Synthesis of Two Oligocarbazoles Enabling Efficient Dopamine Detection

Herein, using carbazole as the building block, two oligocarbazoles (CzOa and CzOb) were designed and synthesized. After the structures were characterized, their photophysical properties were studied by steady-state and transient spectra. Notably, with an increasing number of carbazole moieties, the oligomer CzOb exhibited a distinct red shift in both UV–vis absorption spectra and fluorescence emission spectra. Furthermore, CzOa and CzOb exhibited intense and stable electrochemiluminescence (ECL) emissions. Intriguingly, CzOb with more carbazole units showed decreased fluorescence, while an enhanced ECL emission was observed. Subsequently, CzOb, which has a stronger ECL emission, was employed as an electrode surface modification material to construct an ECL sensor for dopamine analysis. This study provides a molecular design strategy for developing high-efficiency, stable carbazole-based ECL luminophores, advancing their application in high-performance biosensing platforms.