ChemistryMelting points were determined with a Kofler melting point apparatus and are uncorrected. 1H and 13C NMR spectra were obtained using Bruker 500 spectrometers. Tetramethylsilane (TMS) was used as an internal standard. δ in ppm related to TMS. Also the IR spectra were obtained on a Nicolet Magna FTIR 550 spectrophotometer (KBr discs). All reagents and solvents used in this study were obtained from Merck and Sigma-Aldrich. All new compounds displayed 1H NMR and 13C NMR spectra consistent with the assigned structure. Yields have not been optimized.General procedure for the synthesis of diphenylamine-2-carboxylic acids intermediate (compound 3) As shown in Fig. 2, 2, 4-dichlorobenzoic acid (3 mmol), 4-methoxy aniline (5 mmol), Cu (0. 2 mmol) and K2CO3 were poured into a flask containing DMF (30 ml) and stirred under reflux condition for 7h. Then the mixture was cooled to room temperature, mixed with water (1L) containing activated carbon and heated to boil. Subsequently, the mixture was filtered by Diatomite and then acidified with HCl to precipitate. For more purification, the resulting solid was recrystallized with ethanol (yield 85%).Yield 85%; m.p.; 206–208 °C; IR (KBr) cm−1; 3321 (N–H), 3008 (C–H), 2954 (OH), 2833, 1662 (CO), 1596, 1570, 1515, 1460, 1426, 1334, 1250, 1232, 1178,1156, 1102, 1038;1H NMR (DMSO-d6) δ in ppm: 3.76 (s, 3H, OCH3), 6.65 (dd, 1H, Ar–H), 6.77 (d, 1H, Ar–H), 6.95–7.02 (m, 2H, Ar–H), 7.18–7.24 (m, 2H, Ar–H), 7.88 (d, 1H, Ar–H), 9.47 (s, 1H, NH); m/z; 277.18 (100%, (M+)).General procedure for the synthesis of 6,9-Dichloro-2-methoxyacridine (compound 4).A Mixture of compound 3 (1 mmol) and POCl3 (4 mmol) was refluxed for 3 h. Then 500 ml of the water containing ice cubes was added. Subsequently, a little amount of liquid ammonia was added to the resulting mixture, the inorganic phase was extracted with chloroform and the solvents were evaporated. Finally, column chromatography was applied to achieve a pure product (yield 80%).Yield 88%; m.p.; 189–191 °C; IR (KBr) cm−1; 2925, 1633, 1554 (C = N), 1517, 1476, 1420, 1262, 1062, 1027 (C–N); 1H NMR (CDCl3): 8.48 (d, 1H, Ar–H), 8.16 (d, 1H, Ar–H), 8.05 (d, 1H, Ar–H), 7.52 (d, 1H, Ar–H), 7.44–7.49 (m, 2H, Ar–H), 3.97 (s, 3H, OCH3); m/z; 277.05 (100%, (M+)).General procedure for the synthesis of 6-chloro-2-methoxyacridine-9-thiol (compound 5)Compound 4 (1 mmol) was added to a flask containing hot ethanol and stirred for 30 min. Then thiourea (2 mmol) was added to the mixture and stirred for 10 min. Subsequently, the mixture was filtered and washed with NaHCO3 diluted solution. The resulting solid was dried and then washed with NaOH diluted solution and dried again. No more purification was applied to the product (yield 81%).Yield 92%; m.p.: 174–176 °C; IR (KBr) cm−1; 3026, 1954, 1548 (C = N), 1505, 1478, 1418, 1268, 1055, 1016 (C–N); 1H NMR (CDCl3): 8.39 (d, 1H, Ar–H), 8.17 (d, 1H, Ar–H), 8.03 (d, 1H, Ar–H), 7.52 (dd, 1H, Ar–H), 7.44–7.49 (m, 2H, Ar–H), 4.01 (s, 3H, OCH3); m/z; 275.12 (100%, (M+)).General procedure for the synthesis of 6-chloro-9-(ethynylthio)-2-methoxyacridine (compound 6)As shown in Fig. 3, a solution of compound 5 (1 mmol) in DMSO (7 ml) was stirred for 60 min at room temperature. Then propargyl bromide (2 mmol) was added dropwise to the mixture and stirred for 3h. After completion of the reaction, the mixture was poured into cool water and filtered. The yield of the solid product was 70%.Yield 70%; m.p.; 201–203 °C; IR (KBr) cm−1; 3218, 3028, 2974, 1648, 1555 (C = N), 1524, 1478, 1412, 1260, 1085, 1029 (C–N); 1H NMR (CDCl3): 8.49 (d, 1H, Ar–H), 8.16 (d, 1H, Ar–H), 8.05 (d, 1H, Ar–H), 7.52 (dd, 1H, Ar–H), 7.44–7.49 (m, 2H, Ar–H), 4.28 (s, 2H, CH2), 3.92 (s, 3H, OCH3), 3.06 (s, 1H, CH-Acetylene); m/z; 313.24 (100%, (M+)).General procedure for the synthesis of 9-(((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)thio)-6-chloro-2-methoxyacridine derivatives (compound 7a–m)To synthesize compounds 7a–p by click reaction, 1 mmol of compound 6 was added to a tube containing different benzyl halide derivatives (1. 1 mmol), sodium ascorbate (7 mol-%), NaN3 (1. 4 mmol), CuSO4. 5H2O (2 mol-%) and t-Butanol/water (1: 1) stirred for 24 h at room temperature. Then cool water containing cubed ice was added to the mixture and the resulting solid was filtered. Finally recrystallization (ethyl acetate/petroleum ether) was performed for more purification of solid product (90–95%).9-((1-benzyl-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7a)Yellow solid; yield: 91%, mp = 149–151 °C. IR (KBr): 3126, 1684, 1628, 1215, 813 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.515 (d, J = 15 Hz, 1H5, CH)), 8.17 (s, 1H4, CH), 8.05 (d, J = 10 Hz, 1H6, CH (quinoline)), 7.71 (s, 1H1, CH (quinoline), 7.45 (m, 1H11,1CH (benzen)), 7.41–7. 44 (m, 1H10, CH (benzen)), 7.25–7.30 (m, 1H12, CH (benzen), 6.88 (d, J = 10 Hz, 2H2, 3, CH (quinoline)), 6.35 (s, 1H, CH (triazol)), 5.16 (s, 2H9, CH2), 4.13 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 154.3, 149.9, 140.0, 133.9, 131.6, 130.7, 129.2, 128.8, 128.5, 128.2, 127.8, 127.8, 126.9, 126.4, 121.5, 101.6, 55.8, 53.9, 31.0 ppm. MS (70 eV): m/z = 446 (M +); Anal. Calcd for C24H19ClN4OS: C: 64. 50, H: 4. 29, N: 12. 54, Found: C: 64. 46, H: 4. 31, N: 12. 59.9-((1-(3-methoxybenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7b)Yellow solid; yield: 93%, mp = 132–134 °C. IR (KBr): 3167, 1628, 1475, 1218, 809 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.54 (d, J = 10 Hz, 1H2, CH)), 8.17 (s, 1H4, CH), 8.04 (d, J = 10 Hz, 1H3, CH (quinoline)), 7.71 (s, 1H1, CH (quinoline), 7.42–7.44 (dd, 2H5, 6, 2CH (quinoline)), 7.17–7.21 (t, 1H11, CH (benzen)), 7.10–7.15 (m, 1H11, CH (benzen), 6.82–6.85 (dd, 1H12, CH (benzen)), 6.56 (s, 1H, CH (triazol)), 6.44–6.45 (d, 1H10, CH (benzen)), 6.43 (s, 1H9, CH (benzen), 5.13 (s, 2H9, CH2), 4.13 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3 (benzene)), 2.29–3.75 (s, 3H, oCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 159.9, 158.9, 135.2, 130.3, 128.6, 128.5, 128.2, 126.8, 126.3, 125.6, 122.4, 120.0, 117.2, 114.2, 113.8, 113.6, 102.2, 55.8, 55.4, 31.0, 29.8 ppm. MS (70 eV): m/z = 476 (M +); Anal. Calcd for C25H21ClN4O2S: C: 62. 95, H: 4. 44, N: 11. 75, Found: C: 62. 98, H: 4. 42, N: 11. 71.9-((1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7c)Yellow solid; yield: 94%, mp = 106–109 °C. IR (KBr): 3327, 1663, 1594, 1214, 812 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.51 (d, J = 10 Hz, 1H5, CH)), 8.16 (s, 1H4, CH), 8.04 (d, J = 5 Hz, 1H6, CH (quinoline)), 7.68 (s, 1H1, CH (quinoline), 7.41–7.44 (dd, 2H2, 3, 2CH (quinoline)), 6.845 (d, J = 10 Hz, 2H10, 2CH (benzen)), 6.78 (d, J = 10 Hz, 2H11, 2CH (benzen)), 6.31 (s, 1H, CH (triazol)), 5.08 (s, 2H9, CH2), 4.11 (s, 2H7, S (CH2)), 3.92 (s, 3H, OCH3 (benzene)), 3.80 (s, 3H, OCH3 (quinoline)) ppm. 13C NMR (100 MHz, CDCl3): δ = 159.9, 158.5, 140.6, 135.1, 133.8, 131.5, 131.1, 129.4, 128.5, 128.2, 127.8, 126.4, 126.2, 125.9, 123.2, 121.4, 116.7, 114.5, 112.9, 101.9, 55.9, 55.4, 53.5, 31.0 ppm. MS (70 eV): m/z = 476 (M +); Anal. Calcd for C25H21ClN4O2S: C: 62. 95, H: 4. 44, N: 11. 75, Found: C: 62. 99, H: 4. 41, N: 11. 79.6-chloro-2-methoxy-9-(((1-(2-methylbenzyl)-1H-1,2,3-triazol-4yl) methyl)thio)acridine (7d)Yellow solid; yield: 93%, mp = 143–145 °C. IR (KBr): 3229, 1675, 1537, 1214, 803 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.515 (d, J = 10 Hz, 1H5, CH)), 8.16 (s, 1H4, CH), 8.04 (d, J = 10 Hz, 1H3, CH (quinoline)), 7.67 (s, 1H1, CH (quinoline), 7.40–7.43 (dd, 2H2, 3, 2CH (quinoline)), 7.25–7.32 (m, 4H10, 11, 4CH (benzen)), 6.37 (s, 1H, CH (triazol)), 5.48 (s, 2H9, CH2), 4.15 (s, 2H7, S (CH2)), 3.92 (s, 3H, OCH3 (quinoline)). 2.01 (s, 3H, CH3)) ppm. 13C NMR (100 MHz, CDCl3): δ = 157.9, 150.6, 143.9, 136.5, 135.2, 132.2, 131.2, 130.9, 130.5, 130.2, 129.9, 128.9, 128.5, 126.2, 122.1, 118.3, 101.9, 56.0, 4.74, 3.02, 29.4 ppm. MS (70 eV): m/z = 460 (M +); Anal. Calcd for C25H21ClN4OS: C: 65. 14, H: 4. 59, N: 12. 15, Found: C: 65. 17, H: 4. 61, N: 12. 11.6-chloro-2-methoxy-9-(((1-(3-methylbenzyl)-1H-1,2,3-triazol-4-yl) methyl)thio)acridine (7e)Yellow solid; yield: 94%, mp = 140–141 °C. IR (KBr): 3145, 1645, 1412, 1215, 835 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.53 (d, J = 10 Hz, 1H2, CH)), 8.18 (s, 1H4, CH), 8.06 (d, J = 10 Hz, 1H3, CH (quinoline)), 7.71 (s, 1H1, CH (quinoline), 7.43 (d, J = 5 Hz, 2H5, 6, 2CH (quinoline)), 7.16–7.18 (m, 1H12, CH (benzen)), 7.10–7.15 (m, 1H11, CH (benzen), 6.84 (s, 1H10, CH (benzen)), 6.66–6.67 (d, 1H13, CH (benzen)), 6.37 (s, 1H, CH (triazol)), 5.12 (s, 2H9, CH2), 4.13 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3 (quinoline)), 2.29 (s, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 150.0, 148.3, 140.1, 138.9, 133.8, 130.8, 130.2, 129.6, 129.1, 128.8, 128.6, 127.8, 126.2, 125.0, 124.5, 121.6, 102.0, 55.9, 54.0, 31.1, 21.4 ppm. MS (70 eV): m/z = 460 (M +); Anal. Calcd for C25H21ClN4OS: C: 65. 14, H: 4. 59, N: 12. 15, Found: C: 65. 15, H: 4. 59, N: 12. 13.6-chloro-2-methoxy-9-(((1-(4-methylbenzyl)-1H-1,2,3-triazol-4-yl)methyl)thio) acridine (7f.)Yellow solid; yield: 93%, mp = 130–133 °C. IR (KBr): 3126, 1629, 1471, 1217, 814 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.53 (d, J = 10 Hz, 1H5, CH)), 8.17 (s, 1H4, CH), 8.05 (d, J = 15 Hz, 1H6, CH (quinoline)), 7.71 (s, 1H1, CH (quinoline), 7.435 (d, J = 5 Hz, 1H3, CH (quinoline)), 7.415 (d, J = 5 Hz, 1H2, CH (quinoline)), 7.06–7.08 (d, 2H10, 2CH (benzen)), 6.78–6.80 (d, 2H11, 2CH (benzene)), 6.34 (s, 1H, CH (triazol)), 5.12 (s, 2H9, CH2), 4.13 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3 (quinoline)), 2.33 (s, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 153.5, 151.0, 149.9, 143.9, 140.0, 139.4, 138.9, 131.6, 129.5, 129.4, 129.0, 128.2, 127.7, 127.4, 126.5, 124.6, 121.8, 102.2, 55.7, 53.4, 21.4 ppm. MS (70 eV): m/z = 460 (M +); Anal. Calcd for C25H21ClN4OS: C: 65. 14, H: 4. 59, N: 12. 15, Found: C: 65. 16, H: 4. 61, N: 12. 12.9-((1-(3-fluorobenzyl) -1H-1,2,3-triazol-4-yl)methylthio) -6-chloro-2-methoxyacridine (7g)Yellow solid; yield: 94%, mp = 140–144 °C. IR (KBr): 3129, 1655, 1412, 1214, 833 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.57 (s, 1H4, CH (quinoline)), 8.16 (bd, 2H10, 11, 2CH (benzen)), 7.72 (s, 1H1, CH (quinoline)), 7.44 (d, J = 10 Hz, 2H5, 6, 2CH (quinoline), 6.98–7.03 (t, 2H12, 13, 2CH (benzene)), 6.69 (d, J = 10 Hz, 2H3, 2CH (benzen)), 6.63 (d, J = 10 Hz, 2H2, 2CH (benzen)), 6.61 (s, 1H, CH (triazol)), 5.15 (s, 2H9, CH2), 4.14 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3 (quinoline)). 2.01 (s, 3H, CH3)) ppm. 13C NMR (100 MHz, CDCl3): δ = 161.7, 160.0, 158.5, 152.3, 151.1, 149.1, 140.0, 131.1, 130.8, 129.7, 128.5, 127.8, 126.7, 123.3, 120.4, 116.2, 115.9, 115.2, 101.1, 56.0, 39.0, 29.7 ppm. MS (70 eV): m/z = 464 (M +); Anal. Calcd for C24H18ClFN4OS: C: 62. 00, H: 3. 90, N: 12. 05, Found: C: 62. 03, H: 3. 88, N: 12. 07.9-((1-(4-fluorobenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7h)Yellow solid; yield: 92%, mp = 168–170 °C. IR (KBr): 3224, 1662, 1408, 1214, 829 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.505 (d, J = 15 Hz, 1H5, CH)), 8.15 (s, 1H4, CH), 8.02 (d, J = 10 Hz, 1H6, CH (quinoline)), 7.66 (s, 1H1, CH (quinoline), 7.415 (d, J = 15 Hz, 2H10, 2CH (benzen)), 7.95 (t, 2H11, 2CH (benzen)), 6.84–6.87 (dd, 2H2, 3, 2CH (quinoline)), 6.31 (s, 1H, CH (triazol)), 5.11 (s, 2H9, CH2), 4.12 (s, 2H7, S (CH2)), 3.92 (s, 3H, OCH3 (quinoline)) ppm. 13C NMR (100 MHz, CDCl3): δ = 164.0, 161.6, 160.6, 158.4, 148.3, 146.9, 146.5, 137.9, 135.0, 131.6, 130.7, 129.8, 129.7, 128.7, 128.2, 127.8, 126.3, 116.3, 116.1, 104.8, 101.9, 55.9, 53.2, 30.9 ppm. MS (70 eV): m/z = 464 (M +); Anal. Calcd for C24H18ClFN4OS: C: 62.00, H: 3. 90, N: 12. 05, Found: C: 62. 01, H: 3. 92, N: 12. 01.9-((1-(2-chlorobenzyl)-1H-1,2,3-triazol-4-yl)methylthio) -6-chloro-2-methoxyacridine (7i)Yellow solid; yield: 93%, mp = 140–142 °C. IR (KBr): 3126, 1629, 1602, 1212, 811 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.53 (d, J = 10 Hz, 1H5, CH)), 8.17 (s, 1H4, CH), 8.06 (d, J = 10 Hz, 1H6, CH (quinoline)), 7.71–7.72 (s, 1H1, CH (quinoline), 7.41–7.44 (dd, 2H2, 3,2CH (quinoline)), 7.33–7.35 (m, 1H10, CH (benzen)), 7.30–7.32 (m, 1H12, CH (benzen), 7.16–7.25 (m, 1H11, CH (benzen)), 6.81–6.83 (d. 1H13, CH (benzene)), 6.50 (s, 1H, CH (triazol)), 5.30 (s, 2H9, CH2), 4.16 (s, 2H7, S (CH2)), 3.93 (s, 3H, OCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 157.0, 155.2, 148.9, 149.2, 140.0, 143.9, 132.0, 131.8, 130.7, 130.4, 130.3, 130.2, 129.9, 128.6, 127.8, 127.7, 118.4, 101. , 56.1, 31.4, 30.1 ppm. MS (70 eV): m/z = 480 (M +); Anal. Calcd for C24H18Cl2N4OS: C: 59. 88, H: 3. 77, N: 11. 64, Found: C: 59. 92, H: 3. 79, N: 11. 60.9-((1-(2-bromobenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7j)Yellow solid; yield: 95%, mp = 158–160 °C. IR (KBr): 3114, 1651, 1535, 1214, 816 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.55 (d, J = 10 Hz, 1H5, CH)), 8.19 (s, 1H4, CH), 8.05 (d, J = 10 Hz, 1H6, CH (quinoline)), 7.69 (s, 1H1, CH (quinoline), 7.39–7.45 (m, 4H10, 11, 12, 13, 4CH (benzene)), 6.74 (d, 2H2, 3, 2CH (quinoline)), 6.33 (s. 1H, CH (triazol)), 5.09 (s, 2H9, 2CH), 4.14 (s, 2H7, S (CH2)), 3.93 (s, 3H, OCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 154.2, 150.0, 149.6, 148.2, 147.3, 142.4, 140.0, 133.0, 132.4, 129.4, 128.3, 127.8, 126.6, 124.2, 124.1, 123.0, 118.9, 108.1, 101.8, 55.9, 30.0, 85.0, 20.2 ppm. MS (70 eV): m/z = 524 (M +); Anal. Calcd for C24H18BrClN4OS: C: 54. 82, H: 3. 45, N: 10. 65, Found: C: 54. 86, H: 3. 43, N: 10. 64.9-((1-(2,3-dichlorobenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7k)Yellow solid; yield: 94%, mp = 178–180 °C. IR (KBr): 3242, 1641, 1399, 1215, 813 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.525 (d, J = 5 Hz, 1H5, CH)), 8.15 (s, 1H4, CH), 8.03 (d, J = 10 Hz, 1H6, CH (quinoline)), 7.68 (s, 1H1, CH (quinoline), 7.45–7.40 (m, 2H10, 12, 2CH (benzen)), 7.11 (t, 1H11, 1CH (benzen)), 6.605 (d, J = 5 Hz, 2H2, 3, 2CH (quinoline)), 6.49 (s, 1H, CH (triazol)), 5.30 (s, 2H9, CH2), 4.16 (s, 2H7, S (CH2)), 3.92 (s, 3H, OCH3) ppm. 13C NMR (100 MHz, CDCl3): 158.5, 151.2, 1467.0, 146.6, 137.8, 135.0, 134.7, 134.1, 133.9, 131.7, 131.7, 131.0, 130.7, 128.7, 128.3, 128.0, 127.9, 127.7, 126.3, 122.0, 101.896, 55.9, 51.6, 30.8 ppm. MS (70 eV): m/z = 514 (M +); Anal. Calcd for C24H17Cl3N4OS: C: 55. 88, H: 3. 32, N: 10. 86, Found: C: 55. 90, H: 3. 33, N: 10. 82.9-((1-(2,4-dichlorobenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2-methoxyacridine (7l)Yellow solid; yield: 95%, mp = 175–178 °C. IR (KBr): 3250, 1662, 1402, 1214, 816 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.52 (d, J = 10 Hz, 1H5, CH)), 8.15 (s, 1H4, CH), 8.035 (d, J = 5 Hz, 1H6, CH (quinoline)), 7.66 (s, 1H1, CH (quinoline), 7.43 (d, J = 5 Hz, 1H3, CH (quinoline)), 7.39 (d, J = 5 Hz, 1H2, CH (quinoline)), 7.35 (s, 1H10, CH (benzen)), 7.15–7.18 (dd, 1H11, CH (benzene)), 6.75–6.77 (dd, 1H12, CH (benzene)), 6.43 (s, 1H, CH (triazol)), 5.23 (s, 2H9, CH2), 4.15 (s, 2H7, S (CH2)), 3.91 (s, 3H, OCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.4, 153.8, 150.3, 149.9, 146.9, 146.4, 143.9, 131.6, 131.0, 129.9, 128.6, 128.3, 128.0, 127.7, 126.3, 121.8, 110.1, 101.85, 6.84, 50.5, 30.8 ppm. MS (70 eV): m/z = 514 (M +); Anal. Calcd for C24H17Cl3N4OS: C, 55. 88, H: 3. 32, N: 10. 86, Found: C, 55. 91, H: 3. 35, N: 10. 89.9-((1-(2-nitrobenzyl)-1H-1,2,3-triazol-4-yl)methylthio)-6-chloro-2methoxyacridine (7m)Yellow solid; yield: 94%, mp = 200–203 °C. IR (KBr): 3246, 1653, 1509, 1214, 837 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.56 (d, J = 10 Hz, 1H5, CH (quinoline)), 8.14 (s, 1H4, CH (quinoline)), 8.08 (d, J = 10 Hz, 1H6, CH (quinoline)), 8.06–8.08 (t, 1H3, CH (quinoline), 7.44 (s, 1H1,, 1CH (quinoline)), 7.66 (t, 1H2, 1CH (quinoline)), 7.51 (t, 2H10, 2CH (benzene)), 7.40 (t, 2H11, 2CH (benzene)), 6.69 (s, 1H, CH (triazol)), 5.55 (s, 2H9, CH2), 4.20 (s, 2H7, S (CH2)), 3.95 (s, 3H, OCH3 (quinoline)). 2.01 (s, 3H, CH3)) ppm. 13C NMR (100 MHz, CDCl3): δ = 158.5, 157.3, 154.0, 150.0, 149.2, 147.3, 145.1, 140.0, 134.4, 131.7, 130.3, 130.1, 129.9, 129.8, 129.1, 128.3, 127.8, 126.3, 125.5, 101.9, 56.1, 50.7, 36.0 ppm. MS (70 eV): m/z = 491 (M +); Anal. Calcd for C24H18ClN5O3S: C: 58. 60, H: 3. 69, N: 14. 24, Found: C: 58. 62, H: 3. 71, N: 14. 19.9-((1-(4-nitrobenzyl)-1H-1,2,3-triazol-4-yl)methylthio) -6-chloro-2-methoxyacridine (7n)Yellow solid; yield: 95%, mp = 201–203 °C. IR (KBr): 3141, 1659, 1607, 1214, 829 cm−1. 1H-NMR (500 MHz, CDCl3): δ = 8.56 (d, J = 10 Hz, 1H5, CH)), 8.15 (s, 1H4, CH), 8.135 (d, J = 5 Hz, 1H6, CH (quinoline)), 8.13 (s, 1H1, CH (quinoline), 7.74 (d, J = 5 Hz, 2H2, 3, 2CH (quinoline)), 7.45 (d, 2H10, 2CH (benzen)), 6.99–7.01 (d, 2H11, 2CH (benzene)), 6.38 (s, 1H, CH (triazol)), 5.24 (s, 2H9, CH2), 4.18 (s, 2H7, S (CH2)), 3.94 (s, 3H, OCH3 (quinoline)) ppm. 13C NMR (100 MHz, CDCl3): δ = 157.6, 152.2, 148.5, 145.2, 140.9, 138.8, 138.5, 134.9, 132.9, 131.6, 128.8, 128.5, 126.2, 125.525 125.2, 124.1, 120.2, 110.8, 56.1, 51.1, 30.1 ppm. MS (70 eV): m/z = 491 (M +); Anal. Calcd for C24H18ClN5O3S: C: 58. 60, H: 3. 69, N: 14. 24, Found: C: 58. 65, H: 3. 68, N: 14. 24.Screening of α-glucosidase inhibitory activityThe assay was performed according to previously reported procedures20,21,22.Enzyme kinetic studiesThe mode of inhibition of the most active compound 7h, identified with the lowest IC50, was investigated against an α-glucosidase activity with different concentrations of p-nitrophenyl α-D-glucopyranoside (1–16 mM) as substrate in the absence and presence of 7h at different concentrations (0, 24.5, 49, and 98 µM). A Lineweaver–Burk plot was generated to identify the type of inhibition and the Michaelis–Menten constant (Km) value was determined from the plot between the reciprocal of the substrate concentration (1/[S]) and reciprocal of enzyme rate (1/V) over various inhibitor concentrations. The experimental inhibitor constant (Ki) value was constructed by secondary plots of the inhibitor concentration [I] versus Km8.Docking studyMaestro Molecular Modeling platform (version 12.8) by Schrödinger, LLC was performed to uncover out the interaction mode of the best active structures over α-glycosidase enzyme20,21. The protein 3D structure was implemented according to our previous study as a result of homology modeled based on high structural identity and sequence similarity with α-glucosidase (α-1,4-glucosidase) from S. cerevisiae (PDB code 3A4A).The 2D representation of the synthesized compounds were drawn in Marvin 15.10.12.0 program (http://www.chemaxon.com) and converted into pdb file. The Protein Preparation Wizard and the LigPrep module were used to prepare protein and ligand structure properly. The missing side chains of the proteins were filled using the Prime tool and missing residues were updated.The accurate side-chain and backbone flexibility during ligand binding at the active site of α-glycosidase enzyme were predicted by IFD method using Glide software (Schrödinger LLC 2018, USA). As the kinetic study revealed competitive type inhibition mechanism against enzyme, the α-glucosidase active site was used to generate the grid for IFD calculation. The maximum 20 poses with receptor and ligand van der waals radii of 0.7 and 0.5, respectively considered. Residues within 5 Å of the α-D-glucose at the active site were refined followed by side-chain optimization. Structures whose Prime energy is more than 30 kcal/mol are eliminated based on extra precious Glide docking.Molecular dynamic (MD) simulationThe molecular dynamic (MD) simulation of this study was performed by using the Desmond v5.3 module (https://www.schrodinger.com/products/desmond) implemented in the Maestro interface (from Schrödinger 2018‐4 suite)23. The appropriate pose for the MD simulation procedure of the compounds was obtained by the IFD method. In order to build the system for MD simulation, the protein–ligand complexes were solvated with SPC explicit water molecules and placed in the center of an orthorhombic box of appropriate size in the Periodic Boundary Condition. Sufficient counter‐ions and a 0.15 M solution of NaCl were also utilized to neutralize the system and to simulate the real cellular ionic concentrations, respectively. The MD protocol involved minimization, pre-production, and finally, production MD simulation steps. In the minimization procedure, the entire system was allowed to relax for 2500 steps by the steepest descent approach. Then the temperature of the system was raised from 0 to 300 K with a small force constant on the enzyme in order to restrict any drastic changes. MD simulations were performed via NPT (constant number of atoms, constant pressure i.e. 1.01325 bar, and constant temperature i.e. 300 K) ensemble. The Nose‐Hoover chain method was used as the default thermostat with a 1.0 ps interval and Martyna‐Tobias‐Klein as the default barostat with a 2.0 ps interval by applying isotropic coupling style. Long‐range electrostatic forces were calculated based on the Particle-mesh-based Ewald approach with the cut off radius for Columbia forces set to 9.0 Å. Finally, the system was subjected to produce MD simulations for 100 ns for the protein–ligand complex. During the simulation, every 1000 ps of the actual frame was stored. The dynamic behavior and structural changes of the systems were analyzed by the calculation of the root mean square deviation (RMSD) and RMSF. Subsequently, the energy-minimized structure calculated from the equilibrated trajectory system was evaluated to investigate each ligand–protein complex interaction.