Third order nonlinear optical properties and transient dynamics of thiophene-contained pyrene derivatives: Effect of peripheral substituent group

Abstract In this work, two pyrene derivatives with delocalized π-electron system 1-(pyren-1-yl)−3-(5-Chlorothiophene-2-yl)acrylic ketone ( 1612 ) and 1-(pyren-1-yl)−3-(5-Phenylthiophene-2-yl) acrylic ketone ( 1613 ) were synthesized. The third-order nonlinear optical (NLO) response of these compounds dissolved in DMSO were investigated using Z-scan technique with 190 fs laser pulses at 532 nm. Large two-photon absorption was found for the two compounds, while the NLO response of 1613 was larger than 1612 . The femtosecond transient absorption (TA) results demonstrate that both compounds have broad TA absorption band over the visible regime. Compared to 1612 , the TA band of 1613 exhibit a 15-nm blue shift of its peak while its UV–Vis absorption peak have 50 nm red-shift. Meanwhile, the TA decay curve also show that the excited-state lifetime of 1613 is longer, indicating the substituent group functionalization also has a significant impact on the excited-state relaxation processes. Our results show that both the NLO response and photo-physical dynamics of pyrene chromophores are readily tunable via peripheral substituent group, which is essential for the development of novel NLO materials based on this conjugated molecules.