Kamal Kumar Bisht - Hydrogen bonded binary molecular adducts derived from exobidentate N-donor ligand with dicarboxylic acids: Acidcdots, three dots, centeredimidazole hydrogen-bonding interactions in neutral and ionic heterosynthons

Version 1

      Publication Details (including relevant citation   information):

      Journal of Molecular   Structure
        Volume 985, Issues 2-3, 31 January 2011, Pages 361-370


      doi:10.1016/j.molstruc.2010.11.022

      Abstract:

      Four new binary molecular compounds between a flexible   exobidentate N-heterocycle and a series of dicarboxylic acids   have been synthesized. The N-donor   1,4-bis(imidazol-1-ylmethyl)benzene (bix) was reacted with   flexible and rigid dicarboxylic acids viz.,   cyclohexane-1,4-dicarboxylic acid (H2chdc),   naphthalene-1,4-dicarboxylic acid (H2npdc) and   1H-pyrazole-3,5-dicarboxylic acid (H2pzdc),   generating four binary molecular complexes. X-ray   crystallographic investigation of the molecular adducts revealed   the primary intermolecular interactions carboxylic acidcdots, three dots, centeredamine (via O–Hcdots, three dots, centeredN) as well as carboxylatecdots, three dots, centeredprotonated amine (via   N–H+cdots, three dots, centeredO) within the   binary compounds, generating layered and two-dimensional sheet   type H-bonded networks involving secondary weak interactions   (C–Hcdots, three dots, centeredO) including the solvent of   crystallization. Depending on the differences in   pKa values of the selected base/acid   (ΔpKa), diverse H-bonded supramolecular   assemblies could be premeditated. This study demonstrates the   H-bonding interactions between imidazole/imidazolium cation and   carboxylic acid/carboxylate anion in providing sufficient driving   force for the directed assembly of binary molecular complexes. In   the two-component solid form of hetero synthons involving bix and   dicarboxylic acid, only H2chdc exist as cocrystal with   bix, while all the other three compounds crystallized exclusively   as salt, in agreement with the ΔpKa values   predicted for the formation of salts/cocrystals from the base and   acid used in the synthesis of supramolecular solids.

      Address (URL): http://www.sciencedirect.com/science/article/pii/S0022286010008884