Imidazole and Triazole Coordination Chemistry for Antifouling Coatings

Abstract

Fouling of marine organisms on the hulls of ships is a severe problem for the shipping industry. Many antifouling agents are based on five-membered nitrogen heterocyclic compounds, in particular imidazoles and triazoles. Moreover, imidazole and triazoles are strong ligands for Cu2+and Cu+, which are both potent antifouling agents. In this review, we summarize a decade of work within our groups concerning imidazole and triazole coordination chemistry for antifouling applications with a particular focus on the very potent antifouling agentmedetomidine. The entry starts by providing a detailed theoretical description of the azole-metal coordination chemistry. Some attention will be given to ways to functionalize polymers with azole ligands. Then, the effect of metal coordination in azole-containing polymers with respect to material properties will be discussed. Our work concerning the controlled release of antifouling agents, in particular medetomidine, using azole coordination chemistry will be reviewed. Finally, an outlook will be given describing the potential for tailoring the azole ligand chemistry in polymers with respect to Cu2+adsorption and Cu2+→Cu+reduction for antifouling coatings without added biocides.

Antifouling potential of Nature-inspired sulfated compounds

“…Therefore, flavonoids, xanthones, coumarins and other polyphenols with C -glysosyl and O -glycosyl linked to a diversity of saccharidic units, namely glucose, galactose, and rutinose were selected. The linkage between these two molecular moieties was also planned to contain a triazole group in order to mimic potent triazole-based biocides 22 . Furthermore, in order to develop an attractive protection against fouling from a bioenergetic point of view, a low cost synthesis of the potential biologically active compounds was guaranteed by the selection of raw materials such as diosmin, hesperidin, rutin, ethoxyrutin, resveratrol glucoside, gallic acid, and chlorogenic acid, which are readily available.…”

Encapsulation of actives for sustained release

“…The solvent is subsequently removed resulting in a porous material with excellent control of the pore size. [108][109][110] Transition metal ions, such as Cu 2+ and Zn 2+ , are very common, and di-and tricarboxylates, such as o-, m-and p-phthalic acid, unsaturated short aliphatic diacids, benzene-1,3,5-tricarboxylic acid and multidentate azole ligands, [111][112][113][114][115] are examples of popular organic linker molecules. The solvothermal synthesis yields a crystalline material with a very good control of the pore size.…”

“…Strong and specific interactions, such as coordinate interactions 1,114 or hydrogen bonds, 1,96 characterized by an equilibrium constant for binding K eq B , will immobilize a fraction of the active on the shell material. 1,96,132,133 A shell material with a concentration of c B binding sites will result in an immobilized fraction of actives and only the ''free'' fraction K B is available for diffusion according to eqn (8) and (11).…”

Preparation and Evaluation of New Heterocyclic Compounds Based on Benzothiophene Derivatives as Antifouling Additives for Marine Paint

“…Since fouling increases the surface roughness, the skin friction drag is increased, which subsequently results in increased fuel consumption and reduced maneuverability. Traditional countermeasures against marine fouling are coatings containing antifouling toxicants that have had severe environmental consequences on marine ecosystems (28) .…”

“…Moreover, imidazole and triazoles are strong ligands for Cu 2+ and Cu + , which are both potent antifouling agents (28) . Thiophene and their derivatives products are some of the oldest and best known class of nitrogen and sulphur containing compounds.…”