Ionic Liquids as Antifungal Agents for Wood Preservation

Abstract

Ionic liquids represent a class of highly versatile organic compounds used extensively in the last decade for lignocellulose biomass fractionation and dissolution, as well as property modifiers for wood materials. This review is dedicated to the use of ionic liquids as antifungal agents for wood preservation. Wood preservation against fungal attack represents a relatively new domain of application for ionic liquids, emerging in the late 1990s. Comparing to other application domains of ionic liquids, this particular one has been relatively little researched. Ionic liquids may be promising as wood preservatives due to their ability to swell wood, which translates into better penetration ability and fixation into the bulk of the wood material than other conventional antifungal agents, avoiding leaching over time. The antifungal character of ionic liquids depends on the nature of their alkyl-substituted cation, on the size and position of their substituents, and of their anion. It pertains to a large variety of wood-colonizing fungi, both Basidiomycetes and Fungiimperfecti.

Ionic Liquids—A Review of Their Toxicity to Living Organisms

“…Ionic liquids have been widely studied for biomass fractionation processes and even in treating paper artifacts, paper restoration and antifungal agents for wood preservation [ 76 , 77 , 78 , 79 , 80 ]. The ILs that qualify for this application presents several characteristics like the presence of bulkier substituents, halogens or oxygen heteroatoms in the cation side-chain or even the presence of sp 2 double bonds (like alkyl radicals) that promote the antifungal character of ILs due to a better interaction with the fungal cell membrane.…”

“…In didecyldimethylammonium-based ILs, the increasing toxicity efficiency against Coniophora puteana follows nitrate << 3-aminotriazolate < 4-chloro-2-methylphenoxyacetate ≈nitrite. Although for the pyridinium-based ILs, the anion presents a lower influence on ILs antifungal activity [ 78 , 80 ].…”

Phosphonium-based ionic liquids as antifungal agents for conservation of heritage sandstone

“…23 In the eld of cultural heritage conservation, ILs have been successfully used for the removal of corrosion crusts and varnish from cultural heritage surfaces. 24,25 Moreover, ILs are also being considered as antibacterial and antifungal agents, 26 and have been widely exploited for preserving wood, 27,28 paper, 29,30 stone, 31,32 and brick 33 heritages against biodeterioration. The organic cations, typically imidazolium, alkylammonium, and alkylphosphonium, contribute to their superior antimicrobial activities.…”

Alkylimidazolium Ionic Liquids Absorption and Diffusion in Wood

“…Ionic liquids (ILs) are a class of organic compounds with low melting points and negligible vapor pressures, linked since the late 1990s with various wood-related applications. Apart from their ability to dissolve wood, many ILs have been studied for their antifungal character, wood plasticizing effect, antistatic character, or thermal and UV stabilizers (especially those with long-chain alkylammonium and alkylimidazolium cations) [12][13][14][15]. They are reported to present good penetration into the bulk of the wood, swelling it, while at the same time presenting a low leaching ability [16].…”

“…They are reported to present good penetration into the bulk of the wood, swelling it, while at the same time presenting a low leaching ability [16]. Apart from their use as preservatives per se, they can be used in wood-related applications as carriers [16], or as a means for transporting antifungal agents [13].…”