Self-organized arrays of calix[4]arene and calix[4]arene diquinone disulfide on Au(1 1 1)

Calixarene molecules of calix[4]arene and calix[4]arene diquinone disulfide (CDS) have been investigated in aqueous HClO4 solution by using cyclic voltammetry and scanning tunneling microscopy (STM). The two molecules are found to organize ordered arrays on a Au(1 1 1) surface. High-resolution STM images reveal the molecular orientation and packing arrangement in the two ordered adlayers. Calix[4]arene molecules form butterfly shaped dimers through OH groups, and adsorbed at Au(1 1 1) surface via phenolic groups. CDS molecules are upright on the electrode surface through the lower rim groups. The structural models are proposed for the two adlayers.