Three selected non durable tropical wood species namely Alstonia scholaris (pulai), Macaranga triloba (mahang) and Hevea brasiliensis (rubber) were chemically impregnated with five novel organotin(IV) complexes using vacuum-pressure treatment method. The objectives of this study were to determine the treatability and efficacy of novel organotin(IV) complexes against white and brown rot decay fungi. Soil block decay test was performed using Trametes versicolor and Gloeophyllum trabeum for 16 weeks. Ten 19mm x 19mm x 19mm sized wood cubes of each species were treated with three levels of concentration (0.1, 0.5 & 1%) of monomethyltin(IV) (MMT) & monophenyltin(IV) (MPT) of monoseries and dimethyltin(IV) (DMT), diphenyltin(IV) (DPT) & dibutyltin(IV) (DBT) of diseries organotin(IV) complexes with acetylpyridine-N(4)-cyclohexylthiosemicarbazone ligand. The treated wood species were evaluated by preservative retention values. The efficacy of organotin(IV) was estimated using soil block test. The highest retention (10.59 kg m-3) was found in Alstonia scholaris treated with 1% DMT complexes and the lowest retention (0.47 kg m-3) was found in Hevea brasiliensis treated with 0.1% DMT complexes. The best protection against decay fungi was found in 1% dibutyltin complex following diphenyltin, dimethyltin, monophenyltin and monomethyltin complexes with weight loss per cent range from 4 to 5, 5 to 6, 8 to 9, 10 to 11 and 14 to 19, respectively for all aspect while the untreated weight loss per cent was 51 to 65. The moisture content of test cubes exposed to Trametes versicolor was higher than Gloeophyllum trabeum and moisture content increased with weight loss increase. Wood cubes density was measured before treated with chemical and after exposed to fungi. Density decreased with the weight loss increase. Preservative retentions suggest tropical wood species are treatable with novel organotin(IV) complexes as wood preservatives. Soil block test showed that novel organotin(IV) complexes are effective against wood decay fungi.

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