title: Preparation, characterization and magnetic behavior of a spin-labelled physical hydrogel containing a chiral cyclic nitroxide radical unit fixed inside the gelator molecule.
abstract: An optically active amphiphilic nitroxide radical compound [(S,S,R)-], which contains a paramagnetic (2S,5S)-2,5-dimethyl-2,5-diphenylpyrrolidine-N-oxyl radical group fixed in the inner position together with a hydrophobic long alkyl chain and a hydrophilic (R)-alanine residue in the opposite terminal positions, was found to serve as a low-molecular-weight gelator in H2O to give rise to a spin-labelled physical hydrogel. Characterization of the hydrogel was performed by microscopic (SEM, TEM and AFM) techniques, XRD and SAXS measurements, and IR, UV and CD spectroscopies. The gel-sol transition temperature was determined by EPR spectral line-width (ΔHpp) analysis. Measurement of the temperature dependence of relative paramagnetic susceptibility (χrel) for the hydrogel and sol phases was achieved by means of the double-integration of VT-EPR spectra.
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan. tamura.rui.8c@kyoto-u.ac.jp.
authors.forename: Yusa
authors.initials: Y
authors.lastname: Takemoto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Naohiko
authors.initials: N
authors.lastname: Ikuma
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Uchida
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shimono
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Sato
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Oba
authors.forename: Rintaro
authors.initials: R
authors.lastname: Inoue
authors.forename: Masaaki
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Hirohito
authors.initials: H
authors.lastname: Tsue
authors.forename: Tatsuhisa
authors.initials: T
authors.lastname: Kato
authors.forename: Jun
authors.initials: J
authors.lastname: Yamauchi
authors.forename: Rui
authors.initials: R
authors.lastname: Tamura
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D020100:Hydrogels / Q000138:chemical synthesis*; D057927:Hydrophobic and Hydrophilic Interactions; D009589:Nitrogen Oxides / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry; D013113:Spin Labels; D013237:Stereoisomerism; D044366:Transition Temperature
chemical_list: D020100:Hydrogels; D009589:Nitrogen Oxides; D011759:Pyrrolidines; D013113:Spin Labels; C039900:nitroxyl