Controlling function by structure-intermolecular interactions and crystal engineering with N-donor ligands

Doctoral thesis, 2008

In the solid state regime, crystal engineering based on non-covalent synthesis requires an intuition about the intermolecular forces that can dictate the molecular architecture. Hydrogen bonds have become an instrumental tool in the self assembly and supramolecular chemistry. A variety of Schiff’s bases ligands based on azomethine functional units have been synthesized by condensation of the corresponding aldehydes with hydrazine monohydrate and their structures have been revealed by X-ray diffraction. The Br···Br intermolecular interaction in Cambridge Structural Database was studied and a relation between OPL measurements and the positions of bromine atoms in two Schiff’s bases has been drawn. A 2D square grid coordination polymer with a dimension of 16×16Å based on Fe(II) metal centers and bis-pyridinyl methylene hydrazine organic spacer had been assembled and the structure was characterized by X-ray single-crystal diffraction. The square grid with an accessible voids volume of ca. 20% is also hosting [Fe(phen)3]2+ complex as well as free ligand and water solvates which represent a unique example of a coordination polymer host capable of intercalating neutral and cationic guests. The guests assembled inside these grids has independently synthesized and characterized by X-ray single crystal diffraction where σ-π and π-π stacking are the only intermolecular interactions controlling their intercalation behaviour. A different stoichiometry resulted in an 1D coordination chain of Fe(II) centers where the sheets of arrays are supported by hydrogen bonding building up an infinite 2D square grid assembly. Different hydrogen bonding motifs varied with different counter ions in the case of the solely ligands have been emphasized. The crystal packing of 4-bromothiophene porphyrin-Zn(II) was shown to depend on S···S non-covalent interactions and OPL properties of the free bases and Ag(II) porphyrins are discussed. A homochiral double helical packing caused by S···S interactions in [Co(SCN)4]2- with [Ru(phen)3]2+ is manifested.