• Facile crystallization of 2-phenyl benzimidazole-5-sulfonic acid: Characterization of lattice water dependent zwitterionic supramolecular forms, with modulation in proton conductivities

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    • Keywords

       

      2-Phenyl benzimidazole-5-sulfonic acid; aqueous crystallization; lattice water dependent supramolecular structures; proton conduction

    • Abstract

       

      A facile aqueous medium crystallization strategy has been found for this water insoluble title compound. Two crystalline forms, differing in the number of lattice water molecules (mono hydrated; form I & di-hydrated; form II), have been obtained, depending on the duration of crystallization. X-ray structural studies reveal that the compound crystallizes in the zwitterionic state in both the forms, due to the protonation of one imidazole nitrogen by –SO3H group, are engaged in hydrogen bonded interactions, involving lattice water molecule(s), and thus the supramolecular arrangements of the forms are influenced by lattice waters. Additional water molecules in the form II make it more hydrophilic, as confirmed using contact angle measurements. Procedures were optimized for better crystalline yields, and the bulk purity were ascertained by TGA, elementaland PXRD analysis. AC impedance measurements prove that both the crystalline forms are indeed proton conducting electrolytes, with magnitudes of 1×10-5 S cm-1 and 5×10-5 S cm-1 for form I & II, respectively under humidified conditions at 25°C. Proton conducting performance of II has been found to be greater than Iand could be correlated with its higher hydrophilicity and enriched hydrogen bonds for Grotthuss mechanism

    • Author Affiliations

       

      D SARAVANABHARATHI1 M OBULICHETTY2 M KUMARAVEL1

      1. Department of Chemistry, PSG College of Technology, Coimbatore 641 004, Tamilnadu, India
      2. Department of Applied Science, PSG College of Technology, Coimbatore 641 004, Tamilnadu, India
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