Periodic Reporting for period 3 - TOPOCLIP (Topological Explorations with a Clip: New Molecular Nanocarbons)
Berichtszeitraum: 2023-01-01 bis 2024-06-30
The lack of synthetic control over the chirality of curved carbon nanostructures derived from graphene, such as carbon nanotubes (CNTs), prevents the development of molecular electronics applications that require high purity and uniformity of these materials. Single- and multi-walled CNTs are typically formed as a mixture of chiral, armchair, and zigzag nanostructures that significantly differ in their properties. The urgency of controlled chirality-specific synthesis of CNTs advanced the synthesis of curved molecular nanocarbons – molecular precursors for a stepwise synthesis of uniform single-walled CNTs. Applications in bioimaging, sensing, catalysis, and organic electronics have been rapidly emerging on account of the unusual properties of these hoop-like molecular nanocarbons.
Only a few examples of analogous molecular precursors for topologically more complex carbon nanostructures exist because their topologies are difficult to achieve by synthesis or they do not yet have any stable molecular representation. TOPOCLIP develops such stable molecular representations, enables their synthesis by using a molecular clip and delivers unprecedented topological molecular nanocarbons. The molecular clip helps controlling the curvature, preserves the electronic communication throughout the molecular nanocarbon structure, or allows construction of the first molecular nanocarbon with a reversible dynamic behavior. TOPOCLIP (1) improves our understanding of strain and non-covalent interactions that (de)stabilize curved nanocarbons, (2) delivers responsive nanocarbons that can alter shape with an external stimulus, and (3) establishes design principles for tailor-made molecular nanocarbons for future nano- and biotechnology applications.
Only a few examples of analogous molecular precursors for topologically more complex carbon nanostructures exist because their topologies are difficult to achieve by synthesis or they do not yet have any stable molecular representation. TOPOCLIP develops such stable molecular representations, enables their synthesis by using a molecular clip and delivers unprecedented topological molecular nanocarbons. The molecular clip helps controlling the curvature, preserves the electronic communication throughout the molecular nanocarbon structure, or allows construction of the first molecular nanocarbon with a reversible dynamic behavior. TOPOCLIP (1) improves our understanding of strain and non-covalent interactions that (de)stabilize curved nanocarbons, (2) delivers responsive nanocarbons that can alter shape with an external stimulus, and (3) establishes design principles for tailor-made molecular nanocarbons for future nano- and biotechnology applications.
The team has developed synthesis of the precursors to accomplish molecular nanocarbons with new topologies. After achieving the synthesis of the basic precursors, the synthesis of larger molecular scaffolds and the first final molecular nanocarbons has commenced. We have overcome challenges with the stability of a number of synthesized compounds that require protection. We found that the strategies to protect the crucial functional groups reported in the literature are, however, not always sufficient. Therefore, we have developed a new strategy to achieve stable precursors that can be stored for a prolonged period of time.
We successfully synthesized and characterized few molecular nanocarbons with Möbius topology of their pi-electronic system by using helicenes as the topological clip. Investigation of the compounds as the emitters of circularly polarized light revealed that different topologies lead to different handedness of the emitted light. This findings resulted to a major publication in Angewandte Chemie Internation Edition. We now continue exploring the Möbius systems further as compounds with unusual aromaticity by means of synthesis, spectroscopy, and quantum chemical calculations. Investigation of properties of spiral molecular nanocarbons by computational methods have also been accomplished. We have also successfully synthesized a model spiral nanocarbon that switches curvature upon light absorption, one of the major objectives of TOPOCLIP. Another molecular nanocarbon allowed us to experimentally examine the role of exciton delocalization in compounds that display circularly polarized luminescence. Finally, we have commenced the synthesis of double hoops and synthesized the first example, although with a simplified topological clip to test the synthetic approach proposed in the project. In the next period, we will focus our efforts to synthesize more challenging clips permitting new supramolecular systems based on topological molecular nanocarbons.
We successfully synthesized and characterized few molecular nanocarbons with Möbius topology of their pi-electronic system by using helicenes as the topological clip. Investigation of the compounds as the emitters of circularly polarized light revealed that different topologies lead to different handedness of the emitted light. This findings resulted to a major publication in Angewandte Chemie Internation Edition. We now continue exploring the Möbius systems further as compounds with unusual aromaticity by means of synthesis, spectroscopy, and quantum chemical calculations. Investigation of properties of spiral molecular nanocarbons by computational methods have also been accomplished. We have also successfully synthesized a model spiral nanocarbon that switches curvature upon light absorption, one of the major objectives of TOPOCLIP. Another molecular nanocarbon allowed us to experimentally examine the role of exciton delocalization in compounds that display circularly polarized luminescence. Finally, we have commenced the synthesis of double hoops and synthesized the first example, although with a simplified topological clip to test the synthetic approach proposed in the project. In the next period, we will focus our efforts to synthesize more challenging clips permitting new supramolecular systems based on topological molecular nanocarbons.
We reported a straightforward approach to synthesize molecular nanocarbons with a Möbius topology, synthesized new molecular nanocarbons that show circularly polarized luminescence or dynamic behavior that alters the curvature of the nanocarbon, and we developed a new strategy to stabilize important building blocks required to synthesize hoop-like molecular nancarbons.