Nojin Park

Microporous Organic Network Hollow Spheres: Useful Templates for Nanoparticulate Co3O4 Hollow Oxidation Catalysts

Hollow microporous organic networks (H-MONs) were prepared by a template method using silica spheres. The shell thickness was delicately controlled by changing the synthetic conditions. The H-MONs were used as a template for the synthesis of nanoparticulate Co3O4 hollows which showed excellent catalytic performance in H2O2 oxidation.

Metal−Organic Framework@Microporous Organic Network: Hydrophobic Adsorbents with a Crystalline Inner Porosity

This work reports the synthesis and application of metal-organic framework (MOF)@microporous organic network (MON) hybrid materials. Coating a MOF, UiO-66-NH2, with MONs forms hybrid microporous materials with hydrophobic surfaces. The original UiO-66-NH2 shows good wettability in water. In comparison, the MOF@MON hybrid materials float on water and show excellent performance for adsorption of a model organic compound, toluene, in water. Chemical etching of the MOF results in the formation of hollow MON materials.

Photocatalysis by phenothiazine dyes: visible-light-driven oxidative coupling of primary amines at ambient temperature.

New phenothiazine based organic dyes were prepared for visible-light-driven organic transformations. The 3,7-disubstituted phenothiazine derivatives showed visible light absorption and reversible one-electron oxidation behavior. In the presence of 0.5 mol % of 3,7-disubstituted phenothiazines, primary benzylamines showed oxidative coupling under visible light irradiation from a blue LED. The electronic effect of substituents in phenothiazine dyes was observed in catalytic activities. The mechanistic pathway of oxidative coupling was discussed based on the detection of H(2)O(2) after the reaction.

Fe3O4 nanosphere@microporous organic networks: enhanced anode performances in lithium ion batteries through carbonization

Very thin microporous organic networks were formed on the surface of Fe3O4 nanospheres by Sonogashira coupling of tetra(4-ethynylphenyl)methane and 1,4-diiodobenzene. The thickness was controlled by screening the number of building blocks. Through carbonization, Fe3O4@C composites were prepared. The Fe3O4@C composites with 4-6 nm carbon thickness showed promising reversible discharge capacities of up to 807 mA h g(-1) and enhanced electrochemical stability.

Molecular design and synthesis of ruthenium(II) sensitizers for highly efficient dye-sensitized solar cells

We synthesized hydrophobic ruthenium(II) sensitizers (SY-04 and SY-05) with high molar extinction coefficient by extending the π-conjugation of 3,4- or 3-alkylthiophene-substituted bipyridine ligands. Both dyes displayed a remarkably high molar extinction coefficient of 21.7 × 103 M−1 cm−1 arising from red-shift of their metal-to-ligand charge transfer band when compared to a commonly used N3 sensitizer. The solar-to-electrical energy conversion efficiency (η) of the SY-04 based dye-sensitized solar cell (DSC) was 7.70%, which is 27% higher than that (6.05%) of the N3-based DSC under the same cell fabrication conditions. The increased η was attributed to the increase in life time and recombination half-life measured by electrochemical impedance and transition absorption spectroscopy, respectively. Density functional theory and time-dependent density functional theory calculations of two dyes in both gas phase and solution were performed. The calculated values of the highest occupied and the lowest unoccupied molecular orbitals and absorption spectra are in good agreement with the experimental results.

Microporous organic nanorods with electronic push–pull skeletons for visible light-induced hydrogen evolution from water

This work shows that microporous organic network (MON) chemistry can be successfully applied for the development of a visible light-induced hydrogen production system. A visible light harvesting MON (VH-MON) was prepared by the Knoevenagel condensation of tri(4-formylphenyl)amine with [1,1′-biphenyl]-4,4′-diacetonitrile. Scanning electron microscopy (SEM) showed a 1D rod morphology of the VH-MON. Analysis of a N2 sorption isotherm showed a 474 m2 g−1 surface area and microporosity. Solid phase 13C nuclear magnetic resonance (NMR) and infrared (IR) absorption spectroscopy, and elemental analysis support the expected network structure. The VH-MON showed visible light absorption in 400–530 nm and vivid emission at 542 nm. The HOMO and LUMO energy levels of the VH-MON were simulated at −5.1 and −2.4 eV, respectively, by density functional theory (DFT) calculation. The VH-MON/TiO2–Pt composite exhibited promising activity and enhanced stability as a photocatalytic system for visible light-induced hydrogen production from water.

Hollow and sulfonated microporous organic polymers: versatile platforms for non-covalent fixation of molecular photocatalysts

Sulfonated hollow microporous organic polymers (S-HMOP) were prepared by template synthesis and post synthetic approach. The S-HMOP showed excellent non-covalent fixation ability towards various cationic dyes through ionic interaction. Among various dye systems, Zn-porphyrin loaded S-HMOP showed promising activity and stability in the decomposition of 4-chlorophenol under visible light irradiation.

Tandem generation of isocoumarins in hollow microporous organic networks: nitrophenol sensing based on visible light

Hollow microporous organic networks bearing isocoumarin moieties (H-IC-MONs) were prepared via a tandem synthetic approach. Pd catalysts conducted the networking of building blocks by the Sonogashira coupling with the concomitant generation of isocoumarins through cyclization. The H-IC-MONs showed visible light absorption and emission properties and were applied to nitrophenol sensing using visible light.