Petroleum asphaltenes represent the most polar and heavy molecular fraction of crude oil; hence, it comprises a very complex and problematic mixture of molecules that tend to assemble in particles of micrometric size. These particles are difficult to be maintained as flocculations by the interaction with normal dispersants at low concentration values. Additionally, once these flocculations are formed, they can be destabilized, leading to deposition onto metallic and mineral surfaces. In this line, two phthalocyanines, tin (SnPc) and silicon (SiPc), were molecularly engineered, prepared, characterized, and assessed as stabilizers for petroleum asphaltenes. The stabilizing behavior of SnPc and SiPc was experimentally and theoretically determined through two contributions: (i) the inhibitive effect, related to the stabilization of already formed asphaltenes flocculations under the application of an electric field, and (ii) the dispersive effect, directly related to the ability of the molecules to prevent further growing of small asphaltenes flocculations (clustering). Results have shown that, because of stereochemical differences, SnPc is a better inhibitor and dispersant than SiPc. Also, these two surfactants have shown ultraviolet-visible (UV-vis) traceability above 100 parts per billion in crude oil media, an important characteristic to track transportation and general handling of petroleum and its derivatives, to secure the final products. © 2010 American Chemical Society.