| Abstract
| - New cyclic ruthenium porphyrin tetramers1−3 were synthesized and characterized byseveral spectroscopic methods. Stability of the cyclic tetramericstructure was examined by a variable temperature 1H NMRspectral method and kinetic studies. Interactions betweenconstituent ruthenium porphyrin subunits of the cyclic tetramers wereobserved on the UV−vis spectra and the cyclicvoltammograms.
- Tetrameric ruthenium(II) porphyrin complexes,[Ru(4-PyP3P)(CO)]4, 1,[Ru(4-PyT3P)(CO)]4, 2,and [Ru(4-PyT3P)(Py)]4, 3, (4-PyP3P =5-(4-pyridyl)-10,15,20-triphenylporphyrinato dianion,4-PyT3P = 5-(4-pyridyl)-10,15,20-tritolylporphyrinato dianion), were self-assembled and werecharacterized by 1H NMR, IR, and FABMSspectroscopic methods and elemental analyses. The spectroscopicresults certified that the ruthenium porphyrincomplexes have cyclic tetrameric structures. UV−vis spectra ofthe tetramers showed broad Soret bands ascompared with the respective monomer analogues ofRu(TPP)(CO)(Py) and Ru(TPP)(Py)2.The tetramers 1−3underwent reactions with a large amount of pyridine to givecorresponding monomer complexes. Sharpeningand increasing intensity in the Soret bands, accompanied by theprogress of the monomerization, indicated thepresence of the excitonic interactions between cofacially arrangedruthenium porphyrin subunits in these tetramericmolecules. Electrochemical analyses revealed that the firstring-oxidation processes in 1 and 2, and theoxidationprocess of Ru(II) to Ru(III) in 3 proceedstepwise.
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