## 4 Experimental
### Chemistry
#### 4.1.3 Synthesis of [1,2,4]triazoleolo[4,3-\(a\)]quinolin-2-ium-4-carboxylates (**7**-9**)  
Isoxazolo[3,4-\(b\)]quinolin-3(1\(H\))-one (354 mg, 1.9 mmol) was dissolved in methanol (20 mL), then 35% water solution of formaldehyde (0.60 mL, 7.6 mmol) and 0.85 mmol of the corresponding amine was added (piperazine, homopiperazine, \(N\),\(N^{\prime}\)-dimethylethyl)lecmine or \(N\),\(N\)'-dibenzylethylenediamine). The mixture was stirred for 5 min at room temperature. The progress of the reaction was monitored by TLC. The mixture was evaporated under reduced pressure when the red color of the substrate disappeared. The resulting solid was washed with acetone (3 \(\times\) 5 mL). In the case of compound 7, an additional equivalent (0.85 mmol) of piperazine was added since red isoxazolol(3,4-\(b\))quinolin-3(1\(H\))-one was still present in the reaction mixture after 24 h of stirring. 1\(H\)-Spiro[1,2,4]triazoleol[4,3-\(a\)]quinoline-2,1'-piperazin]-2-ium-4-carboxylate (7). Yield: 43% (0.232 g); m.p. 207-209 \({}^{\circ}\)C; 1\({}^{\prime}\)H NMR (400 MHz, CD\({}_{3}\)OD): \(\delta\) = 3.18-3.35 (m, 2H, CH\({}_{2}\)), 3.52-3.58 (m, 2H, CH\({}_{2}\)), 5.91 (s, 4H, CH\({}_{2}\)), 7.21 (d, 2H, J = 8.1 Hz, CH), 7.35 (t, 2H, J = 8.1 Hz, CH), 7.87-7.72 (m, 2H, CH), 8.10 (s, 2H, CH); IR (KBr): 3408, 3264, 3040, 2997, 2956, 2918, 2848, 1633, 1589, 1569, 1541. 1457, 1353, 1297, 1223, 806, 761 cm\({}^{-1}\); MS (ESI) m/z: 285 [M+1]\({}^{+}\). (2R,2\({}^{\prime}\)S)-2,2'-(Ethane-1,2-diyl)bis(2-methyl-1,2-dihydro-[1,2,4]triazoleol[4,3-\(a\)]quinolin-2-ium-4-carboxylate) (8a). The product, which was obtained in the form of inner salt, was quantitatively converted into a hydrochloride form to increase its solubility. Hence, prior to spectral analysis, the solid was dissolved in MeOH, acidified to pH 3-4 with methanolic HCl solution and the resulting solution was evaporated under reduced pressure to give 2,2'-(ethane-1,2-diyl)bis(4-carboxy-2-methyl-1,2-dihydro-[1,2,4]triazoleol[4,3-\(a\)]quinolin-2-ium) dichloride. Yield: 72% (0.340 g); m.p. 237-239 \({}^{\circ}\)C; 1\({}^{\prime}\)H NMR (400 MHz, DMSO-D\({}_{6}\)): \(\delta\) = 3.33 (s, 3H, CH\({}_{3}\)), 4.51-4.60 (m, 4H, CH\({}_{2}\)), 6.04 (d, J\({}^{2}\) = 8.9 Hz, 2H, CH\({}_{2}\)), 6.20 (d, J\({}^{2}\) = 8.9 Hz, 2H, CH\({}_{2}\)), 7.22 (d, 2H, J = 7.9 Hz, CH), 7.43 (t, 2H, J = 7.9 Hz, CH), 7.84 (t, 2H, J = 7.9 Hz, CH), 8.06 (d, 2H, J = 7.9 Hz, CH), 8.80 (s, 2H, CH); IR (KBr): 3438, 3055, 3021, 2967, 1723, 1616, 1571, 1541, 1456, 1313, 1222, 1200, 1167, 784, 765, 746, 705 cm\({}^{-1}\); MS (ESI) m/z: 243 [(M+2)/2]\({}^{+}\), 485 [M+1]\({}^{+}\). (2R,2\({}^{\prime}\)S)-2,2'-(Ethane-1,2-diyl)bis(2-benzyl-1,2-dihydro-[1,2,4]triazoleol[4,3-\(a\)]quinolin-2-ium-4-carboxylate) (8b). Yield: 79% (0.49 g); m.p. 156-157 \({}^{\circ}\)C; 1\({}^{\prime}\)H NMR (400 MHz, CD\({}_{3}\)OD): \(\delta\) = 4.61-4.76 (m, 4H, CH\({}_{2}\)), 4.95 (s, 4H, CH\({}_{2}\)), 6.08 (d, J\({}^{2}\) = 9.6 Hz, 1H, CH\({}_{2}\)), 6.19 (d, J\({}^{2}\) = 9.6 Hz, 1H, CH\({}_{2}\)), 7.12-7.17 (m, 8H, CH), 7.33 (t, 2H, J = 7.7 Hz, CH), 7.59-7.62 (m, 4H, CH), 7.67 (t, 2H, J = 8.3 Hz, CH), 7.71 (d, 2H, J = 7.7 Hz, CH), 8.23 (s, 2H, CH); IR (KBr): 3407, 3064, 3020, 1627, 1586, 1570, 1541, 1458, 1376, 1224, 807, 759, 705, 669, 595 cm\({}^{-1}\); MS (ESI) m/z: 319 [(M+2)/2]\({}^{+}\), 637 [M+1]\({}^{+}\); elemental analysis: calcd. (%) for (%) C\({}_{3}\)R\({}_{3}\)I\({}_{3}\)I\({}_{8}\)O\({}_{4}\)X\({}_{5}\)H\({}_{2}\)O; C 62.80, H 5.82, N 11.56; found C 62.65, F 5.79, N 11.70.