TY - JOUR
T1 - Threading/dethreading processes in pseudorotaxanes. A thermodynamic and kinetic study
AU - Venturi, Margherita
AU - Dumas, Stephane
AU - Balzani, Vincenzo
AU - Cao, Jianguo
AU - Stoddart, J. Fraser
PY - 2004/8
Y1 - 2004/8
N2 - Pseudorotaxanes are host-guest complexes made of a thread-like component penetrating a bead-like component. We have investigated, by a stopped-flow technique, the threading/dethreading kinetics of pseudorotaxanes formed between a tetracationic cyclophane, cyclobis(paraquat-p-phenylene), and thread-like compounds consisting of a naphthalene ring system with appended -(OCH 2CH2)nOH groups (n from 0 to 3) on the 1 and 5 positions. The association and rate constants have been measured in MeCN (from 276 to 293 K) and H2O (from 276 to 313 K). In MeCN solution, the association constant increases with increasing length of the appended chain (e.g., Kass = 1.0 × 103 M-1 for n = 0 and Kass = 4.0 × 104 M-1 for n = 3, at 293 K); in H2O, the association constants are larger than in MeCN, but almost independent of the chain length. Both the threading (kt) and dethreading (kd) rate constants are larger in MeCN than in H 2O and decrease with increasing chain length (e.g., kt > 108 and kt = 4 × 106 M-1 s-1 for n = 0 and n = 3, respectively, in H2O at 276 K). Thermodynamic and kinetic parameters have been obtained and the role played by the length of the chains appended to the naphthalene ring system is discussed.
AB - Pseudorotaxanes are host-guest complexes made of a thread-like component penetrating a bead-like component. We have investigated, by a stopped-flow technique, the threading/dethreading kinetics of pseudorotaxanes formed between a tetracationic cyclophane, cyclobis(paraquat-p-phenylene), and thread-like compounds consisting of a naphthalene ring system with appended -(OCH 2CH2)nOH groups (n from 0 to 3) on the 1 and 5 positions. The association and rate constants have been measured in MeCN (from 276 to 293 K) and H2O (from 276 to 313 K). In MeCN solution, the association constant increases with increasing length of the appended chain (e.g., Kass = 1.0 × 103 M-1 for n = 0 and Kass = 4.0 × 104 M-1 for n = 3, at 293 K); in H2O, the association constants are larger than in MeCN, but almost independent of the chain length. Both the threading (kt) and dethreading (kd) rate constants are larger in MeCN than in H 2O and decrease with increasing chain length (e.g., kt > 108 and kt = 4 × 106 M-1 s-1 for n = 0 and n = 3, respectively, in H2O at 276 K). Thermodynamic and kinetic parameters have been obtained and the role played by the length of the chains appended to the naphthalene ring system is discussed.
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U2 - 10.1039/b315933g
DO - 10.1039/b315933g
M3 - Article
AN - SCOPUS:4644250557
VL - 28
SP - 1032
EP - 1037
JO - New Journal of Chemistry
JF - New Journal of Chemistry
SN - 1144-0546
IS - 8
ER -