**Author details**

206 Nitroxides – Theory, Experiment and Applications

molecular shape anisotropy of achiral diamagnetic IL solvents.

SQUID magnetometer at a field of 0.5 T showed the high radical purity and antiferromagnetic interactions below 10K. Ionic conductivity and viscosity of (±)-**14b** were determined to be 5.23 x 10–5 S cm–1 and 1.087 x 10–3 cP, respectively, at 25 °C. Electrochemical studies using cyclic voltammetry (CV) were carried out for a CH3CN solution (1 mM) of (±)- **14b** and the neat IL ( = 1.49 g cm–3; the radical concentration is 2.34 M at 25°C), without an additional supporting electrolyte (Figure 18). The voltammogram measured in CH3CN exhibited a quasireversible wave with half-wave oxidation potential (*E*1/2ox) of +0.363 V (*vs*. Fc/Fc+), while that in the neat IL measured with a micro CV cell showed a wider quasireversible wave with *E*1/2ox = +0.458 V. The diffusion coefficient of **14b** or the corresponding oxoammonium ion in the neat IL was determined to be 2 x 10–10 cm2 s–1. Thus, paramagnetic (±)-**14b** with high radical purity turned out to be air-stable room temperature IL which can exhibit ionic conductivity and a quasireversible redox behavior in the absence of additional solvent and electrolyte. Notably, (±)-**14b** with molecular shape anisotropy proved to serve as the first IL EPR spin probe that can recognize the local structure or the

**Figure 18.** Cyclic voltammograms of (±)-**14b** recorded at 25°C for (a) the MeCN solution (1.0 mM) at a scan rate of 100 mV s–1 (five scans) using Pt working and counter electrodes and an Ag reference electrode without an additional supporting electrolyte and (b) the neat ionic liquid sample at a scan rate of 0.5 mV s–1 (single scan) using a micro cell with Pt working, counter and reference electrodes without solvent and an additional supporting electrolyte. Ref. (Uchida et al., 2009a) – Reproduced by permission

The unique magnetic and electric properties of organic NR LCs and ILs were briefly surveyed. Noteworthy is the first observation of positive magneto-LC effects ( *J* > 0) under weak magnetic fields in both chiral and achiral rod-like LC phases of the second-generation

and negative magneto-LC effects ( *J* > 0 and *J* < 0) were observed in the chiral and achiral

< 0), while positive

of all-organic NR compounds **12** with negative dielectric anisotropy (

M of the least viscous (±)-**14b** (X = NTf2) measured on a

The temperature dependence of

of The Royal Society of Chemistry.

**5. Conclusions and prospects** 

Rui Tamura, Yoshiaki Uchida and Katsuaki Suzuki *Graduate School of Human and Environmental Studies, Kyoto University, Japan* 

## **Acknowledgement**

We Acknowledge Professor Takeji Takui, Professor Hiroyuki Nohira, Dr. Yoshio Aoki, Professor Hideo Takezoe, Dr. Yoshio Shimbo, Ms. Reiri Kogo, Professor Jun Yamauchi, Dr. Yohei Noda, Dr. Naohiko Ikuma and Dr. Satoshi Shimono for their collaboration.

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