摘要:
                                A thieno[2,3-b] thiophene core has been utilized as a pi-donor component to design two series of push-pull thienothiophenes by introducing various acceptor groups either via olefinic or aza-spacers. The molecules show a UV-visible cut-off wavelength below the second harmonic generation (SHG) at lambda/2 of 532 nm, thereby conforming to the nonlinearity-transparency trade-off. Second order molecular nonlinearity, beta measured by Hyper-Rayleigh scattering technique was found in the range of 9.58-47.66x10(-30) esu, while the Kurtz powder technique produced signals of the order of 0.43-1.02 U. Thermal decomposition temperatures measured by differential scanning calorimetry revealed decomposition temperatures >= 275 degrees C, indicating high thermal stability. (c) 2007 Elsevier Ltd. All rights reserved.