Ju Hongyu, Wang Boyu, Li Mengmeng, Hao Jie, Si Wei, Song Shuxin, Mei Kunrong, Sue Andrew C-H, Wang Jinying, Jia Chuancheng, Guo Xuefeng
Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Microscale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300350, P. R. China.
School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P. R. China.
J Am Chem Soc. 2024 Sep 11;146(36):25290-25298. doi: 10.1021/jacs.4c09504. Epub 2024 Aug 28.
Noncovalent interactions involving aromatic rings, such as π-stacking and π-ion interactions, play an essential role in molecular recognition, assembly, catalysis, and electronics. However, the inherently weak and complex nature of these interactions has made it challenging to study them experimentally, especially with regard to elucidating their properties in solution. Herein, the noncovalent interactions between π and π-hole, π and cation, and π-hole and anion in molecular complexes in nonpolar solution are investigated in situ through single-molecule electrical measurements in combination with theoretical calculations. Specifically, phenyl and pentafluorobenzyl groups serve as π and π-hole sites, respectively, while Li and Cl are employed as the cation and anion. Our findings reveal that, in comparison with homogeneous π···π interactions, heterogeneous π···π-hole and π···cation interactions exhibit greater binding energies, resulting in a longer binding lifetime of the molecular junctions. Meanwhile, π···Li and π-hole···Cl interactions present significantly distinct binding characteristics, with the former being stronger but more flexible than the latter. Furthermore, by changing the molecular components, similar conductivity can be achieved in both molecular dimers or sandwich complexes. These results provide new insights into π- and π-hole-involved noncovalent interactions, offering novel strategies for precise manipulation of molecular assembly, recognition, and molecular device.
涉及芳环的非共价相互作用，如π-堆积和π-离子相互作用，在分子识别、组装、催化和电子学中起着至关重要的作用。然而，这些相互作用固有的弱性和复杂性使得通过实验研究它们具有挑战性，特别是在阐明它们在溶液中的性质方面。在此，通过单分子电学测量结合理论计算，原位研究了非极性溶液中分子复合物中π与π-空穴、π与阳离子以及π-空穴与阴离子之间的非共价相互作用。具体而言，苯基和五氟苄基分别作为π和π-空穴位点，而锂和氯分别用作阳离子和阴离子。我们的研究结果表明，与均匀的π···π相互作用相比，异质的π···π-空穴和π···阳离子相互作用表现出更大的结合能，导致分子结的结合寿命更长。同时，π···锂和π-空穴···氯相互作用呈现出明显不同的结合特征，前者比后者更强但更灵活。此外，通过改变分子组分，在分子二聚体或夹心复合物中都可以实现相似的导电性。这些结果为涉及π和π-空穴的非共价相互作用提供了新的见解，为精确操纵分子组装、识别和分子器件提供了新策略。
