**1. Introduction**

210 Nitroxides – Theory, Experiment and Applications

978-3-31889-6, Weinheim, Germany.

Sons, ISBN 978-1-118-07861-7, Chichester, UK.

*Materials Chemistry*, Vol.19, pp.415-418.

Vol.40, pp. 3105-3118.

401-404.

157-168.

pp. 6877-6881.

9752.

Sugawara, T.; Komatsu, H. & Suzuki, K. (2011). Interplay between Magnetism and Conductivity Derived from Spin-Polarized Donor Radicals. *Chemical Society Reviews*,

Suzuki, K.; Uchida, Y.; Tamura, R.; Shimono, S. & Yamauchi, J. (2012). Observation of Positive and Negative Magneto-LC Effects in All-Organic Nitroxide Radical Liquid Crystals by EPR Spectroscopy, *Journal of Materials Chemistry*, DOI: 10.1039/c2jm16278d. Tamura, M.; Nakazawa, Y.; Shiomi, D.; Nozawa, K.; Hosokoshi, Y.; Ishikawa, M.; Takahashi, M. & Kinoshita, M. (1991). Bulk Ferromagnetism in the -Phase Crystal of the *p*-Nitrophenyl Nitronyl Nitroxide Radical. *Chemical Physics Letters*, Vol.186, No.4 & 5, pp.

Tamura, R. (2008a). Organic Functional Materials Containing Nitroxide Radical Units, In: *Nitroxides: Applications in Chemistry, Biomedicine, and Materials Science*, G.I.Likhtenshtein, J.Yamauchi, S.Nakatsuji, A.I.Smirnov & R.Tamura, (Eds.), 303-329, Wiley-VCH, ISBN

Tamura, R.; Uchida, Y. & Ikuma, N. (2008b). Paramagnetic All-Organic Chiral Liquid

Tamura, R.; Uchida, Y. & Suzuki, K. (2012). Magnetic Liquid Crystals, In: *Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications*, Q, Li (Ed.), Chap. 3, John Wiley &

Terazzi, E.; Suarez, S.; Torelli, S.; Nozary, H.; Imbert, D.; Mamula, O.; Rivera, J-P.; Guillet, E.; Bénech, J-M.; Bernardinelli, G.; Scopelliti, R.; Donnio, B.; Guillon, D.; Bünzli, J-C. G. & Piguet, C. (2006). Introducing Bulky Functional Lanthanide Cores into Thermotropic Metallomesogens: A Bottom-Up Approach. Advanced Functional Materials, Vol.16, pp.

Uchida, Y.; Ikuma, N.; Tamura, R.; Shimono, S.; Noda, Y.; Yamauchi, J.; Aoki, Y. & Nohira, H. (2008). Unusual Intermolecular Magnetic Interaction Observed in an All-Organic

Uchida, Y.; Oki, S.; Tamura, R.; Sakaguchi, T.; Suzuki, K.; Ishibashi, K. & Yamauchi, J. (2009a). Electric, Electrochemical and Magnetic Properties of Novel Ionic Liquid Nitroxides, and Their Use as an EPR Spin Probe. *Journal of Materials Chemistry*, Vol.19,

Uchida, Y.; Suzuki, K.; Tamura, R.; Ikuma, N.; Shimono, S.; Noda, Y. & Yamauchi, J. (2010). Anisotropic and Inhomogeneous Magnetic Interactions Observed in All-Organic Nitroxide Radical Liquid Crystals, *Journal of the American Chemical Society*, Vol.132, 9746-

Uchida, Y.; Tamura, R.; Ikuma, N.; Shimono, S.; Yamauchi, J.; Shimbo, Y.; Takezoe, H.; Aoki, Y. & Nohira, H. (2009b). Magnetic-Field-Induced Molecular Alignment in an Achiral Liquid Crystal Spin-Labeled by a Nitroxyl Group in the Mesogen Core, *Journal of* 

Radical Liquid Crystal, *Journal of Materials Chemistry*, Vol.18, pp. 2950-2952.

Crystals, *Journal of Materials Chemistry*, Vol.18, pp. 2872-2876.

Many inorganic materials are widely used as adsorbents and catalysts. For example, silica gels efciently absorb vapors and gases in chemical reactors and are applied as lters for the purication of mineral oils and water (Buyanov, 1998). Different aluminum oxide modications show good adsorption and catalytic properties in many organic reactions due to the presence of active sites on their surface (Lisichkin et al., 2003). TiO2 gels are widely used in heterogeneous catalysis owing to their enhanced chemical stability, the accessibility of active sites on their surface throughout the reaction volume, simplicity of reaction product separation, and the feasibility of repeated regeneration (Petrov et al., 1998).

The efficiency of these materials mainly depends on the degree of surface development, texture and structural characteristics, availability of active centers, and possibly medium acidity near these centers. The specific surface diminishes on drying in any procedure for the preparation of xerogels. It can be maintained constant by a number of methods, including the use of additions (Ur'ev & Potanin, 1992), for example, powder cellulose (PC) (Shishmakov et al., 2007). Cellulose is a linear high molecular polysaccharide, which forms rigid chain structures due to the inter-molecular hydrogen bonding. It functions in nature as an agent that imparts high mechanical stability to plant tissues (Nikitin, 1962). The deposition of SiO2 and TiO2 xerogels on the PC surface affords composite materials (CMs) with a high dispersity of particles (Shishmakov et al., 2010).

The use of hybrid organo-inorganic materials as supports is a new area in the development of new metal-containing catalytic materials. It allows to obtain supports with specific surfaces that are capable of retaining the metallic component of a catalytic system more strongly.

© 2012 Kovaleva and Molochnikov, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Kovaleva and Molochnikov, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Chitosan, poly-D-β-glucosamine, is a commercially available amino polymer that is a perfect complexing agent, due to the strong donor properties of both the amino and hydroxyl groups (Varma et al., 2004). Chitosan is thus widely used in obtaining various catalytic materials, including those containing Au0 that are used in the hydroamination of alkenes (Corma et al., 2007); Pd0 used for the reduction of ketones (Yin et al., 1999); the Pd0–Ni0 bimetallic system, used for carbonylation (Zhang & Xia, 2003); Os (VIII), used for hydroxylation (Huang et al., 2003); Co2+, used for hydration (Xue et al., 2004); and Cu2+, used for the oxidation of catecholamines (Paradossi et al., 1998).

SiO2 is usually used as the inorganic component for these systems. The obtained hybrid materials are used to create sorbents of 3d-metal ions (Liu et al., 2002); to immobilize enzymes (Airoldi & Monteiro, 2000); as a solid phase for the liquid chromatography of organic compounds (Budanova et al., 2001), including enantiomers (Senso et al., 1999); and to improve the mechanical properties of other polymers (Yeh et al., 2007). Other oxides in combination with chitosan allow us to obtain biosensors based on ZnO substrate (Khan et al., 2008), selective sorbents of fluoride ions based on Al2O3 substrate (Viswanathana & Meenakshib, 2010) and magnetic materials based on Fe3O4 substrate (Li et al., 2008). Using an organic polymer (e.g., cellulose) as a substrate also has advantages in the sorption of metal ions (Corma et al., 2007). Metal-containing hybrid organo–inorganic materials can also be used as antibacterial composites (Mei et al., 2009), as sorbents of proteins (Shi et al., 2003), and as pervaporation membranes (Varghese et al., 2010).

Nanostructured metal oxides, which are distinguished by extremely developed surface and porosity of particles, are new promising materials for different elds of science and technology, especially, for heterogeneous catalysis and chemistry of adsorption phenomena (Zakharova et al., 2005).

Many sorption and catalytic processes are pH-dependent. Therefore, the determination of acidity and other acid–base characteristics in pores of inorganic, organo-inorganic materials is of great practical interest, since the catalytic and adsorption properties of solid-phase objects are affected by not only the chemical nature of solutions, but also specic conditions inside pores and on the surface of these materials. The mobility of liquid molecules in pores of inorganic sorbents was investigated by some authors using the spin probe method (Borbat et al., 1990; Martini et al., 1985 ). Recently, a new method was developed for the determination of medium acidity in pores of solids (pHint) by means of pH-sensitive nitroxide radicals (NRs) as spin probes (Molochnikov et al., 1996 ; Zamaraev et al., 1995). In recent years, this method was used to measure pHint in micropores of various cross-linked organic polyelectrolytes (ion-exchange resins and lms) (Molochnikov et al., 1996, 2004) and in pores of some zeolites and kaolin (Zamaraev et al., 1995). We found that pHint inside sorbents differ from the pH of external solutions by 0.8–2.1 units (Molochnikov et al., 1996). The method developed allowed us to study the processes of sorption and hydrolysis in ionexchange resins and the catalytic properties of Cu2+- containing carboxyl cation exchangers (Kovaleva et al., 2000), to determine ionization constants of functional groups and to give a critical estimation to the regularities previously found for the behavior of adsorbents in aqueous media.

pH-sensitive nitroxide radicals (NR) as labels were also used to determine surface electrical potential (SEP) of different biological objects like phospholipids (SLP) - derivatives of 1,2 dipalmitoyl-sn-glycero-3-phosphothioethanol (PTE) (Voinov et al., 2009) and the mixed bilayers composed of dimyristoylphosphatidylglycerol and dimyristoylphosphatidilcholine (Khramtsov & Weiner, 1988).

This work is aimed to review the applications of pH-sensitive NR as probes and labels for determination of local acidic and electrochemical characteristics of inorganic and organoinorganic materials and systems such as :

