TY - JOUR
T1 - Interaction of cesium ions with calix[4]arene-bis(t-octylbenzo-18-crown-6)
T2 - NMR and theoretical study
AU - Kříž, Jaroslav
AU - Dybal, Jiří
AU - Makrlík, Emanuel
AU - Vaňura, Petr
AU - Moyer, Bruce A.
PY - 2011/6/16
Y1 - 2011/6/16
N2 - Using 1H, 13C, and 133Cs 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-d5. 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 βnb(L•Cs+) = 8.8 ± 0.1. According to 133Cs NMR spectra, the value of the equilibrium constant of the second complex is log Knb(2)(L•2Cs+) = 6.3 ± 0.2, i.e., its stabilization constant is log βnb(L•2Cs+) = 15.1 ± 0.3. Self-diffusion measurements by 1H 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 133Cs NMR technique, the correlation times τex 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.
AB - Using 1H, 13C, and 133Cs 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-d5. 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 βnb(L•Cs+) = 8.8 ± 0.1. According to 133Cs NMR spectra, the value of the equilibrium constant of the second complex is log Knb(2)(L•2Cs+) = 6.3 ± 0.2, i.e., its stabilization constant is log βnb(L•2Cs+) = 15.1 ± 0.3. Self-diffusion measurements by 1H 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 133Cs NMR technique, the correlation times τex 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.
UR - http://www.scopus.com/inward/record.url?scp=79958780926&partnerID=8YFLogxK
U2 - 10.1021/jp203221k
DO - 10.1021/jp203221k
M3 - Article
AN - SCOPUS:79958780926
SN - 1520-6106
VL - 115
SP - 7578
EP - 7587
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 23
ER -