Preparation and Characterization of New Inclusion Compounds Using Stable Nitroxide Radicals and an Organic 1-D Nanochannel as a Template

Hirokazu Kobayashi,Tetsuo Asaji,Atsushi Tani

doi:10.3390/ma3063625

Hirokazu Kobayashi, Tetsuo Asaji + Show 1 more

Open Access

https://doi.org/10.3390/ma3063625

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Journal: Materials	Publication Date: Jun 9, 2010
Citations: 35	License type: CC BY 3.0

Affiliation: Nihon University, Osaka University

Abstract

A new inclusion compound (IC) using di-t-buthyl nitroxide (DBNO) radical and tris(o-phenylenedioxy)cyclotriphosphazene (TPP) (1), which has an organic one-dimensional (1-D) nanochannel in the crystal, is reported. According to the characterization using thermogravimetric analysis (TG), ESR measurements, etc., the composition of the inclusion compound was assigned as TPP:DBNO = 1:0.62. The narrowing of the isotropic ESR adsorption line of 1 was observed with a temperature increase from 103 K to room temperature. The line shape indicated a type of 1-D spin diffusion as observed in our previous study of the IC using TPP and 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO).

Highlights

The crystal of tris(o-phenylenedioxy)cyclotriphosphazene (TPP, Scheme 1 a) [1,2,3,4] has a onedimensional (1-D) homogeneous nanochannel [5,6,7]
Since the temperature-dependent 1-4] has a onedimensional (1-D) inter-spin interaction is closely related to the molecular orientation and dynamics of TEMPO in the TPP nanochannels, the temperature dependence of the ESR spectrum of the inclusion compound (IC) was investigated in detail using TPP and TEMPO diluted by diamagnetic molecules [26]
The chemical analysis (CA) of 1 revealed the following: H, 3.99%; C, 50.55%; N, 8.96%. These results did not coincide with the composition: H, 3.98%; C, 49.73%; N, 9.22% of the expected compound with TPP:di-t-buthyl nitroxide (DBNO) = 1:0.5 in contrast with the case of TPP/TEMPO IC, which has the composition of TPP:TEMPO = 1:0.5 within an experimental error of ± 0.3 %

Summary

Introduction

The crystal of tris(o-phenylenedioxy)cyclotriphosphazene (TPP, Scheme 1 a) [1,2,3,4] has a onedimensional (1-D) homogeneous nanochannel [5,6,7]. Since the temperature-dependent 1-D inter-spin interaction is closely related to the molecular orientation and dynamics of TEMPO in the TPP nanochannels, the temperature dependence of the ESR spectrum of the IC was investigated in detail using TPP and TEMPO diluted by diamagnetic molecules [26]. For clarification of the relation between the temperature-dependent 1-D inter-spin interaction of TPP/TEMPO IC and the molecular dynamics of TEMPO in the TPP nanochannels, a new IC using a differently sized nitroxide radical to TEMPO was prepared. On the basis of the ESR measurements of the prepared ICs, it was found that the molecular orientation of TEMPOL in the TPP nanochannels is similar to observed in the case of TPP/TEMPO IC. These results provide important ideas for the design of a new organic magnet

Sample characterization of compound 1

Sample characterization and evaluation of compound 2

Chemicals

Sample preparation

Instruments

Conclusions