Access to a primary aminosporopollenin solid support from plant spores

Sporopollenin, which is a naturally occurring and highly resilient organic polymer constituting the external shell of spores and pollen grains, has been converted into a primary amine form with a loading of 0.58 +/- 0.04 mmol. g(-1) by reductive amination with ammonia and lithium aluminium hydride successively. The presence of the amine and precursor amide groups were established by combustion elemental analysis, ICP-OES, FTIR, solid-state NMR and reactivity of the primary amine group to salt formation and nucleophilic addition and substitution with phenyl isothiocyanate and benzene sulfonyl chloride, respectively. This relatively simple conversion has served to provide further information regarding the presence and reactivity of carboxylic acid functions on this relatively uncharted polymer and offers aminosporopollenin as a new material for potential solid-phase applications.