13.15
Crystal engineering charge transfer complexes of
phenothiazine with various electron acceptor
molecules
Sanaz Khorasani1, Manuel Fernandes2
1
School of Chemistry, 2School of Chemistry, University of the Witwatersrand,
Johannesburg, South Africa
Sanaz Khorasani, Manuel. A. Fernandes
Molecular Sciences Institute, School of Chemistry, University of the
Witwatersrand, Private Bag 3, 2050 Johannesburg. [email protected]
Charge transfer interactions have been described as non-covalent
interactions which occur between two molecules in which one acts as an
electron donor and the other as an electron acceptor. Dispersive and
electrostatic forces also play an important role in the stability of CT
complexes and strongly influence the orientation of acceptor and donor
molecules with respect to each other. Phenothiazine is a flexible
heterocyclic aromatic compound containing electron rich atoms (S and N) and
is consequently a good electron donor molecule. These characteristics
(flexible molecule, an N-H capable of hydrogen bonding, and electron rich
S) make the study of CT complex formation of phenothiazine with various
acceptors interesting as it provides an opportunity to discover how these
attributes affect the formation of CT complexes. Such knowledge would allow
new CT materials to be created by design which is an aim of the crystal
engineering field. In this work the crystal structures of ten new CT
complexes with phenothiazine and various acceptors have been elucidated.
The CT complexes are all composed of stacks of alternating phenothiazine
and acceptor molecules in which molecular overlap, and hence CT and π…π
interactions is maximized. To determine the importance of individual
molecule...molecule interactions in the various structures, lattice energy
calculation methods were carried out and analyzed for trends. Hirshfeld
surfaces represented as regions in which the most significant
intermolecular interactions between donor and acceptor molecules are
highlighted, and 2D fingerprint plots were also drawn to indicate the
significance of various close contacts to the stability of each structure.