Hydrothermal/ Solvothermal Synthesis of Novel Ni and Co Complexes Containing Unsaturated Pyridine Moieties and Their Application in Water Electrolysis Catalysts = 불포화 피리딘을 포함하는 새로운 Ni,Co complex 의 수열/용매열 합성과 수전해 촉매로 의 응용

다국어 초록 (Multilingual Abstract)

Five novel coordination compounds were successfully synthesized via hydro/solvothermal methods using a ternary reaction system of amine ligands, metal salts (Ni²+, Co²+), and itaconic acid. The obtained compounds are: [Ni(SO₄)(4,4'-bipyridine)(H₂O)]n (1), Ni(5-amino-2-chloropyridine)2(H₂O)₂Cl₂ (2), Co₃(4-amino-3,5-dichloropyridine)₂(acetate)6 (3), Co(4-amino-3,5-dichloropyridine)₄Cl₂ (4), and Co(4-amino-3,5-dichloropyridine)₃(acetate)₂ (5). The structural study shows that the five compounds adopt quite different architectures. Compound (1) gives a three-dimensional interpenetrating framework. Compounds (2), (4) and (5), on the other hand, consist of discrete molecules. In compound (2), these molecules are further linked by intermolecular hydrogen bonds to build up a three-dimensional supramolecular network. For compounds (4) and (5), the molecules simply pack as molecular crystals, and their packing is mainly stabilized by van der Waals contacts in (4) and by both hydrogen bonding and π–π stacking interactions in (5). Compound (3) is different again: trinuclear cobalt units are connected by acetate ligands to form a one-dimensional coordination polymer chain. All of these compounds were characterized by single-crystal and powder X- ray diffraction. The structures of all compounds were determined by single-crystal X-ray diffraction (SXRD) and corroborated by powder X-ray diffraction (PXRD). Further characterization included infrared spectroscopy (IR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis (TGA) to analyze their functional groups, morphology, elemental distribution, and thermal properties. Additionally, in this work, we conducted a preliminary investigation into the electrochemical properties of compounds (1) through (5), which revealed their promising potential for application as catalysts in water electrolysis.

국문 초록 (Abstract)

아민 리간드, 금속 염(Ni²+ Co²+) 및 이타콘산의 3성분 반응 시스템을 통해 수열/솔보열법으로 5가지 새로운 배위 화합물을 성공적으로 합성하였다. 얻어진 화합물은 다음과 같다: [Ni(SO₄)(4,4'-bipyridine)(H₂O)]n (1), Ni(5-amino-2-chloropyridine)2(H₂O)₂Cl₂ (2), Co₃(4-amino-3,5-dichloropyridine)₂(acetate)6 (3), Co(4-amino-3,5-dichloropyridine)₄Cl₂ (4), Co(4-amino-3,5-dichloropyridine)₃(acetate)₂ (5). 구조 분석 결과, 다섯 화합물은 상이한 구조적 특성을 나타낸다. 화합물 (1)은 3차원(3D) 관통 네트워크 구조를 형성하며, 화합물 (2), (4), (5)는 분리된 분자 종으로 존재한다. 이 가운데 화합물 (2)는 분자 간 수소 결합에 의해 3차원 초분자 골격으로 확장되며, 화합물 (4)와 (5)는 각각 반데르발스 상호작용 및 75 수소 결합과 π–π 적층 상호작용의 조합으로 안정화된 분자 결정 구조를 이룬다. 한편, 화합물 (3)은 아세테이트 리간드로 연결된 3핵 코발트 클러스터들로부터 1차원 배위 고분자 사슬을 구성한다. 모든 화합물은 단결정 X-선 회절(SXRD), 분말 X-선 회절(PXRD), 주사전자현미경에너지 분산형 X-선 분광법(SEM-EDS), 적외선 분광법(IR), 열중량 분석(TGA)을 통해 종합적으로 특성화되었다. 또한 화합물 (1)–(5)의 전기화학적 거동을 예비적으로 평가하여, 이들 화합물이 물 전기분해용 산소발생반응(OER) 촉매로 활용될 수 있는 가능성을 확인하였다

목차 (Table of Contents)

• Ⅰ. Introduction 1
• Ⅱ. Experimental 5
• 2.1. Materials Synthesis and Analytical Techniques 5
• 2.1.1. Synthesis Method 5
• 2.1.2. Analytical Characterization Techniques 7
• 2.2. Synthesis 9
• 2.2.1. [Ni(SO4)(4,4'-bipy)(H2O)]n 9
• 2.2.2. Ni(5-amino-2-chloropyridine)2(H2O)2Cl 10
• 2.2.3. Co3(4-amino-3,5-dichloropyridine )2(acetate) 11
• 2.2.4. Co(4-amino-3,5-dichloropyridine)4Cl2 12
• 2.2.5. Co(4-amino-3,5-dichloropyridine)3(acetate)2 13
• Ⅲ. Results and discussion 14
• 3.1. Crystal structure 14
• 3.1.1. [Ni(SO4)(4,4'-bipy)(H2O)]n 14
• 3.1.2. Ni(5-amino-2-chloropyridine)2(H2O)2Cl2 19
• 3.1.3. Co3(4-amino-3,5-dichloropyridine )2(acetate)6 21
• 3.1.4. Co(4-amino-3,5-dichloropyridine)4Cl2 24
• 3.1.5. Co(4-amino-3,5-dichloropyridine)3(acetate)2 27
• 3.2. Thermogravimetric analysis (TGA) 30
• 3.3. Electrochemical Testing for the Oxygen Evolution Reaction 45
• 3.3.1. OER Performance of Co-based Coordination Compounds 46
• 3.3.2. OER Performance of Ni-based Coordination Compounds 47
• Ⅳ. Conclusion 51
• References 53
• Appendix (option) 57
• Abstract (in Korean) 74