Template-assisted ligand encapsulation; the impact of an unusual coordination geometry on a supramolecular pyridylphosphine-Zn(II)porphyrin assembly

The tris(para-pyridyl)phosphine template (1) has been used in conjunction with a series of meso-substituted Zn(II)-tetraphenylporphyrins complexes (2-10) to create supramolecular encapsulated ligand assemblies via Zn-N-pyr interactions. The structural features of supramolecular ligand 1(.)[2](3) have been investigated in detail using X-ray crystallography, NMR specroscopy, and UV-vis spectroscopy. The pyridylphosphine-porphyrin stoichiometry determined in solution (1:3) differs markedly with that observed in the solid state (2:5, for assembly [1](2)(.)[2](5)). The difference originates from an unusual coordination behavior of one of the Zn centers, which is octahedrally surrounded through double axial coordination by the pyridyl groups of the two different molecules of 1.