ESR study of rotational motions of spin-labeled long-chain nitroxides in solution

Yoshimi Sueishi; Takashi Takeuchi

doi:10.1002/(sici)1099-1395(199604)9:4<234::aid-poc776>3.0.co;2-%23

ESR study of rotational motions of spin-labeled long-chain nitroxides in solution

Yoshimi Sueishi, Takashi Takeuchi

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

Abstract

Information on the rotational motion of various types of spin-labelled long-chain nitroxides was obtained from the anisotropic ESR signals. By varying the position of the nitroxide moiety along the chain, the intrinsic flexibility of molecular chain was examined. The rotational correlation times (τ_c) of spin-labelled long-chain nitroxides were about 10^-10 s. The activation parameters for rotational motion were estimated from the temperature and pressure dependences of τ_c. It was found that the activation entropy observed for methyl 16-doxyl stearate is obviously large compared with those for methyl 5- and methyl 12-doxyl stearates. The results suggest an increase in the molecular motions at the end of the hydrocarbon chain. The viscosity dependence of τ_c is discussed in terms of the difference in the strength between solute-solvent and solvent-solvent interactions.

Original language	English
Pages (from-to)	234-240
Number of pages	7
Journal	Journal of Physical Organic Chemistry
Volume	9
Issue number	4
DOIs	https://doi.org/10.1002/(sici)1099-1395(199604)9:4<234::aid-poc776>3.0.co;2-%23
Publication status	Published - Jan 1 1996

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry

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10.1002/(sici)1099-1395(199604)9:4<234::aid-poc776>3.0.co;2-%23

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abstract = "Information on the rotational motion of various types of spin-labelled long-chain nitroxides was obtained from the anisotropic ESR signals. By varying the position of the nitroxide moiety along the chain, the intrinsic flexibility of molecular chain was examined. The rotational correlation times (τc) of spin-labelled long-chain nitroxides were about 10-10 s. The activation parameters for rotational motion were estimated from the temperature and pressure dependences of τc. It was found that the activation entropy observed for methyl 16-doxyl stearate is obviously large compared with those for methyl 5- and methyl 12-doxyl stearates. The results suggest an increase in the molecular motions at the end of the hydrocarbon chain. The viscosity dependence of τc is discussed in terms of the difference in the strength between solute-solvent and solvent-solvent interactions.",

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AU - Takeuchi, Takashi

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N2 - Information on the rotational motion of various types of spin-labelled long-chain nitroxides was obtained from the anisotropic ESR signals. By varying the position of the nitroxide moiety along the chain, the intrinsic flexibility of molecular chain was examined. The rotational correlation times (τc) of spin-labelled long-chain nitroxides were about 10-10 s. The activation parameters for rotational motion were estimated from the temperature and pressure dependences of τc. It was found that the activation entropy observed for methyl 16-doxyl stearate is obviously large compared with those for methyl 5- and methyl 12-doxyl stearates. The results suggest an increase in the molecular motions at the end of the hydrocarbon chain. The viscosity dependence of τc is discussed in terms of the difference in the strength between solute-solvent and solvent-solvent interactions.

AB - Information on the rotational motion of various types of spin-labelled long-chain nitroxides was obtained from the anisotropic ESR signals. By varying the position of the nitroxide moiety along the chain, the intrinsic flexibility of molecular chain was examined. The rotational correlation times (τc) of spin-labelled long-chain nitroxides were about 10-10 s. The activation parameters for rotational motion were estimated from the temperature and pressure dependences of τc. It was found that the activation entropy observed for methyl 16-doxyl stearate is obviously large compared with those for methyl 5- and methyl 12-doxyl stearates. The results suggest an increase in the molecular motions at the end of the hydrocarbon chain. The viscosity dependence of τc is discussed in terms of the difference in the strength between solute-solvent and solvent-solvent interactions.

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ESR study of rotational motions of spin-labeled long-chain nitroxides in solution

Abstract

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