  We report on inelastic electron tunneling spectroscopy measurements carried
out on single molecules incorporated into a mechanically controllable
break-junction of Au and Pt electrodes at low temperature. Here we establish a
correlation between the molecular conformation and conduction properties of a
single-molecule junction. We demonstrate that the conductance through single
molecules crucially depends on the contact material and configuration by virtue
of their mechanical and electrical properties. Our findings prove that the
charge transport via single molecules can be manipulated by varying both the
molecular conformation (e.g., trans or gauche) and the contact material.
