Synthesis of Boron Diisoindolmethene Compounds and Spectral Properties

The new boron diisoindolmethene compounds were synthesized from ethyl benzoate and 1-phenylethanone, and characterized by H-1 NMR, HRMS and IR. These compounds exhibited the long UV-absorption and fluorescence emission wavelength. The effects of substituents on the molar extinction coefficient, fluorescence quantum yield and singlet oxygen yield were easily noticed, methoxy substituted compound 6b and CF3 substituted compound 6f showed the higher molar extinction coefficient than other halogen substituted compounds, and compound 6e containing Br substituent exhibited the higher singlet oxygen yield and the lower fluorescence quantum yield than other compounds.