46 research outputs found
The Wiener polarity index of benzenoid systems and nanotubes
In this paper, we consider a molecular descriptor called the Wiener polarity
index, which is defined as the number of unordered pairs of vertices at
distance three in a graph. Molecular descriptors play a fundamental role in
chemistry, materials engineering, and in drug design since they can be
correlated with a large number of physico-chemical properties of molecules. As
the main result, we develop a method for computing the Wiener polarity index
for two basic and most commonly studied families of molecular graphs, benzenoid
systems and carbon nanotubes. The obtained method is then used to find a closed
formula for the Wiener polarity index of any benzenoid system. Moreover, we
also compute this index for zig-zag and armchair nanotubes
On the Szeged Index of Unbranched Catacondensed Benzenoid Molecules
The Szeged index (Sz) of unbranched catacondensed benzenoid
(UBCB) hydrocarbons is examined. An efficient method for the calculations of their Sz is put forward. Among the UBCB molecules
with a fixed number of hexagons, the linear polyacene has a rnaximal
and the helicene a minimal Sz