Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes
Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging because they can be either donor–acceptor interactions or radical pairing interactions, depending on the charge states and multiplicities in the different components of the MIMs. In this work, for the fi...
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MDPI AG
2023-02-01
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| author | Wei Wang Wei Wu Peifeng Su |
| author_facet | Wei Wang Wei Wu Peifeng Su |
| author_sort | Wei Wang |
| collection | DOAJ |
| description | Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging because they can be either donor–acceptor interactions or radical pairing interactions, depending on the charge states and multiplicities in the different components of the MIMs. In this work, for the first time, the interactions between cyclobis(paraquat-p-phenylene) (abbreviated as CBPQT<sup>n+</sup> (<i>n</i> = 0–4)) and a series of recognition units (RUs) were investigated using the energy decomposition analysis approach (EDA). These RUs include bipyridinium radical cation (BIPY<sup>•+</sup>), naphthalene-1,8:4,5-bis(dicarboximide) radical anion (NDI<sup>•−</sup>), their oxidized states (BIPY<sup>2+</sup> and NDI), neutral electron-rich tetrathiafulvalene (TTF) and neutral bis-dithiazolyl radical (BTA<sup>•</sup>). The results of generalized Kohn–Sham energy decomposition analysis (GKS-EDA) reveal that for the CBPQT<sup>n+</sup>···RU interactions, correlation/dispersion terms always have large contributions, while electrostatic and desolvation terms are sensitive to the variation in charge states in CBPQT<sup>n+</sup> and RU. For all the CBPQT<sup>n+</sup>···RU interactions, desolvation terms always tend to overcome the repulsive electrostatic interactions between the CBPQT cation and RU cation. Electrostatic interaction is important when RU has the negative charge. Moreover, the different physical origins of donor–acceptor interactions and radical pairing interactions are compared and discussed. Compared to donor–acceptor interactions, in radical pairing interactions, the polarization term is always small, while the correlation/dispersion term is important. With regard to donor–acceptor interactions, in some cases, polarization terms could be quite large due to the electron transfer between the CBPQT ring and RU, which responds to the large geometrical relaxation of the whole systems. |
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| spelling | doaj.art-f60261b2e51b4820a149d6c0134e5f612023-11-17T08:11:27ZengMDPI AGMolecules1420-30492023-02-01285205710.3390/molecules28052057Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion ComplexesWei Wang0Wei Wu1Peifeng Su2Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, The State Key Laboratory of Physical Chemistry of Solid Surfaces, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, ChinaFujian Provincial Key Laboratory of Theoretical and Computational Chemistry, The State Key Laboratory of Physical Chemistry of Solid Surfaces, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, ChinaFujian Provincial Key Laboratory of Theoretical and Computational Chemistry, The State Key Laboratory of Physical Chemistry of Solid Surfaces, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, ChinaUnderstanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging because they can be either donor–acceptor interactions or radical pairing interactions, depending on the charge states and multiplicities in the different components of the MIMs. In this work, for the first time, the interactions between cyclobis(paraquat-p-phenylene) (abbreviated as CBPQT<sup>n+</sup> (<i>n</i> = 0–4)) and a series of recognition units (RUs) were investigated using the energy decomposition analysis approach (EDA). These RUs include bipyridinium radical cation (BIPY<sup>•+</sup>), naphthalene-1,8:4,5-bis(dicarboximide) radical anion (NDI<sup>•−</sup>), their oxidized states (BIPY<sup>2+</sup> and NDI), neutral electron-rich tetrathiafulvalene (TTF) and neutral bis-dithiazolyl radical (BTA<sup>•</sup>). The results of generalized Kohn–Sham energy decomposition analysis (GKS-EDA) reveal that for the CBPQT<sup>n+</sup>···RU interactions, correlation/dispersion terms always have large contributions, while electrostatic and desolvation terms are sensitive to the variation in charge states in CBPQT<sup>n+</sup> and RU. For all the CBPQT<sup>n+</sup>···RU interactions, desolvation terms always tend to overcome the repulsive electrostatic interactions between the CBPQT cation and RU cation. Electrostatic interaction is important when RU has the negative charge. Moreover, the different physical origins of donor–acceptor interactions and radical pairing interactions are compared and discussed. Compared to donor–acceptor interactions, in radical pairing interactions, the polarization term is always small, while the correlation/dispersion term is important. With regard to donor–acceptor interactions, in some cases, polarization terms could be quite large due to the electron transfer between the CBPQT ring and RU, which responds to the large geometrical relaxation of the whole systems.https://www.mdpi.com/1420-3049/28/5/2057radical pairing interactionsdonor–acceptor interactionsmechanically interlocked moleculesenergy decomposition analysis |
| spellingShingle | Wei Wang Wei Wu Peifeng Su Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes Molecules radical pairing interactions donor–acceptor interactions mechanically interlocked molecules energy decomposition analysis |
| title | Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes |
| title_full | Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes |
| title_fullStr | Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes |
| title_full_unstemmed | Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes |
| title_short | Radical Pairing Interactions and Donor–Acceptor Interactions in Cyclobis(paraquat-p-phenylene) Inclusion Complexes |
| title_sort | radical pairing interactions and donor acceptor interactions in cyclobis paraquat p phenylene inclusion complexes |
| topic | radical pairing interactions donor–acceptor interactions mechanically interlocked molecules energy decomposition analysis |
| url | https://www.mdpi.com/1420-3049/28/5/2057 |
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