Four novel calix[4]resorcinarene core arborols 2a～2d bearing sufficient hydroxyl groups to impart the desired water solubility were conveniently synthesized by the reaction of calix[4]resorcinarene esters 1a～1b with tris(hydroxymethyl)aminomethane and bis(2-hydroxyethyl)amine respectively. These highly hygroscopic white solids were refluxed in Ac₂O to form the corresponding acyl derivatives 3a～3d. The aggregation of arborol 2c containing hydrocarbon (lipophilic) backbone and twenty-four surface hydroxyl groups was observed in aqueous solution by TEM.

Key words: dendrimer, arborol, electron microscope, calix[4]resorcinarene, calixarene