Metal oxide-based compounds porous structure

Other uses of nanostructured chromophores may include fluorescent nanoparticles or nanoparticle-based porous materials that change their light absorption or emission when a toxin is encountered. Some metal oxides and POMs already exhibit such properties. Likewise, electrochemical properties, including induced photocurrents, could be sensitive to encountering a toxin. Clearly, both decontamination and detection are relevant aspects here. Basic research is needed on the design and synthesis of engineered nanostructures whose electronic structures, thermal catalytic, photophysical (emission), and photocatalytic properties are strongly perturbed by the presence or absence of toxic compounds. 

Nitrogen-based radicals like nitroxides and verdazyl derivatives fulfill the basic requirements, since they share high stability and persistency and can be functionalized to coordinate metal ions. Charged radicals such as tetracyanoeth-ylene [68, 69] and tetracyanoquinone radical anions have also been reported [70], and a special case is represented by the o-quinone ligands that can be found in different oxidation states in valence tautomeric compounds [71]. Recently, PTM radicals substituted with carboxylate groups have been used to obtain metal-radical coordination polymers, which, in some cases, exhibit porous structures and relevant magnetic properties. Example of such porous magnets will be reported in detail in Section 4.3.3 [72]. 

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