AN ATOMIC-FORCE MICROSCOPY STUDY OF SELF-ASSEMBLED MONOLAYERS OF CALIX[4]RESORCINARENE ADSORBATES ON AU(111)

The structure and orientation of calix[4]resorcinarene receptor adsorb ate self-assembled monolayers (SAMs) on Au(111) were studied with atom ic force microscopy (AFM). In molecularly-resolved images, two hexagon al periodicities with lattice constants of 11.6 +/- 0.4 and 4.2 +/- 0. 2 Angstrom, respectively, were observed. These two periodicities could be observed separately as well as simultaneously by changing the imag ing force. The experimentally determined distances are assigned to dif ferent parts of the adsorbates; the 11.6 Angstrom repeat distance is r elated to the lattice of the calix[4] resorcinarene recognition sites of the adsorbates, while the smaller repeat length bts well with the i nterchain distance of a closest packing of alkyl chains. These measure ments confirm our previous assumption regarding the high degree of ord er of the calix[4]resorcinarene SAMs on gold.