In Silico Discovery of Covalent Organic Frameworks for Carbon Capture.

We screen a database of more than 69 000 hypothetical covalent organic frameworks (COFs) for carbon capture using parasitic energy as a metric. To compute CO2-framework interactions in molecular simulations, we develop a genetic algorithm to tune the charge equilibration method and derive accurate framework partial charges. Nearly 400 COFs are identified with parasitic energy lower than that of an amine scrubbing process using monoethanolamine; more than 70 are better performers than the best experimental COFs and several perform similarly to Mg-MOF-74. We analyze the effect of pore topology on carbon capture performance to guide the development of improved carbon capture materials.

Ligand and Metal Effects on the Stability and Adsorption Properties of an Isoreticular Series of MOFs Based on T-Shaped Ligands and Paddle-Wheel Secondary Building Units.

The synthesis of stable porous materials with appropriate pore size and shape for desired applications remains challenging. In this work a combined experimental/computational approach has been undertaken to tune the stability under various conditions and the adsorption behavior of a series of MOFs by subtle control of both the nature of the metal center (Co2+ , Cu2+ , and Zn2+ ) and the pore surface by the functionalization of the organic linkers with amido and N-oxide groups. In this context, six isoreticular MOFs based on T-shaped ligands and paddle-wheel units with ScD0.33 topology have been synthesized. Their stabilities have been systematically investigated along with their ability to adsorb a wide range of gases (N2 , CO2 , CH4 , CO, H2, light hydrocarbons (C1 -C4 )) and vapors (alcohols and water). This study has revealed that the MOF frameworks based on Cu2+ are more stable than their Co2+ and Zn2+ analogues, and that the N-oxide ligand endows the MOFs with a higher affinity for CO2 leading to excellent selectivity for this gas over other species.

Isolation of Renewable Phenolics by Adsorption on Ultrastable Hydrophobic MIL-140 Metal-Organic Frameworks.

The isolation and separation of phenolic compounds from aqueous backgrounds is challenging and will gain in importance as we become more dependent on phenolics from lignocellulose-derived bio-oil to meet our needs for aromatic compounds. Herein, we show that highly stable and hydrophobic Zr metal-organic frameworks of the MIL-140 type are effective adsorbent materials for the separation of different phenolics and far outperform other classes of porous solids (silica, zeolites, carbons). The mechanism of the hydroquinone-catechol separation on MIL-140C was studied in detail by combining experimental results with computational techniques. Although the differences in adsorption enthalpy between catechol and hydroquinone are negligible, the selective uptake of catechol in MIL-140C is explained by its dense π-π stacking in the pores. The interplay of enthalpic and entropic effects allowed separation of a complex, five-compound phenol mixture through breakthrough over a MIL-140C column. Unlike many other metal-organic frameworks, MIL-140C is remarkably stable and maintained structure, porosity and performance after five adsorption-desorption cycles.

Design of hydrophilic metal organic framework water adsorbents for heat reallocation.

A new hydrothermally stable Al polycarboxylate metal-organic framework (MOF) based on a heteroatom bio-derived aromatic spacer is designed through a template-free green synthesis process. It appears that in some test conditions this MOF outperforms the heat reallocation performances of commercial SAPO-34.

A biocompatible porous Mg-gallate metal-organic framework as an antioxidant carrier.

A microporous magnesium gallate MOF was prepared from highly biocompatible reagents under environmentally friendly conditions. Its slow degradation in physiological fluids leads to the release of gallic acid and hence a high antioxidant activity, which was illustrated in the HL-60 cell line.

Inhomogeneous transport in model hydrated polymer electrolyte supported ultrathin films.

The structure of polymer electrolyte membranes, e.g., Nafion, inside fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultrathin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films and, in turn, on transport properties has not been sufficiently explored yet. Here, we report classical molecular dynamics simulations of hydrated Nafion thin films in contact with unstructured supports, characterized by their global wetting properties only. We have investigated structure and transport in different regions of the film and found evidence of strongly heterogeneous behavior. We speculate about the implications of our work on experimental and technological activity.