Publications by authors named "Kyoungmoo Koh"

The application of a core-shell architecture allows the formation of a polymer-coated metal-organic framework (MOF) maintaining high surface area (2289-2857 m(2) g(-1)). The growth of a MOF shell from a MOF core was used to spatially localize initiators by post-synthetic modification. The confinement of initiators ensures that polymerization is restricted to the outer shell of the MOF.

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Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly.

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The diffusion of individual Nile red molecules in three different crystalline microporous coordination polymers (MCPs) is visualized with single-molecule fluorescence microscopy. By localizing molecules with high spatial resolution, the trajectories of the diffusing dyes are reconstructed with nanometer-scale precision. A detailed analysis of these tracks reveals different dynamics and guest-host interactions in each crystal as well as distinct motion types within the same system, suggesting the presence of structural heterogeneities in local environments.

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High reversibility during crystallization leads to relatively defect-free crystals through repair of nonperiodic inclusions, including those derived from impurities. Microporous coordination polymers (MCPs) can achieve a high level of crystallinity through a related mechanism whereby coordination defects are repaired, leading to single crystals. In this work, we discovered and exploited the fact that this process is far from perfect for MCPs and that a minority ligand that is coordinatively identical to but distinct in shape from the majority linker can be inserted into the framework, resulting in defects.

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Isolated successes of coordination copolymerization for the production of microporous coordination polymers (MCPs) have been reported recently; the logic for this synthetic approach has not been established nor have the key features of the synthetic conditions needed to generalize the method. Here, we establish guidelines for application of the copolymerization technique by exploring coordination modes and report, in addition to details on two previous coordination copolymers with exceptional properties, three new MCPs: UMCM-3 (Zn(4)O(2,5-thiophenedicaboxylate)(1.2)(1,3,5-tris(4-carboxyphenyl)benzene)(1.

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A predictive tool termed the linker to metal cluster (LiMe) ratio is introduced as a method for understanding surface area in microporous coordination polymers (MCPs). Calibrated with geometric accessible surface area computations, the LiMe ratio uses molecular weight of building block components to indicate the maximum attainable surface area for a given linker and metal cluster combination. MOF-5 and HKUST-1 are used as prototypical structures to analyze MCPs with octahedral M(4)O(CO(2)R)(6) and paddlewheel M(2)(CO(2)R)(4) metal clusters.

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A diverse collection of 14 metal-organic frameworks (MOFs) was screened for CO(2) capture from flue gas using a combined experimental and modeling approach. Adsorption measurements are reported for the screened MOFs at room temperature up to 1 bar. These data are used to validate a generalized strategy for molecular modeling of CO(2) and other small molecules in MOFs.

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Mixing two different linkers with the same topology has been applied to make metal-organic frameworks (MOFs) either in one batch or sequentially to generate coordination copolymers with either a randomly mixed or a core-shell composition of linkers.

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New levels of surface area are achieved in a coordination polymer (UMCM-2, University of Michigan Crystalline Material) derived from zinc-mediated coordination copolymerization of a dicarboxylic and tricarboxylic acid. In addition to a large micropore contribution to the surface area, mesopores are also present. In contrast to the recently reported coordination copolymer UMCM-1, which has a mesoporous channel, UMCM-2 is built from three types of cages.

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Chemical patterning of inorganic substrates by soft lithography has enabled various high-tech applications and cutting-edge fundamental research. In this paper, we report on methods for the grafting and patterned grafting of block copolymer nanotubes onto glass and mica surfaces. Under optimized conditions the density of such grafted nanotubes can be high, and most of the grafted tubes are in a standing position even after solvent evaporation.

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