Synthesis and unprecedented electro-optic response properties of twisted π-system chromophores

A series of unconventional twisted intramolecular charge-transfer (TICT) chromophores was designed and synthesized. These chromophores exhibit ultra-large first hyperpolarizabilities. The structural characteristic that promotes this unusual nonlinear optical response is a sterochemically enforced reduction of the D-π-A conjugation that enforces zwitterionic behavior in the ground state and provides a low-energy, large-oscillator strength intramolecular excitation feature. The consequence is that molecules with relatively small numbers of π-electrons exhibit responses far larger than those of traditional planar π-conjugated chromophores. At 1907 nm, non-resonant μβ values as high as -466,000 × 10^-48 esu are observed.