化学学报 ›› 2022, Vol. 80 ›› Issue (8): 1061-1065.DOI: 10.6023/A22060283 上一篇    下一篇

研究通讯

巨型给-受体分子开关化合物的合成及性质研究

眭玉光, 周锦荣, 廖攀, 梁文杰, 徐海*()   

  1. 中南大学化学化工学院 长沙 410083
  • 投稿日期:2022-06-29 发布日期:2022-08-05
  • 通讯作者: 徐海
  • 基金资助:
    国家自然科学基金(21975288); 国家重点研发计划子课题(2018YFC1800401)

A Gaint Donor-Acceptor Molecular Switch Compound: Synthesis and Properties

Yuguang Sui, Jinrong Zhou, Pan Liao, Wenjie Liang, Hai Xu()   

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083
  • Received:2022-06-29 Published:2022-08-05
  • Contact: Hai Xu
  • Supported by:
    National Natural Science Foundation of China(21975288); National Key Research and Development Plan of China(2018YFC1800401)

以构象可变的间苯二酚杯[4]芳烃孔穴化合物(Cavitand)为分子开关母体, 合成了一种新颖的给-受体(D-A)型分子开关化合物(化合物1), 该分子是目前已知分子量最大的D-A型间苯二酚杯[4]芳烃Cavitand (分子量为3064.9966). 其中, 以卟啉为给体, 富勒烯为受体. 在pH诱导下, 化合物1可发生构象变化, 即由原来的关闭状(vase)转为打开状(kite); 而在降低温度和引入Zn2+的条件下, 不能促使化合物1发生构象变化. pH诱导构象发生变化的原因, 是酸的加入会导致喹喔啉手臂上的N原子发生质子化, 从而使得形成的静电排斥作用促使手臂之间相互远离. 此外, 对化合物1的光物理性质研究表明, 存在卟啉向富勒烯的单线态能量转移, 其单线态能量转移速率常数为1.1×107 s-1, 单线态能量转移效率为9.63%.

关键词: 分子开关, 给-受体, 卟啉-富勒烯, 杯[4]芳烃孔穴化合物, 能量转移

A novel donor-acceptor (D-A) molecular switch compound (compound 1) in which porphyrin is the donor and fullerene is the acceptor was synthesized using a conformationally variable resorcin[4]arene cavitand as the molecular switch parent. As far as we know, this molecule is the largest D-A resorcin[4]arene cavitand (molecular weight: 3064.9966). In order to synthesize this D-A molecular switch, firstly, compounds 4 and 9 were synthesized by Sonogashira coupling and Suzuki coupling, respectively. Then, both compounds 4 and 9 react with compound 5 to obtain arm compounds 6 and 10. Considering the low yield in the process of synthesizing porphyrins, compound 6 was first reacted with resorcin[4]arene 11 to obtain compound 12. Undoubtedly, a by-product with two compound 6 arms simultaneously will be produced. So, compound 12 can be obtained in a higher yield by adding compound 6 in batches. Then compound 13 can be obtained by the Prato reaction, and finally, compound 1 can be obtained by reacting with porphyrin arm 10. The structure of 1 was thoroughly confirmed by 1H NMR spectroscopy (nuclear magnetic resonance spectroscopy), 13C NMR spectroscopy, 2D (two-dimensional) NMR spectroscopy and HRMS (high-resolution mass spectrometry). Under pH induction, compound 1 can undergo a conformational change from the original contracted state (vase) to the expanded state (kite). However, the conformational change of 1 cannot be induced under the conditions of lowering the temperature and introducing Zn2+. The reason for the pH-induced conformational change may be that the addition of acid causes the protonation of the N atom on the quinoxaline arm, which makes the formed electrostatic repulsion push the arms away from each other. In addition, the photophysical properties of 1 were also studied. The photophysical processes were investigated with steady-state UV-visible absorption and transient fluorescence spectroscopies. Compound 1 shows efficient intramolecular singlet-singlet energy transfer from the porphyrin moiety to the fullerene moiety. The rate constants and efficiency of the singlet-singlet energy transfer are calculated at 1.1×107 s-1 and 9.63%, respectively.

Key words: molecular switch, donor-acceptor, porphyrin-fullerene, resorcin[4]arene cavitand, energy transfer