Fluorinated porous organic cages - Syntheses, Properties and Functionalization

• Applicant: Dr. Bernd M. Schmidt
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2021 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 457772810

• Final Report Year: 2024

Final Report Abstract

The presented research project aimed to specifically develop new supramolecular, metal-free cage-like compounds that could serve as functional materials in the future. Error-correcting supramolecular systems were used to synthesize complex organic cages in a single reaction step through dynamic covalent chemistry (DCC) from organic amines and aldehydes. For this purpose, partially and highly fluorinated aromatic building blocks were used, offering two main advantages: firstly, fluorinated building blocks can achieve new material properties such as increased stability, selectivity, and sensitivity in gas adsorption applications. Various electron-rich amines were combined with partially and highly fluorinated aromatic aldehydes to produce a variety of [2+3] and [4+6] imine cages, contributing to the exploration of structure-property relationships of these compounds. In addition to synthesizing a highly fluorinated macrocycle, which forms helical, one-dimensional pores in the solid state due to steric effects, a novel COF (Covalent Organic Framework) was obtained by collaborative work within the department using the same highly-fluorinated building block. Planned self-sorting experiments for larger cages showed no self-sorting phenomena but rather the formation of statistical mixtures, which appeared as inseparable cage alloys. Despite the lack of porosity in the cages, the investigation of gas uptake depending on the degree of fluorination was still pursued, particularly with a larger aromatic panel and its perhydrogenated congener. Initial results include a crystal structure and gas adsorption measurements in an international collaboration with groups from England and Japan. The second part of this research work allows the unusual reactivity of the fluorinated building blocks to selectively post-functionalize macrocycles and cage compounds. While iminebased DCC cages are stable only under certain conditions, hydrogenation to the corresponding amine can produce a "locked" cage, whose intrinsic pore collapses in most known cases due to the increased flexibility of the amines. As part of the now completed project, a new reaction with iso(thio)cyanates was introduced, which allows flexible functionalization of the locked cages as well as the expansion and adjustment of pore size by introducing a variety of possible aromatic substituents through multiple aza-defluorination cyclizations on the selfassembled structures.

Publications

• Highly Fluorinated Trianglimine Macrocycles: A Supramolecular Organic Framework. Synlett, 33(02), 161-165.
  Kunde, Tom; Pausch, Tobias; Schmidt, Bernd M. & Reiss, Guido J.
  
• Porous Organic Compounds – Small Pores on the Rise. European Journal of Organic Chemistry, 2021(43), 5844-5856.
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• Supramolecular Alloys from Fluorinated Hybrid Tri 4 Di 6 Imine Cages. Chemistry – A European Journal, 27(33), 8457-8460.
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• „Fluorinated Building Blocks For Porous Organic Compound Self-Assembly”, International Symposium on Macrocyclic and Supramolecular Chemistry ISMSC 2021, Webkonferenz, Juli 2021, Oregon (USA), Webkonferenz [Poster].
  Kunde, Tom & Schmidt, Bernd M.
  
• „Fluorinated Porous Imine Cages”, Chemiedozententagung 2021, März 2021, Webkonferenz, Rostock (Germany) [Vortrag].
  Schmidt, Bernd M.
  
• „Fluorinated Porous Imine Cages”, The 101st Annual Meeting of The Chemical Society of Japan, März 2021, Webkonferenz [Vortrag].
  Schmidt, Bernd M.
  
• „Fluorinated Porous Organic Cage Compounds”, Wiley’s Virtual Edition of the 2020 Young Investigator Workshop, Dezember 2021, Webkonferenz [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Fluorinated Porous Organic Cage Compounds”, XII Young Investigator Workshop 2020 – EuChemS Division of Organic Chemistry, November 2021, Barcelona (Spanien) [eingeladener Vortrag].
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• Observation of Rare Tri6Di9 Imine Cages Using Highly Fluorinated Building Blocks. Organic Materials, 4(04), 255-260.
  Fleck-Kunde, Tom; Wolpert, Emma H.; zur Horst, Laura; Oestreich, Robert; Janiak, Christoph; Jelfs, Kim E. & Schmidt, Bernd M.
  
• Synthesis and Characterization of a Crystalline Imine-Based Covalent Organic Framework with Triazine Node and Biphenyl Linker and Its Fluorinated Derivate for CO2/CH4 Separation. Materials, 15(8), 2807.
  Bügel, Stefanie; Hähnel, Malte; Kunde, Tom; de Sousa, Amadeu Nader; Sun, Yangyang; Spieß, Alex; Beglau, Thi Hai Yen; Schmidt, Bernd M. & Janiak, Christoph
  
• „Cage Fighter Fluorine Edition“, Suprachem 2022, Juni 2022, Mainz (Deutschland) [Poster].
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• „Fluorinated Porous Organic Cages and Macrocycles“, 20th European Symposium on Fluorine Chemistry, August 2022, Berlin (Deutschland) [Vortrag].
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• „Fluorinated Porous Organic Cages and Macrocycles“, Suprachem 2022, Juni 2022, Mainz (Deutschland) [Vortrag].
  Kunde, Tom; Pausch, Tobias & Schmidt, Bernd M.
  
• „Metal-containing and Metal-free Functional Supramolecular Systems”, AC/OC Colloquium of the Technical University of Dortmund, Mai 2022, Dortmund (Deutschland) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Fluorinated Porous Organic Cage Compounds“, Tokyo Institute of Technology Okayama Campus, Januar 2023, Tokyo (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Functional Supramolecular Systems”, ICReDD Hokkaido University, Januar 2023, Sapporo (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Mechanochemical Release by Ultrasound of Non-Covalently Bound Guests from a Supramolecular Cage”, Kyoto University, Januar 2023, Kyoto (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Mechanoresponsive Metal-Organic Cages & Fluorinated Porous Organic Cage Compounds“, Osaka University, Januar 2023, Osaka (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Mechanoresponsive Metal-Organic Cages & Fluorinated Porous Organic Cage Compounds“, The University of Tokyo, Januar 2023, Tokyo (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• „Mechanoresponsive Metal-Organic Cages & Fluorinated Porous Organic Cage Compounds“, Tokyo Institute of Technology Suzukakedai Campus, Februar 2023, Tokyo (Japan) [eingeladener Vortrag].
  Schmidt, Bernd M.
  
• Mehrfache Postmodifizierung von Makrozyklen und Käfigen durch Isocyanat‐induzierte Azadefluorierungszyklisierung. Angewandte Chemie, 136(15).
  Pausch, Tobias; David, Tim; Fleck‐Kunde, Tom; Pols, Hendrik; Gurke, Johannes & Schmidt, Bernd M.
  
• „Fluorinated Cages and Postmodification Thereof“, Suprachem 2024, Februar 2024, Ulm (Deutschland) [Poster].
  Pausch, Tobias; David, Tim; Fleck-Kunde, Tom; Pols, Hendrik; Gurke, Johannes & Schmidt, Bernd M.