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 (Me2SO) 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-RuCl2(Me2SO)(3)(CO) yielded the 1:1 monomer cis,cis,cis-RuCl2(Me2SO)(2)(CO)(MPyP), while reaction with trans,cis,cis-RuCl2(Me2SO)(4) or trans,cis,cis-RuCl2(CO)2(Me2SO)2 (2:1 ratio) gave the 1:2 monomers trans,cis,cis-RuCl2(Me2SO)(2)(MPyP)(2) and tmr cis,cis-RuCl2(CO)(2)(MPyP)(2), respectively. Synthesis of the dimers, (cis-DPyP) [cis,cis,cis-RuCl2(Me2SO)2(CO)](2) and (trans-DPyP) [fis, cis, cis-RuCl2(Me2SO)(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 (5,1 5-bis(4-pyridyl)-10,20-diphenylporphyrin), respectively, with an excess of cis,fac-RuCl2(Me2SO)3(CO), Similarly, treatment of 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TPyP) with an excess of cis,fac-RuCl2(Me2SO)(3)(CO) yielded the symmetric tetramer, (TPyP)[cis,cis,cis-RuCl2(Me2SO)(2)(CO)(4)](4). H-1 NMR spectroscopy proved particularly useful for characterizing the Ru-PyPs. Coordination of Ru to the Lt-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 CHCl3 and very robust in solution, where they remain intact for weeks. TH NMR and electronic absorption spectra provided evidence that only the Ru-Zn PyPs with residual Me2SO units self-assemble spontaneously in solution. The observations are consistent with a self-assembly mode process occuring between the oxygen atom of a Me2SO ligand of one molecule and the zinc of another molecule.