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0Journal of Saudi Chemical Society (2013) xxx, xxx-xxx
King Saud University Journal of Saudi Chemical Society
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ORIGINAL ARTICLE
Synthesis, characterization and antimicrobial activity of some new 4-(4-(2-isonicotinoylhydrazinyl)-6-((aryl)amino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl) benzenesulfonamides
N.C. Desai a *, Atul H. Makwana b, R.D. Senta a
a Department of Chemistry, UGC NON-SAP & DST-FIST Sponsored Department, Mahatma Gandhi Campus, Division of Medicinal Chemistry, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364 002, India b XRF, St. Xavier's College, Navrangpura, Ahmedabad 380 009, India
Received 1 May 2013; revised 31 August 2013; accepted 24 September 2013
KEYWORDS
1,3,5-Triazine;
Pyrimidine;
Isoniazid;
Benzenesulfonamide; Antimicrobial activity; MIC
Abstract In the present study, we have synthesized some novel 4-(4-(2-isonicotinoylhydrazinyl)-6-((aryl)amino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide derivatives (3a-v) and evaluated their in vitro antimicrobial activity against the representative panel of Gram-positive bacteria [Staphylococcus aureus (MTCC 96), Staphylococcus pyogenes (MTCC 442)], Gram-negative bacteria [Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688)] and fungal strains [Candida albicans (MTCC 227), Aspergillus niger (MTCC 282), Aspergillus clavatus (MTCC 1323)]. Evaluation of antimicrobial activity revealed that compounds 3g, 3h, 3t, and 3v were the most active antibacterial, while compounds 3g, and 3h were the most potent antifungal agents. The structures of synthesized compounds (3a-v) were elucidated by IR, NMR spectroscopy and elemental analysis.
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1. Introduction
After years of misuse and overuse of antibiotics, bacteria are becoming antibiotic resistant, therefore recent efforts have
been directed toward exploring novel antibacterial agents [16]. In order to overcome this rapid development of drug resistance, new agents should preferably consist of chemical characteristics that clearly differ from those of existing agents. Nowadays the discovery and commercial development of numerous therapeutic agents [12] afford reliably effective treatment for many infectious diseases which had previously caused extensive mortality and morbidity. In this context, substituted s-triazine and benzenesulfonamide derivatives have received considerable attention due to their significant activities like antimicrobial [2,3,8,22,23], antibacterial [11], antifungal [19], antitumor [4,18], anti-inflammatory [17],
* Corresponding author. Tel.: +91 9825209177. E-mail address: dnisheeth@rediffmail.com (N.C. Desai). Peer review under responsibility of King Saud University.
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anticancer [3,10,15,20], antiprotozoals [21], antimalarials [1,3,14]. Profound medicinal applications associated with isonicotinohydrazide render them as useful structural units in drug research [13].
Due to rapid development of drug resistance, tolerance and side effects there is a fundamental and critical need for the development of a new generation of antimicrobial agents which would exhibit improved pharmacological properties and drug-resistance profiles. Previously, our research group has also reported synthesis, characterization and antimicrobial evaluation of N-(4-(arylamino)-6-(thiazol-2-ylamino)-1,3,5-triazin-2-yl)isonicotinohydrazide derivatives [5]. Keeping this in mind we have subsequently carried out the synthesis of s-tri-azine based isoniazid and benzenesulfonamide derivatives to explore the synthesis of more potential bioactive molecules in one framework.
2. Experimental part
2.1. Materials and physical measurements
The completion of reaction and purity of compounds were checked on aluminum coated TLC plates 60 F245 (E. Merck) using n-hexane:ethyl acetate (7.5:2.5 V/V) as mobile phase and visualized under ultraviolet (UV) light or in an iodine chamber. Melting points were determined on an electro thermal melting point apparatus and were reported uncorrected. Elemental analysis (% C, H, N) was carried out by a Perkin-Elmer 2400 CHN analyzer. IR spectra of all the compounds were recorded on a Perkin-Elmer FT-IR spectrophotometer in KBr. NMR (300 MHz) and 13C NMR (100 MHz) spectra were recorded on Bruker spectrometer using DMSO-d6 as solvent and TMS as an internal standard. Mass spectra were obtained on SHIMA-DZU LC-MS 2010 spectrophotometer. In the conventional method, compounds were synthesized using Random synthesizer.
2.2. Preparation of N'-(4,6-dichloro-1 ,3,5-triazin-2-yl)isonicotinohydrazide (1)
A mixture of 2,4,6-trichloro-1,3,5-triazine (0.01 mol) in acetone (15 mL) and isoniazid (0.01 mol) was taken in a conical flask. To this mixture, 4% NaOH was added drop-wise at 05 0C temperature. The solution was stirred for 2 h. The reaction mixture was then poured onto crushed ice with constant stirring and neutralized with dil. HCl. The solid formed was filtered, washed with water, dried and recrystallized from acetone. Yield: 80.0%; m.p.: 180 0C; IR (KBr, v, cm"1): 780 (CCl, Stretching), 1587 (N-H, bending), 1640 (C=C, stretching), 1690 (C=O, stretching), 1890 (C=N, stretching), 3444 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.72 (s, 1H, triazine-NH-NH-), 7.82 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.89 (d, 2H, J = 7.8 Hz, C2-H & C6-H pyridine ring), 9.74 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.9 (1C, C=O), 169.2 (2C, C-Cl), 184.8 (1C, C-NH- triazine ring); LC-MS (m/z): 284.0 (M+), Anal. Calcd. For C9H6Cl2N6O, C - 37.92, H - 2.12, N - 29.48; Found: C -37.93, H - 2.10, N - 29.45%.
2.3. Preparation of 4-(4-chloro-6-(2-isonicotinoylhydrazinyl)-1 ,3,5-triazine-2-ylamino)-N-(pyrimidine-2-yl)benzenesulfonamide (2)
A mixture of N-(4,6-dichloro-1,3,5-triazine-2-yl) isonicotinohydrazide (0.01 mol) in acetone (15 mL) and 4-amino-N-(pyrimidine-2-yl)benzenesulfonamide (0.01 mol) was taken in a conical flask. To this mixture, 4% NaOH was added drop-wise at room temperature and was stirred for 3 h. The reaction mixture was then poured onto crushed ice with constant stirring and neutralized with dil. HCl. The solid obtained was filtered, washed with water, dried and recrystallized from 1,4-dioxane. Yield: 70.0%; m.p.: 235 0C; IR (KBr, v, cm"1): 788 (C-Cl, Stretching), 895 (S-N, stretching), 1135 (S=O, stretching in SO2), 1592 (N-H, bending), 1640 (C=C, stretching), 1690 (C=O, stretching), 1890 (C=N, stretching), 3035 (CH, stretching in aromatic), 3445 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.54 (s, 2H, Ar-NH-triazine), 6.72 (s, 1H, triazine-NH-NH-), 6.93 (t, 1H, pyrimidine), 7.1-7.83 (d, 4H, Ar-H), 7.86 (d, 2H, J = 8.0 Hz, C3-H & C5-H pyridine ring), 8.03 (s, 1H, -SO2-NH-), 8.87 (d, 2H, pyrimidine), 8.95 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.78 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.1 (1C, C-NH- attached with arylsulfonamide group), 164.6 (1C, C=O), 166.4 (1C, C-Cl), 169.2 (1C, C-NHSO2-), 169.9 (1C, C-NH-), 181.4 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 498.07 (m+), Anal. Calcd. For C19H15ClN10O3S, C - 45.74, H -
3.03, N - 28.07; Found: C - 45.75, H - 3.01, N - 28.04%.
2.4. Preparation of 4-(4-(2-isonicotinoylhydrazinyl)-6-((aryl)amino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3a-v)
Intermediate compound 4-(4-chloro-6-(2-isonicotinoylhydrazi-nyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfon-amide (2) (0.01 mol) in 1,4-dioxane (20 mL) was taken in a round bottom flask and different aromatic amines (0.01 mol) were added to it. To this mixture, 8% NaOH was added drop-wise and it was then refluxed for 2-4 h. Finally the reaction mixture was poured onto crushed ice with constant stirring and neutralized with dil. HCl. The product formed was filtered, washed with cold water, dried and recrystallized from methanol.
2.4.1. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(phenyl amino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3a)
Yield: 63.0%; m.p.: 265-268 0C; IR (KBr, v, cm"1): 795 (C-H, bending in aromatic), 895 (S-N, stretching), 1120 (S=O, stretching in SO2), 1592 (N-H, bending), 1640 (C=C, stretching), 1690 (C=O, stretching), 1890 (C=N, stretching), 3020 (C-H, stretching in aromatic ring), 3038 (C-H, stretching in aromatic), 3448 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.64 (s, 2H, Ar-NH-triazine), 6.82 (s, 1H, triazine-NH-NH-), 6.91 (t, 1H, pyrimidine), 7.027.62 (m, 9H, Ar-H), 7.84 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.13 (s, 1H, -SO2-NH-), 8.84 (d, 2H, pyrimidine), 8.98 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.78 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d,
ppm): 164.1 (1C, C-NH- attached with arylsulfonamide group), 164.4 (1C, C=O), 168.9 (1C, C-NH-Ar), 169.3 (1C, C-NHSO2-), 176.7 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 555.15 (M+), Anal. Calcd. For C25H21NuO3S, C - 54.05, H - 3.81, N - 27.73; Found: C - 54.12, H - 3.90, N- 27.67%.
2.4.2. Physical constants and characterization of 4-(4-(4-bromophenylamino)-6-(2-isonicotinoylhydrazinyl)-1 ,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide(3b)
Yield: 72.0%, m.p. 259 0C; IR (KBr, v, cm"1): 530 (C-Br, stretching), 780 (C-H, bending in aromatic), 898 (S-N, stretching), 1158 (S=O, stretching in SO2), 1592 (N-H, bending), 1648 (C=C, stretching), 1730 (C=O, stretching), 1890 (C=N, stretching), 3025 (C-H, stretching in aromatic), 3059 (C-H, stretching in aromatic ring), 3447 (N-H, stretching in amine); NMR (300 MHz, DMSO-d6, d, ppm): 6.67 (s, 2H, Ar-NH-triazine), 6.84 (s, 1H, triazine-NH-NH-), 6.92 (t, 1H, pyrimidine), 7.03-7.64 (m, 8H, Ar-H), 7.86 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.14 (s, 1H, -SO2-NH-), 8.87 (d, 2H, pyrimidine), 8.95 (d, 2H, J = 7.6 Hz, C2-H & C6-H pyridine ring), 9.82 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.3 (1C, C-NH- attached with arylsulfonamide group), 164.9 (1C, C=O), 168.7 (1C, C-NH-Ar), 169.4 (1C, C-NHSO2-),
176.8 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 635.06 (M+), Anal. Calcd. For: C25H20BrNuO3S, C - 47.33, H - 3.18, N - 24.28; Found: C - 47.23, H - 3.20, N - 24.38%.
2.4.3. Physical constants and characterization of 4-(4-(2-chlorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide(3c)
Yield: 78.0%, m.p. 270 0C; IR (KBr, v, cm"1): 643 (C-Cl, stretching), 780 (C-H, bending in aromatic), 898 (S-N, stretching), 1156 (S=O, stretching in SO2), 1602 (N-H, bending), 1648 (C=C, stretching), 1730 (C=O, stretching), 1890 (C=N, stretching), 3038 (C-H, stretching in aromatic), 3458 (N-H, stretching in amine); NMR (300 MHz, DMSO-d6, d, ppm): 6.64 (s, 2H, Ar-NH-triazine), 6.82 (s, 1H, triazine-NH-NH-), 6.99 (t, 1H, pyrimidine), 7.08-7.84 (m, 7H, Ar-H), 7.87 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.13 (s, 1H, -SO2-NH-), 8.81 (d, 2H, pyrimidine), 8.94 (d, 2H, J = 7.6 Hz, C2-H & C6-H pyridine ring), 9.81 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.8 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-),
176.9 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 589.12 (M+), Anal. Calcd. For: C25H20ClNuO3S, C - 50.89, H - 3.42, N - 26.11; Found: C - 50.87, H - 3.41, N - 26.14%.
2.4.4. Physical constants and characterization of 4-(4-(3-chlorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide( 3d) Yield: 69.0%, m.p. 292 0C; IR (KBr, v, cm"1): 675 (C-Cl, stretching), 1738 (C=O, stretching), 784 (C-H, bending in aromatic), 889 (S-N, stretching), 1153 (S=O, stretching in SO2), 1612 (N-H, bending), 1645 (C=C, stretching), 1892 (C=N, stretching), 3057 (C-H, stretching in aromatic ring), 3445 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.65 (s, 2H, Ar-NH-triazine), 6.85 (s, 1H, triazine-NH-NH-), 6.94 (t, 1H, pyrimidine), 7.07-7.67
(m, 7H, Ar-H), 7.78 (s, 1H, Ar-H), 7.88 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.11 (s, 1H, -SO2-NH-), 8.84 (d, 2H, pyrimidine), 8.96 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.83 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.6 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-), 176.7 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 589.12 (M+), Anal. Calcd. For: C25H20ClNuO3S, C - 50.89, H - 3.42, N - 26.11; Found: C - 50.85, H - 3.44, N - 26.01%.
2.4.5. Physical constants and characterization of 4-(4-(4-chlorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3e)
Yield: 70.0%, m.p. 250 0C; IR (KBr, v, cm"1): 680 (C-Cl, stretching), 781 (C-H, bending in aromatic), 890 (S-N, stretching), 1160 (S=O, stretching in SO2), 1612 (N-H, bending), 1658 (C=C, stretching), 1890 (C=N, stretching), 1742 (C=O, stretching), 3042 (C-H, stretching in aromatic), 3059 (C-H, stretching in aromatic ring), 3449 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.62 (s, 2H, Ar-NH-triazine), 6.83 (s, 1H, triazine-NH-NH-), 6.97 (t, 1H, pyrimidine), 7.13-7.65 (m, 8H, Ar-H), 7.87 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.15 (s, 1H, -SO2-NH-), 8.83 (d, 2H, pyrimidine), 8.94 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.81 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.4 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.8 (1C, C-NH-Ar), 169.5 (1C, C-NHSO2-), 176.7 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 589.12 (M+), Anal. Calcd. C25H20ClN11O3S, C - 50.89, H - 3.42, N - 26.11; Found: C - 50.77, H - 3.43, N - 26.11%.
2.4.6. Physical constants and characterization of 4-(4-(2,5-dichlorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1 ,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3f)
Yield: 69.0%, m.p. 240 0C; IR (KBr, v, cm"1): 658 (C-Cl, stretching), 781 (C-H, bending in aromatic), 896 (S-N, stretching), 1151 (S=O, stretching in SO2), 1615 (N-H, bending), 1657 (C=C, stretching), 1747 (C=O, stretching), 1889 (C=N, stretching), 3047 (C-H, stretching in aromatic), 3062 (C-H, stretching in aromatic ring), 3449 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.68 (s, 2H, Ar-NH-triazine), 6.85 (s, 1H, triazine-NH-NH-), 6.99 (t, 1H, pyrimidine), 7.09-7.64 (m, 6H, Ar-H), 7.76 (s, 1H, Ar-H), 7.85 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.17 (s, 1H, -SO2-NH-), 8.81 (d, 2H, pyrimidine), 8.97 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.86 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.5 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.8 (1C, C-NH-Ar), 169.5 (1C, C-NHSO2-), 176.9 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 623.08 (M+), Anal. Calcd. For: C25H19Cl2NuO3S, C -48.08, H - 3.07, N - 24.67; Found: C - 48.03, H - 3.07, N -26.55%.
2.4.7. Physical constants and characterization of 4-(4-(2,6-dichlorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1 ,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide(3g) Yield: 62.0%, m.p. 270 0C; IR (KBr, v, cm"1): 645 (C-Cl, stretching), 789 (C-H, bending in aromatic), 894 (S-N, stretch-
ing), 1157 (S=O, stretching in SO2), 1622 (N-H, bending), 1659 (C=C, stretching), 1750 (C=O, stretching), 1885 (C=N, stretching), 3050 (C-H, stretching in aromatic), 3082 (C-H, stretching in aromatic ring), 3453 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.67 (s, 2H, Ar-NH-triazine), 6.88 (s, 1H, triazine-NH-NH-), 6.94 (t, 1H, pyrimidine), 7.01-7.65 (m, 7H, Ar-H), 7.83 (d, 2H, J = 7.7 Hz, C3-H & C5-H pyridine ring), 8.18 (s, 1H, -SO2-NH-), 8.84 (d, 2H, pyrimidine), 8.96 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.87 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.6 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.2 (1C, C-NHSO2-), 176.5 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 623.08 (M+), Anal. Calcd. For: C25H19Cl2NuO3S, C - 48.08, H - 3.07, N - 24.67; Found: C - 48.09, H - 3.13, N - 24.68%.
2.4.8. Physical constants and characterization of 4-(4-(4-fluorophenylamino)-6-(2-isonicotinoylhydrazinyl)-1 ,3 ,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide(3h)
Yield: 75.0%, m.p. 240 0C; IR (KBr, v, cm"1): 791 (C-H, bending in aromatic), 908 (S-N, stretching), 1030 (C-F, stretching), 1152 (S=O, stretching in SO2), 1622 (N-H, bending), 1652 (C=C, stretching), 1753 (C=O, stretching), 1875 (C=N, stretching), 3050 (C-H, stretching in aromatic), 3093 (C-H, stretching in aromatic ring), 3462 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.66 (s, 2H, Ar-NH-triazine), 6.84 (s, 1H, triazine-NH-NH-), 6.97 (t,1H, pyrimidine), 7.12-7.83 (m, 8H, Ar-H), 7.89 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.16 (s, 1H, -SO2-NH-), 8.83 (d, 2H, pyrimidine), 8.98 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.89 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.6 (1C, C-NH-Ar), 169.5 (1C, C-NHSO2-), 176.4 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 573.15 (M+), Anal. Calcd. For: C25H20FNUO3S, C - 52.35, H - 3.51, N - 26.86; Found: C - 52.37, H - 3.50, N - 26.8
2.4.9. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(o-tolylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3i)
Yield: 78.0%, m.p. 260 0C; IR (KBr, v, cm"1): 710 (C-H, bending in aromatic), 902 (S-N, stretching), 1149 (S=O, stretching in SO2), 1622 (N-H, bending), 1651 (C=C, stretching), 1749 (C=O, stretching), 1872 (C=N, stretching), 3462 (N-H, stretching in amine), 3050 (C-H, stretching in aromatic), 2890 (C-H, stretching in -CH3), 3086 (C-H, stretching in aromatic ring); 1H NMR (DMSO-d6, d, ppm): 2.12 (s, 3H, -CH3), 6.61 (s, 2H, Ar-NH-triazine), 6.80 (s, 1H, triazine-NH-NH-), 6.90 (t, 1H, pyrimidine), 6.98-7.77 (m, 8H, Ar-H), 7.86 (d, 2H, J = 7.7 Hz, C3-H & C5-H pyridine ring), 8.10 (s, 1H, -SO2-NH-), 8.85 (d, 2H, pyrimidine), 8.94 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.87 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 17.8 (1C, -CH3), 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.6 (1C, C=O), 168.4 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-), 176.5 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 569.17 (M+), Anal. Calcd. For: C26H23N11O3S, C - 54.82, H - 4.07, N - 27.05; Found: C - 54.85, H - 4.05, N - 27.08%.
2.4.10. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(p-tolylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3j)
Yield: 73.0%, m.p. 225 0C; IR (KBr, v, cm"1): 715 (C-H, bending in aromatic), 905 (S-N, stretching), 1153 (S=O, stretching in SO2), 1628 (N-H, bending), 1649 (C=C, stretching), 1753 (C=O, stretching), 1868 (C=N, stretching), 2879 (C-H, stretching in -CH3), 3048 (C-H, stretching in aromatic), 3091 (C-H, stretching in aromatic ring), 3458 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 2.07 (s, 3H, -CH3), 6.60 (s, 2H, Ar-NH-triazine), 6.79 (s, 1H, tri-azine-NH-NH-), 6.89 (t, 1H, pyrimidine), 7.04-7.73 (m, 8H, Ar-H), 7.87 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.08 (s, 1H, -SO2-NH-), 8.86 (d, 2H, pyrimidine), 8.94 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.80 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 21.6 (1C, -CH3), 164.0 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.9 (1C, C-NH-Ar), 169.7 (1C, C-NHSO2-), 176.4 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 569.17 (M+), Anal. Calcd. For: C26H23NUO3S, C
- 54.82, H - 4.07, N - 27.05; Found: C - 54.84, H - 4.05, N
- 27.09%.
2.4.11. Physical constants and characterization of 4-(4-(2,4-dimethylphenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3k) Yield: 80.0%, m.p. 200 0C; IR (KBr, v, cm"1): 715 (C-H, bending in aromatic), 910 (S-N, stretching), 1158 (S=O, stretching in SO2), 1622 (N-H, bending), 1648 (C=C, stretching), 1762 (C=O, stretching), 1862 (C=N, stretching), 2882 (C-H, stretching in -CH3), 3057 (C-H, stretching in aromatic), 3089 (C-H, stretching in aromatic ring), 3452 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 2.13 (s, 3H, p-CH3), 2.35 (s, 3H, o-CH3), 6.58 (s, 2H, Ar-NH-triazine), 6.80 (s, 1H, triazine-NH-NH-), 6.91 (t, 1H, pyrimidine), 6.95-7.62 (m, 7H, Ar-H), 7.80 (d, 2H, J = 7.7 Hz, C3-H & C5-H pyridine ring), 8.07 (s, 1H, -SO2-NH-), 8.82 (d, 2H, pyrimidine), 8.92 (d, 2H, J = 8.0 Hz, C2-H & C6-H pyridine ring), 9.79 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 17.7 (1C, o-CH3), 21.4 (1C, p-CH3), 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.3 (1C, C-NHSO2-), 176.6 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 583.19 (M + ), Anal. Calcd. For: C27H25NUO3S, C -55.56, H - 4.32, N - 26.40; Found: C - 55.55, H - 4.30, N -26.42%.
2.4.12. Physical constants and characterization of 4-(4-(2,6-dimethylphenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3l)
Yield: 78.0%, m.p. 282 0C; IR (KBr, v, cm"1): 720 (C-H, bending in aromatic), 912 (S-N, stretching), 1149 (S=O, stretching in SO2), 1629 (N-H, bending), 1651 (C=C, stretching), 1771 (C=O, stretching),1867 (C=N, stretching), 2878 (C-H, stretching in -CH3), 3062 (C-H, stretching in aromatic), 3091 (C-H, stretching in aromatic ring), 3445 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 2.13 (s, 6H, -CH3), 6.60 (s, 2H, Ar-NH-triazine), 6.79 (s, 1H, triazine-NH-NH-), 6.89 (t, 1H, pyrimidine), 6.96-7.61 (m, 7H, Ar-H), 7.82 (d, 2H, J = 7.6 Hz, C3-H & C5-H pyridine ring), 8.06 (s, 1H, -SO2-NH-), 8.82 (d, 2H, pyrimidine), 8.91 (d, 2H,
J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.80 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 17.6 (2C, -CH3), 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.4 (1C, C-NH-Ar), 169.7 (1C, C-NHSO2-), 176.9 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 583.19 (M+), Anal. Calcd. For: C27H25NUO3S, C - 55.56, H - 4.32, N - 26.40; Found: C - 55.55, H - 4.34, N-26.41%.
2.4.13. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-((3-(trifluoromethyl)phenylamino)-1 ,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3m)
Yield: 68.0%, m.p. 300 0C; IR (KBr, v, cm"1): 727 (C-H, bending in aromatic), 918 (S-N, stretching), 1035 (C-F, stretching), 1147 (S=O, stretching in SO2), 1632 (N-H, bending), 1657(C=C, stretching), 1782 (C=O, stretching), 1864 (C=N, stretching), 2879 (C-H, stretching in -CH3), 3092 (C-H, stretching in aromatic ring), 3455 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.68 (s, 2H, Ar-NH-triazine), 6.86 (s, 1H, triazine-NH-NH-), 6.98 (t, 1H, pyrimidine), 7.08-7.65 (m, 7H, Ar-H), 7.71 (s, 1H, Ar-H), 7.87 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.16 (s, 1H, -SO2-NH-), 8.88 (d, 2H, pyrimidine), 8.98 (d, 2H, J = 7.5 Hz, C2-H & C6-H pyridine ring), 9.89 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 124.4 (1C, -CF3), 164.1 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.4 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-), 176.5 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 623.14 (m+), Anal. Calcd. For: C26H20F3NUO3S, C - 50.08, H -3.23, N - 24.71; Found: C - 50.16, H - 3.25, N - 24.75%.
2.4.14. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-((4-(trifluoromethyl)phenylamino)-1 , 3, 5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3n)
Yield: 63.0%, m.p. 275 0C; IR (KBr, v, cm"1): 730 (C-H, bending in aromatic), 917 (S-N, stretching), 1015 (C-F, stretching), 1152 (S=O, stretching in SO2), 1628 (N-H, bending), 1639 (N-H, bending), 1649 (C=C, stretching), 1785 (C=O, stretching), 1862 (C=N, stretching), 2875 (C-H, stretching in -CH3), 3098 (C-H, stretching in aromatic ring), 3451 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.64 (s, 2H, Ar-NH-triazine), 6.84 (s, 1H, triazine-NH-NH-), 6.95 (t, 1H, pyrimidine), 7.11-7.67 (m, 8H, Ar-H), 7.88 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.15 (s, 1H, -SO2-NH-), 8.89 (d, 2H, pyrimidine), 8.97 (d, 2H, J = 7.8 Hz, C2-H & C6-H pyridine ring), 9.87 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 124.5 (1C, -CF3), 164.0 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.4 (1C, C-NHSO2-), 176.9 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 623.14 (M+), Anal. Calcd. For: C26H20F3NuO3S, C - 50.08, H - 3.23, N - 24.71; Found: C - 50.06, H - 3.21, N - 24.72%.
2.4.15. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(4-methoxyphenylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3o) Yield: 69.0%, m.p. 220 0C; IR (KBr, v, cm"1): 730 (C-H, bending in aromatic), 917 (S-N, stretching), 1013 (C-F,
stretching), 1152 (S=O, stretching in SO2), 1629 (N-H, bending), 1632 (N-H, bending), 1649 (C=C, stretching), 1785 (C=O, stretching), 1862 (C=N, stretching), 2835 (C-H, stretching in C-O-CH3), 3098 (C-H, stretching in aromatic ring), 3449 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 3.82 (s, 3H, -OCH3), 6.60 (s, 2H, Ar-NH-triazine), 6.80 (s, 1H, triazine-NH-NH-), 6.91 (t, 1H, pyrimidine), 7.03-7.73 (m, 8H, Ar-H), 7.84 (d, 2H, J = 7.7 Hz, C3-H & C5-H pyridine ring), 8.09 (s, 1H, -SO2-NH-), 8.82 (d, 2H, pyrimidine), 8.94 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.80 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 55.4 (1C, -OCH3), 164.0 (1C, C-NH- attached with arylsulfonamide group), 164.3 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-),
176.5 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 585.17 (m+), Anal. Calcd. For: C26H23NUO4S, C - 53.33, H - 3.96, N - 26.31; Found: C - 53.31, H - 3.93, N - 26.28%.
2.4.16. Physical constants and characterization of 4-(4-(2,4-dimethoxyphenylamino)-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide(3p)
Yield: 67.0%, m.p. 289 0C; IR (KBr, v, cm"1): 728 (C-H, bending in aromatic), 919 (S-N, stretching), 1151 (S=O, stretching in SO2), 1624 (N-H, bending), 1644 (C=C, stretching), 1779 (C=O, stretching), 1859 (C=N, stretching), 2835 (C-O-CH3, stretching), 2871 (C-H, stretching in -CH3), 3092 (C-H, stretching in aromatic ring), 3438 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 3.83 (s, 6H, -OCH3), 6.59 (s, 2H, Ar-NH-triazine), 6.79 (s, 1H, triazine-NH-NH-), 6.89 (t, 1H, pyrimidine), 7.01-7.62 (m, 6H, Ar-H), 7.72 (s, 1H, Ar-H), 7.81 (d, 2H, J = 7.7 Hz, C3-H & C5-H pyridine ring), 8.07 (s, 1H, -SO2-NH-), 8.82 (d, 2H, pyrimidine), 8.92 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.78 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 52.8 (1C, o-OCH3), 55.7 (1C, p-OCH3), 164.0 (1C, C-NH- attached with arylsulfonamide group),
164.6 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.3 (1C, C-NHSO2-), 176.6 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 615.18 (M+), Anal. Calcd. For: C27H25NUO5S, C - 52.68, H - 4.09, N - 25.03; Found: C - 52.67, H - 4.08, N - 25.05%.
2.4.17. Physical constants and characterization of 4-(4-ethoxyphenylamino)-6-(2-isonicotinoylhydrazinyl)-1 ,3 ,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3q)
Yield: 59.0%, m.p. 304 0C; IR (KBr, v, cm"1): 723 (C-H, bending in aromatic), 925 (S-N, stretching), 1156 (S=O, stretching in SO2), 1173 (C-O, stretching in C-O-C), 1628 (N-H, bending), 1638 (N-H, bending), 1642 (C=C, stretching), 1781 (C=O, stretching), 1852 (C=N, stretching), 2873 (C-H, stretching in -CH3), 3084 (C-H, stretching in aromatic ring), 3431 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 1.31 (t, 3H, -OCH2CH3), 4.08 (q, 2H, -OCH2CH3), 6.60 (s, 2H, Ar-NH-triazine), 6.79 (s, 1H, triazine-NH-NH-), 6.92 (t, 1H, pyrimidine), 7.08-7.68 (m, 8H, Ar-H), 7.81 (d, 2H, J = 7.6 Hz, C3-H & C5-H pyridine ring), 8.08 (s, 1H, -SO2-NH-), 8.83 (d, 2H, pyrimidine), 8.90 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.79 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 14.6 (1C, -OCH2CH3), 64.9 (1C, -OCH2CH3), 164.2 (1C, C-NH-attached with arylsulfonamide group), 164.8 (1C, C=O),
168.3 (1C, C-NH-Ar), 169.6 (1C, C-NHSO2-), 176.4 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 599.18 (M+), Anal. Calcd. For: C27H25N11O4S, C - 54.08, H - 4.20, N - 25.70; Found: C - 54.07, H - 4.21, N - 25.70%.
2.4.18. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(2-nitrophenylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3r) Yield: 70.0%, m.p. 269 0C; IR (KBr, v, cm"1): 728 (C-H, bending in aromatic), 929 (S-N, stretching), 1154 (S=O, stretching in SO2), 1582 (C-NO2, stretching), 1632, (N-H, bending), 1641 (C=C, stretching), 1778 (C=O, stretching), 1851 (C=N, stretching), 2878 (C-H, stretching in -CH3), 3081 (C-H, stretching in aromatic ring), 3441 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.67 (s, 2H, Ar-NH-triazine), 6.86 (s, 1H, triazine-NH-NH-), 6.95 (t, 1H, pyrimidine), 7.07-7.69 (m, 8H, Ar-H), 7.89 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.17 (s, 1H, -SO2-NH-), 8.88 (d, 2H, pyrimidine), 8.99 (d, 2H, J = 8.0 Hz, C2-H & C6-H pyridine ring), 9.91 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.6 (1C, C-NH-Ar), 169.5 (1C, C-NHSO2-), 176.6 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 600.14 (M+), Anal. Calcd. For: C25H20N12O5S, C - 50.00, H - 3.36, N - 27.99; Found: C - 50.01, H - 3.35, N - 27.99%.
2.4.19. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(3-nitrophenylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3s) Yield: 65.0%, m.p. 298 0C; IR (KBr, v, cm"1): 732 (C-H, bending in aromatic), 923 (S-N, stretching), 1142 (S=O, stretching in SO2), 1573 (C-NO2, stretching), 1635 (N-H, bending), 1644 (C=C, stretching), 1775 (C=O, stretching), 1853 (C=N, stretching), 2883 (C-H, stretching in -CH3), 3088 (C-H, stretching in aromatic ring), 3442 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.66 (s, 2H, Ar-NH-triazine), 6.86 (s, 1H, triazine-NH-NH-), 6.97 (t, 1H, pyrimidine), 7.13-7.75 (m, 7H, Ar-H), 7.81 (s, 1H, Ar-H), 7.88 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.16 (s, 1H, -SO2-NH-), 8.87 (d, 2H, pyrimidine), 8.98 (d, 2H, J = 7.8 Hz, C2-H & C6-H pyridine ring), 9.89 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.0 (1C, C-NH- attached with arylsulfonamide group), 164.7 (1C, C=O), 168.6 (1C, C-NH-Ar), 169.2 (1C, C-NHSO2-), 176.3 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 600.14 (M+), Anal. Calcd. For: C25H20N12O5S, C - 50.00, H - 3.36, N - 27.99; Found: C - 50.00, H - 3.38, N - 27.97%.
2.4.20. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(4-nitrophenylamino)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (3t)
Yield: 63.0%, m.p. 301 0C; IR (KBr, v, cm"1): 733 (C-H, bending in aromatic), 924 (S-N, stretching), 1146 (S=O, stretching in SO2), 1569 (C-NO2, stretching), 1637 (N-H, bending), 1641 (C=C, stretching), 1773 (C=O, stretching), 1851 (C=N, stretching), 2881 (C-H, stretching in -CH3), 3091 (C-H, stretching in aromatic ring), 3441 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.65 (s, 2H, Ar-NH-triazine), 6.85 (s, 1H, triazine-NH-NH-), 6.97
(t, 1H, pyrimidine), 7.18-7.78 (m, 8H, Ar-H), 7.86 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.16 (s, 1H, -SO2-NH-), 8.85 (d, 2H, pyrimidine), 8.96 (d, 2H, J = 7.7 Hz, C2-H & C6-H pyridine ring), 9.87 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.2 (1C, C-NH- attached with arylsulfonamide group), 164.6 (1C, C=O), 168.4 (1C, C-NH-Ar), 169.3 (1C, C-NHSO2-), 176.5 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 600.14 (M+), Anal. Calcd. For: C25H20N12O5S, C - 50.00, H - 3.36, N - 27.99; Found: C - 50.03, H - 3.35, N - 27.95%.
2.4.21. Physical constants and characterization of 4-(4-(2-isonicotinoylhydrazinyl)-6-(4-N-(pyrimidin-2-ylsulfamoyl)phenylamino)-1,3,5-triazin-2-ylamino)benzoic acid (3u)
Yield: 58.0%, m.p. 279 0C; IR (KBr, v, cm"1): 739 (C-H, bending in aromatic), 924 (S-N, stretching), 948 (O-H, bending), 1149 (S=O, stretching in SO2), 1639 (N-H, bending), 1649 (C=C, stretching), 1731 (C=O, stretching), 1854 (C=N, stretching), 2780 (O-H, stretching), 2878 (C-H, stretching in -CH3), 3093 (C-H, stretching in aromatic ring), 3444 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 6.67 (s, 2H, Ar-NH-triazine), 6.88 (s, 1H, triazine-NH-NH-), 6.98 (t, 1H, pyrimidine), 7.14-7.76 (m, 8H, Ar-H), 7.91 (d, 2H, J = 7.9 Hz, C3-H & C5-H pyridine ring), 8.19 (s, 1H, -SO2-NH-), 8.90 (d, 2H, pyrimidine), 8.99 (d, 2H, J = 8.1 Hz, C2-H & C6-H pyridine ring), 9.92 (s, 1H, -NH-CO-), 11.01 (s, 1H, -COOH); 13C NMR (100 MHz, DMSO-d6, d, ppm): 164.1 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 168.5 (1C, C-NH-Ar), 169.2 (1C, C-NHSO2-), 169.8 (1C, -COOH), 176.6 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 599.14 (M+), Anal. Calcd. For: C26H21NUO5S, C - 52.08, H - 3.53, N - 25.70; Found: C - 52.14, H - 3.61, N - 25.78%.
2.4.22. Physical constants and characterization of ethyl-4-(4-(2-isonicotinoylhydrazinyl)-6-(4-(N-pyrimidin-2-ylsulfamoyl)phenylamino)-1,3,5-triazin-2-ylamino)benzoate (3v)
Yield: 66.0%, m.p. 288 0C; IR (KBr, v, cm"1): 742 (C-H, bending in aromatic), 928 (S-N, stretching), 1146 (S=O, stretching in SO2), 1248 (C-O, stretching, ester), 1633 (N-H, bending), 1643 (C=C, stretching), 1742 (C=O, stretching in ester), 1856 (C=N, stretching), 2885 (C-H, stretching in -CH3), 3092 (C-H, stretching in aromatic ring), 3442 (N-H, stretching in amine); 1H NMR (300 MHz, DMSO-d6, d, ppm): 1.30 (t, 3H, -COOCH2CH3), 4.30 (q, 2H, -COOCH2CH3), 6.65 (s, 2H, Ar-NH-triazine), 6.86 (s, 1H, triazine-NH-NH-), 6.95 (t, 1H, pyrimidine), 7.08-7.71 (m, 8H, Ar-H), 7.86 (d, 2H, J = 7.8 Hz, C3-H & C5-H pyridine ring), 8.12 (s, 1H, -SO2-NH-), 8.87 (d, 2H, pyrimidine), 8.98 (d, 2H, J = 7.9 Hz, C2-H & C6-H pyridine ring), 9.91 (s, 1H, -NH-CO-); 13C NMR (100 MHz, DMSO-d6, d, ppm): 14.4 (1C, -COOCH2CH3), 60.7 (1C, -COOCH2CH3), 164.3 (1C, C-NH- attached with arylsulfonamide group), 164.8 (1C, C=O), 165.7 (1C, -COOCH2CH3), 168.6 (1C, C-NH-Ar), 169.2 (1C, C-NHSO2-), 176.3 (1C, C-NHNHCO- triazine ring); LC-MS (m/z): 627.18 (M+), Anal. Calcd. For: C28H25NuO5S, C - 53.58, H - 4.01, N - 24.55; Found: C - 53.57, H - 4.05, N - 24.54%.
2.5. Antibacterial assay
The synthesized compounds were screened for their antibacterial activity against Gram Positive bacteria [Staphylococcus aureus (MTCC-96), Staphylococcus pyogenes (MTCC-442)] and Gram-negative bacteria [Escherichia coli (MTCC-443), Pseudomonas aeruginosa (MTCC-1688)]. The antibacterial activity was carried out by preparing serial dilution of given solution using the Mueller Hinton Broth dilution method (Bec-ton Dickinson, USA) [9,6,7]. The standard strains used for antimicrobial activity were procured from the Institute of Microbial Technology, Chandigarh. The compounds (3a-v) were screened for their antibacterial activity in triplicate sets against these bacteria at different concentrations of 1000, 500, 250, and 200 ig/mL. The drugs which were found to be active in primary screening were further diluted to obtain 100, 50, and 25 ig/mL concentrations. Ten ig/mL suspensions were further inoculated on appropriate media and growth was noted after 24 and 48 h. The lowest concentration, which showed no growth after spot subculture was considered as MIC for each drug. The highest dilution showing at least 99% inhibition was taken as minimum inhibitory concentration (MIC). The test mixture should contain 108 cells/mL. The standard drug used in this study was ampicillin for evaluating antibacterial activity which showed (100, 100, 250, and 100 ig/mL) MIC against E. coli, P. aeruginosa, S. aureus, and S. pyogenes, respectively.
2.6. Antifungal assay
Similarly, various concentrations of compounds (3a-v) were tested for antifungal activity in triplicate sets against Candida albicans, Aspergillus niger and Aspergillus clavatus at various concentrations of 1000, 500, 250, 200, and 100 ig/mL and the obtained results were recorded in the form of primary and secondary screening. The synthesized compounds were prepared as stock solution diluted to 1000 ig/mL concentra-
tion. The compounds which were found to be active in this primary screening were further tested in a second set of dilution against all microorganisms. The lowest concentration, which showed no growth after spot subculture was considered as MIC for each drug. The highest dilution showing at least 99% inhibition was taken as MIC. The test mixture should contain 108 spores/mL MIC. Griseofulvin was used as a standard drug for antifungal activity, which showed (500, 100, and 100 ig/mL) MIC against C. albicans and A. niger, respectively.
3. Results and discussion
3.1. Chemistry
The synthetic route for intermediates and final compounds (3a-v) is shown in the reaction (Scheme 1). The present scaffold (3a) is a part of the synthesis of new chemical entities in the form of antimicrobial agents. The starting material 1,3,5-trichlorotriazine was reacted with isoniazid (i.e., ison-icotinohydrazide) and the intermediate compound N-(4,6-di-chloro-1,3,5-triazine-2-yl)isonicotinohydrazide (1) was obtained in good yield. Compound (1) was stirred for 3 h with 4-amino-N-(pyrimidin-2-yl)benzenesulfonamide in acetone. Then the reaction mixture was treated with dil. HCl to form compound (4-(4-chloro-6-(2-isonicotinoylhydrazinyl)-1,3,5-triazin-2-ylamino)-N-(pyrimidin-2-yl)benzenesulfonamide (2). Compound (2) was then refluxed in 1,4-dioxane with different aromatic amines to furnish final compounds (3a-v). Characterization of the newly synthesized compounds was accomplished by different spectral techniques. IR spectra of the synthesized compound (3a) (molecular formula C25H21NuO3S, m. wt. 555.15 g/mol) showed different types of absorption bands in the spectrum, i.e., N-H stretching in amide link showed strong absorption band at 3448 cm"1 whereas N-H stretching in thi-oamide linkage exhibited vibrational intensity band at 3471 cm"1. In addition, N-H attached with the triazine and aryl group showed absorption at 3388 cm"1, while N-H linked
(3a-v)
Where,R=
-H, -4-Br, -2-Cl, -3-Cl, -4-Cl, -2,5-(Cl)2, -2,6-(Cl)2, -4F, -2-CH3, -4-CH3, -2,4-(CH3)2, -2,6-(CH3)2, -3-CF3, -4-CF3, -4-OCH3, -2,4-(OCH3)2, -4-OC2H5, -2-NO2, -3-NO2, -4-NO2, -4-COOHand -4-COOC2H5
Scheme 1 Synthetic route for final compounds (3a-v).
with the triazine ring and -NHCO appeared at 3412 cm"1. Medium intensity absorption band was exhibited at 3038 cm"1 due to C-H stretching in the pyridine ring and it closely resembled monosubstituted benzene derivatives, while C-H stretching in the aromatic ring appeared at 3020 cm"1. The stretching bands appearing over the range 1640 and 1890 cm"1 showed the presence of C=C and C=N stretching in pyridine, pyrimidine and phenyl rings respectively. Strong intensity absorption peak at 795 cm"1 showed C-H bending vibration in the aromatic ring. Medium intensity band appeared at 895 cm"1 due to the presence of S-N stretching in compound (3a). Strong IR band appearing at 1690 cm"1 showed C=O stretching and the medium intensity absorption peak observed at 1120 cm"1 exhibited the presence of S=O stretching in SO2.
In 1H NMR spectra of the titled compound (3a), five singlets were observed for five protons of-NH i.e., a -NH proton attached with triazine and -NHCO appeared at d = 6.82 ppm, two -NH protons attached with the triazine and aryl group exhibited signal at d = 6.64 ppm, a -NH proton in sulfonamide linkage showed chemical shift at d = 8.13 ppm and -NH attached with the carbonyl group displayed chemical shift at d = 9.78 ppm. Due to the presence of nine aromatic protons (Ar-H) a multiplet was observed at d = 6.93-7.65 ppm. A chemical shift was observed at d = 6.98-8.89 ppm due to the presence of seven multiplet (Ar-H) in the pyridine and pyrim-idine rings of the titled compound. The final compound (3a) possessed three moieties pyridine, pyrimidine and 1,3,5-tri-azine. On the basis of 13C NMR of the final compound (3a), the chemical shift varied from d = 113.0 to 176.5 ppm. Carbon nucleus under the influence of strong electronegative environ-
ment appeared downfield i.e., carbonyl carbon present in amide linkage directly attached to nitrogen exhibited chemical shift value at d = 164.4 ppm. Carbon present in the pyrimidine nucleus directly linked to nitrogen atoms appeared downfield at d = 169.3 ppm. Three carbons of triazine nucleus displayed chemical shift value at d = 164.1, 168.9 and 176.7 ppm corresponding to carbons attached with the phenyl sulfonamide group, aniline and -NH of the hydrazide group, respectively.
3.2. Antimicrobial activity
Many of the newly synthesized compounds were found to exhibit good to excellent antimicrobial activity. The individual minimum inhibitory concentration (MIC, ig/mL) values of tested compounds (3a-v) against the test microbes are listed in Table 1 along with MIC values of reference compounds ampicillin (for bacteria) and griseofulvin (for fungi). The results revealed that majority of synthesized compounds showed varying degrees of inhibition against the tested panel of species. The obtained antimicrobial activity of tested compounds could be correlated to structural variations and modifications of the respective compounds. From antimicrobial activity data (Table 1), it is observed that compounds 3a (-H), 3b (-4-Br), 3c (-2-Cl), 3f (-2,5-(Cl)2), 3i (-2-CH3), 3k (-2,4-(CH3)2), 3n (-4-CF3), 3p (-2,4-(OCH3)2, 3r (-2-NO2) and 3s (-3-NO2) possessed good activity against E. coli at MIC 100 ig/mL. Compounds 3g (-2,6-(Cl)2), 3h (-4-F), 3t (-4-NO2) and 3v (-4-COOC2H5) showed excellent activity against E. coli at MIC 50 ig/mL, respectively. Compounds 3a (-H), 3d (-3-Cl), 3e (-4-F), 31 (-2,6-(CH3)2), 3r (-2-NO2), 3s (-3-NO2) and 3t (-4-NO2) exhibited very good activity against
Table 1 Results of antibacterial and antifungal activities of compounds 3a-v.
Sr. No. -R Minimum inhibitory concentration (MIC) in ig/mL Minimum inhibitory concentration (MIC) in ig/mL
E. coli P. aeruginosa S. aureus S. pyogenes C. albicans A. niger A. clavatus
MTCC 443 MTCC 1688 MTCC 96 MTCC 442 MTCC 227 MTCC 282 MTCC 1323
3a -H 100 100 250 100 1000 >1000 >1000
3b -4-Br 100 200 100 100 500 >1000 >1000
3c -2-Cl 100 250 100 100 500 >1000 >1000
3d -3-Cl 250 100 250 250 250 >1000 >1000
3e -4-Cl 250 100 100 500 1000 1000 1000
3f -2,5-(Cl)2 100 500 500 250 100 250 500
3g -2,6-(Cl)2 50 250 500 250 50 100 500
3h -4-F 50 500 250 1000 50 250 500
3i -2-CH3 100 500 250 500 250 500 1000
3j -4-CH3 250 500 500 250 500 500 1000
3k -2,4-(CH3)2 100 250 250 500 250 500 1000
31 -2,6-(CH3)2 250 100 100 500 1000 >1000 >1000
3m -3-CF3 200 500 250 500 100 >1000 >1000
3n -4-CF3 100 250 100 500 100 1000 1000
3o -4-OCH3 250 500 500 250 500 1000 500
3p -2,4-(OCH3)2 100 500 500 500 1000 200 500
3q -4-OC2H5 200 250 500 500 500 500 1000
3r -2-NO2 100 100 500 500 500 1000 >1000
3s -3-NO2 100 100 250 250 250 500 1000
3t -4-NO2 50 100 50 100 >1000 >1000 >1000
3u -4-COOH 250 500 100 100 500 1000 >1000
3v -4-COOC2H5 50 500 50 500 >1000 >1000 >1000
Ampicillin 100 100 250 100 - - -
Griseofulvin - - - - 500 100 100
P. aeruginosa at MIC 100 ig/mL. Compounds 3b (-4-Br), 3c (-2-Cl), 3e (-4-F), 31 (-2,6-(CH3)2), 3n (-4-CF3) and 3u (-4-COOH) possessed very good activity against S. aureus at MIC 100 ig/mL, while compounds 3t (-4-NO2) and 3v (-4-COOC2H5) flaunted excellent activity against S. aureus at MIC 50 ig/mL. Compounds 3a (-H), 3b (-4-Br), 3C (-2-Cl), 3t (-4-NO2) and 3u (-COOH) exhibited very good activity against S. pyogenes at MIC 100 ig/mL. Among all the synthesized compounds, 3f (-2,5-(Cl)2), 3m (-3-CF3) and 3n (-4-CF3) possessed very good activity against C. albicans at MIC 100 ig/mL. Compounds 3g (-2,6-(Cl)2 and 3h (-4-F) showed excellent activity against C. albicans at MIC 50 ig/mL.
4. Structure-activity relationship (SAR)
The substitution pattern of s-triazine derivatives was carefully selected to confer different electronic environment to molecules. The results from antimicrobial activity suggested that s-triazine derivatives were remarkably influenced by various substituents on the benzene ring. Majority of the synthesized compounds of this series exhibited significant antibacterial and moderate antifungal activity. Compounds 3g, 3h, 3t and 3v exhibited highest inhibition against bacterial strains
5. aureus and E. coli at MIC 50 ig/mL. Furthermore, compounds 3g and 3h showed significant inhibition against fungi strains C. albicans at MIC 50 ig/mL. The data revealed that incorporation of electron withdrawing groups like halogen, nitro and ester on the phenyl ring enhanced antimicrobial activity against selected microorganisms. Thus, our aim was to explore SAR trends and to find out lead molecule for further optimization.
5. Conclusions
A series of twenty-two s-triazine derivatives were synthesized and tested for their in vitro antibacterial activity against four strains of bacteria (Gram-positive, Gram-negative). The preliminary in vitro antibacterial and antifungal screening results of new 1,3,5-triazine-isonicotinohydrazide derivatives exhibited remarkable antimicrobial potency. The newly synthesized compounds differed in their corresponding antimicrobial activity depending on the type of substituents on the phenyl ring. Presence of the electron withdrawing group on the aromatic ring increased the antimicrobial activity compared to compounds with electron donating groups. Based on the results, we can further optimize the above compounds by substituting a series of electron withdrawing groups on the aromatic ring and selectively modifying them. Thus, it may be considered a promising lead for further design and development of new chemical entities. The results described here, demand further investigations in our laboratory using a forward chemical genetic approach for finding lead molecules as antimicrobial agents.
Acknowledgements
Authors are thankful to the University Grants Commission, New Delhi and Department of Science & Technology, New Delhi for financial support under the NON-SAP and DST-FIST programs respectively. The authors are also thankful to the Maharaja Krishnakumarsinhji Bhavnagar University,
Bhavnagar for providing research facilities and XRF, St. Xa-
vier's College, Ahmedabad for providing research facilities.
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