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Functionally rigid and degenerate molecular shuttles

หน่วยงาน Nanyang Technological University, Singapore

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ชื่อเรื่อง : Functionally rigid and degenerate molecular shuttles
นักวิจัย : Yoon, Il. , Benítez, Diego , Zhao, Yanli , Miljanić, Ognjen Š. , Kim, Soo Young , Tkatchouk, Ekaterina , Leung, Ken C. F. , Khan, Saeed I. , Goddard III, William A. , Stoddart, J. Fraser
คำค้น : DRNTU::Science::Chemistry::Organic chemistry.
หน่วยงาน : Nanyang Technological University, Singapore
ผู้ร่วมงาน : -
ปีพิมพ์ : 2552
อ้างอิง : Yoon, II, Benítez, D., Zhao, Y. L., Miljanić, O. Š., Kim, S. Y., Tkatchouk, E., et al. (2009). Functionally Rigid and Degenerate Molecular Shuttles. Chemistry - a European Journal, 15, 1115-1122. , 1521-3765 , http://hdl.handle.net/10220/6949 , http://dx.doi.org/10.1002/chem.200802096 , 159745
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : Chemistry - a European journal
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

The preparation and dynamic behavior of two functionally rigid and degenerate [2]rotaxanes (1⋅4 PF6 and 2⋅4 PF6) in which a π-electron deficient tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (CBPQT4+) ring, shuttles back and forth between two π-electron-rich naphthalene (NP) stations by making the passage along an ethynyl-phenylene-(PH)-ethynyl or butadiyne rod, are described. The [2]rotaxanes were synthesized by using the clipping approach to template-directed synthesis, and were characterized by NMR spectroscopic and mass spectrometric analyses. 1H NMR spectra of both [2]rotaxanes show evidence for the formation of mechanically interlocked structures, resulting in the upfield shifts of the resonances for key protons on the dumbbell-shaped components. In particular, the signals for the peri protons on the NP units in the dumbbell-shaped components experienced significant upfield shifts at low temperatures, just as has been observed in the flexible [2]rotaxanes. Interestingly, the resonances for the same protons did not exhibit a significant upfield shift at 298 K, but rather only a modest shift. This phenomenon arises from the much reduced binding of the ethynyl-NP unit compared to the 1,5-dioxy-NP unit. This effect, in turn, increases the shuttling rate when compared to the 1,5-dioxy-NP-based rotaxane systems investigated previously. The kinetic and thermodynamic data of the shuttling behavior of the CBPQT4+ ring between the NP units were obtained by variable-temperature NMR spectroscopy and using the coalescence method to calculate the free energies of activation (ΔGc≠) of 9.6 and 10.3 kcal mol−1 for 1⋅4 PF6 and 2⋅4 PF6, respectively, probed by using the rotaxane's α-bipyridinium protons.

บรรณานุกรม :
Yoon, Il. , Benítez, Diego , Zhao, Yanli , Miljanić, Ognjen Š. , Kim, Soo Young , Tkatchouk, Ekaterina , Leung, Ken C. F. , Khan, Saeed I. , Goddard III, William A. , Stoddart, J. Fraser . (2552). Functionally rigid and degenerate molecular shuttles.
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Yoon, Il. , Benítez, Diego , Zhao, Yanli , Miljanić, Ognjen Š. , Kim, Soo Young , Tkatchouk, Ekaterina , Leung, Ken C. F. , Khan, Saeed I. , Goddard III, William A. , Stoddart, J. Fraser . 2552. "Functionally rigid and degenerate molecular shuttles".
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Yoon, Il. , Benítez, Diego , Zhao, Yanli , Miljanić, Ognjen Š. , Kim, Soo Young , Tkatchouk, Ekaterina , Leung, Ken C. F. , Khan, Saeed I. , Goddard III, William A. , Stoddart, J. Fraser . "Functionally rigid and degenerate molecular shuttles."
    กรุงเทพมหานคร : Nanyang Technological University, Singapore, 2552. Print.
Yoon, Il. , Benítez, Diego , Zhao, Yanli , Miljanić, Ognjen Š. , Kim, Soo Young , Tkatchouk, Ekaterina , Leung, Ken C. F. , Khan, Saeed I. , Goddard III, William A. , Stoddart, J. Fraser . Functionally rigid and degenerate molecular shuttles. กรุงเทพมหานคร : Nanyang Technological University, Singapore; 2552.