Modulation of naphthanthryl chalcone derivatives by push-pull electronic substituents: Ultrafast nonlinear absorption and transient dynamics

Abstract

The ultrafast optical nonlinearities of two novel naphthanthryl chalcone derivatives (NAn-1 and NAn-2) with different push-pull effects were investigated and compared. Combined with femtosecond Z-scan and quantum chemical calculations, the results indicate that both compounds exhibited broadband (532–800 nm) two-photon-induced excited-state absorption, and NAn-2 exhibited wider spatial electron delocalization. The push electronic effects of the peripheral substituent increased the transition dipole moment, originating from the main nonlinear group retained stronger local excitation and ultimately enhanced the nonlinear absorption of NAn-2. Transient absorption spectroscopy revealed a transition from the locally excited to charge transfer state and showed that the dynamic processes of excited states were readily tunable via peripheral push-pull substituents. The results suggest that NAn-2 possess the potential in optical limiting applications and provide guidance for designing polycyclic aromatic hydrocarbon (PAH)-based nonlinear optical materials.