Conjugation,number of Dewar resonance structures (DSs) in homologous polyzethrene and related conjugated polycyclic hydrocarbon series,and kinked versus straight

Kinked polyzethrenes are more stable than linear polyzethrenes making them better candidates as materials for organic electronic devices (e.g., organic field effect transistors, nonlinear optics, and semiconductors) because of their greater singlet biradical properties. For series of molecules constructed by successive attachment of a given aufbau unit, we are able to derive analytical or recursion expressions relating certain properties. For example, starting with a few known number of Dewar resonance structures (DSs) for such a series, one is often able to derive analytical or recursion expressions for these DS values by our method of successive differences which then lead to either constant or Fibonacci numbers, respectively. The increasing order of π-electronic stability of isomers with the same number of Kekulé structures (K) is determined by their increasing number of DSs. Kinked polycyclic conjugated polyenes with a single classical structure (i.e., K = 1) are more conjugated and stable than their straight polycyclic isomers with a single classical structure.