Molecular Descriptors for Natural Diamondoid Hydrocarbons and Quantitative Structure-Property Relationships for Their Chromatographic Data

Diamond hydrocarbons (or diamondoids) are hydrocarbons that have a carbon skeleton superimposable on the diamond lattice and contain one or more adamantane units. Recently it was found that many higher diamondoids (contain- ing four to eleven adamantane units) are present in petroleum and can be isolated by a series of methods that include HPLC and GC techniques. We develop QSPR equations using molecular descriptors derived from the topology and geo- metry of diamondoids, by means of dualist graphs consisting of vertices placed at the centers of adamantane cells forming the diamondoid, and of edges connecting vertices centered in adamantane cells sharing faces. From distance (or distance- distance) matrices encoding the topology and geometry of diamondoids one can obtain distance-sums, distance-distance sums, or eigenvectors as molecular descriptors characterizing the diamondoids. These descriptors afford satisfactory cor- relations with GC and HPLC retention data, and may also facilitate the identification of diamondoid isomers.