*3.1. General Experimental Details*

1H-, and 13C-NMR were recorded via JNM ECA600 FT NMR (1H-NMR 600 MHz, 13C-NMR 151 MHz). 1H-NMR spectra are reported as follows: a chemical shift in ppm downfield of tetramethylsilane (TMS) and referenced to residual solvent peak (CDCl3) at 7.26 ppm, or ((CD3)2CO) at 2.05 ppm, multiplicities (s = singlet, d = doublet, dd = doublet of doublets, t = triplet, q = quartet, m = multiplet), and coupling constants (Hz). 13C-NMR spectra reported in ppm relative to the central line of triplet for CDCl3 at 77.16 ppm, or the central line of septet for ((CD3)2CO) at 29.84 ppm. APCI-MS spectra were obtained with JMS-T100LC (JEOL). FT-IR spectra were recorded on a JASCO FT-IR system (FT/IR4100). Photoluminescence (PL) spectra were recorded on JASCO FP-8550 Spectrofluorometer. UV spectra were recorded on a JASCO v-770 spectrophotometer. Column chromatography on SiO2 was performed with Kanto Silica Gel 60 (63–210 μm). Commercially available organic and inorganic compounds were used without further purification. The electro-oxidation was carried out using sing ElectraSyn® 2.0 (designed by IKA) at a constant current of 1.5 mA, under air (1 atm.) [62].

#### *3.2. Synthetic Procedures*

3.2.1. General Procedure for the Synthesis of Double 3-Hydroxy Benzo[c]carbazole **2**

To a solution of *N1*,*N4*-di(naphthalen-2-yl)benzene-1,4-diamine **1** (36 mg, 0.1 mmol) and *p*-benzoquinone (27 mg, 0.25 mmol, 2.5 equiv.) in dry toluene (1.5 mL), orthophosphoric acid (10.6 μL, 2.0 equiv.) dissolved in (0.5 mL) toluene was added dropwise. The reaction mixture was stirred at 50 ◦C for 5 h under N2 atmosphere until its completion. Next, the reaction was quenched via water, extracted with EtOAc and the combined organic extracts dried over Na2SO4, and evaporated *in vacuo*. The crude mixture was purified on silica column chromatography (eluent: *n*-hexane/DCM/ethyl acetate = 7/1/1) to give double 3-Hydroxy benzo[c]carbazole **2** as a white solid in 54% yield.

• 7,7'-(1,4-Phenylene)bis(*7H*-benzo[*c*]carbazol-10-ol) **2**

1H NMR (600 MHz, (CD3)2CO): *δ* 8.80 (d, *J* = 8.2 Hz, 2H), 8.31 (s, 2H), 8.17 (d, *J* = 2.1 Hz, 2H), 8.07 (d, *J* = 8.2 Hz, 2H), 7.92–7.96 (m, 6H), 7.75–7.78 (m, 4H), 7.58 (d, *J* = 8.9 Hz, 2H), 7.50 (dd, *J* = 8.3, 6.9 Hz, 2H), 7.14 (dd, *J* = 8.6, 2.4 Hz, 2H); 13C NMR (151 MHz, (CD3)2CO): *δ* 153.39, 139.70, 137.52, 135.41, 130.82, 130.43, 130.13, 129.80, 128.33, 127.95, 125.47, 123.91, 123.75, 115.93, 115.05, 112.67, 111.86, 107.78; DEPT-135 NMR (151 MHz, (CD3)2CO): *δ* 130.12, 129.80, 128.32, 127.95, 123.91, 123.74, 115.03, 112.67, 111.86, 107.76; HRMS (APCI): calcd for C38H24N2O2: m/z 541.1911 [M + H]+, found 541.1912.; IR (KBr): 3334, 3042, 2977, 2926, 1620, 1517, 1473, 1165, 831, 803 cm<sup>−</sup>1; mp: 198–199 ◦C.
