Fluorescein (1), a known fluorescent tracer in microscopy with high photophysical properties, was esterified to have fluorescein ethyl ester (2) and O-ethyl-fluorescein ethyl ester (3) in excellent yields. All of them were investigated for the photophysical and electrochemical properties as potential organic semiconductor materials. Absorptions and emission spectra were taken in various solvents, compound 2 showed emission maxima at λ_max = 545 and compound 3 showed λ_max = 550 nm. Optical band gap energy (E_g) was calculated for 1–3 and the values were found in between 2.34 – 2.39 eV. Possibility of shifting emission maxima was studied in various pH (5–9) buffers, and finally the thermal stability was examined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Increasing of conjugation system of 2 and 3 were studied by HOMO and LUMO distributions of 1–3. Experimental results showed that compounds 2 and 3 have excellent photophysical and electrochemical properties hence can be used as excellent organic semiconductor materials.

荧光素 ( 1 ) 是一种在显微镜下具有高光物理特性的已知荧光示踪剂，经酯化得到荧光素乙酯 ( 2 ) 和O-乙基-荧光素乙酯 ( 3 )，收率极好。所有这些都被研究作为潜在的有机半导体材料的光物理和电化学性能。在各种溶剂中获取吸收和发射光谱，化合物2在 λ _max  = 545处显示发射最大值，化合物3显示 λ _max  = 550 nm。光学带隙能量 ( E _g ) 计算为1–3并且发现值在 2.34 – 2.39 eV 之间。研究了在各种 pH (5-9) 缓冲液中移动发射最大值的可能性，最后使用差示扫描量热法 (DSC) 和热重分析 (TGA) 检查热稳定性。通过1-3 的HOMO 和 LUMO 分布研究了2和3共轭系统的增加。实验结果表明，化合物2和3具有优异的光物理和电化学性能，可作为优良的有机半导体材料。