Design of electric field controlled molecular gates mounted on metal–organic frameworks

In this study we propose and computationally demonstrate the concept of electric field controlled molecular gates mounted on the open-metal coordination sites in metal–organic framework (MOF) materials. The MOF-molecular gate complex functions by opening and closing under the effect of an electric field. Our design involves Mg-MOF-74, a MOF with hexagonal channels with open-metal coordination sites at each corner, and a multifunctional gate molecule with permanent dipole which anchors itself on the host MOF material and responds to changes in the direction of an electric field by rotating around its backbone which acts as an axle. By carrying out density functional theory (DFT) calculations and molecular dynamics (MD) simulations we show that the MOF-molecular gate complex can be switched between two stable configurations, open and closed, by turning on and off an external electric field. We further show that the molecular gate can be controlled to block or allow the diffusion of methane molecules through the channels of the MOF like a nanoscale butterfly valve. Electric field controlled molecular gates mounted on MOFs can pave the way for new molecular machines and nanodevices which can store, deliver or select molecules on demand and with atomic precision

Anhydrous proton conducting poly(vinyl alcohol) (PVA)/ poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS)/1,2,4-triazole composite membrane

The design and fabrication of anhydrous proton exchange membranes are critically important for high temperature proton exchange membrane fuel cell (HT-PEMFC) operating between 100 and 200 °C. Herein, we demonstrate a novel proton conducting membrane consisting of poly(vinyl alcohol) (PVA), poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) and 1,2,4-triazole, which was fabricated by physical blending, casting and solvent evaporation techniques. The in-situ chemical cross-linking was performed by glutaraldehyde (GA) to improve the water management of the membranes. The molecular structure of the membranes and intermolecular interactions between the constituents were confirmed by Fourier-transform infrared spectroscopy (FT-IR). The surface and cross-section morphologies of the membranes were observed by scanning electron microscopy (SEM). The thermal stability performance of the membranes was studied with thermogravimetric analysis (TGA). In order to determine the physico-chemical properties of the membranes, water uptake (WU), dimensional change and ion exchange capacity (IEC) tests were carried out. The proton conductivities of composite membranes increase with the temperature and the temperature dependencies exhibit an Arrhenius behavior. Proton conductivity measurements revealed an optimum ratio between PAMPS and 1,2,4-triazole content to achieve higher proton conductivity. In anhydrous state at 150 °C, the highest proton conductivity measured was 0.002 S/cm for PVA:PAMPS:1,2,4-triazole (1:1:1) composition. Overall, our investigation showed that 1,2,4-triazole is a promising proton carrier reagent above 100 °C when it is embedded into appropriate host polymers

From 2-methylimidazole to 1,2,3-triazole: a topological transformation of ZIF-8 and ZIF-67 by post-synthetic modification

Bridging ligand replacement in zeolitic imidazolate frameworks, ZIF-8 and ZIF-67, by 1,2,3-triazole was investigated. A complete substitution of 2-methylimidazole by 1,2,3-triazole resulted in a topological transformation of the parent framework from a sodalite (SOD) network to a diamond (DIA) network

Gas permeation through single-crystal ZIF-8 membranes

Dataset supporting publication: Chen Chen, Aydin Ozcan, A. Ozgur Yazaydin and Bradley P. Ladewig, Gas permeation through single-crystal ZIF-8 membranes, Journal of Membrane Science, https://doi.org/10.1016/j.memsci.2019.01.027 Dataset supporting preprint: Chen, Chen; Ozcan, Aydin; Yazaydin, A. Ozgur; Ladewig, Bradley (2019): Gas Permeation Through Single-Crystal ZIF-8 Membranes. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.7571186.v1Dataset supporting publication: Chen Chen, Aydin Ozcan, A. Ozgur Yazaydin and Bradley P. Ladewig, Gas permeation through single-crystal ZIF-8 membranes, Journal of Membrane Science, https://doi.org/10.1016/j.memsci.2019.01.027 Dataset supporting preprint: Chen, Chen; Ozcan, Aydin; Yazaydin, A. Ozgur; Ladewig, Bradley (2019): Gas Permeation Through Single-Crystal ZIF-8 Membranes. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.7571186.v

Grand canonical molecular dynamics simulation of supercritical carbon dioxide and methane intercalation in smectite interlayers

International audienc

Investigation of geochemically relevant supercritical fluids interaction with clay minerals present in deep geological formations using grand canonical molecular

International audienc

Synergistic Interaction of Paclitaxel and Curcumin with Cyclodextrin Polymer Complexation in Human Cancer Cells

The use of cytotoxic chemotherapic agents is the most common method for the treatment of metastatic cancers. Poor water solubility and low efficiency of chemotherapic agents are among the major hurdles of effective chemotherapy treatments. Curcumin and paclitaxel are well-known chemotherapic agents with poor water solubility and undesired side effects. In this study, a novel drug nanocarrier system was formulated by encapsulating curcumin and paclitaxel in poly­(β-cyclodextrin triazine) (PCDT) for the therapy of four cancer models; ovarian, lung, prostate, and breast cancer. Cell viability and colony formation assays revealed enhanced curcumin cytotoxicity upon complexation. Annexin V apoptotic studies showed that the PCDT complexation improved curcumin induced apoptosis in human ovarian cancer cell lines A2780 and SKOV-3, human nonsmall cell lung carcinoma cell line H1299, and human prostate cancer line DU-145, while no significant effect was observed with paclitaxel/PCDT complexation. The bioactivity of combining curcumin and paclitaxel was also investigated. A synergism was found between curcumin and paclitaxel, particularly when complexed with PCDT on A2780, SKOV-3, and H1299 cancer cell lines