Ju Hong Ko

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.

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.

5-Substituted isophthalate-based organic electrochromic materials

A new series of isophthalate-based electrochromic materials were prepared. The functional groups at the 5-position of isophthalate have a significant influence on the observed color. In particular, an electrochemically active nitro group induced a multi-color display, indicating that further electrochromic properties could be manipulated using more diverse 5-substituted isophthalate derivatives.

Molecular Design and Preparation of Bis-isophthalate Electrochromic Systems having Controllable Color and Bistability

New electrochromic systems based on bis-isophthalates were designed and prepared. They showed electrochromism behavior by two-electron reduction. The displayed colors showed greatly enhanced bistability and were dependent on the length of the conjugated bridge between the two isophthalate groups. We believe that the connection of two electrochromic systems with a conjugated bridge is a good basic strategy to obtain new bistable electrochromic systems.

Designed Synthesis of Ferrocenylanthraquinones and Their Bifunctional Electrochromic Properties

New bifunctional electrochromic systems were developed by combination of reductive anthraquinone with oxidative ferrocene redox systems. The resultant ferrocenylanthraquinones demonstrated enhanced stability in electrochromic performance through the concomitant reductive electrochromism and oxidative counting action. The displayed colors were dependent on the position of the ferrocenyl group.

Adhesive organic network films with a holey microstructure: useful platforms for the engineering of flexible energy devices

Pure silica zeolite (Silicalite-1) bricks with a 2D morphology were assembled on a slide glass and used as templates for the preparation of microstructured organic network films (MONFs) with a hollow space and holes by the Sonogashira coupling of tetrakis(4-ethynylphenyl)methane and 1,4-diiodobenzene and silica etching. The MONFs were adhesive to polyethylene terephthalate (PET) films due to their unique structural effects. Cu was loaded on the MONF/PET by electroless deposition. The Cu/MONF/PET showed excellent retention of conductivities in repeated severe bending.

Microporous organic network@PET hybrid membranes: removal of minute organic pollutants dissolved in water

This work shows that microporous organic network (MON) chemistry can be applied for the engineering of hybrid membranes. While a polyethylene terephthalate (PET) membrane did not work for the removal of minute organic pollutants dissolved in water, the MON@PET hybrid membranes showed promising filtration towards aromatic pollutants in water.

Control algorithm for a power split type hybrid electric vehicle

In the power split type hybrid electric vehicle(HEV), since the two motors are used to assist the engine or to charge the battery, it is essential how to control the two motors while minimizing the fuel consumption and satisfying the drivers demand. In this paper, a control algorithm of a power split type HEV is investigated for optimal engine operation. The control algorithm is designed in such a way that it could control the torques of two motors, MG1 and MG2 to enable the engine to operate on the optimal operation line according to the engine power and battery power that can be determined from the drivers acceleration intention. To verify the performance of the proposed control algorithm, a power split transmission is designed using two planetary gears. It is verified that the engine could be in operation at around the optimal operation line while satisfying the desired battery power limitation, using the MG1 and MG2 torque control algorithm proposed in this study.

Enhanced redox activity of a hollow conjugated microporous polymer through the generation of carbonyl groups by carbonylative Sonogashira coupling

Redox active 1,4-bis(3-phenylpropynoyl)benzene moieties were incorporated into a hollow conjugated microporous polymer via carbonylative Sonogashira coupling of 1,3,5-triethynylbenzene with 1,4-diiodobenzene in the presence of carbon monoxide. The resultant redox active material showed enhanced energy storage performance for pseudocapacitors.