Influence of Porous Materials on the Reactivity and Stability of Transition Metal Catalysts

Organometallic chemists have historically studied the influence of ligands and counteranions on homogeneous transition metal catalysts in order to improve their selectivities and reactivities. Recently, these interests have expanded to incorporate supramolecular hosts and heterogeneous porous materials as supports which can influence catalyst properties. This work encompasses such an integration of catalysts with heterogeneous supports, wherein two types of chiral porous materials are evaluated for their abilities to induce enantioselectivity with nano- and molecular- scale catalysts. Furthermore, the strategy of architectural stabilization is developed to improve a gold(III) catalyst via introduction into robust metal-organic frameworks.Chapter 1. A variety of catalysts were immobilized in chiral mesoporous silica, and their reactivities were evaluated. Efforts towards the enantioenrichment of MOF-520 are described. Additionally, a novel post-synthetic metalation strategy is described for the introduction of a transition metal catalysts into metal-organic frameworks via oxidative addition.Chapter 2. A novel architectural stabilization strategy is described with a structurally well- defined gold(III) catalyst in metal-organic frameworks. The robustness of IRMOF-10 and bio- MOF-100 were used to rigidify a gold(III) catalyst to suppress a unimolecular decomposition pathway – reductive elimination. Through this architectural stabilization strategy, decomposition of the incorporated gold(III) catalyst in the metal-organic frameworks was not observed; in contrast, the homogeneous analogue was prone to decomposition in solution. Stabilization of the gold(III) catalyst in these metal-organic frameworks precluded leaching and enabled recyclability, which is crucial for productive heterogeneous catalysis

Influence of Porous Materials on the Reactivity and Stability of Transition Metal Catalysts

Organometallic chemists have historically studied the influence of ligands and counteranions on homogeneous transition metal catalysts in order to improve their selectivities and reactivities. Recently, these interests have expanded to incorporate supramolecular hosts and heterogeneous porous materials as supports which can influence catalyst properties. This work encompasses such an integration of catalysts with heterogeneous supports, wherein two types of chiral porous materials are evaluated for their abilities to induce enantioselectivity with nano- and molecular- scale catalysts. Furthermore, the strategy of architectural stabilization is developed to improve a gold(III) catalyst via introduction into robust metal-organic frameworks.Chapter 1. A variety of catalysts were immobilized in chiral mesoporous silica, and their reactivities were evaluated. Efforts towards the enantioenrichment of MOF-520 are described. Additionally, a novel post-synthetic metalation strategy is described for the introduction of a transition metal catalysts into metal-organic frameworks via oxidative addition.Chapter 2. A novel architectural stabilization strategy is described with a structurally well- defined gold(III) catalyst in metal-organic frameworks. The robustness of IRMOF-10 and bio- MOF-100 were used to rigidify a gold(III) catalyst to suppress a unimolecular decomposition pathway – reductive elimination. Through this architectural stabilization strategy, decomposition of the incorporated gold(III) catalyst in the metal-organic frameworks was not observed; in contrast, the homogeneous analogue was prone to decomposition in solution. Stabilization of the gold(III) catalyst in these metal-organic frameworks precluded leaching and enabled recyclability, which is crucial for productive heterogeneous catalysis

Electrolytically Ionized Abrasive-Free CMP (EAF-CMP) for Copper

Chemical–mechanical polishing (CMP) is a planarization process that utilizes chemical reactions and mechanical material removal using abrasive particles. With the increasing integration of semiconductor devices, the CMP process is gaining increasing importance in semiconductor manufacturing. Abrasive-free CMP (AF-CMP) uses chemical solutions that do not contain abrasive particles to reduce scratches and improve planarization capabilities. However, because AF-CMP does not use abrasive particles for mechanical material removal, the material removal rate (MRR) is lower than that of conventional CMP methods. In this study, we attempted to improve the material removal efficiency of AF-CMP using electrolytic ionization of a chemical solution (electrolytically ionized abrasive-free CMP; EAF-CMP). EAF-CMP had a higher MRR than AF-CMP, possibly due to the high chemical reactivity and mechanical material removal of the former. In EAF-CMP, the addition of hydrogen peroxide (H2O2) and citric acid increased the MRR, while the addition of benzotriazole (BTA) lowered this rate. The results highlight the need for studies on diverse chemical solutions and material removal mechanisms in the future

Development and Performance Evaluation of Light Shelves Using Width-Adjustable Reflectors

In recent years, there has been an increase in the consumption of energy for lighting purposes, which has led to an increase in the number of studies being conducted on this subject. Most studies have focused on light shelves, which are daylighting systems used for reducing the lighting energy required for the interiors of buildings. However, the existing light shelves cannot actively deal with external environmental factors, which often lead to an infringement of the right to light during the night when the performance of the light shelf deteriorates. Therefore, in this study, we propose a light shelf with a width-adjustable reflector and verify its validity using a testbed. The reflector of the proposed light shelf system is modularized so that the length can be adjusted in stages. The optimum width of the light shelf is calculated in terms of the energy reduction and uniformity ratio improvement, and the obtained optimum width is varied depending on the season. We find that the width-adjustable reflector can save 20% and 21.6% more lighting energy than light shelves with fixed reflector widths of 0.3 m and 0.6 m, respectively

Distribution Characteristics of Indoor PM2.5 Concentration Based on the Water Type and Humidification Method

With the industrialization and rapid development of technology that can measure the concentration of pollutants, studies on indoor atmosphere assessment focusing on occupants have been recently conducted. Pollutants that worsen indoor atmosphere include gaseous and particulate matter (PM), and the effects and diffusion characteristics that influence indoor atmosphere vary depending on the indoor and outdoor concentration. White dust is a PM generated from minerals in water used for humidifiers during winter. Therefore, studies on the impact of white dust on human health and its size distribution are being actively conducted. However, since the indoor PM concentration varies depending on the humidification method and water type used, relevant studies are needed. Accordingly, this study examined the change in the PM2.5 concentration and relative humidity on the basis of water types and humidification method. It was found that the indoor PM2.5 concentration varied from 16 to 350 ug/m3, depending on the water types used for an ultrasonic humidifier. Conversely, when using a natural evaporative humidifier, white dust did not increase the indoor PM2.5 concentration, regardless of the mineral content of the water used. Considering both humidification ability and continuous humidifier use indoors, water purifier with nano-trap filters must be utilized for ultrasonic humidifiers

Full Color Tactile Sensor by Using Upconversion Nanoparticle Embedded Microarray

Rare-earth-doped upconversion nanoparticles (UCNP) release a visible ranged luminescence property under exposed near-infrared (NIR) light by multiphoton excitation. These particles are highly photochemical stability, absence of background autofluorescence, and showing various colors through one kind of light source. Therefore, UCNP have been studied extensively for applications such as a photodynamic therapy, bioimagings, and a luminescence display. In this work, we rationally utilized the unique properties of UCNP and report a new type of colorimetric tactile sensor using lanthanide doped upconverting nanoparticles. We fabricated full color array using lithography technique and applied this array into the NIR based sensor to recognize the direction and magnitude of applied pressure