Unveiling size-selective host-guest interaction of photoresponsive nanorings with carbon nanotubes and fullerenes
Abstract The intricate host-guest chemistry of π-conjugated nanorings, such as [6]Cycloparaphenyleneacetylenes ([6]CPPAs) and [6]Cycloparaphenylenediazenes ([6]CPPDs), has emerged as a focal point in the study of advanced materials due to their versatile applications in molecular electronics, chirop...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-08-01
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| Series: | Scientific Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-025-14535-6 |
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| Summary: | Abstract The intricate host-guest chemistry of π-conjugated nanorings, such as [6]Cycloparaphenyleneacetylenes ([6]CPPAs) and [6]Cycloparaphenylenediazenes ([6]CPPDs), has emerged as a focal point in the study of advanced materials due to their versatile applications in molecular electronics, chiroptical switches, and energy storage. This research presents a novel theoretical framework for understanding the size-selective supramolecular interactions between the nanorings and a range of guest molecules, including armchair-type carbon nanotubes [(3,3), (4,4), (5,5)] and fullerenes (C60 and C70). Utilizing the density functional theory (DFT), i.e., M06-2X/6-31G(d) level with Grimme’s dispersion correction, we evaluate interaction energies, binding constants (Ka), electrostatic potentials, frontier molecular orbitals, and the nature of non-covalent interactions within these complexes. Our results reveal a nuanced picture of host-guest compatibility, where the (4,4) armchair-type nanotube is more suitably accommodated within the photoresponsive [6]CPPDs nanoring, compared to its (3,3) and (5,5) counterparts. Conversely, the (5,5) nanotube exhibits the most robust encapsulation within the [6]CPPAs nanoring. Regarding fullerene interactions, C70 demonstrates a stronger binding affinity than C60 when encapsulated within [6]CPPAs, consistent with previous computational studies. The calculated Gibbs free energies for the host-guest complexes reveal a delicate balance of forces at play, with [6]CPPAs yielding values of 14, 27, 37, 20, and 25 kcal/mol for the (3,3), (4,4), (5,5) nanotubes, C60, and C70, respectively. Similarly, the corresponding energies for [6]CPPDs are 23, 39, 15, 18, and 19 kcal/mol. These interaction energies suggest that complexes are highly dependent on the specific structural configuration of the host and guest molecules. Anomalies in the thermodynamic parameters, particularly in the interaction of (5,5) and C60 with [6]CPPDs, led to the development of two novel models: the hand-lever and ball-in-a-bowl models. These configurations, designed to explore elevated interaction scenarios, provide deeper insight into the binding mechanisms. The photoresponsivity of [6]CPPDs, particularly in complexes involving the (5,5) nanotube, was found to be superior to that of [6]CPPAs, with a notably narrow band gap of 2.99 eV. Our results establish a foundation for further innovation and exploration in the field, paving the way for creating new and enhanced materials for various applications. |
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| ISSN: | 2045-2322 |