Source of materialTo an ethanol solution (5 ml) of 2-hydroxy-5-bromobenzaldehyde (202.6mg, 1.01 mmol) was added an ethanol solution (5 ml) of 4-aminophenylethanone oxime(151.9 mg, 1.01 mmol). After the solution had been stirred at 327 Kfor 5h,the mixture was filtered. Ther esidue was washed successively with ethanol and hexane, respectively. Theisolated compound was dried under reduced pressure to yield 262.8 mg of yellow solid (yield 78 %, m.p. 493-494 K). The single crystals were obtained by slow evaporation from an acetonitrile solution at room temperature. Elemental analysis -found: C, 54.07 %; H, 3.93 %; N, 8.41 %; Br, 23.98 %; calculated for C 15 H 13 BrN 2 O 2 :C ,5 4.23 %; H, 3.98 %; N, 8.32 %; Br, 23.87 %. DiscussionThe Schiff base compounds and their derivatives have been playing an important role in the development of coordination chemistry[1,2] because they can accommodate one, two or more metal centers and form homo-and heteronuclear metal complexes [3-6], being excellent catalysts for epoxidation, aziridination [7], models of reaction centers of metalloenzymes [8],and nonlinear optical materials [9]. Moreover, in biological and artificial systems, allosteric regulation is effective in controlling molecular functions, such as molecular recognition and biological activity [10].Schiff base compounds are easily prepared from the corresponding carbonyl compounds and amine. Most of Schiff base derivatives are stable in solution and solid state, and are stable to hydrolysis compared with the corresponding imines [11,12]. The title crystal structure is only built up by the C 15 H 13 BrN 2 O 2 molecules, in which all bond lengths are in normalranges. The two benzene rings form ad ihedral angle of 43.11°. Therea re strong intramolecular O-H×××Nh ydrogen bonds between the hydroxyl( O2-H2)g roups and the Schiff base nitrogen (N2) atoms, with d(N2×××O2) =2 .615 Å. The molecules are held together by two pairs of intermolecular O1-H1×××N1 and C5-H5×××O2 hydrogen bonds, forming an infinite 1D supramolecular structure along the c axis [13,14].

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Source of materialTo ah ot ethanol solution (7 ml) of 3-amino-acetophenone (818.2 mg, 6.00 mmol) was added amixture of ahot ethanol solution (10 ml) of hydroxylamine hydrochloride (423.5 mg, 6.00 mmol) and ahot ethanol solution (5 ml) of sodiumacetate. After the solution had been stirred at 55°C for 12 h, the mixture wasconcentrated. Then 30 ml distilled waterwas added. After refrigeratingat-6°Cfor 24 h, thesolutiongavethe yellow solid3-amino-acetophenone oxime, whichwas filtered andwashedsuccessivelywithdistilledwater andethanol/ hexane (1:4). Theisolatedcompoundwas dried under vacuum and gave 551.0 mg of yellow crystalline solid (yield 60.9 %; m. p. 135 -137°C). Thetitle compound 3,3'-[2,2'-(1,2-ethylenedioxy)dibenzylmethylimino]bis(acetophenone oxime) was prepared in as imilar way from 3-amino-acetophenone oximea nd 2,2'-(1,2-ethylenedioxy)dibenzaldehyde. The title compound was dried under vacuum and gave 302.2 mg of light pink solid (yield 76.4 %; m. p. 199 -200°C). Block-shaped colorless single crystals of the title compound suitable for X-ray diffraction studies could be obtained by slow evaporation of an ethanol solution at room temperature. In the crystal structure, the molecules are held together by two pairs of intermolecular C12-H12×××O1 hydrogen bonds between the oxime-oxygen atom and -C12H12 group of the aromatic ring with the distance d(C12-O1) =3 .518(2) Å. In addition, the adjacent rings (C10-C15)a re further linked by aw eak intermolecular p×××p stacking interaction (centroid-centroid distance of 4.106 Å). Thus, every molecule is linked with four other molecules into al ayer supramolecular structure via intermolecular C-H×××Ohydrogen bonds and p×××p stacking interactions.

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