## 8 New Technologies
### Ionic Liquids
ILs have been widely exploited for the pretreatment, processing, and preservation of lignocellulosic materials [76; 77], displaying, among other characteristics, effective antibacterial and antifungal activities and wettability properties. Protic ionic liquids, based on the 1-ammonium-2-propanol cation and a series of carboxylates anions, have been recently proposed as \"green\" cleaner agents, as an alternative to thymol [78]. [PERSON] et al. [79] observed that imidazolium ILs used in \"paper de-acidification and reinforcement processes\" have high similarity with well-known antimicotic agents such as Clotrimazole and Micronazole. For this reason, the authors investigated the antifungal capabilities of chloride and acetate imidazolium ILs against common paper molds and the permanence of ILs after the treatment. The results of this study were positive and, as the authors suggest, may represent the basis of future research aimed at obtaining simultaneous repair and protection against microorganisms in treated documents. Regarding the application of ILs in stone restoration, very little has been done. An interesting example is represented by ILs based on the multifunctional polyoxametalated [\(\alpha\)-SiW\({}_{11}\)O\({}_{39}\)]8-(POM) polyanion, a multifunctional class of metal cluster oxides never exploited in this frame. The two tetalkylammonium POM-ILs (Figure 7), namely [(n-C\({}_{7}\)H\({}_{15}\))\({}_{4}\)N]8[\(\alpha\)-SiW\({}_{11}\)O\({}_{39}\)] (1) and [(n-C\({}_{6}\)H\({}_{13}\))\({}_{3}\)[(n-C\({}_{14}\)H\({}_{29}\))N]8[\(\alpha\)-SiW\({}_{11}\)O\({}_{39}\)] (2), respectively, have been investigated both as antimicrobial and anticorrosive stone coatings [80]. Figure 6: Luminescent anions: (**a**) 1-pyrenecarboxylate and (**b**) 8-Anilino-1-naphthalene sulfonate, respectively. Both 1 and 2 POM-ILs coatings proved very resistant to acid exposure. The degree of corrosion was dependent on stone features (> porosity = > damage), while the thickness of the coating was important to reduce the acidic corrosion. Their antimicrobial activity was tested by using Gram-positive strain (_B. subtilis_) and Gram-negative one (_E. coli_) as bacterial models [80]. The data obtained in vitro revealed a good activity for both POM-ILs against the two strains (particularly vs. _B. subtilis_) being better performing. They have also shown good antifouling activity on different stone substrates. However, as the same authors declared, the data needs further research, in that the tests were performed on strains not derived from stone, and over a short time (72 h). Water wettability (absorbency/hydrophobicity) significantly contributes to the surface deterioration process of stone artifacts and buildings and also to biological colonization. ILs anion exchange constitutes a useful means to control the wettability of ILs based materials. Studies regarding a series of ammonium ILs species based on a variety of SA anions, both fluorinated and non-fluorinated, have shown that dodecylbenzenesulfonate (DBS) anion produced the most hydrophobic behavior [81; 82]. These results prompted an investigation on the influence of surface-active anions on the antimicrobial activity of the IL series, named [QA][X], as reported by [PERSON] et al. [83] and in Figure 8.  
The antimicrobial assessment of 1-6 was carried out on four microbial strains isolated from deteriorated monuments and compared with that of Preventol(r) 80 (CTS) (S1) and Rocima(tm) 103 (CTS) (S2) used as standards. The results obtained substantiate that lipophilicity of anions plays a pivotal role in determining the antimicrobial activities of these ILs, in that only the DBS derivative 3, and to some extent, the decanesulfonate one, 6, displayed significant bioactivity. In particular, the DBS based IL was remarkably active against the G (+) _Microoccus_ strain with an efficiency significantly higher than that of the two standards [83].