## 2 Experimental
### General Procedure for the Preparation of 2-Aryldiendehydrazineyl-4-phenylthiazole **2a-d**
Reaction mixture was stirred and refluxed for 6 h, cooled to room temperature and poured into water, the precipitate was filtered off and recrystallized from the appropriate solvent. 2-(2-(2,4-dihydroxybenzylidene)hydrazineylidene)-4-oxothiazoltion-5-yl)acetic acid (**5a**) prepared from maleic anhydride and **1a** (0.35 g). Yellow solid. Yield 91% (0.46 g), m.p. 295-297 \({}^{\circ}\)C (EOAc). \({}^{1}\)H NMR (DMSO-d6, \(\delta\), ppm, \({}^{3}\)\({}_{\rm HH}\), Hz): 12.25 bs (1H, COOH), 11.06 s (1H, OH), 10.11 s (1H, OH), 8.47 s (1H, CH=N), 7.34 d (\(J\) = 9.0 Hz, 1H, Har), 6.38 d (\(J\) = 9.0 Hz, 1H, Har), 6.29 s (1H, Har), 4.40 s (1H, CH), 3.06 m (2H, CH\({}_{2}\)COOH). \({}^{13}\)C NMR (DMSO-d6, \(\delta\), ppm): 175.4, 172.2, 161.8, 161.8, 160.6, 158.7, 133.0, 110.8, 108.4, 102.8, 44.4, 36.9. FT-IR, v, cm\({}^{-1}\): 3368 (O-H), 1728 (C=O), 1695 (S-C=O), 1625 (C=N Ar), 1274 (C-H). Calc, %: C, 46.60; H, 3.58; N, 13.59; S, 10.37. Found, %: C, 46.53; H, 3.64; N, 13.54; S, 10.32. 2-(2-(4-hydroxy-3-methoxybenzylidene)hydrazineylidene)-4-oxothiazoltion-5-yl)acetic acid (**5b**) prepared from maleic anhydride and **1b** (0.37 g). Yellow solid. Yield 87% (0.46), m.p. 265-267 \({}^{\circ}\)C (EtOAc). NMR \({}^{1}\)H (DMSO-d6, \(\delta\), ppm, \({}^{3}\)\({}_{\rm HH}\), Hz): 8 12.27 bs (1H, COOH), 9.61 s (1H, OH), 8.24 s (1H, CH=N), 7.30 s (1H, Har), 7.18 d (\(J\) = 9.0 Hz, 1H, Har), 6.83 d (\(J\) = 9.0 Hz, 1H, Har), 4.30 t (\(J\) = 4.0 Hz, 1H, CH), 3.79 s (3H, O-CH\({}_{3}\)) 3.03 s (2H, CH\({}_{2}\)COOH). \({}^{13}\)C NMR (DMSO-d6, \(\delta\), ppm): 8 175.8, 172.2, 162.7, 156.8, 149.8, 148.2, 126.0, 122.6, 115.9, 110.7, 55.9, 43.8, 37.1. FT-IR, v, cm\({}^{-1}\): 3483 (O-H), 1724 (C=O), 1710 (S-C=O), 1602 (C=N), 1579 (C=C Ar), 1274 (C-H). Calc, %: C, 48.29; H, 4.05; N, 13.00; S, 9.92. Found, %: C, 48.37; H, 4.20; N, 13.01; S, 9.85. 2-(2-(3,5-di-_tert_-butyl-4-hydroxybenzylidene)hydrazineylidene)-4-oxothiazoltion-5-yl)acetic acid (**5c**) prepared from maleic anhydride and **1c** (0.50 g). Yellow solid. Yield 93% (0.61 g), m.p. 208-209 \({}^{\circ}\)C (EtOH:H\({}_{2}\)O 1.5:1). NMR \({}^{1}\)H (DMSO-d6, \(\delta\), ppm, \({}^{3}\)\({}_{\rm HH}\), Hz): 12.12 bs (1H, COOH) \(\delta\) 9.80 s (1H, NH), 8.27 s (1H, CH=N), 7.53 s (2H, Har), 7.44 s (1H, OH), 4.31 m (, 1H, CH), 3.03 m (2H, CH\({}_{2}\)COOH), 1.39 s (18H, t-Bu). \({}^{13}\)C NMR (DMSO-d6, \(\delta\), ppm): 192.5, 175.8, 172.1, 157.0, 139.4, 127.3, 126.0, 125.0, 43.8, 37.0, 34.9, 30.5. FT-IR, v, cm\({}^{-1}\): 3628 (O-H), 1721 (C=O), 1667 (S-C=O), 1634 (C=N), 1601 (C=C Ar). Calc, %: C, 59.24; H, 6.71; N, 10.36; S, 7.91. Found, %: C, 59.22; H, 6.87; N, 10.41; S, 7.87. 2-(2-(4,6-di-_tert_-butyl-2,3-dihydroxybenzylidene)hydrazineylidene)-4-oxothiazoltion-5-yl)acetic acid (**5d**) prepared from maleic anhydride and **1d** (0.53 g). Yellow solid. Yield 82% (0.56 g), m.p. 302-304 \({}^{\circ}\)C (EtOH:H\({}_{2}\)O 1.0:1). NMR \({}^{1}\)H (DMSO-d6, \(\delta\), ppm, \({}^{3}\)\({}_{\rm HH}\), Hz): 12.36 s (1H, COOH), 9.17 s 1H (1H, CH=N), 8.54 s (1H, OH), 6.78 s (1H, Har), 4.52 m (1H, CH), 3.11 m (2H, CH\({}_{2}\)COOH), 1.36 s (9H, t-Bu), 1.33 s (9H, t-Bu). \({}^{13}\)C NMR (DMSO-d6, \(\delta\), ppm): 175.4, 172.4, 163.5, 159.2, 149.4, 142.7, 139.5, 137.4, 115.0, 112.7, 44.9, 37.0, 35.5, 35.4, 33.1, 29.5. FT-IR, v, cm\({}^{-1}\): 1677 (C=O), 1599 (C=N), 1415 (C-H), 1243 (C-C). Calc, %: C, 56.99; H, 6.46; N, 9.97; S, 7.61. Found, %: C, 57.03; H, 6.55; N, 9.88; S, 7.68.