An Imidazole-Based Bisphenol 2-((2-Hydroxy-3,5-dimethylphenyl)(imidazol-4-yl)methyl)-4,6-dimethylphenol: A Versatile Host for Anions

2012-03-07T00:00:00Z (GMT) by Bhaskar Nath Jubaraj B. Baruah
Imidazole containing bisphenol 2-((2-hydroxy-3,5-dimethylphenyl)­(imidazol-4-yl)­methyl)-4,6-dimethylphenol (<b>1</b>), (abbreviated as Imbp) and its salts with dicarboxylic acids and mineral acids, namely, maleic acid (H2mal), fumeric acid (H2fum), adipic acid (H2adpt), perchloric acid, sulphuric acid (sulfate and bisulphate), tetrafluoroboric acid, and nitric acid are structurally characterized. The crystal packing in the solid state structures of the salts are assisted by electrostatic N<sup>+</sup>–H···O and related weak interactions. The bisphenol <b>1</b> and its methanol solvate have extensive hydrogen bonded structures; in the later case the methanol molecule acts as a bridge through N–H···O and O–H···O interactions and strong π···π interactions between the two imidazole rings. Both the structures have strong intramolecular O–H<sup><b>...</b></sup>O hydrogen bonds among the hydroxyl groups of the Imbp molecule. The mono-deprotonated salts of <b>1</b> with maleic acid, adipic acid, have layered structure, whereas anion encapsulation takes place in the case of dideprotonated salts of fumeric acid. In the case of perchlorate, bisulphate, tetrafluoroborate, and nitrate salts of <b>1</b> the intramolecular O–H···O is retained. The sulfate anchors trimeric self-assemblies formed through R<sub>3</sub><sup>3</sup> (6) type of hydrogen bond in the protonated <b>1</b> and finally they form circular structures with a diameter of 15.193 Å, in which anion is embedded. A bisulphate salt of <b>1</b> is prepared by the reaction of magnesium sulfate with sulphuric acid in methanol in the presence of <b>1</b>; in this structure bisulphate occurs in pairs through intermolecular hydrogen bonds and it assists in the formation of an assembled structure of the protonated bisphenol <b>1</b>.