TY - JOUR

T1 - ESE-Detected Molecular Motions of Spin-Labeled Molecules on a Solid Inorganic Surface

T2 - Motional Models and Onset Temperatures

AU - Golysheva, Elena A.

AU - Samoilova, Rimma I.

AU - De Zotti, Marta

AU - Formaggio, Fernando

AU - Gobbo, Marina

AU - Dzuba, Sergei A.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Electron spin echo (ESE) decays are highly sensitive to stochastic librations which are a general property of molecular solids of various origins. Adsorption of spin-labeled molecules on a solid inorganic surface under diluted conditions allows studying the motion devoid of the effects of cooperativity. Here, the temperature dependence of the motion-induced spin relaxation was studied for different types of spin-labeled molecules adsorbed on a SiO2 surface. The spin relaxation rate for all the systems was found to attain well-defined maxima, which is in agreement with the model of uniaxial molecular librations. For spin-labeled stearic acid, the enhanced maximal relaxation rate was found which was interpreted as manifestation of two-axial (or planar) motion that is naturally expected for long flexible molecules. The data obtained suggest that the onset of the motions observed at two different temperatures, 100 K and 130 K, may be attributed to torsional and bending types of the motion, respectively. The models of non-cooperative motion developed for adsorbed molecules may become useful for analyzing motions in complex biological media, frozen ionic liquids, polymers, etc.

AB - Electron spin echo (ESE) decays are highly sensitive to stochastic librations which are a general property of molecular solids of various origins. Adsorption of spin-labeled molecules on a solid inorganic surface under diluted conditions allows studying the motion devoid of the effects of cooperativity. Here, the temperature dependence of the motion-induced spin relaxation was studied for different types of spin-labeled molecules adsorbed on a SiO2 surface. The spin relaxation rate for all the systems was found to attain well-defined maxima, which is in agreement with the model of uniaxial molecular librations. For spin-labeled stearic acid, the enhanced maximal relaxation rate was found which was interpreted as manifestation of two-axial (or planar) motion that is naturally expected for long flexible molecules. The data obtained suggest that the onset of the motions observed at two different temperatures, 100 K and 130 K, may be attributed to torsional and bending types of the motion, respectively. The models of non-cooperative motion developed for adsorbed molecules may become useful for analyzing motions in complex biological media, frozen ionic liquids, polymers, etc.

KW - HIGH-FIELD EPR

KW - ELECTRON-PARAMAGNETIC-RESONANCE

KW - TRICHOGIN GA IV

KW - DYNAMICAL TRANSITION

KW - LIBRATIONAL MOTION

KW - LIPID-MEMBRANES

KW - IONIC LIQUIDS

KW - ECHO

KW - BILAYERS

KW - CENTERS

UR - http://www.scopus.com/inward/record.url?scp=85088403753&partnerID=8YFLogxK

U2 - 10.1007/s00723-020-01212-2

DO - 10.1007/s00723-020-01212-2

M3 - Article

AN - SCOPUS:85088403753

VL - 51

SP - 1019

EP - 1029

JO - Applied Magnetic Resonance

JF - Applied Magnetic Resonance

SN - 0937-9347

IS - 9-10

ER -