Highly promising hybrid materials consisting of silica, titania, or zirconia nanoparticles linked with ionic liquid-like imidazolium units have been developed. The nanoparticle networks are prepared by click-chemistry-like process through a nucleophilic substitution reaction. The type of metal oxide nanoparticles appears to play a key role regarding the pore size of the hybrid material. 1. Introduction Recently the materials community is focusing on the development of specific materials based on assemblies of nanoparticles. These new materials aim at making use of nanoparticle collective properties. In this context, various synthetic pathways were proposed, such as template-assisted synthesis [1, 2], layer-by-layer deposition [3], or using covalent organic mediator [4–8]. These nanoparticle assemblies are already highly promising for numerous applications, like plasmonics, catalysis, or gas sorption/gas sequestration applications. For catalysis and gas sorption/sequestration applications, the porosity of these materials is an important aspect [9, 10]. Wacker et al. developed a purely inorganic porous nanoparticle assembly, by the bridging of magnetite nanoparticle with silica colloids, for catalytic applications [11], while Gao and coworkers prepared porous magnetite nanochain assemblies for water treatment [12]. However, for such applications like catalysis and gas separation, the use of hybrid inorganic-organic porous materials can be even more interesting, as the organic counterpart is able to interact with gas molecules or precursors. Thus, it was shown that the presence of ionic linker can enhance the adsorbent-adsorbate interactions through charge-induced forces [13]. In particular, ionic liquid-like linkers were pointed out to be extremely interesting [14–18]. More specifically, the high affinity of carbon dioxide for imidazolium moieties was evidenced [8, 19, 20]. For example, Lee et al. have reported the effective absorbtion of carbon dioxide over methane by copper imidazolium microporous frameworks [21]. This separation is enabled by the effects of both the metal site and the ionic imidazolium species. In this context, we have already reported the synthesis of titania Ionic Nanoparticle Networks (INNs), where the titania nanoparticles are covalently linked by means of imidazolium bridges [22]. The titania INNs have shown to possess pores with a diameter centred on 2？nm. The present communication describes a new INN material based on zirconia nanoparticles and compares the porous characteristics of different INNs, with various metal oxide
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