The growing interest in fluorescent molecules capable of absorbing two photons has been driven by their significance in two-photon absorption (2PA) microscopy. However, challenges persist due to low 2PA in small molecules. Derivatives of dithienyl-diketopyrrolopyrrole (DPP2Ts) offer a solution with their easily modifiable nature, high fluorescence quantum yield, and structural planarity. In this work, two symmetric DPP2T derivatives were studied, exploring the influence of bromine on 2PA using the Z-scan technique. The results showed absorption in the near-infrared with a 1.4-fold increase in 2PA values (19-27 GM) due to the presence of bromine. However, bromine negatively affected emissive properties, reducing fluorescence from 73% to 56%. These findings hold promise for the utilization of DPP2Ts as fluorescent markers.
|