Charge transfer properties of two polymorphs of luminescent (2-fluoro-3-pyridyl)(2,2′-biphenyl)borinic 8-oxyquinolinate

Abstract

Single crystal X-ray structures of two polymorphs of (2-fluoro-3-pyridyl)(2,2′-biphenyl)borinic 8-oxyquinolinate: orthorhombic (space group Pca2₁), and triclinic (space group P) have been established and analysed. A fast rate of crystallization results in the orthorhombic polymorph, whereas slow crystallization gives the triclinic polymorph. Physicochemical and theoretical results prove that both polymorphs form similar crystals with very similar geometry of molecules. The main differences between both forms are intermolecular interactions and their impact on the charge transporting properties of both polymorphs which was evaluated through Marcus theory. The orthorhombic polymorph is a slightly more effective electron and hole transporting material than the other polymorph. In both forms the CH⋯π interactions contributed the most to the CT properties. Small changes in the molecular geometry of moieties in both polymorphs affect their molecular energies significantly.