Ordered Supramolecular Porphyrin Arrays from a Building Block Approach Utilizing Pyridylporphyrins and Peripheral Ruthenium Complexes and Identification of a New Type of Mixed-Metal Building Block

Supramolecular ruthenium complexes (Ru−PyPs) with 4-pyridyl/phenyl porphyrins (PyPs) have been designed and characterized spectroscopically. Ruthenium−dimethyl sulfoxide (Me 2 SO) complexes and their carbonyl derivatives were used as precursors to synthesize adducts with Ru:PyP ratios of 1:1 and 1:2 (monomers), 2:1 (dimers), and 4:1 (tetramers). For example, treatment of mono-(pyridyl)porphyrin MPyP (5-(4-pyridyl)-10,15,20-triphenylporphyrin) with cis,fac -RuCl 2 (Me 2 SO) 3 (CO) yielded the 1:1 monomer cis,cis,cis -RuCl 2 (Me 2 S O) 2 (CO)(MPyP), while reaction with trans -RuCl 2 (Me 2 S O) 4 or trans,cis,cis -RuCl 2 (CO) 2 (Me 2 S O ) 2 (2:1 ratio) gave the 1:2 monomers trans,cis,cis -RuCl 2 (Me 2 S O) 2 (MPyP) 2 and trans,cis,cis -RuCl 2 (CO) 2 (MPyP) 2, respectively. Synthesis of the dimers, ( cis -DPyP)[ cis,cis,cis -RuCl 2 (Me 2 S O) 2 (CO)] 2 and ( trans -DPyP)[ cis,cis,cis -RuCl 2 (Me 2 S O) 2 (CO)] 2, was accomplished by reaction of the bis-(pyridyl)porphyrins, cis -DPyP (5,10-bis(4-pyridyl)-15,20-diphenylporphyrin) and trans -DPyP (5,15-bis(4-pyridyl)-10,20-diphenylporphyrin), respectively, with an excess of cis,fac -RuCl 2 (Me 2 SO) 3 (CO). Similarly, treatment of 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TPyP) with an excess of cis,fac -RuCl 2 (Me 2 SO) 3 (CO) yielded the symmetric tetramer, (TPyP)[ cis,cis,cis -RuCl 2 (Me 2 S O) 2 (CO)] 4 . 1 H NMR spectroscopy proved particularly useful for characterizing the Ru−PyPs. Coordination of Ru to the 4-pyridyl groups affected mainly the resonances of the pyridyl ring(s) of the PyPs, causing downfield shifts (H2,6 signals from 0.3 to 0.9 ppm; H3,5 from 0.03 to 0.18 ppm). The pyrrole proton resonances were particularly informative about the geometry of the porphyrin. Treatment of selected Ru−PyP adducts with an excess of zinc acetate produced the corresponding zinc compounds, Ru−Zn·PyPs, in good yield. Most of the Ru−PyPs and Ru−Zn·PyPs are quite soluble in organic solvents like CHCl 3 and very robust in solution, where they remain intact for weeks. 1 H NMR and electronic absorption spectra provided evidence that only the Ru−Zn·PyPs with residual Me 2 S O units self-assemble spontaneously in solution. The observations are consistent with a self-assembly mode process occuring between the oxygen atom of a Me 2 S O ligand of one molecule and the zinc of another molecule.