Synthesis and investigation of a hexyl substituted thieno-fused BODIPY derivative as a versatile near-IR fluorophore

The synthesis, photophysical and electrochemical properties of hexyl thiophene substituted thieno[b]-fused BODIPY structure are reported within this work. One such derivative, HTFBod, has been studied, which is one of the rare compounds that has a maximum absorbance wavelength greater than 750 nm among fused BODIPY compounds. In addition, it preserves its significant spectral properties such as high molar absorptivity and fluorescence quantum yield. Electrochemical characterizations indicated that the compound could be a successful candidate for an organic solar cell donor compound due to its low band gap, which is known to improve the short-circuit current (J(sc)) values. The compound could also harvest the near-IR portion of the solar irradiance where maximum solar photon flux exists. In addition, its low LUMO value of -4.13 eV contributes to its air stability. Hexyl substituents provide greater solubility which is required in solution-processable organic photovoltaics and further bathochromic shift when compared to similar compounds. Next, the synthesis was accomplished in five steps with higher yields compared to similar compounds in the literature. Heavy atom-free singlet oxygen production analysis has also been performed while it has been shown that the compound cannot produce singlet oxygen, while this property could be acquired via halogen substitution.