New boron-based biocides for the protection of wood
D G Humphrey, P J Duggan, E M Tyndall, J M Carr, L J Cookson
Boric acid and other simple inorganic oxides of boron are amongst the oldest wood preservatives currently in use. Their relatively low toxicity and broad-spectrum activity are just some of their desirable characteristics. The primary disadvantage associated with conventional boron-based preservatives is their lack of permanence in exposed applications. A collaborative project between CSIRO and the Centre for Green Chemistry is developing new complexes for wood protection based on boron. The approach involves the binding of boron with specifically designed ligands that interact with the wood constituents to reduce leaching. Accelerated weathering trials and cellulose paper bioassays have been used as a means of assessing the performance of large numbers of complexes, and building up qualitative structure-property and structure-activity
relationships. The results obtained to date have been promising, with significant improvement in leach resistance and increased biological activity. This paper will discuss the approach adopted
and the results obtained thus far. For reasons of confidentiality, some details of the complexes cannot be disclosed.