Surface Mounted Molecular Dipolar Rotors and Rotor Arrays

Rotor Synthesis and Surface Mounting Considerable effort has gone into the synthesis of rotors and their mounting on surfaces. In addition to the commercially available analogs of rotors 1 4 lacking the triple bond [such as ClCH2-Si(OEt)3], and the easily synthesized molecule 2, all of which have small dipole moments but a small footprint, permitting high surface densities, we have worked on structures of the types 5 8, with much higher dipoles. The free acetylene of 5 has been synthesized in five steps from veratrole, but the direct addition of the triethoxysilyl group needed for surface binding (to quartz) is difficult (deprotonation proceeds well but silane reagents seem to trigger phthalocyanine formation). Currently, we are synthesizing compounds 6 and 7 in a way that avoids this problem.