Dynamic Covalent Radical Recombination for the Assembly of Tuneable Responsive Porous Organic Cages Yannic Hartmann, Robert Oestreich, Yuki Wada, Philippe de Bary, Masaki Kawano, Christoph Janiak, Bernd M. Schmidt Angewandte Chemie International Edition, 2026 The construction of discrete organic cages via radical recombination offers a powerful yet underexplored route toward stimuli ‐responsive, C─C‐linked molecular architectures. Here, we introduce aryldicyanomethyl radical dynamic covalent chemistry as a general strategy for the controlled assembly of porous organic cages. Systematic variation of a single substituent governs both radical and σ‐bond stability as well as the resulting cage geometry, enabling precise, substituent‐dependent control over cage topology and responsiveness. A thiophenoxy‐substituted monomer S selectively affords a discrete Tri 2 dimer in 99% yield, whereas the N ‐methylaniline‐substituted analogue N forms the tetrahedral Tri 4 tetramer in 83% yield. N 4 possesses permanent porosity and pronounced selectivity for CO 2 and H 2 over CH 4 and N 2 , as confirmed by gas sorption experiments, arising from narrow pore apertures and strong host–guest interactions. Both cages display reversible mechano‐ and thermochromic behaviour. Moreover, the combination of a highly dynamic bond formation process with three‐dimensional preorganisation of the cage enables efficient self‐healing, which is markedly accelerated upon exposure to THF vapour. Collectively, these results establish radical recombination as an unexplored dynamic covalent motif for the synthesis of responsive organic cage architectures, enabling substituent‐dependent fine‐tuning of topology, stability, and material function through simple substituent modification.
Porous Organic Cages as Building Blocks for Framework Materials Marcos Martínez‐Fernández, Yannic Hartmann, Bernd M. Schmidt Angewandte Chemie International Edition, 2025 Confined nanospaces play a fundamental role in nature, inspiring synthetic analogues that emulate biological precision and efficiency. Among these, porous crystalline materials such as covalent organic frameworks (COFs), metal‐organic frameworks (MOFs), and molecular cage compounds have emerged as powerful platforms for catalysis, separation, and energy storage. Recent developments highlight the potential of porous organic cages (POCs) as modular building blocks for the construction of advanced materials. In this Minireview, their integration into extended frameworks, such as Cage‐COFs and Cage‐MOFs, is described, as they allow precise control over porosity and enhance chemical robustness. These hybrids merge the structural regularity of COFs with the discrete functionality of cages, enabling the design of lightweight, hierarchically organised materials. In addition, cage‐containing polymers and supramolecular frameworks are discussed. Collectively, these developments position POCs as versatile synthons for next‐generation porous materials, unlocking pathways toward functional, adaptive, and recyclable architectures.
Structural control of dynamic covalent cages: kinetic vs. thermodynamic assembly and PFAS removal from water Tobias Pausch, Pablo Martínez Mestre, Fabiola Zapata, Andreas Mix, Bernd M. Schmidt Chemical Science, 2025 Selective formation of low-symmetry Tri22Tri2via dynamic covalent chemistry was achieved. Solvent choice enabled kinetic or thermodynamic control, directing assembly towards Tri22Tri2 or high-symmetry Tri4Tri4 cages.
Visible-Light Switchable Rings and Chains in Dynamic Covalent Imine Chemistry Jona Voss, Yannic Hartmann, Esther Nieland, Andreas Mix, Bernd M. Schmidt Chemistry A European Journal, 2025 The self‐assembliy of red‐light switchable, functionalised ortho‐difluoroazobenzene isomers E‐/Z‐A with aliphatic diamines exhibits an alternating match/mismatch behaviour depending on the diamine's chain length. While even‐numbered diamines exclusively form imine macrocycles with the Z‐configured azobenzene isomer, odd‐numbered diamines form photoswitchable, defined macrocycles. The formation of Z,Z‐A2X2‐type macrocycles was demonstrated with butane‐1,4‐ (B) and hexane‐1,6‐diamine (H), while additionally E,E‐A2X2‐type macrocycles were obtained with propane‐1,3‐ (Pr), pentane‐1,5‐diamine (Pe), and diethylene glycol bisamine (O), validated by single‐crystal X‐ray structures of E,E‐A2Pr2 and E,E‐A2O2. The observed reactivity differences arise from the preferred conformations of the flexible diamines in solution, which alternate predictably with odd and even numbers of methylene groups, investigated by 19F‐DOSY NMR experiments, MALDI‐MS measurements, and UV/Vis spectroscopy. These findings provide detailed insight into photoresponsive self‐assembled systems and highlight the potential of azobenzenes in dynamic covalent chemistry, offering new opportunities for controlling structure and function in adaptive materials.
Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds Tobias Pausch, Samanta Clopot, Dustin N. Jordan, Oliver Weingart, Christoph Janiak, Bernd M. Schmidt Angewandte Chemie International Edition, 2024 The development of more energy‐efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy‐intensive processes. Herein, we introduce a novel class of electron‐deficient macrocycles with a unique rectangular structure to optimise interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42‐based crystalline functional material is directly obtained from the reaction mixture in a single self‐assembly step in high yields of 83 %, alongside the larger NDI2F82 congener, which can be obtained in 69 % yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97 : 3 for benzene over cyclohexane and 93 : 7 for toluene over methylcyclohexane, while single‐crystal and powder X‐ray diffraction studies indicate that the selectivity is primarily governed by directed interactions between the electron‐deficient panels and aromatic guests.
Fluorinated vs. non-fluorinated tetrahedral Tri4Tri4 porous organic cages for H2, CO2, and CH4 adsorption Tim David, Robert Oestreich, Tobias Pausch, Yuki Wada, Tom Fleck-Kunde, Masaki Kawano, Christoph Janiak, Bernd M. Schmidt Chemical Communications, 2024 The fluorinated Et4F4 and non-fluorinated Et4H4 were characterized using single-crystal X-ray diffraction and sorption studies, revealing correlations in stability, porosity, and selectivity due to structural and electronic differences.
Accessing a Diverse Set of Functional Red-Light Photoswitches by Selective Copper-Catalyzed Indigo N-Arylation Amit K. Jaiswal, Priya Saha, Julong Jiang, Kimichi Suzuki, Anna Jasny, Bernd M. Schmidt, Satoshi Maeda, Stefan Hecht, Chung-Yang Dennis Huang Journal of the American Chemical Society, 2024 The ability to correlate the structure of a molecule with its properties is the key to the rational and accelerated design of new functional compounds and materials. Taking photoswitches as an example, the thermal stability of the metastable state is a crucial property that dictates their application in molecular systems. Indigos have recently emerged as an attractive motif for designing photoswitchable molecules due to their red-light addressability, which can be advantageous in biomedical and material applications. The lack of synthetic techniques to derivatize the abundant parent dye and a thorough understanding of the impact of structural factors on the photochemical and thermal properties hinder broad applications of this emerging photoswitch class. Herein, we report an efficient copper-catalyzed indigo N-arylation that enables the installation of a wide variety of aryl moieties carrying useful functional groups. The exclusive selectivity for monoarylation likely originates from a bimetallic cooperative mechanism through a binuclear copper-indigo intermediate. Functional N-aryl-N′-alkylindigos were prepared and shown to photoisomerize efficiently under red light. Moreover, this design allows for the modulation of thermal half-lives through N-aryl substituents, while the N′-alkyl groups enable the independent attachment of functional moieties without affecting the photochromic properties. A strong correlation between the structure of the N-aryl moiety and the thermal stability of the photogenerated Z-isomers was achieved by multivariate linear regression models obtained through a data-science workflow. This work thus builds an avenue leading to versatile red-light photoswitches and a general method for structure–property correlation that is expected to be broadly applicable to the design of photoresponsive molecules.
Multifold Post-Modification of Macrocycles and Cages by Isocyanate-Induced Azadefluorination Cyclisation Tobias Pausch, Tim David, Tom Fleck‐Kunde, Hendrik Pols, Johannes Gurke, Bernd M. Schmidt Angewandte Chemie International Edition, 2024 We present the multiple post‐modification of organic macrocycles and cages, introducing functional groups into two‐ and three‐dimensional supramolecular scaffolds bearing fluorine substituents, which opens up new possibilities in multi‐step supramolecular chemistry employing the vast chemical space of readily available isocyanates. The mechanism and scope of the reaction that proceeds after isocyanate addition to the benzylamine motif via an azadefluorination cyclisation (ADFC) were investigated using DFT calculations, and a series of aromatic isocyanates with different electronic properties were tested. The compounds show excellent chemical stability and were fully characterised. They can be used for subsequent cross‐coupling reactions, and ADFC can be used directly to generate cross‐linked membranes from macrocycles or cages when using ditopic isocyanates. Single‐crystal X‐ray (SC‐XRD) analysis shows the proof of the formation of the desired supramolecular entity together with the connectivity predicted by calculations and from 19F NMR shifts, allowing the late‐stage functionalisation of self‐assembled macrocycles and cages by ADFC.
Supramolecular networks by imine halogen bonding Esther Nieland, Daniel Komisarek, Stephan Hohloch, Klaus Wurst, Vera Vasylyeva, Oliver Weingart, Bernd M. Schmidt Chemical Communications, 2022
Optically switchable organic light-emitting transistors Lili Hou, Xiaoyan Zhang, Giovanni F. Cotella, Giuseppe Carnicella, Martin Herder, Bernd M. Schmidt, Michael Pätzel, Stefan Hecht, Franco Cacialli, Paolo Samorì Nature Nanotechnology, 2019
