Polyoxometalate‐Ionic Liquids (POM‐ILs) as Anticorrosion and Antibacterial Coatings for Natural Stones

Abstract

Corrosion of stone by acid rain and deterioration from biofilms are global problems for industrial and residential buildings as well as cultural heritage, such as statues or historic buildings. Herein we show how typical building stones can be protected from corrosion ("weathering") and biofilm formation ("biodeterioration") by application of thin films of polyoxometalate-based ionic liquids (POM-ILs). Stone samples are coated with hydrophobic, acid resistant POM-ILs featuring biocidal properties. Exposure of the samples to simulated acid rain showed negligible corrosion compared to the significant deterioration of unprotected samples; in addition the biocidal properties of the POM-ILs suppress the formation of biofilms on coated stone slabs. A new class of modular molecular materials for protecting stones can now be developed for use in construction, environmental protection, and cultural heritage preservation.

Water Purification and Microplastics Removal Using Magnetic Polyoxometalate‐Supported Ionic Liquid Phases (magPOM‐SILPs)

“…TheP OM-IL is synthesized as described in the literature [10,12,24,25] by combination of the lacunary-Keggin cluster anion ([a-SiW 11 O 39 ] 8À ) [26] and the antimicrobial tetra-n-heptyl ammonium cation (Q 7 (= (n-C 7 H 15 ) 4 N + ) [27] (Figure 1). The magPOM-SILPs were prepared by dispersing SiO 2 @Fe 3 O 4 particles (4.0 g) in aP OM-IL solution in acetone (50 mL, [POM-IL] = 3.36 mm, m(POM-IL = 1.0 g) and subsequent vacuum drying, giving the composite magPOM-SILP 2 with aP OM-IL loading of 20 wt %, see Supporting Information for details.A saresult of the partial filling of the pores in 2 with the POM-IL, the BET specific surface area of 2 was reduced to around 100 m 2 g À1 and the BJH pore volume was 0.70 cm 3 g À1 ;for further characterization details,see Support-ing Information.…”

Beyond Charge Balance: Counter‐Cations in Polyoxometalate Chemistry

“…More recently, Streb and co-workers have prepared POM-ILs from lacunary Keggin derivatives including [SiW 11 O 39 ] 8À and [a-PW 9 O 34 ] 9À and simple QAAs, predominantly tetrahexyl-, tetraheptyl-, tetraoctyl-, and trihexyl(tetradecyl)-ammonium cations. [25,[118][119][120] Their targeted applications included water filtration and treatment, [118,120] and anticorrosive/antibacterial coatings for metals and building stone. [25,119] In these applications, both components of the POM-IL were engaged in the application.…”

“…[25,[118][119][120] Their targeted applications included water filtration and treatment, [118,120] and anticorrosive/antibacterial coatings for metals and building stone. [25,119] In these applications, both components of the POM-IL were engaged in the application. Lacunary POMs which feature accessible metal cation binding sites, served to remove heavy metal contaminants in water treatment, while the organic cation attracts organic contaminants by hydrophobic interactions.…”

Jenseits von Ladungsausgleich: Gegenkationen in der Polyoxometallat‐Chemie

“…Vor kurzem zeigten Streb und Mitarbeiter, dass POM‐ILs auf Basis von lakunären Keggin‐Derivaten wie [SiW 11 O 39 ] 8− und [α‐PW 9 O 34 ] 9− sowie einfachen QAAs, insbesondere Tetrahexyl‐, Tetraheptyl‐, Tetraoctyl‐ und Trihexyl(tetradecyl)ammoniumkationen, zugänglich sind . Ihre Zielanwendungen umfassen Wasserfiltration und ‐reinigung sowie Korrosionsschutzbeschichtungen für Metalle und Werksteine . In diesen Anwendungen haben beide Komponenten der POM‐IL eine Funktion.…”

“…Diese Eigenschaften bilden jedoch die Grundlage für viele der komplexen QA(AP)-POM-Phasen, die wir nun besprechen. [25,[118][119][120] Ihre Zielanwendungen umfassen Wasserfiltration und -reinigung [118,120] sowie Korrosionsschutzbeschichtungen für Metalle und Werksteine. [25,119]…”