Aza-crown ether derivatives based on stilbene: Two-photon absorption and bioimaging

• We have synthesized two D–π–D dyes with two-photon absorption.
• Aza-crown ether was electron donor and stilbene was the conjugated chain.
• Linear and nonlinear optical properties of dyes 1 and 2 were investigated.
• The results revealed that the dyes 1 and 2 have moderate δ2PA.
• SPFM imaging of dye 1 in HepG2 cells was demonstrated.

Two novel aza-crown ether derivatives based on stilbene were synthesized and characterized. Their linear photophysical properties were systematically investigated in various solvents. The nonlinear photophysical properties were investigated by two-photon induced fluorescence method. The two-photon absorption cross sections values measured by two-photon excited fluorescence were determined to be 328.2 GM and 246.55 GM for the dyes derived from monoaza 15-crown-5 and 18-crown-6, respectively, which accorded with dipole moment changes under photoexcitation. In addition, a single-photon fluorescence cell imaging experiment proved that dye derived from monoaza 15-crown-5 was suitable for biomedical imaging.