A benzofuran-[]-fused BODIPY trimer enabled by dual TBET and PET mechanisms for high-performance two-photon fluorescence imaging.

A benzofuran-[]-fused BODIPY trimer has been efficiently synthesized, featuring a unique structural design that harmoniously integrates TBET (through bond energy transfer) and PET (photo-induced electron transfer) mechanisms. This trimer boasts exceptional optical properties, including a large pseudo-Stokes shift of 100 nm, an impressive fluorescence quantum yield ( = 0.931), an outstandingly high extinction coefficient (182 100 M cm), a remarkable FEF (fluorescence enhancement factors, 22.4-fold) values as well as exhibiting AIE (aggregation-induced emission) activity, and has been successfully utilized in two-photon fluorescence imaging of live-cell lipid droplets.