Molecular engineering of push–pull dipolar and quadrupolar molecules for two-photon absorption: A multivalence-bond states approach

Abstract

In the search of organic molecules with large two-photon absorption cross-sections, the push–pull dipolar and quadrupolar chromophores have both attracted major attention. In order to provide the basis of molecular engineering and comparison of these two families of molecules, we implement multivalence-bond states models based on measurable parameters. The analytical expressions of the resonant two-photon absorption cross-sections are derived for both families of molecules. Difference and likeness in a number of features are outlined by comparing the results obtained for these molecular systems. The multivalence-bond states models provide useful guidelines for the design of push–pull dipolar and quadrupolar chromophores with enhanced two-photon absorption cross-sections.