Synthesis, characterization and biological activity of Schiff bases based on chitosan and arylpyrazole moiety
-(4-methyl-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (2)
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- 3-(4-methoxy-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (3)
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- Table 4 Page 27 of 31 Accepted Manuscript Figure 1
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3-(4-methyl-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (2)
FT-IR (KBr, cm -1 ): 3119- 3064 (C-H stretching in aromatic ring), 2920 and 2863 (C-H stretching in alkyl group), 2834 and 2777 (C-H aldehydic doublet), 1671 (strong C=O stretching), 1597 (C=N cyclic), 781, 753 and 684 (CH=CH of mono- and disubstituted benzene), 1518, 1449 and 1360 (pyrazole ring). 1 H NMR (DMSO, δ, ppm): 7.3- 7.5 (m, 5H, NArH), 7.6- 8.0 (dd, 4H, CArH), 2.3 (S, 3H, CH 3 ), 9.3 (s, 1H, H-5), 9.98 (s, 1H, CHO). 3-(4-methoxy-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (3) FT-IR (KBr, cm -1 ): 3121- 3068 (C-H stretching in aromatic ring), 2998 and 2928 (C-H stretching in alkyl group), 2838 and 2779 (C-H aldehydic doublet), 1671 (strong C=O stretching), 1607 (C=N Page 22 of 31 Accepted Manuscript 18 cyclic), 782, 754 and 686 (CH=CH of mono- and disubstituted benzene), 1522, 1455 and 1364 (pyrazole ring). 1 H NMR (DMSO, δ, ppm): 7.0- 7.5 (m, 5H, NArH), 7.8- 8.0 (dd, 4H, CArH), 3.8 (S, 3H, CH 3 ), 9.3 (s, 1H, H-5), 9.98 (s, 1H, CHO). 3-(4-nitro-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (4) FT-IR (KBr, cm -1 ): 3131- 3060 (C-H stretching in aromatic ring), 2926 and 2859 (C-H stretching in alkyl group), 2837 and 2782 (C-H aldehydic doublet), 1687 (strong C=O stretching), 1599 (C=N cyclic), 783, 754 and 687 (CH=CH of mono- and disubstituted benzene), 1634, 1523 and 1450 (pyrazole ring), 1345 (C-NO 2 ). 1 H NMR (DMSO, δ, ppm): 7.4- 7.6 (m, 5H, NArH), 7.9- 8.3 (dd, 4H, CArH), 9.4 (s, 1H, H-5), 10 (s, 1H, CHO). 3-(4-chloro-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (5) FT-IR (KBr, cm -1 ): 3121- 3064 (C-H stretching in aromatic ring), 2923 and 2859 (C-H stretching in alkyl group), 2831 and 2776 (C-H aldehydic doublet), 1671 (strong C=O stretching), 1597 (C=N cyclic), 813, 754 and 684 (CH=CH of mono- and disubstituted benzene), 1520, 1449 and 1358 (pyrazole ring), 728 (C-Cl). 1 H NMR (DMSO, δ, ppm): 7.4- 7.5 (m, 5H, NArH), 7.55- 8.0 (dd, 4H, CArH), 9.4 (s, 1H, H-5), 9.98 (s, 1H, CHO). Page 23 of 31 Accepted Manuscript Table 1 Yield percent, elemental analyses, Degree of substitution (DS), and solubility characteristic of chitosan Schiff bases. Degree of substitution (DS) and solubility of Chitosan Schiff bases in different solvents (+, soluble; ±, partially soluble or swell; and –, insoluble). Sample code Elemental analyses Solubility C% N% DS Yield % Distilled water DMSO DMF THF Acetone Aqueous Acetic acid Ch-H Ch-CH 3 Ch-OCH 3 Ch-Cl Ch-NO 2 88.55 56.51 48.69 54.18 45.72 4.57 10.25 10.00 9.81 9.76 1..0 0.67 0.63 0.62 0.52 45.4 48.6 50.1 47.2 49.0 ± ± ± ± ± + + + + + Table 1 Page 24 of 31 Accepted Manuscript Table 2 Thermal characteristic of Ch and ChBs derivatives. Sample code Temperature range ( o C) Weight loss (wt%) T i ( o C) T max ( o C) DTA ( o C) E a (± 3%) (kJ mol -1 ) r 2 Ch 50-170 170-369 369-599 7.0 44.8 45.5 253 61 296 535 62 305 534 - 119 88 - 0.997 0.992 Ch-H 48-180 180-457 457-733 8.9 39.8 49.8 246 62 294 629 62 299 633 - 123 84 - 0.998 0.998 Ch-CH 3 27-173 195-387 387-599 9.0 41.9 46.0 230 63 275 492 63 275 493 - 123 121 0.999 0.992 Ch-OCH 3 28-130 190-417 417-647 7.8 47.2 43.7 225 59 282 524 59 290 529 - 92 129 - 0.999 0.995 Ch-Cl 31-140 140-387 387-685 7.4 39.7 52.0 240 65 285 558 65 286 573 - 96 80 - 0.992 0.998 Ch-NO 2 28-206 206-369 369-672 8.6 30.2 54.4 241 71 289 609 71 291 611 - 117 50 - 0.999 0.996 Table 2 Page 25 of 31 Accepted Manuscript Table 3 Antibacterial activity of chitosan and chitosan Schiff base derivatives Samples Gram positive bacteria Gram negative bacteria S. pneumonia (RCMB 010010) B. subtilis (RCMB 010067) E. coli (RCMB 010052) Inhibition MIC ( g mL -1 ) Zone (mm) Inhibition MIC ( g mL -1 ) Zone (mm) Inhibition MIC ( g mL -1 ) Zone (mm) Ch 15.1± 0.44 17.3± 0.25 13.4± 0.44 Ch-H 18.6± 0.43 7.81 20.4± 0.53 3.90 20.3± 0.25 3.90 Ch-CH 3 17.2± 0.15 31.25 19.8± 0.42 3.90 18.3± 0.53 15.63 Ch-OCH 3 16.3± 0.63 31.25 18.6± 0.44 7.81 17.9± 0.37 15.63 Ch-Cl 16.3± 0.63 31.25 18.4± 0.44 7.81 17.2± 0.58 31.25 Ch-NO 2 17.3± 0.44 19.4± 0.67 16.4± 0.46 Ampicillin 23.8± 0.2 0.49 32.4± 0.3 0.12 - Gentamicin - - 17.3±0.1 3.90 Table 3 Page 26 of 31 Accepted Manuscript Table 4 Antifungal activity of chitosan and chitosan Schiff base derivatives. Samples A. fumigatus (RCMB 02568) G. candidum (RCMB 05097) S. recemosum (RCMB 05922) Inhibition Zone (mm) MIC ( g mL -1 ) Inhibition Zone (mm) MIC ( g mL -1 ) Inhibition Zone (mm) MIC ( g mL -1 ) Ch 14.3± 0.44 16.2± 0.37 13.2± 0.58 Ch-H 20.3± 0.58 3.90 22.3± 0.38 0.98 18.2± 0.25 15.63 Ch-CH 3 19.2± 0.33 7.81 21.3± 0.34 1.95 17.1± 0.25 31.25 Ch-OCH 3 18.2± 0.44 15.63 19.8± 0.25 3.90 16.4± 0.58 31.25 Ch-Cl 18.2± 0.63 15.63 20.3± 0.25 3.90 16.3± 0.44 31.25 Ch-NO 2 17.3± 0.25 17.2± 0.58 15.3± 0.34 Amphotericine B 23.7± 0.1 0.98 28.7± 0.2 0.24 19.7± 0.2 3.90 Table 4 Page 28 of 31 Accepted Manuscript Figure 2 Click here to download high resolution image Page 29 of 31 Accepted Manuscript Figure 3 Click here to download high resolution image Page 30 of 31 Accepted Manuscript Figure 4 Click here to download high resolution image Page 31 of 31 Accepted Manuscript Figure 5 Click here to download high resolution image Download 1.04 Mb. Do'stlaringiz bilan baham: 
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