Surov, Artem Olegovich2; Solanko, Katarzyna A.3; Bond, Andrew5; Bauer-Brandl, Annette2; Perlovich, German L4
1 Pharmaceutical Technology and Engineering, Department of Pharmacy, Faculty of Health and Medical Sciences, Københavns Universitet2 Institut for Fysik, Kemi og Farmaci3 Syddansk Universitet4 unknown5 Pharmaceutical Technology and Engineering, Department of Pharmacy, Faculty of Health and Medical Sciences, Københavns Universitet
The calcium-channel blocking agent felodipine (Fel) forms co-crystals with 4,4′-bipyridine (BP) with 1:1 and 2:1 molar ratios. The [Fel + BP] (1:1) co-crystal exists in two polymorphic forms. Differential scanning calorimetry and solution calorimetry show that form I of the [Fel + BP] (1:1) co-crystal is the most thermodynamically stable phase. The difference in the crystal lattice energies between different polymorphs of the co-crystal is found to be comparable with that between the polymorphic forms of pure felodipine. The enthalpies of formation of the co-crystals are small, which indicates that the packing energy gain originates from only weak van der Waals interactions. Analysis of Hirshfeld surfaces of the felodipine molecule shows a similar distribution of intermolecular contacts in the co-crystals and pure felodipine.
Crystengcomm, 2014, Vol 16, Issue 29, p. 6603-6611