Synthesis and nonlinear optical properties of end-group modified aromatic esters as chained chromophores

Abstract

We synthesized aromatic ester derivatives with some electron accepting groups at molecular ends as new class of nonlinear optical (NLO) active chromophores (ArESn-X, n = 2, 3, X = CN, CF 3 , NO 2 , DCV). Some second-order NLO properties for poled polymer films consisting of poly(methyl methacrylate) (PMMA) doped with 10 wt.-% ArESn-X (ArESn-X/PMMA) were investigated. UV/vis spectra of these polymer films have cutoff wavelengths (λ co ) of about 300-380 nm, which are much shorter than in the case of p-nitroaniline (pNA) (λ co = ca. 450 nm) as a typical strong donor-acceptor (D-A) molecule. In addition, some of these polymer films exhibited larger second-order nonlinear coefficient (d 33 ) values than PMMA film doped with 10 wt.-% pNA (pNA/PMMA) (2.8 x 10 -9 esu). Namely, ArES3-CN (d 33 = 3.1 x 10 -9 esu, 10 wt.-% in PMMA), ArES3-NO 2 (3.0 x 10 -9 esu, 10 wt.-% in PMMA) and ArES2-DCV (4.0 x 10 -9 esu, 10 wt.-% in PMMA) showed not only excellent second-order NLO activity but also excellent transparency in the visible region (λ co = 304 nm (ArES3-CN), 340 nm (ArES-NO 2 ) and 370 nm (ArES2-DCV), respectively). Consequently, these compounds are believed to be promising chromophores for second-order nonlinear optics.