Synthesis of III-V Alloy-Based Semiconductor Nanoclusters and Nanostructures

Anastasia Agnes Department of Chemistry, Pohang University of Scie 2019 국내석사

This thesis particularly discuss the synthesis process of III-V alloy-based semiconductor nanoclusters and nanostructures. Gallium-incorporated nanoclusters, named as 360-Cl&MA InGaP clusters were synthesized through conversion reaction of assynthesized-386-MA InP magic-sized clusters (MSCs) with the additional of gallium(III) chloride. The amount of gallium(III) chloride as well reaction temperature are known to hold substantial roles in forming the 360-Cl&MA InP clusters out of 386-MA InP MSCs. Moroever, both parameters also affect the stability of the as-synthesized-cluster. It is revealed that the addition of gallium(III) chloride into the as-synthesized 386-MA InP MSCs resulted in the in-situ formation of hydrochloric acid (HCl), which then etches the 386-MA InP MSCs and form the smaller size cluster, 360-Cl&MA InGaP clusters. Further characterization was done in order to understand the structure and the composition of 360- Cl&MA InGaP. The as-synthesized 360-Cl&MA InGaP clusters then were utilized to form alloy-based InP nanostructures. However, instead of seed-growth mechanism, it is proven that during the formation of larger InP nanostructures out of InP nanoclusters, InP nanoclusters were dissolved back to their monomers or fragments prior to the nucleation and growth to form larger InP nanoclusters. In addition, several studies were completed, aiming to optimize the optical properties of the-as synthesized alloy-based InP nanostructures by the additional of additives, such indium-myristate complex. During the synthesis process, phosphorous precursor’s amount in the reservoir should be sufficient during the growth stage to ensure continuous growth and evade the Ostwald ripening stage. One of the strategy is by introducing the phosphorous precursors in form of zinc-phosphorous complex, which lower down the reactivity and slow down the reaction rate and leads to the formation of more monodisperse quantum dots. On top of that, by tuning the amount of added-phosphorous molecular precursor onto the zinc-phosphorous complex, the morphology of the assynthesized InP nanostructures could be controlled. In this case, instead of 360-Cl&MA InGaP clusters, 360-InZnP clusters were utilized for this particular purpose.

Synthesis and Anion Binding Properties of 2-(2-Hydroxyphenyl)-4-arylthiazole Derivatives : 2-(2-히드록시페닐)-4-아릴싸이아졸 유도체의 합성과 음이온 인지특성

Thu Thao, uyen Thi Department of Applied Chemistry, Major in Applied 2004 국내석사

2-(2-히드록시페닐)-4-아릴싸이아졸 화합물을 두 가지의 방법으로 합성하였다. 첫째 방법은 2-메톡시싸이오아미드와 2-브로모아세토페논 유도체를 반응시켜 2-(2?메톡시페닐)-4-아릴싸이아졸 유도체를 얻은 후 메톡시기를 히드록시기로 변환시켜 목적물을 얻는 것으로 두 단계의 반응을 거치나 수율은 76-95%로 높았다. 둘째 방법은 살리실-싸이오아미드와 2-브로모아세토페논 유도체를 반응시켜 최종 목적물을 한 단계의 반응으로 얻는 것으로 수율은 71-90% 였다. 합성한 화합물들의 음이온에 대한 선택적 인지특성을 UV-vis 흡수 스펙트럼과 형광 스펙트럼으로 조사하여 F-이온에 대하여 화합물 13 <2 < 8 의 순으로 선택성이 높은 것을 관찰하였으며, OAc-, H2PO4 - 이온에 대해서도 선택성이 확인되었다.

Syntheses of phenyl-substituted unnatural carotenoids

Wu, Bo Department of Chemistry Myong Ji University 2005 국내석사

We have developed an efficient method to make phenyl-substituted C5 (1) and C10 units (2). The phenyl substituted C10 unit, bis(4-chloro-3-phenyl-2-butenyl) sulfide (2), can be used as a stable substitute for the highly unstable 1,8-dichloro-2,7-diphenyl-2,4,6-octatriene when making the central part of the phenyl substituted unnatural ß-carotene (4), where the sulfur moiety not only allows efficient assembly of two allylic chains but also provides the polyene systems with stability during the coupling reaction with two C15-monosulfones (3). Then we can oxidize the sulfide to sulfone and use Ramberg-Backlund reaction to create the three conjugated double bonds. We finally accomplished the total syntheses based on the Julia sulfone-olefination protocol, which is presumed to be the best method to produce doubl bonds with the (E)-configuration. ◁그림 삽입▷(원문을 참조하세요)

Synchrotron X-ray Scattering and Reflectivity Studies on Topological Polymers and Polymeric Nanoparticles

XIANG, LI Department of Chemistry, Pohang University of Scie 2020 국내박사

By synchrotron grazing incidence X-ray scattering and quantitative data analysis, crystalline characteristics of poly(ε-caprolactone) (PCL) in thin films were investigated. Particularly, topology effect (linear and cyclic) and molecular weight dependence were discussed in detail. Also, three types of polymer nanoparticle structures in solution were quantitatively studied and compared by small angle X-ray scattering, including highly branched single polymer nanoparticles (stars and dendrimers), self-assembled polymer micelle nanoparticles and synthetic anionic polystyrene nanoparticles. In Chapter II, higher equilibrium melting temperature of cyclic PCL compared with two types of linear PCLs was obtained by both linear and nonlinear Hoffman-Weeks analysis of isothermal crystallization experimental data. Grazing Incidence Small Angle and Wide Angle X-ray Scattering (GISAXS and GIWAXS) were employed to explore the morphology and crystalline characteristics in nanoscale thin films. Upon quantitative analysis of GISAXS data, detailed information of lamellar morphology in each PCL thin film was revealed. Cyclic PCLs were proved to have smaller long periods but greater crystal size than linear precursors. Molecular weight dependence of morphology features was also discussed for both linear and cyclic PCLs. GIWAXS data analysis provided the lattice parameters of orthorhombic lattice formed in each PCL thin film, and no significant difference was recognized for crystal lattice formed by linear and cyclic PCLs. Relative crystallinity was calculated through peak separation of crystalline and amorphous peaks appeared in circularly averaged WAXS data. By X-ray reflectivity analysis, cyclic PCLs were found to have a higher averaged electron density as well as higher electron density of each sublayers in the formed nanostructures. In Chapter III, single polymer nanoparticles of stars and dendrimers in solution were examined by synchrotron solution X-ray scattering, including three groups of homo star polymers PMMA, PMA and PnBA with same molecular weight but different number of arms, two groups of diblock star polymers s-(PMEA-b-PnBA)24 and s-(PnBA-b-PMEA)24, 4-generration dendrimer (PMMA-G4) and 5-generation dendrimer (PMMA-G5). Through quantitative data analysis, 3, 4, 6, 8, 12arm- star polymers were found to be ellipsoids rather than sphere with the degree of distortion strongly dependent on the topology (i.e., the number and length of the arm). 24arm- diblock star polymers quite approximate globular shape in solution. Two dendrimers greatly shifted away from a perfect sphere and appeared to be oblate ellipsoids in solution. The overall size, segmental dimension and radial density distribution features were quantitatively determined as well. Also, star polymers in thin film state were subjected to X-ray reflectivity analysis and electron density was obtained which reflected topology possesses both positive and negative effect on the dense packing of star polymers to form thin films. In Chapter IV, a series of block copolymers of various topologies (symmetric and asymmetric linear diblock and triblock, and star-shaped) were synthesized, and inverse micelles were successfully formed in hexane or hexane/THF cosolvents investigated by synchrotron solution X-ray scattering. Discriminated by topology, core-shell micelles, 4-, 8-, 10-layer “onion-like” micelles were discovered. Surprisingly, linear triblock copolymer D10M20D10 was able to form several nanostructures varied with changing volume ratio of hexane/THF cosolvent. Structures of all micelles were explained through quantitative analysis of X-ray scattering data. Effects of polymer topology on micelle size, structural characteristics, aggregation number, micelle stability as well as critical micellization concentration were discussed. In Chapter V, a group of anionic polymer nanoparticles with radius ranging from 19nm to 460nm were synthesized via soup free emulsion polymerization. DLS was conducted to determine hydrodynamic radii and polydispersities of these anionic particles. More comprehensive structure analysis was done by solution X-ray scattering, which provided quantitative data describing particle shape, size and radial density characteristics. X-ray scattering data were well fitted by a sphere model with local density fluctuation, which revealed that anionic particles were almost spherical in shape with locally fluctuated density inside the particles. Size distributions for each particle were also determined by model fitting and compared with DLS results. These particles were found to be close to monodisperse in size. In Chapter VI, Bacillus licheniformis α-amylase (BLA) in a biomimetic buffer and extrinsic solutions (various pH values, temperatures, and metal ions) has been investigated for the first time in the view of three-dimensional (3D) structure by synchrotron X-ray and dynamic light scattering analyses. BLA in buffer is determined to have a structure resembling its crystallographic structure; but the 3D structure is slightly larger than the crystal structure. Such a structure is maintained with little variations in extrinsic solutions of pH 4.09.7, temperature 455 C, and metal ions such as Ba2+, Mg2+, and Li+. These results collectively inform that BLA tends to favorably form a stable monomeric structure, which could provide structural clues to its enzymatic activities in moderate levels. Interestingly, BLA is found to reveal highly expanded structures at 6575 C and in Co2+ solution, which could correlate to the significantly pronounced enzymatic activities. However, BLA shows somewhat shrunken structures at pH 3.0 and in Hg2+ solution, supporting for the suppressed activities under these conditions.

Palladium- and Ruthenium-Catalyzed Synthesis of 2-Aryl- and 2-Ferrocenylquinolines : 팔라듐 및 루테늄 촉매를 사용한 2-아릴 및 2-페로세닐퀴놀린의 합성

Seok, Hyo Jin Department of Applied Chemistry, Major in Organic 2004 국내석사

본 학위 논문은 팔라듐 및 루테늄촉매를 사용하여 퀴놀린 유도체의 합성에 관한 연구에 관한 것이다. 팔라듐촉매를 사용하여 1-arylprop-2-yn-1-ol의 반응으로부터 2-iodoaniline과 2-arylquinoline 유도체의 합성에 관하여 연구하였다. 이 반응은 Sonogashira coupling, isomerization, cyclodehydration과 같은 일련의 반응을 통하여 퀴놀린이 생성되는 것으로 예측되었다. 또한 루테늄촉매를 사용하여 2-aminobenzyl alcohol과 키톤 및 이차알코올의 반응으로부터 2-ferrocenylquinoline 유도체를 합성하였다. 마지막으로 3-(2-aryl)1-1arylprop-2-yn-1-ol이 KOH 하에서 chalcone으로 전환하는 이성화반응에 대하여 연구하였다.

N-Heterocyclic Carbene and Fe(III) Catalyzed Heterocycle Synthesis

Won Sun Kim Department of Chemistry Graduate School Kyung Hee 2012 국내석사

Oxazolidinones, which are widely used as chiral auxiliaries in asymmetric synthesis and bioactive scaffolds in numerous natural products, have been attractive synthetic targets due to the importance of their structures. However, previously reported procedures were mostly applied to the construction of 4-methylene-1,3-oxazolidin-2-ones. As part of an ongoing study aimed at developing the N-heterocyclic carbene-catalyzed reaction, we could demonstrate concise catalytic methods for the direct synthesis of 4-substituted methylene oxazolidinones, as an atom economical and environmentally benign process using internal propargylic alcohols and phenylisocyanates or benzoylisocyanates. 옥사졸리디논은 비대칭합성반응에서 카이랄한 옥실러리로 넓게 사용되며, 생리활성이 있어 다양한 천연물에서 발견된다. 이에 옥사졸리디논의 구조적 중요성때문에 합성방법이 많이 연구되어있다. 하지만 4-메틸렌-1,3-옥사졸리딘-2온의 합성방법은 보고된바가 많지않다. 이에 우리는 N-헤테로고리 카빈 촉매를 이용한 연구를 해왔다. 우리는 프로파질릭알콜과 페닐아이오싸이아네이트, 벤질아이소싸이아네이트를 통한 경제적이고 친환경적인 파라-치환기를 가진 메틸렌옥사졸리디논의 합성법을 고안했다. The intramolacular cyclization reactions of alkynyl aldehydes in the presence of a catalytic a mount of a organic catalyst such as N-Heterocyclic Carbene afforded the corresponding (E)-configurated a,ß-unsaturated acylidene-indane. NHC treated with base is effective reagent for generating allene species from alkynyl aldehydes, and this nucleophilic intermediate can be protonated by equimolar amount of ethanol, thereby promoting a efficient conversion into a a,ß-unsaturated acylidene-indane. Further investigations and applications of these acylidene-indane species are being actively pursued: reactions of the CO- groups as well as acylations with cleav age of a,ß-unsaturated ester. NHC 촉매하에 알카이닐 알데하이드의 분자내 반응을 통해 E-형태의 알파,베타-불포화 아실리딘-인데인을 합성 할 수 있었다. 염기처리를 한 NHC 촉매는 알카이닐 알데하이드로 부터 알렌을 만드는데에 효과적인 시약이며, 그 과정 중 생성되는 친핵성 중간체는 당량으로 들어가는 에탄올에 의해 중화 됨으로써, 알파,베타-불포화 아실리딘-인데인을 효율적으로 합성 할 수 있다. 알파,베타-불포화 아실리딘-인데인에 존재하는 알파,베타-불포화 에스터 기의 아실화 반응과 같은 이 물질의 연구와 적용분야는 현재 연구 중에 있다. The use of transition metals as catalysts to induce new C-C, C-O, or C-N bond formation continues to grow exponentially for efficient and atom-economic organic transformations. It is worthy to investigate the cheaper and more easily available eco-friendly catalyst as unsaturated C-C bond activators toward nucleophilic attack. In our research aiming to develop green catalytic reactions, the nucleophilic cyclization reactions of allenes were catalyzed by Fe(III) to afford the corresponding heterocycle compound. Fe(III) catalysts were applied in the reactions of allenyl amides or allenyl alcohols and cyclized compounds containing O or N heteroatom were produced with moderate to good yields. 전이 금속의 사용은 새로운 C-C, C-O, 또는 C-N 결합 형성을 유도하는 촉매가 효율적이고 원자 경제적 유기 변환에 대한 지속적으로 성장을 할수 있도록 한다. 그것은 친핵성 공격으로 불포화 C-C 결합을 위한 활성화물로 저렴하며 더 쉽게 사용할 환경 친화적인 촉매를 조사 가치가있다. 친환경 촉매 반응 개발을 목표로 연구해 알렌의 친핵성 고리화 반응에 철 촉매를 사용하게 되었습니다. 철 촉매는 알레닐 아마이드 또는 알레닐 알콜 및 O 또는 N 등의 이종 원자가 고리화 반응에 좋은 수율로 생산될수 있게끔 하였습니다.

The effect of medium on the alpha-effect : nucleophilic displacement reactions at Carbonyl and Related Centers

Um, Ik-Hwan Department of Chemistry, Queen's University 1987 해외박사

여러가지 치환기를 갖는 Aryl Acetates, Thioaryl Acetates, Aryl Benzoates 및 ph enyl Thionbenzoate를 반응기질로, 하고 HO�� 4-ClPho��및 CH��(O)C=NO�玖�각각 표준친핵체, 정상친핵체 및 이에 대응하는 알파 친핵체로 삼아 친핵성 치환반응을 실 시하였다. 이때 반응용매는 물과 또 물-DMSO 혼합용매로서 DMSO의 몰함량을 체계적으 로 변화시키면서 (0,10,20,30,…,80,90 mole%) 각 용매조성 변화에 따른 반응속도 상 수를 구하고 또 이로부터 알파효과의 크기 변화를 구하였다. 반응온도를 25℃ 뿐만 아 니라 35℃와 45℃로 변화시켜 반응을 실시하고 이 결과로 부터 반응의 활성화 에너지 를 구하므로서 전이상태의 에너지에 관한 연구를 수행하였으며 또한 반응의 전이상태 구조를 보다 명확히 이해하기 위하여 반응메카니즘 규명에 관한 연구를 아울러 실시하 였다. 한편 반응물질의 바닥상태 에너지를 연구하기 위하여 반응 출발물질과 생성물질 에 대한 각 혼합용매에서 용해열을 열량계를 이용하여 측정하였다. 이와 같은 체계적 이고 심도 깊은 연구결과로부터 알파효과에 미치는 용매효과를 바닥상태와 전이상태가 관여하는 정도를 정량적으로 나누었다. 이로부터 용매효과는 알파효과의 중요한 원인 이라는 결론을 내릴 수 있었으며 또한 여러가지로 난립되어 있는 이에 관련된 학설을 정립하는데 보탬이 되는 부수적인 증거들을 많이 얻었다.

Vibration-rotation band contour of methyl chloride in infrared absorption spectra

양병윤 Department of Chemistry, Graduate School, Kyung He 1982 국내박사

Controlling the molecular structure and composite formation for ion-conducting polymers as high-performance AEM and PEM materials

MAYADEVI T S Department of Chemistry, Graduate School, Incheon 2022 국내박사

본 연구의 목적은 음이온 교환막 연료전지(AEMFC) 및 수전해(AEMWE)에서의 응용을 위한 우수한 전기화학적 및 물리화학적 특성을 가진 신규 고분자 전해질 막을 개발하는 것이다. 본 논문은 총 5 Chapter로 구성되어 있으며 주요 내용은 아래와 같다. Chapter 1에서는 연료전지와 수전해의 기본적 이론을 개략적인 시스템과 전기화학적 반응을 포함하여 설명하였다. 또한 다양한 유형의 연료전지(PEMFC 및 AEMFC)에서의 고체 고분자 전해질의 장점 및 단점과 신규 고성능 AEM 및 PEM 고분자 소재별 맥락을 고려하여 고분자 전해질의 종류와 특성을 정리하였다. Chapter 2에서는 블록 공중합체의 사슬 길이를 조절하여 서로 다른 소수성 및 친수성 블록 비율을 가지는 4차 암모늄 전도기를 가진 poly(ether sulfone ketone) 블록 공중합체 (QA-PESKs)의 개발에 대해 설명하였다. 이 장에서는 QA-PESK 공중합체 멤브레인의 블록 비율을 변경하여 모폴로지, 수산화 이온 전도도, 열역학적 특성 및 안정성에 대한 체계적인 연구를 제공한다. Chapter 3에서는 AEM 응용 분야에서 새로운 이온 전도기 그룹으로 수산화 이온 작용기를 갖는 N-헤테로사이클릭 피페리디늄 4차 암모늄의 도입을 자세히 설명하였다. OH-Pip-PPO 및 Trop-PPO의 추가적인 수산화 이온 그룹의 존재는 수소 결합을 통해 고분자 막에서 물리적 가교를 위한 분자 상호작용 사이트로 기능할 것으로 예상된다. 이 장에서는 실험 및 시뮬레이션 연구를 사용하여 새로운 AEM의 모폴로지, 이온 전도 채널 형성, 열역학적 특성 및 화학적 안정성에 대한 집중적인 연구를 제공한다. Chapter 4에서는 meta/para-terphenylene 메틸 피페리디늄 공중합체 고분자의 개발에 대해 설명하였다. 이 장에서는 향상된 자유 부피와 균형 잡힌 입체 구조를 제공할 수 있는 meta-terphenyl 유닛의 최적의 몰분율을 찾기 위해 rigid/ linear para-terphenyl과 뒤틀린 입체 구조의 meta-terphenyl 사이 공중합체 조성을 체계적으로 분석하였다. 고분자 막은 AEM의 기본적인 특성과 셀 성능에 대해 연구되었다. Chapter 5에서는 함침제로 polydopamine 유도체를 사용하는 in situ swelling-filling 방법에 의한 Nafion 복합막 제조에 대해 자세히 설명하였다. polydopamine 유도체로 채워진 Nafion 복합막은 열적 및 기계적 안정성을 개선하고 기존의 Nafion-212에 비해 더 높은 이온 전도성을 나타낼 것으로 예상되는 한편, polydopamine 유도체와 Nafion 사이 강력한 분자 상호 작용은 수소 크로스오버를 효과적으로 낮출 것이라고 예상되었다. The aim of the present study is to develop new polymer electrolyte membranes with enhanced electrochemical and physicochemical properties for fuel cell and water electrolysis applications. This dissertation contains 5 chapters, and the major contents are summarized below. Chapter 1 explains the basic theory of both fuel cells and water electrolyzers, including their schematic system and electrochemical reactions. Different types of fuel cells, their electrolytes, and their recent advances are also explained. The advantages and disadvantages of solid polymer electrolytes in fuel cells (PEMFCs and AEMFCs) are further detailed. Moreover, the types and characteristics of polymer electrolytes are summarized in consideration of the context of designing new high-performance AEM and PEM materials. Chapter 2 describes the development of quaternary ammonium-functionalized poly(ether sulfone ketone) block copolymers (QA-PESKs) with different hydrophobic and hydrophilic block ratios by controlling the block oligomer chain length. This chapter provides the systematic investigation on the morphology, hydroxide conductivity, thermo-mechanical properties, and stability by varying the block ratio of QA-PESKs co-polymer membranes. Chapter 3 details the introduction of N-heterocyclic piperidinium quaternary ammoniums having hydroxy groups as new ion-conducting groups in AEM application. The presence of additional OH groups is expected to function as molecular interaction sites for physical crosslinking through hydrogen bonding in OH-Pip-PPO and Trop-PPO membranes. This chapter gives an intense investigation on the morphology, ion-conducting highways, thermo-mechanical properties, and chemical stability of new AEMs using both experimental and simulation studies. Chapter 4 describes the development of poly(meta/para-terphenylene-methyl piperidinium) copolymers. This chapter systematically analyzed the copolymer composition between rigid/linear para-terphenyl and kink-structured meta-terphenyl to find the optimum molar content of meta-phenyl unit that can provide balanced conformational structure with enhanced free volume. The membranes are investigated for their fundamental properties and cell performance of AEMs. Chapter 5 details the preparation of Nafion composite membranes by in situ swelling-filling method using polydopamine derivatives as impregnating agents. The polymer-filled Nafion composite membrane is expected to improve thermal and mechanical stability and exhibit a higher ionic conductivity compared to the pristine Nafion-212, while the strong molecular interaction with the filler molecules effectively lowers its hydrogen crossover.

Corrosion of metals by soils

Srivastava, Kumkum Department of Chemistry, University of Allahabad 1981 국내박사