Verbenone‐based push–pull chromophores with giant first hyperpolarizabilities: A new structure–property correlation study

Abstract

AbstractNovel chromophores Ch1–8 based verbenone bridge with various strong donors and acceptors were designed for applications in nonlinear optics, and the nonlinear optical (NLO) properties of those verbenone‐type chromophores were systematically investigated using the bond length alteration (BLA) theory, two states model (TSM) and sum‐over‐states (SOS) model. The results show that several verbenone‐based chromophores possess remarkably large molecular second‐order hyperpolarizabilities, which is due to its electron distribution close to the cyanine limit, the appropriate strength of acceptor, rather large change in dipole moment and low excitation energy. Computed hyperpolarizability (βtot) of Ch6 also approach an outstanding 2922 × 10−30 esu in TFE. The hyperpolarizability density analyses and two states model (TSM) were carried out to make a further insight into the origination of molecular nonlinearity of this unique system, suggesting that tuning structure of acceptor and polarity of the medium have great influence on the second‐order nonlinear optical properties. More importantly, chromophores Ch1–Ch8 exhibited distinct features in two‐dimensional second order NLO responses, and the strong electro‐optical Pockels effect and optical rectification responses. The excellent electronic sum frequency generations (SFG) and difference frequency generations (DFG) effect are observed in these verbenone‐type chromophores. These chromophores have a possibility to be appealing second‐order nonlinear optical (NLO) materials, data storage materials and DSSCs materials from the standpoint of large β values, high LHE, and excellent two‐dimensional second order NLO responses.