Convenient preparation of self-assembled monolayers derived from calix[4]resorcinarene derivatives exhibiting resistance to desorption

Crown conformers of O-carboxymethylated calix[4]resorcinarenes (CRA-CMs) be aring four perfluorooctyl- and octylazobenzene residues at the lower rim of the cyclic skeleton were synthesized to investigate the resistance to deso rption of CRA-CMs forming self-assembled monolayers on aminosilylated silic a substrates and the surface energy photocontrol based on E-to-Z photoisome rization of the azobenzene moiety. In comparison with CRA-CM monolayers on silica substrates, the desorption of CRA-CMs on the aminated substrate was remarkably suppressed even when CRA-CM monolayers were sonicated in polar s olvents and even in water. The high desorption-resistance was attributable to multi-point adsorption of CRA-CMs through COOH/NH2 interactions. UV-Vis spectral studies revealed that CRA-CM substituted with p-octylazobenzene ex hibited high E- to-Z photoisomerizability up to 92% in self-assembled monol ayers, while less photoisomerizability was observed for CRA-CM bearing p-pe rfluorooctylazobenzenes due to the steric hindrance of the larger perfluoro alkyl chains. Photoinduced changes of contact angles for water up to 8.3 de grees were observed for a CRA-CM monolayer.