## 2 Materials and Methods
### Synthetic Methods: Experimental Protocols and Spectral Data  
#### 2.3.1 Synthesis of Lepidine Methyl Tosyllate  
To a solution of lepidine **(1)** (1.0800 g, 7.5 mmol) in dry toluene (20 mL), methyl 4-methylbenzenesulfonate (methyl toylate) **(2)** (2.4800 g, 7.5 mmol) was added. The quaternary salt was obtained in 14 h reflux. The resulting crystals were filtered and washed with toluene to remove unreacted lepidine and dried over P\({}_{2}\)O\({}_{5}\) at room temperature, with a yield of 84%.  
IR [KBr]: \(\gamma\)[cm\({}^{-1}\)] 2919, 1620, 1607, 1591, 1531, 1494, 1442, 1402, 1384, 1369, 1348, 1267, 1220, 1191, 1117, 1033, 963, 828, 772.  
The obtained salt was applied directly for the synthesis of SQ.  
3.2 Synthesis of SQ (5) (E)-4-(2-(2-Hydroxynaphthalen-1-yl)vinyl)-1-methylquinolin-1-ium 4-Methylbenzenesulfonate  
Lepidine methyl toylate **(3)** (0.50 g, 1.5 mmol) and 2-hydroxynaphthaldehyde **(4)** (0.26 g, 1.5 mmol) were dissolved in 20 mL of dry benzene. Piperidine (0.01 g, 0.15 mmol), glacial acetic acid (0.02 g, 0.3 mmol), and 5 mL of dimethylformamide were added, and the reaction mixture was refluxed for 28 h (Warning: Benzene can cause cancer or birth defects!). Then, the crystals were filtered off, washed with benzene, dried at room temperature, and recrystallized from methanol. The yield of orange needle crystals was 71.4%, with a melting point of 252.6 \({}^{\circ}\)C (DSC) (Figure 2).  
H NMR: 11.12 (broad s, 1H, naphtol OH), 9.27 (d, J = 6.5, 1H, quinolinium H2), 8.66 (d, J = 6.5, 1H, quinolinium H3), 8.63 (d, J = 8.4, 1H, quinolinium H5), 8.59 (s, 2H, H\(\alpha\), H\(\beta\)), 8.46-8.38 (m, J = 8.4, 7.7, 2H, quinolinium H8, naphtol H8\({}^{\prime}\)), 8.23 (m, 1H, quinolinium H7), 8.02 (t, J = 7.7, 1H, quinolinium H6), 7.90 (d, J = 8.9, 1H, naphtol H5\({}^{\prime}\)), 7.87 (d, J = 7.5, 1H, naphtol H4\({}^{\prime}\)), 7.58 (ddd, J = 8.4, 6.9, 1.2, 1H, naphtol H7\({}^{\prime}\)), 7.51 (d, J = 8.1, 2H, tosylate H2\({}^{\prime\prime}\), H6\({}^{\prime\prime}\)), 7.41 (t, J = 7.4, 1H, naphtol H6\({}^{\prime}\)), 7.35 (d, J = 8.9, 1H, naphtol H3\({}^{\prime}\)), 7.10 (d, J = 7.9, 2H, Ar, tosylate H3\({}^{\prime\prime}\), H5\({}^{\prime\prime}\)), 4.54 (s, 3H, quinolinium N-CH\({}_{3}\)), 2.26 (s, 3H, CH\({}_{3}\) tosylate).  
C NMR: 157.24 (naphtol C2\({}^{\prime}\)), 153.92 (quinolinium C4), 148.32 (quinolinium C2), 146.14 (tosylate C1\({}^{\prime\prime}\)), 139.11 (quinolinium C8\({}_{\alpha}\)), 138.12 (tosylate C4\({}^{\prime\prime}\)), 136.74 (C\(\beta\)), 135.21 (quinolinium C7), 133.30 (naphtol C8\({}^{\prime}\)a), 132.92 (naphtol C5\({}^{\prime}\)), 129.88 (quinolinium C6), 129.24 (naphtol C4\({}^{\prime}\)), 128.55 (naphtol C4\({}^{\prime}\)a), 128.53 (tosylate C3\({}^{\prime\prime}\), C5\({}^{\prime\prime}\)), 127.99 (naphtol C7\({}^{\prime}\)), 126.55 (quinolinium C4a), 126.01 (quinolinium C5), 125.96 (tosylate C2\({}^{\prime\prime}\), C6\({}^{\prime\prime}\)), 123.92 (naphtol C6\({}^{\prime}\)), 123.80 (C\(\alpha\)), 123.32 (naphtol C8\({}^{\prime}\)), 119.88 (quinolinium C8), 119.00 (naphtol C3\({}^{\prime}\)), 116.58 (quinolinium C3), 114.57 (naphtol C1\({}^{\prime}\)), 44.97 (quinolinium N-CH\({}_{3}\)), 21.23 (tosylate CH\({}_{3}\)).  
HESI, m/z calculated for C\({}_{22}\)H\({}_{18}\)NO\({}^{+}\) = 312.384, found 312.142 (mass error 2.42 ppm).