We summarize our contributions on the quest of new planar tetracoordinate carbon entities (new carbon molecules with exotic chemical structures and strange bonding schemes). We give special emphasis on the rationalization why in this type of molecules the planar configuration is favored over the tetrahedral one. We will concentrate on the latter and will show that molecules containing planar tetracoordinate carbons have a stabilizing system of delocalized π electrons, which shows similar properties as π systems in aromatic molecules. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 362–372, 2007

Carbon black (CB), a material consisting of finely divided particles, can be obtained by the partial combustion of heavy petroleum feedstock. The commercial preparation of CB nanoparticles require sophisticated equipment, chemical pre-treatment, and combination of complex separation and purification techniques. CB nanoparticles can also be recovered from scrubbed rubber, but yields are modest and the process is technically complex. Here, we report the development of a simple and inexpensive method for the preparation of CB nanoparticles from waste tires. Under optimal conditions, the yield of recovered CB nanoparticles (∼22 nm) was of approximately 81%; the nanomaterial presents good thermal stability and conductivity, and forms chain-like agglomerates; chemical composition analysis and solubility tests indicates that it is partly oxidized (C, 84.9%; S, 10.21%; O, 4.9%). The product was fully characterized by FTIR, Raman, TGA, BET, SEM and TEM. This preparation method could become a viable alternative to reduce the large amount of waste tires and decreasing their negative environmental impact, producing good quality CB nanoparticles useful for batteries, sensors, electronic devices, catalysis, pigments, concrete, and plastics, among many other applications.