Information Indices with High Discriminative Power for Graphs

In this paper, we evaluate the uniqueness of several information-theoretic measures for graphs based on so-called information functionals and compare the results with other information indices and non-information-theoretic measures such as the well-known Balaban index. We show that, by employing an information functional based on degree-degree associations, the resulting information index outperforms the Balaban index tremendously. These results have been obtained by using nearly 12 million exhaustively generated, non-isomorphic and unweighted graphs. Also, we obtain deeper insights on these and other topological descriptors when exploring their uniqueness by using exhaustively generated sets of alkane trees representing connected and acyclic graphs in which the degree of a vertex is at most four

New Polynomial-Based Molecular Descriptors with Low Degeneracy

In this paper, we introduce a novel graph polynomial called the ‘information polynomial’ of a graph. This graph polynomial can be derived by using a probability distribution of the vertex set. By using the zeros of the obtained polynomial, we additionally define some novel spectral descriptors. Compared with those based on computing the ordinary characteristic polynomial of a graph, we perform a numerical study using real chemical databases. We obtain that the novel descriptors do have a high discrimination power

QSAR studies on a number of pyrrolidin-2-one antiarrhythmic arylpiperazinyls

The activity of a number of 1-[3-(4-arylpiperazin-1-yl)propyl]pyrrolidin-2-one antiarrhythmic (AA) agents was described using the quantitative structure–activity relationship model by applying it to 33 compounds. The molecular descriptors of the AA activity were obtained by quantum chemical calculations combined with molecular modeling calculations. The resulting model explains up to 91% of the variance and it was successfully validated by four tests (LOO, LMO, external test, and Y-scrambling test). Statistical analysis shows that the AA activity of the studied compounds depends mainly on the PCR and JGI4 descriptors

C-70 dimers - Energetics and topology

Nagy CL, Stefu M, Diudea MV, Dress A, Müller A. C-70 dimers - Energetics and topology. CROATICA CHEMICA ACTA. 2004;77(3):457-464.All sp(2) peanut-shaped dimeric fullerenes derived from D-5h C-70 are modeled. Construction of the isomers was monitored by a cyclic permutation of bonds in the linking zone of the two caps resulting from deleting the boundary of a face from the parent C-70 fullerene. Local curvature was calculated in terms of both angular defects and strain energy. Topological equivalence classes of the constituent substructures were evaluated by calculating the topological indices of the parent cages, their medials and duals. Detailed network transformation, starting from C-70, through sp(3) dimer, peanut sp(2) dimer, up to the corresponding tubulene is given. Semiempirical calculations showed a monotonic decrease in the heat of formation along the above pathway