Institute of Macromolecular Chemistry AS CR, v. v. i., Heyrovského Square 2, 162 06 Prague, Czech Republic.
J Phys Chem B. 2011 Jun 16;115(23):7578-87. doi: 10.1021/jp203221k. Epub 2011 May 18.
Using (1)H, (13)C, and (133)Cs NMR spectra, it is shown that calix[4]arene-bis(t-octylbenzo-18-crown-6) (L) forms complexes with one (L·Cs(+)) and two (L·2Cs(+)) Cs(+) ions offered by cesium bis(1,2-dicarbollide) cobaltate (CsDCC) in nitrobenzene-d(5). The ions interact with all six oxygen atoms in the crown-ether ring and the π electrons of the calixarene aromatic moieties. According to extraction technique, the stability constant of the first complex is log β(nb)(L·Cs(+)) = 8.8 ± 0.1. According to (133)Cs NMR spectra, the value of the equilibrium constant of the second complex is log K(nb)((2))(L·2Cs(+)) = 6.3 ± 0.2, i.e., its stabilization constant is log β(nb)(L·2Cs(+)) = 15.1 ± 0.3. Self-diffusion measurements by (1)H pulsed-field gradient (PFG) NMR combined with density functional theory (DFT) calculations suggest that one DCC(–) ion is tightly associated with L·Cs(+), decreasing its positive charge and consequently stabilizing the second complex, L·2Cs(+). Using a saturation-transfer (133)Cs NMR technique, the correlation times τ(ex) of chemical exchange between L·Cs(+) and L·2Cs(+) as well as between L·2Cs(+) and free Cs(+) ions were determined as 33.6 and 29.2 ms, respectively.
利用 (1)H、(13)C 和 (133)Cs NMR 谱，证明杯[4]芳烃-双（叔辛基苯并-18-冠-6）（L）与铯双（1,2-二羧酸根合钴酸根）（CsDCC）在硝基苯-d(5)中形成与一个（L·Cs(+)）和两个（L·2Cs(+)）铯（+)离子的配合物。这些离子与冠醚环中的所有六个氧原子和杯芳烃芳香部分的π电子相互作用。根据萃取技术，第一个配合物的稳定常数为 log β(nb)(L·Cs(+)) = 8.8 ± 0.1。根据 (133)Cs NMR 谱，第二个配合物的平衡常数的数值为 log K(nb)((2))(L·2Cs(+)) = 6.3 ± 0.2，即其稳定常数为 log β(nb)(L·2Cs(+)) = 15.1 ± 0.3。通过 (1)H 脉冲场梯度（PFG）NMR 与密度泛函理论（DFT）计算相结合的自扩散测量表明，一个 DCC(–)离子与 L·Cs(+)紧密结合，降低了其正电荷，从而稳定了第二个配合物 L·2Cs(+)。利用饱和转移（133)Cs NMR 技术，确定了 L·Cs(+)与 L·2Cs(+)之间以及 L·2Cs(+)与游离 Cs(+)离子之间的化学交换相关时间 τ(ex)分别为 33.6 和 29.2 ms。
