Abstract

The field of molecular electronics involves the use of molecules as building blocks for the assembly of devices. The ability to tune the intrinsic properties of such molecules through chemical modifications, such changing the length, conjugation, conformation and/oranchoring groups,plays a central role in order to establish a relation between these intrinsic properties and theirdevice performance.[1] We design molecules called curcuminoids (CCMoids),a family of organic conjugated molecules, previously studied by Nuria Aliaga's group as components in molecular junctions based on graphene, presenting reasonable conductance values at room temperature.[2] Our work started with the study of the electrode/molecule/electrode interaction of two thiophene–curcuminoid molecules, 2-thphCCM(1) and 3-thphCCM(2), using a mechanically controlled break-junction (MCBJ) setup,where the only structural difference between these molecules was the position of the sulfur atoms in the terminal thiophene anchoring groups.[3] Single-molecule measurements showed that the conductance of molecule 2 was an order of magnitude higher than that of molecule 1. That difference was attributed to the different type of bonding between the molecules and the gold electrodes, where molecule 2 had a more available position of the sulfur atoms to form a coordinated bond with the electrodes, an example of how the molecular conductance can be influenced by the molecule-electrode interaction.[3] Based on these results, we are working on a new family of curcuminoid molecules synthesized with different anchoring groups, which have shown similar conductance values, but giving better yields due to improved interactions between the molecule and the gold electrodes. Studies of the chemical modifications on the central β-diketone group of the conjugated scheleton with metallic or nonmetalic atoms are going to be presented, to see how these chemical changes can affect the conductance values of the molecules.