Synthetic and Methodological Studies in Copper and Palladium–Catalyzed Carbon-Carbon and Carbon-Heteroatom Bond Formation

Carbon-hydrogen bond functionalization of arenes using transition metal catalysis has experienced a renaissance in recent decade. This powerful approach offers the most straightforward way to build up molecular complexity and streamline the synthesis of otherwise difficult to access organic compounds. In this dissertation, general methods for rapid introduction of fluorinated substituents via copper catalysis have been developed. A broadly applicable method for deprotonative, copper-catalyzed C-H arylation of 1H-perfluoroalkanes with aryl iodides was developed. Unparalleled reaction scope with respect to aryl iodides and fluorinated counterparts allows rapid access to multitude of structurally related molecules. Additionally, a method for the direct introduction of trifluoromethylsulfenyl group onto aromatic ring via removable auxiliary directed, copper-catalyzed C-H bond activation of carboxylic acid derivatives was developed. Finally, copper-promoted palladium-catalyzed C-H arylation of polyfluoroarenes bearing sensitive functional groups with aryl iodides was applied to the synthesis of precursors for the supramolecular assemblies and functional materials such as HOFs and MOFs. These materials are anticipated to have unique adsorption and binding properties.Chemistry, Department o

Construction of Nitrogen-abundant Graphyne Scaffolds via Mechanochemistry-Promoted Cross-Linking of Aromatic Nitriles with Carbide Toward Enhanced Energy Storage

The 2D graphyne-related scaffolds linked by carbon–carbon triple bonds have demonstrated promising applications in the field of catalysis and energy storage due to their unique features including high conductivity, permanent porosity, and electron-rich properties. However, the construction of related scaffolds is still mainly limited to the cross-linking of CaC2 with multiple substituted aromatic halogens and there is still a lack of efficient methodology capable of introducing high-concentration heteroatoms within the architectures. The development of alternative and facile synthesis procedures to afford nitrogen-abundant graphyne materials is highly desirable yet challenging in the field of energy storage, particularly via the facile mechanochemical procedure under neat and ambient conditions. Herein, graphyne materials with abundant nitrogen-containing species (nitrogen content of 6.9–29.3 wt.%), tunable surface areas (43–865 m2 g−1), and hierarchical porosity are produced via the mechanochemistry-driven pathway by deploying highly electron-deficient multiple substituted aromatic nitriles as the precursors, which can undergo cross-linking reaction with CaC2 to afford the desired nitrogen-doped graphyne scaffolds efficiently. Unique structural features of the as-synthesized materials contributed to promising performance in supercapacitor-related applications, delivering high capacitance of 254.5 F g−1 at 5 mV s−1, attractive rate performance, and good long-term stability.This is a manuscript of an article published as Fan, Juntian, Tao Wang, Bishnu P. Thapaliya, Meijia Li, Chi‐Linh Do‐Thanh, Takeshi Kobayashi, Ilja Popovs, Zhenzhen Yang, and Sheng Dai. "Construction of Nitrogen‐abundant Graphyne Scaffolds via Mechanochemistry‐Promoted Cross‐Linking of Aromatic Nitriles with Carbide Toward Enhanced Energy Storage." Small 19, no. 11 (2023): 2205533. DOI: 10.1002/smll.202205533. Copyright 2022 Wiley-VCH GmbH. Posted with permission. DOE Contract Number(s): AC02-07CH1135

Fully Conjugated Poly(phthalocyanine) Scaffolds Derived from a Mechanochemical Approach Towards Enhanced Energy Storage

Phthalocyanines (Pc)-derived materials represent an attractive category of porous organic scaffolds featured by extensive π-conjugated networks, but their construction is still limited to the solution-based pathways, producing materials with inferior conductivity and porosity. Herein, a mechanochemistry-driven approach was developed leveraging the on-surface polymerization of aromatic nitrile monomers with ortho-positioned dicyano groups in the presence of metal catalysts (magnesium, zinc, or aluminum) under neat and ambient conditions. Diverse Pc-functionalized conjugated porous networks (Pc-CPNs) were obtained featured by extensively and fully π-conjugated skeletons, high surface areas, and hierarchical porosities. The monomers in this mechanochemical approach could be extended to those difficult to be handled in solution-based procedures. The Pc-CPNs displayed attractive electrochemical performance as supercapacitor and anodes in batteries, together with superb long-term stability.This is a manuscript of an article published as Fan, Juntian, Tao Wang, Bishnu P. Thapaliya, Liqi Qiu, Meijia Li, Zongyu Wang, Takeshi Kobayashi, Ilja Popovs, Zhenzhen Yang, and Sheng Dai. "Fully Conjugated Poly (phthalocyanine) Scaffolds Derived from a Mechanochemical Approach Towards Enhanced Energy Storage." Angewandte Chemie International Edition 61, no. 38 (2022): e202207607. DOI: 10.1002/anie.202207607. Copyright 2022 Wiley-VCH GmbH. Posted with permission. DOE Contract Number(s): AC02-07CH11358; AC05-00OR22725

Mechanochemistry-Driven Construction of Aza-fused π-Conjugated Networks Toward Enhanced Energy Storage

The current approaches toward synthesis of conjugated microporous polymers (CMPs) functionalized by aza-fused functionalities are still limited to solution-based procedures or ionothermal polymerizations, which requires monomers with rigid/high steric hindrance structures and multiple reactive sites and extra arene-based cross-linkers, and generated CMPs with low content of aza-fused functionalities. Herein, a facile mechanochemistry-driven procedure is developed capable of affording a series of CMPs composed of abundant aza-fused functionalities via a homocoupling process. Simple and linear aromatic bromide monomers with phenanthroline or bipyridine cores are deployed as the starting materials, which can coordinate on the metal surface to form 3D assembly and be polymerized in the presence of catalytic amount of magnesium powder driven by mechanochemical treatment under solvent- and additive-free conditions. CMPs composed of solely phenanthroline or bipyridine moieties being connected by C–C bonds are afforded with high surface areas (up to 789 m2 g-1), permanent and hierarchical porous architectures (micro- and mesopores), abundant aza-fused moieties, and π-conjugated networks. All these unique features made them promising candidates as supercapacitors, which exhibit outstanding electrocapacitive performance with a capacitance of 296 F g-1 at 0.3 A g-1 and capacitance retention of 103% for 5000 cycles at 5 A g-1.This is a manuscript of an article published as Fan, Juntian, Tao Wang, Hao Chen, Zongyu Wang, Bishnu P. Thapaliya, Takeshi Kobayashi, Yating Yuan, Ilja Popovs, Zhenzhen Yang, and Sheng Dai. "Mechanochemistry‐Driven Construction of Aza‐fused π‐Conjugated Networks Toward Enhanced Energy Storage." Advanced Functional Materials 32, no. 32 (2022): 2202669. DOI: 10.1002/adfm.202202669. Copyright 2022 Wiley-VCH GmbH. Posted with permission. DOE Contract Number(s): AC05-00OR22725; AC02-07CH11358

Construction of Fluorine- and Piperazine-Engineered Covalent Triazine Frameworks Towards Enhanced Dual-Ion Positive Electrode Performance

Organic positive electrodes featuring lightweight and tunable energy storage modes by molecular structure engineering have promising application prospects in dual-ion batteries. Herein, a series of highly porous covalent triazine frameworks (CTFs) were synthesized under ionothermal conditions using fluorinated aromatic nitrile monomers containing a piperazine ring. Fluorinated monomers can result in more defects in CTFs, leading to a higher surface area up to 2515 m2 g−1 and a higher N content of 11.34 wt % compared to the products from the non-fluorinated monomer. The high surface area and abundant redox sites of these CTFs afforded high specific capacities (up to 279 mAh g−1 at 0.1 A g−1), excellent rate performance (89 mAh g−1 at 5 A g−1), and durable cycling performance (92.3 % retention rate after 500 cycles at 2.0 A g−1) as dual-ion positive electrodes.This is a manuscript of an article published as Wang, Tao, James Anthony Gaugler, Meijia Li, Bishnu Prasad Thapaliya, Juntian Fan, Liqi Qiu, Debabrata Moitra et al. "Construction of Fluorine‐and Piperazine‐Engineered Covalent Triazine Frameworks Towards Enhanced Dual‐Ion Positive Electrode Performance." ChemSusChem 16, no. 4 (2023): e202201219. DOI: 10.1002/cssc.202201219. Copyright 2022 Wiley-VCH GmbH. Posted with permission. DOE Contract Number(s): AC02-07CH11358; AC05-00OR22725

Benchmark CO2 separation achieved by highly fluorinated nanoporous molecular sieve membranes from nonporous precursor via in situ cross-linking

Molecular sieve membranes with rigid micropores and CO2-philic functionalities within the architectures are promising candidates in CO2 separation. However, the development of effective approaches for their fabrication still remains a significant challenge. Herein, an in situ cross-linking strategy is developed for the preparation of nanoporous fluorinated molecular sieve membranes using commercially available dense and non-porous polystyrene (MPS) as a precursor template. Based on the dehydrative Friedel-Crafts reactions with highly fluorinated benzylic alcohols, MPS membranes are cross-linked in situ upon exposure to Brønsted acid (CF3SO3H), affording fluorinated microporous polymeric membranes with surface areas up to 523 m2 g−1 and the presence of micropores centered at 1.1–1.3 nm as well as ultra-micropores (~0.6 nm). The obtained modified membranes exhibit good ideal CO2 permeability of 797 barrer and CO2/N2 selectivity of 28.5. In addition, high fluorine content (up to 28.5 wt%) and good thermal stability made the cross-linked membranes promising candidates to produce fluorinated carbon molecular sieve membranes with improved textural properties, exhibiting surface areas up to 1020 m2 g−1 and ultra-micropores of ~0.4 nm. These membranes achieve superior CO2/N2 separation performances exceeding the Robeson upper bound limit (2008).This article is published as Yang, Zhenzhen, Wei Guo, Hao Chen, Takeshi Kobayashi, Xian Suo, Tao Wang, Song Wang et al. "Benchmark CO2 separation achieved by highly fluorinated nanoporous molecular sieve membranes from nonporous precursor via in situ cross-linking." Journal of Membrane Science 638 (2021): 119698. DOI: 10.1016/j.memsci.2021.119698. Copyright 2021 Published by Elsevier B.V. DOE Contract Number(s): AC05-00OR22725; AC02-07CH11358