## 2 Materials and Methods
### Synthesis of Chalcone Derivatives  
To a mixture of 2-hydroxyacetophenone (1 Eq) and the appropriate benzaldehyde (**1a-1k**) (1 Eq) in ethanol/water (8:2) (10 mL), was added dropwise aqueous NaOH 50% (4 mL) at 0 \({}^{\circ}\)C. The reaction was stirred at room temperature till completion of reaction (monitored by TLC). The reaction solvent was completely evaporated to redissolve the crude in water and neutralize with a 10% HCl solution. The precipitate was filtered, washed with cold water, dried, and purified by column chromatography, employing eluent mixtures of n-hexane/ethyl acetate and dichloromethane/ethyl acetate in different proportions; some products were purified by recrystallization with a methanol/H\({}_{2}\)O (1:2) mixture. All of the structures were confirmed by mass and NMR spectra as discussed below. (_E_)-1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-one (**2a**): White solid (yield 46%). C\({}_{15}\)H\({}_{12}\)O\({}_{2}\), Mp = 58-60 \({}^{\circ}\)C. IR (ATR diamond, cm\({}^{-1}\)) = 3358 (O-H), 3031 (C-H), 1683 (C=O) cm\({}^{-1}\). \({}^{1}\)H NMR (400 MHz, CDCl\({}_{3}\)) \(\delta\): 12.79 (s, 1H, OH), 7.93 (d, \(J\) = 15.3 Hz, 1H, H7), 7.92 (d, \(J\) = 8.1 Hz, 1H, H2), 7.67 (d, \(J\) = 15.2 Hz, 1H, H8), 7.50-7.37 (m, 6H, H2, H3, H4, H5, H6, H4\({}^{\prime}\)), 7.06 (d, \(J\) = 8.6 Hz, 1H, H5\({}^{\prime}\)), 6.95 (d, \(J\) = 7.3 Hz, 1H, H3\({}^{\prime}\)). \({}^{13}\)C NMR (100 MHz, CDCl\({}_{3}\)) \(\delta\): 193.8 (s, C9), 163.7 (s, C6\({}^{\prime}\)), 145.5 (d, C7), 136.5 (d, C4\({}^{\prime}\)), 134.7 (s, C1), 131.0 (d, C2\({}^{\prime}\)), 129.7 (d, C3, C5), 129.1 (d, C2, C6), 128.7 (d, C4), 126.2 (d, C3\({}^{\prime}\)), 120.3 (s, C1\({}^{\prime}\)), 118.9 (d, C8), 118.7 (d, C5\({}^{\prime}\)). GC-MS m/z (rel. int.) = 224.15 [M]\({}^{+}\) (11), 223.16 (12), 147.08 (17), 120.06 (49), 104.11 (54), 92.05 (100), 77.08 (54). (_E_)-1,3-bis(2-hydroxyphenyl)prop-2-en-1-one (**2b**): Yellow crystals (yield 41%). C\({}_{15}\)H\({}_{12}\)O\({}_{3}\). Mp = 137 \({}^{\circ}\)C. IR (ATR diamond, cm\({}^{-1}\)) = 3267 (O-H), 3033 (C-H), 1683 (C=O), 1150 (C-O) cm\({}^{-1}\). \({}^{1}\)H NMR (400 MHz, CDCl\({}_{3}\)) \(\delta\): 12.63 (s, 1H, OH), 10.36 (s, 1H, OH), 8.21 (d, \(J\) = 15.3 Hz, 1H, H7), 8.21 (dd, \(J_{1}\) = 7.9, \(J_{2}\) = 1.4 Hz, 1H, H2\({}^{\prime}\)), 8.00 (d, \(J\) = 15.6 Hz, 1H, H8), 7.92 (dd, \(J_{1}\) = 7.8, \(J_{2}\) = 1.0 Hz, 1H, H6), 7.58 (dddd, \(J_{1}\) = 8.2, \(J_{2}\) = 8.6, \(J_{3}\) = 1.4 Hz, 1H, H4\({}^{\prime}\)), 7.33 (dddd, \(J_{1}\) = 8.2, \(J_{2}\) = 8.4, \(J_{3}\) = 1.3 Hz, 1H, H4), 7.03 (ddd, \(J_{1}\) = 7.1 Hz, 1H, H5\({}^{\prime}\)), 6.99 (dd, \(J_{1}\) = 8.3 Hz, 1H, H5\({}^{\prime}\)), 6.92 (dd, \(J_{1}\) = 7.5 Hz, 1H, H3\({}^{\prime}\)), 6.02 (ddd, \(J_{1}\) = 8.3 Hz, 1H, H3). \({}^{13}\)C NMR (100 MHz, CDCl\({}_{3}\)) \(\delta\): 193.8 (s, C9), 157.4 (s, C2), 140.3 (d, C7), 136.0 (d, C4\({}^{\prime}\)), 132.4 (d, C2\({}^{\prime}\)), 130.5 (d, C4), 128.9 (d, C6), 121.1 (s, C1), 120.7 (d, C3\({}^{\prime}\)), 120.2 (s, C1\({}^{\prime}\)), 119.4 (d, C8), 119.0 (d, C5), 117.7 (d, C5\({}^{\prime}\)), 116.2 (d, C3). GC-MS m/z (rel. int.) = 240.18 [M]\({}^{+}\) (1), 222.18 (8), 147.11 (2), 121.09 (28), 92.1 (100), 63.07 (73), 39.06 (56). (_E_)-3-(4-hydroxy-3-methoxyphenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (**2c**): Orange crystals (yield 42%). C\({}_{16}\)H\({}_{14}\)O\({}_{4}\). Mp = 120 \({}^{\circ}\)C. IR (ATR diamond, cm\({}^{-1}\)) = 3377 (O-H), 3009 (C-H), 2965 (C-H), 1682 (C=O) cm\({}^{-1}\).