New chromophoric monomers with nonlinear optical properties

The first hyperpolarizability (FH) of maleimides and acrylates of the chromophoric derivatives containing azo and sulfonyl or a nitro group, was evaluated by ab initio (GAMESS and GAUSSIAN) and semiempirical (INDO1/S) quantum-chemical calculation. The monomeric compounds contained a sulfonyl or nitro group as an electron acceptor and amine or imide nitrogen as an electron donor. It was found that a carbonyl group of the imide structure reduced the electron donor ability of the imide nitrogen atom resulting in low values of FH of the maleimides. The results obtained for acrylates with the carbonyl group separated from an electron donating nitrogen atom by two methylene groups appeared to be almost three times higher than those of the maleimides. The values of beta(0) were in the range 186.3 x 10(-40)-203.7 x 10(-40) m(4)/V, while beta(SHG) in the range 308.1 x 10(-40)-327.6 x 10(-40) m(4)/V. The agreement between the results obtained from ab initio and semiempirical calculation was good except for the compounds with a nitro group. The acrylate monomers which exhibited promising FH values were synthesised in the condensation reaction of N-methyl-N-phenylamino-2-ethanol with acryloyl chloride followed by diazonium salts preparation and coupling. The monomers were obtained with high yield of ca. 95%. (C) 2000 Elsevier Science Ltd. All rights reserved.