Edited by: De-Xian Wang, Institute of Chemistry (CAS), China
Reviewed by: Xiao-Yu Hu, Nanjing University of Aeronautics and Astronautics, China; Tangxin Xiao, Changzhou University, China; Haibo Yang, East China Normal University, China
This article was submitted to Supramolecular Chemistry, a section of the journal Frontiers in Chemistry
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Pillar[
Mechanically interlocked molecules (MIMs) are a type of “star” molecule due to their beautiful and interesting architectures and wide applications in the area of biology and nanoscience (Bissell et al.,
Pillar[
Herein, we designed and synthesized a series of pillar[5]arene-based [1]rotaxanes with
Based on previous work (Han et al.,
Synthetic route to a series of pillar[5]arene based [1]rotaxanes.
Yellow solid, 78.6%, m.p. 106.9-108.5°C; 1H NMR (400 MHz, CDCl3) δ: 7.05–6.89 (m, 7 H, ArH), 6.84 (d,
Yellow solid, 42.9%, m.p. 107.4-109.2°C; 1H NMR (400 MHz, CDCl3) δ 7.02–6.76 (m, 10 H, ArH), 5.67 (s, 1 H, NH), 5.26 (s, 1 H, NH), 4.75 (s, 2 H, CH2), 4.59 (s, 2 H, ArH), 4.40 (s, 2 H, ArH), 4.24 (d,
Yellow solid, 38.9%, m.p. 109.9-112.1°C; 1H NMR (400 MHz, CDCl3) δ: 6.98–6.70 (m, 10 H, ArH), 5.85 (s, 1 H, NH), 5.18 (s, 1 H, NH), 4.72 (s, 2 H, CH2), 4.58 (s, 2 H, ArH), 4.39 (s, 2 H, ArH), 4.24 (s, 5 H, ArH), 4.00–3.59 (m, 36 H, 24 OCH3, 12 CH2), 3.42 (s, 2 H, CH2), 3.29 (s, 2 H, CH2), 1.86–1.79 (m, 2 H, CH2), 1.60 (q,
Yellow solid, 25.9%, m.p. 114.6-116.8°C; 1H NMR (400 MHz, CDCl3) δ 6.95–6.80 (m, 9H, ArH), 6.71 (s, 1H, ArH), 5.23 (s, 1H, NH), 5.02 (s, 1H, NH), 4.68 (t,
Yellow solid, 78.6%, m.p. 104.4–106.2°C; 1H NMR (400 MHz, CDCl3) (
Yellow solid, 71.9 %, m.p. 105.6-107.3°C;1H NMR (400 MHz, CDCl3) (
Synthetic route to monomer
All reactions were performed in atmosphere unless noted. All reagents were commercially available and used as supplied without further purification. NMR spectra were collected on either a Bruker AVIII-400 MHz spectrometer or a Bruker AV-600 MHz spectrometer with internal standard tetramethylsilane (TMS) and signals as internal references, and the chemical shifts (δ) were expressed in ppm. High-resolution Mass (ESI) spectra were obtained with a Bruker Micro-TOF spectrometer. X-ray data were collected on a Bruker Smart APEX-2 CCD diffractometer.
The 1H NMR spectra of
1H NMR spectra (400 MHz, 298K) of:
The formation of [1]rotaxane was then confirmed by 2D Nuclear Overhauser Effect Spectroscopy (NOESY). Here we also take
Partial 2D NOESY spectrum of a choroform-d solution of
The direct evidence for the formation of [1] rotaxanes only when the length of axle longer than three CH2 groups is from single crystal investigation. As shown in
X-ray single-crystal structure of:
With the [1]rotaxanes in hand, we then investigated their reversible redox property by electrochemistry methods. Take
Cyclic voltammogram (scan rate = 100 mV s−1) of the
In this paper, we synthesized a series of amide-linked pillar[5]arene-based [1]rotaxanes with ferrocene unit as the stopper. Under the catalysis of HOBT/EDCL, the mono-amido-functionalized pillar[5]arenes were amidated with ferrocene carboxylic acid, to constructed ferrocene-based [1]rotaxanes, respectively. The structure of the [1]rotaxanes were characterized by 1H NMR, 13C NMR, 2D NMR, mass spectroscopy and single-crystal X-ray structural determination. In the formation of [1]rotaxane, the key role is the length of the alkyl chain in this process, and only when the number of C on the alkyl chain is larger than three can the formation of [1]rotaxane occur. In addition, due to the ferrocene units, the pillar[5]arene-based [1]rotaxanes display electrochemically reversible properties. Based on this nature, we hope these pillar[5]arene-based [1]rotaxanes can be applied in battery devices in future.
The raw data supporting the conclusions of this manuscript will be made available by the authors, without undue reservation, to any qualified researcher.
RZ prepared all the pillar[5]arene-based [1]rotaxanes. CW and RL prepared the monomer M3. TC and CY analyzed the data. YY analyzed the data and wrote the paper.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This work was supported by the National Natural Science Foundation of China (21801139), Natural Science Foundation of Jiangsu Province (BK20180942), the Natural Science Foundation of Nantong University for High-Level Talent (03083004), and the Large Instruments Open Foundation of Nantong University (KFJN1814).
The Supplementary Material for this article can be found online at: