Inter-Spin Interactions of 1D Chains of Different-Sized Nitroxide Radicals Incorporated in the Organic 1D Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene

Abstract

Variable-temperature electron spin resonance (ESR) was measured for one-dimensional (1D) molecular chains formed using different-sized organic radicals incorporated into the 1D nanochannels of tris(o-phenylenedioxy)cyclotriphosphazene (TPP). The ESR spectra for the molecular chains of 4-oxo-2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPONE) incorporated in the TPP nanochannels ([TPP-TEMPONE]) exhibited anisotropic three-dimensional (3D) spin diffusion at temperatures close to room temperature. In contrast, 1D spin diffusion was observed even at low temperatures indicating a longer rotational diffusion correlation time or the termination of molecular motion of the guest radicals dispersed in the TPP nanochannels. The temperature range for 1D spin diffusion in [TPP-TEMPONE] was higher and wider than that of TPP inclusion compounds incorporating smaller nitroxide radicals, such as di-t-butyl nitroxide (DTBN), or 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO) radicals, as previously reported. Thus, inter-spin interactions of the organic-radical 1D molecular chains formed in size-adjustable nanochannels, such as TPP, are influenced by the molecular size and dynamics of guest radicals, and temperature.

Materials Nanoarchitectonics for Advanced Physics Research

“…Kobayashi et al constructed one-dimensional nanochannels using tris(o-phenylenedioxy)cyclotriphosphazene and observed that organic radicals of different sizes that were trapped in 4-oxo-2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl molecular chain were investigated by temperature-variable electron spin resonance. [61] Spin interactions of organic radical onedimensional molecular chains formed in nanochannels are affected by the size, dynamics, and temperature of the guest molecules. It is found that one-dimensional spin diffusion is enhanced at low temperatures in size-tunable nanochannels.…”

Materials Nanoarchitectonics at Dynamic Interfaces: Structure Formation and Functional Manipulation

“…Furthermore, we can analyze and understand phenomena in those nanoregions [ 168 , 169 , 170 , 171 ]. Such technologies have been applied to analytical chemistry [ 172 , 173 , 174 , 175 , 176 ] and physical chemistry [ 177 , 178 , 179 , 180 , 181 ], and the impact of the structure of a material on its function has been studied.…”

“…Furthermore, we can analyze and understand phenomena in those nanoregions [168][169][170][171]. Such technologies have been applied to analytical chemistry [172][173][174][175][176] and physical chemistry [177][178][179][180][181], and the impact of the structure of a material on its function has been studied. The next step in nanotechnology is to establish a methodology to assemble new functional materials based on the knowledge of nanotechnology.…”