General procedure for the synthesis of 3-iodo-9-phenylcarbazole from N-phenylcarbazole: 2.433 g (10 mmol) of intermediate compound A (N-phenylcarbazole) was dissolved in 100 mL of 80% acetic acid solution, followed by the sequential addition of 1.357 g (5.35 mmol) of iodine monomers (I2) and 0.333 g (1.46 mmol) of o-n-octanoic acid ( H5IO6). The reaction mixture was stirred at 80 °C for 2 h under nitrogen protection. After completion of the reaction, the reaction mixture was extracted three times with ether (50 mL). The organic layers were combined and dried with anhydrous magnesium sulfate, followed by evaporation under reduced pressure to remove the solvent. The resulting crude product was purified by silica gel column chromatography to afford 3.23 g of intermediate compound B (3-iodo-9phenylcarbazole) as a white solid in 87% yield.1H NMR (CDCl3, 300 MHz) δ (ppm): 8.43 (d, 1H), 8.05 (d, 1H), 7.62 (dd, 1H), 7.61-7.75 (m, 2H) , 7.51-7.43 (m, 3H), 7.41-7.35 (m, 2H), 7.27 (dd, 1H), 7.14 (d, 1H).
