To a solution of benzoic hydrazide (0.110g, 0.830 mmol) in absolute ethanol (7 mL) containing 2 drops of 37% hydrochloric acid was added to 2-pyridine carboxaldehyde (0.093g, 0.870 mmol). The mixture was stirred at 30oC for 24hrs. The reaction mixture was poured into cold water and neutralized with 10% aqueous sodium bicarbonate solution. Using a stirring rod to scratch the beaker resulted in formation of a white precipitate, which was filtered off and dried, (0.131g, 70%). M.p.: 166-168oC; (Lit m.p. 166-168oC).16 1H NMR (δH; 400 MHz, DMSO-d6): 12.09 (s, 1H), 8.62 (d, 1H, J = 9.6Hz), 8.49 (s, -N=CH), 7.98 (m, 4H), 7.61 (m, 3H), 7.42 (t, 1H, J = 12.4Hz); IR (ATR ZnSe crystal): υ 3403 (N-H), 2982, 1666 (C=O), 1576 (C=N), 1290 (C-O), 1141, 1076, 776 cm-1.
5.2.2 Synthesis of cocrystals
5.2.2.1 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone octanoic acid hydrate (1:1), 20OCT
20 (0.030g, 0.133 mmol) and octanoic acid (0.038g, 0.266 mmol) were added to a beaker along with 4 mL of ethanol. The mixture was heated gently until components were in solution. Colorless plates suitable for X-ray diffraction were obtained after twenty days via slow evaporation of ethanol. M.p.: 72-74oC. IR (KBr pellet): υ 2533 cm
-1, 1951 cm-1 (O-H…N, br), 1667 cm-1 (C=O acid, s).
5.2.2.2 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone hexanoic acid hydrate (1:1), 20HEX
20 (0.030g, 0.133 mmol) was dissolved in 4 mL of ethanol and added to beaker containing hexanoic acid (0.031g, 0.266 mmol) in 4 mL of ethanol. The mixture was left at ambient temperature to undergo slow evaporation. After ten days colorless plates were obtained. M.p.: 77-79oC. IR (KBr pellet): υ 2525 cm-1, 1900 cm-1 (O-H…N, br), 1675 cm-1 (C=O acid, s).
5.2.2.3 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone fumaric acid (1:1), 20FUM
20 (0.0565g, 0.245 mmol) was dissolved in 4 mL of ethanol and added to beaker containing fumaric acid (0.029g, 0.245 mmol) in 4 mL of ethanol. The mixture was allowed to slowly evaporate at room temperature. After seven days light orange prism were obtained. M.p.: 208-210oC. IR (KBr pellet): υ 2510 cm-1, 1884 cm-1 (O-H…N, br), 1674 cm-1 (C=O acid, s).
5.2.2.4 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone adipic acid hydrate (1:1), 20ADI
5.2.2.5 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone suberic acid hydrate (1:1), 20SUB
A solution of 20 (0.025g, 0.109 mmol) in 4 mL of ethanol was mixed with a solution of suberic acid (0.019g, 0.109 mmol) in 4 mL of ethanol and allowed to stand at room temperature for slow evaporation. Colorless prisms were obtained after eleven days. M.p.: 134-136oC. IR (KBr pellet): υ 2461 cm-1, 1953 cm-1 (O-H…N, br), 1679 cm-1 (C=O, s).
5.2.2.6 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone sebacic acid dihydrate (1:1), 20SEB
A solution of 20 (0.030g, 0.133 mmol) in 4 mL of nitromethane was mixed with a solution of suberic acid (0.027g, 0.133 mmol) in 4 mL of nitromethane and allowed to stand at room temperature for slow evaporation. Colorless prisms were obtained after five days. M.p.: 105-106oC. IR (KBr pellet): υ 2561 cm-1, 1933 cm-1 (O-H…N, br), 1693 cm-1 (C=O, s).
5.2.2.7 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone 3-fluorobenzoic acid hydrate (1:1) 20FBA
In a test tube containing 20 (0.019g, 0.086 mmol) in 2 mL of ethanol was added to 3-fluorobenzoic acid (0.024g, 0.171 mmol) in 2 mL of ethanol. The solution was placed at room temperature to undergo slow evaporation. After ten days colorless plates were obtained. M.p.: 117-119oC. IR (KBr pellet): υ 2544 cm-1, 1923 cm-1 (O-H…N, br), 1669 cm-1 (C=O, s).
5.2.2.8 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone 4-nitrobenzoic acid hydrate (1:1) 20NBA
A solution of 20 (0.014g, 0.0.059 mmol) in 2 mL of ethanol was added to a solution of 4-nitrobenzoic acid (0.020g, 0.119 mmol) in 2 mL of ethanol and allowed to stand at room temperature for slow evaporation in a test tube. After eleven days colorless prisms were obtained. M.p.: 210-212oC. IR (KBr pellet): υ 2361 cm-1, 1943 cm-1 (O-H…N, br), 1669 cm-1 (C=O, s).
5.2.2.9 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone 2,4- difluorobenzoic acid hydrate (1:1), 20F2BA
In a test tube containing 20 (0.030g, 0.133 mmol) in 2 mL of ethanol was added to 2,4-difluorobenzoic acid (0.084g, 0.531 mmol) in 2 mL of ethanol. The solution was placed at room temperature to undergo slow evaporation. Colorless plate-like crystals were obtained after twenty days. M.p.: 154-156oC. IR (KBr pellet): υ 2498 cm-1, 1900 cm-1 (O-H…N, br), 1684 cm-1 (C=O, s).
5.2.2.10 Synthesis of 2-pyridylcarboxaldehyde isonicotinoylhydrazone 4- aminobenzoic acid hydrate (1:1) 20ABA
In a beaker containing 20 (0.015g, 0.070 mmol) in 3 mL of ethanol-acetonitrile 4-aminobenzoic acid (0.010g, 0.070 mmol) in 3 mL of ethanol-acetonitrile was added. The solution was placed at room temperature to undergo slow evaporation. Transparent orange block-like crystals were obtained after fifteen days. M.p.: 105-107oC. IR (KBr pellet): υ 2489 cm-1, 1879 cm-1 (O-H…N, br), 1684c m-1 (C=O acid, s), 3416 cm-1 (NH2
acid, s).
5.2.2.11 Synthesis of 4-pyridylcarboxaldehyde isonicotinoylhydrazone succinic acid dihydrate (1:1), 21SUC
21 (0.030g, 0.133 mmol) was gently heated in 4 mL of ethanol and added to a solution containing succinic acid (0.0157g, 0.133 mmol) in 4 mL of ethanol. The solution was left to stand at room temperature for slow evaporation. After nine days colorless plate-like crystals were obtained. M.p.: 212-214oC. IR (KBr pellet): υ 2431 cm-1, 1948 cm-1 (O-H…N, br), 1679 cm-1 (C=O acid, s).
5.2.2.12 Synthesis of 4-pyridylcarboxaldehyde isonicotinoylhydrazone adipic acid hydrate (1:1), 21ADI
A solution of 21 (0.030g, 0.133mmol) in 4 mL of ethanol was gently heated and added to a solution of adipic acid (0.019g, 0.133mmol) in 4 mL of ethanol. The mixture was allowed to stand at ambient temperature. After nine days colorless plate-like crystals were obtained. M.p.: 190-192oC. IR (KBr pellet): υ 2476 cm-1, 1903 cm-1 (O-H…N, br), 1677 cm-1 (C=O acid, s).
5.2.2.13 Synthesis of 4-pyridylcarboxaldehyde isonicotinoylhydrazone suberic acid hydrate (1:1), 21SUB
21 (0.030g, 0.133 mmol) was dissolved in 1 mL methanol-1 mL ethyl acetate and added to a beaker containing suberic acid (0.023g, 0.133 mmol) in 1 mL methanol-1 mL ethyl acetate. The solution was allowed to stand at room temperature for slow evaporation. After twelve days colorless plates were obtained. M.p.: 179-181oC. IR (KBr pellet): υ 2500 cm-1, 1900 cm-1 (O-H…N, br), 1678 cm-1 (C=O acid, s).
5.2.2.14 Synthesis of 4-pyridylcarboxaldehyde picolinoylhydrazone fumaric acid (1:1), 23FUM
23 (0.030g, 0.133 mmol) was dissolved in 4 mL of ethanol and added to a beaker containing fumaric acid (0.015g, 0.133 mmol) in 4 mL of ethanol. The solution was left to stand at room temperature for slow evaporation. Colorless prisms were obtained ten days later. M.p.: 207-209oC. IR (KBr pellet): υ 2498 cm-1, 1924 cm-1 (O-H…N, br), 1695 cm-1 (C=O acid, s).
5.2.2.15 Synthesis of 4-pyridylcarboxaldehyde picolinoylhydrazone glutaric acid (1:1), 23GLU
23 (0.030g, 0.133 mmol) was dissolved in 4 mL of ethanol and added to a beaker containing glutaric acid (0.018g, 0.133 mmol) in 4 mL of ethanol. The solution was left to stand at room temperature for slow evaporation. After eight days colorless plate-like crystals were obtained. M.p.: 156-157oC. IR (KBr pellet): υ 2484 cm-1, 1928 cm-1 (O-H…N, br), 1715 cm-1 (C=O acid, s).
5.2.2.16 Synthesis of 3-pyridylcarboxaldehyde nicotinoylhydrazone adipic acid dihydrate (1:1), 24ADI
A solution of 24 (0.030g, 0.133 mmol) in 4 mL of ethanol was gently heated and added to a solution of adipic acid (0.019g, 0.133 mmol) in 4 mL of ethanol. The solution was allowed to stand at ambient temperature for slow evaporation. After ten days colorless prisms were obtained. M.p.: 139-141oC. IR (KBr pellet): υ 2495 cm-1, 1918 cm
-1 (O-H…N, br), 1669 cm-1 (C=O acid, s).
5.2.2.17 Synthesis of 3-pyridylcarboxaldehyde nicotinoylhydrazone suberic acid