an aqueous environment.