2-Aminopyridinium maleate: A structural study

A new complex of 2-aminopyridine and maleate in 1:1 stoichiometric ratio was obtained. The complex crystallizes in non-centrosymmetric space group Pc. This complex is held by network of hydrogen bonding between the protonated 2-aminopyridinium cation and maleate anion and also by pi–pi stacking. There is no phase transition observed in this complex, which has been verified using DSC and single crystal X-ray measurement studies. A comparison between 2-aminopyridinium maleate and bis(2-aminopyridinium) maleate structure shows that the positive charge resides on the ring nitrogen in the present complex unlike the case in bis(2-aminopyridinium) maleate where the charge is on the amino nitrogen. This complex has higher meting point compared to that of bis(2-aminopyridinium) maleate which is due to the difference in hydrogen bonding pattern between the two complexes.