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Wang ST, Liu XY, Li QH, Fang WH, Zhang J, Chen SM. Aluminum Molecular Ring Meets Deep Eutectic Solvents: Adaptive Assembly and Optical Behavior. Inorg Chem 2024; 63:12100-12108. [PMID: 38896443 DOI: 10.1021/acs.inorgchem.4c01090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Different from the previous neutral reaction solvent system, this work explores the synthesis of Al-oxo rings in ionic environments. Deep eutectic solvents (DESs) formed by quaternary ammonium salts hydrogen bond acceptor (HBA) and phenols hydrogen bond donor (HBD) further reduce the melting point of the reaction system and provide an ionic environment. Further, the quaternary ammonium salt was chosen as the HBA because it contains a halogen anion that matches the size of the central cavity of the molecular ring. Based on this thought, five Al8 ion pair cocrystals were synthesized via "DES thermal". The general formula is Q+ ⊂ {Cl@[Al8(BD)8(μ2-OH)4L12]} (AlOC-180-AlOC-185, Q+ = tetrabutylammonium, tetrapropylammonium, 1-butyl-3-methylimidazole; HBD = phenol, p-chlorophenol, p-fluorophenol; HL = benzoic acid, 1-naphthoic acid, 1-pyrenecarboxylic acid, anthracene-9-carboxylic acid). Structural studies reveal that the phenol-coordinated Al molecular ring and the quaternary ammonium ion pair form the cocrystal compounds. The halogen anions in the DES component are confined in the center of the molecular ring, and the quaternary ammonium cations are located in the organic shell. Such an adaptive cocrystal binding pattern is particularly evident in the structures coordinated with low-symmetry ligands such as naphthoic acid and pyrene acid. Finally, the optical behavior of these cocrystal compounds is understood from the analysis of crystal structure and theoretical calculation.
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Affiliation(s)
- San-Tai Wang
- College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of Chinese Academy of Sciences, No.155 Yangqiao West Road, Fuzhou, Fujian 350002, China
| | - Xi-Yan Liu
- College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of Chinese Academy of Sciences, No.155 Yangqiao West Road, Fuzhou, Fujian 350002, China
| | - Qiao-Hong Li
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of Chinese Academy of Sciences, No.155 Yangqiao West Road, Fuzhou, Fujian 350002, China
| | - Wei-Hui Fang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of Chinese Academy of Sciences, No.155 Yangqiao West Road, Fuzhou, Fujian 350002, China
| | - Jian Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of Chinese Academy of Sciences, No.155 Yangqiao West Road, Fuzhou, Fujian 350002, China
| | - Shu-Mei Chen
- College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China
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Azbell TJ, Milner PJ. Cobalt(III) Halide Metal-Organic Frameworks Drive Catalytic Halogen Exchange. J Am Chem Soc 2024. [PMID: 38607314 DOI: 10.1021/jacs.3c13872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
The selective halogenation of complex (hetero)aromatic systems is a critical yet challenging transformation that is relevant to medicinal chemistry, agriculture, and biomedical imaging. However, current methods are limited by toxic reagents, expensive homogeneous second- and third-row transition metal catalysts, or poor substrate tolerance. Herein, we demonstrate that porous metal-organic frameworks (MOFs) containing terminal Co(III) halide sites represent a rare and general class of heterogeneous catalysts for the controlled installation of chlorine and fluorine centers into electron-deficient (hetero)aryl bromides using simple metal halide salts. Mechanistic studies support that these halogen exchange (halex) reactions proceed via redox-neutral nucleophilic aromatic substitution (SNAr) at the Co(III) sites. The MOF-based halex catalysts are recyclable, enable green halogenation with minimal waste generation, and facilitate halex in a continuous flow. Our findings represent the first example of SNAr catalysis using MOFs, expanding the lexicon of synthetic transformations enabled by these materials.
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Affiliation(s)
- Tyler J Azbell
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Phillip J Milner
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
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Azbell TJ, Pitt TA, Jerozal RT, Mandel RM, Milner PJ. Simplifying the Synthesis of Metal-Organic Frameworks. ACCOUNTS OF MATERIALS RESEARCH 2023; 4:867-878. [PMID: 38226178 PMCID: PMC10788152 DOI: 10.1021/accountsmr.3c00121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
Metal-organic frameworks (MOFs) are porous, crystalline materials constructed from organic linkers and inorganic nodes that have attracted widespread interest due to their permanent porosity and highly modular structures. However, the large volumes of organic solvents and additives, long reaction times, and specialized equipment typically required to synthesize MOFs hinder their widespread adoption in both academia and industry. Recently, our lab has developed several user-friendly methods for the gram-scale (1-100 g) preparation of MOFs. Herein, we summarize our progress in the development of high-concentration solvothermal, mechanochemical, and ionothermal syntheses of MOFs, as well as in minimizing the amount of modulators required to prepare highly crystalline Zr-MOFs. To begin, we detail our work elucidating key features of acid modulation in Zr-MOFs to improve upon current dilute solvothermal syntheses. Choosing an optimal modulator maximizes the crystallinity and porosity of Zr-MOFs while minimizing the quantity of modulator needed, reducing the waste associated with MOF synthesis. By evaluating a range of modulators, we identify the pKa, size, and structural similarity of the modulator to the linker as controlling factors in modulating ability. In the following section, we describe two high-concentration solvothermal methods for the synthesis of Zr-MOFs and demonstrate their generality among a range of frameworks. We also target the M2(dobdc) (M = Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd; dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate) family of MOFs for high-concentration synthesis and introduce a two-step preparation of several variants that proceeds through a novel kinetic phase. The high-concentration methods we discuss produce MOFs on multi-gram scale with comparable properties to those prepared under traditional dilute solvothermal conditions. Next, to further curtail solvent waste and accelerate reaction times, we discuss the mechanochemical preparation of M2(dobdc) MOFs utilizing liquid amine additives in a planetary ball mill, which we also apply to the synthesis of two related salicylate frameworks. These samples exhibit comparable porosities to traditional dilute solvothermal samples but can be synthesized in just minutes, as opposed to days, and require under 1 mL of liquid additive to prepare ~0.5 g of material. In the following section, we discuss our efforts to avoid specialized equipment and eliminate solvent use entirely by employing ionothermal conditions to prepare a variety of azolate- and salicylate-based MOFs. Simply combining metal chloride (hydrate) salts with organic linkers at temperatures above the melting points of the salts affords high-quality framework materials. Further, ionothermal conditions enable the syntheses of two new Fe(III) M2(dobdc) derivatives that cannot be synthesized under normal solvothermal conditions. Last, as a demonstrative example, we discuss our efforts to synthesize 100 g of high-quality Mg2(dobdc) in a single batch using a high-concentration (1.0 M) hydrothermal synthesis. Our Account will be of significant interest to researchers aiming to prepare gram-scale quantities of MOFs for further study.
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Affiliation(s)
- Tyler J Azbell
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, United States
| | - Tristan A Pitt
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, United States
| | - Ronald T Jerozal
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, United States
| | - Ruth M Mandel
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, United States
| | - Phillip J Milner
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, United States
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Ahmad BIZ, Keasler KT, Stacy EE, Meng S, Hicks TJ, Milner PJ. MOFganic Chemistry: Challenges and Opportunities for Metal-Organic Frameworks in Synthetic Organic Chemistry. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:4883-4896. [PMID: 38222037 PMCID: PMC10785605 DOI: 10.1021/acs.chemmater.3c00741] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Metal-organic frameworks (MOFs) are porous, crystalline solids constructed from organic linkers and inorganic nodes that have been widely studied for applications in gas storage, chemical separations, and drug delivery. Owing to their highly modular structures and tunable pore environments, we propose that MOFs have significant untapped potential as catalysts and reagents relevant to the synthesis of next-generation therapeutics. Herein, we outline the properties of MOFs that make them promising for applications in synthetic organic chemistry, including new reactivity and selectivity, enhanced robustness, and user-friendly preparation. In addition, we outline the challenges facing the field and propose new directions to maximize the utility of MOFs for drug synthesis. This perspective aims to bring together the organic and MOF communities to develop new heterogeneous platforms capable of achieving synthetic transformations that cannot be replicated by homogeneous systems.
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Affiliation(s)
- Bayu I. Z. Ahmad
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
| | - Kaitlyn T. Keasler
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
| | - Emily E. Stacy
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
| | - Sijing Meng
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
| | - Thomas J. Hicks
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
| | - Phillip J. Milner
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, United States
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