Synthesis and nonlinear optical properties of aromatic esters with an electron donor and an electron acceptor end group

We synthesized a series of aromatic esters having an electron donating and an electron accepting end group as a new class of nonlinear optical (NLO) active chromophores ( ArESn D‐A , n = 2,3, D = MeO (as reference), MeS and Me₂N, A = CN). Second‐order NLO properties for poled polymer films consisting of poly(methyl methacrylate) ( PMMA ) doped with 10 wt.‐% ArESn D‐A ( ArESn D‐A/PMMA ) were investigated. The UV/vis spectra of these polymer films have cutoff wavelengths (λ_co) of about 350 ? 370 nm, which are much shorter than in the case of p‐nitroaniline (pNA) (λ_co = 473 nm) which is a typical strong donor‐acceptor (D‐π‐A) molecule. In addition, some of these polymer films exhibit higher second‐order nonlinear coefficients (d₃₃) than a PMMA film doped with 10 wt.‐% pNA ( pNA/PMMA ) (2.8×10^–9 esu). Namely, ArES3 Me₂N‐CN (d₃₃ = 5.6×10^–9 esu, 10 wt.‐% in PMMA) and ArES2 Me₂N‐CN (3.8×10^–9 esu, 10 wt.‐% in PMMA) showed excellent second‐order NLO activity as well as transparency in the visible region (λ_co: 362 nm for ArES3 Me₂N‐CN and 366 nm for ArES2 Me₂N‐CN , respectively).