1141898-35-2Relevant academic research and scientific papers
Double helix formation of oligoresorcinols in water: Thermodynamic and kinetic aspects
Goto, Hidetoshi,Furusho, Yoshio,Miwa, Kazuhiro,Yashima, Eiji
supporting information; experimental part, p. 4710 - 4719 (2009/09/26)
We previously reported that the oligoresorcinols formed double-stranded helices in neutral water through interstrand aromatic interactions. In the present study, we synthesized a new series of oligomers from the 2merto the 15mer to explore the thermodynamics, kinetics, and mechanism of the double helix formation of the oligoresorcinols in water. The double helix formation was dependent on the chain length of the oligomers and s ignificantly affected by solvent, pH, salt, and temperature. The free energy change (-?G) for the double helix formation linearly increased withthe chain length from the 4mer to the 11mer (ΔΔG = -0.94 kc al mol-1 unit-1), whereas it did not change for the oligomers longer than the 11 mer. The van't Hoff analysis of the 9mer revealed that the double helix formation was an enthalpically driven process (ΔH = -27 ± 1.5 kcal mol-1 and ΔS = -70 ± 5 cal mol-1 K-1), which was consistentwith the upfield shifts in the 1H NMR spectra and the hypoch romicity of the absorption spectra as a result of the interstrand aromatic interactions in water. Furthermore, the kinetic analysis of the chainexchange reaction between the double helices of the optically active an d optically inactive 11mers revealed a small ΔS?, suggesting that the chain exchange proceeds not via the dissociation-association pathway, but via the direct exchange pathway.
