Investigation of two-photon absorption properties in new A–D–A compounds emitting blue and yellow fluorescence

• Three new A–D–A structure compounds based on pyridine were synthesized.
• The comprehensive photophysical properties of three compounds were investigated.
• The structure–properties relationship was discussed in various solvents.
• BYQ has a good solubility in water.
• BYQ shows promising applications in pharmaceutical and biological fields.

Three new acceptor–donor–acceptor compounds (LBQ, DBQ, BYQ) were synthesized and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their photophysical properties were investigated including linear absorption, single-photon excited fluorescence, fluorescence quantum yield and two-photon absorption. These compounds in CH2Cl2 exhibit good fluorescence quantum yield which are 0.36, 0.26, and 0.25 and the largest two-photon absorption cross-section which are 48, 36, and 181 GM respectively. Under the excitation of Ti: sapphire laser with a pulse width of 140 fs, LBQ and DBQ emit blue two-photon excited fluorescence (TPEF), while BYQ emits bright yellow TPEF. BYQ has a good solubility in water and the σ can be as large as 130 GM, so it shows promising applications in many pharmaceutical and biological fields.